muscle cells stimulated: Topics by Science.gov

Sample records for muscle cells stimulated

Catechins activate muscle stem cells by Myf5 induction and stimulate muscle regeneration.

PubMed

Kim, A Rum; Kim, Kyung Min; Byun, Mi Ran; Hwang, Jun-Ha; Park, Jung Il; Oh, Ho Taek; Kim, Hyo Kyeong; Jeong, Mi Gyeong; Hwang, Eun Sook; Hong, Jeong-Ho

2017-07-22

Muscle weakness is one of the most common symptoms in aged individuals and increases risk of mortality. Thus, maintenance of muscle mass is important for inhibiting aging. In this study, we investigated the effect of catechins, polyphenol compounds in green tea, on muscle regeneration. We found that (-)-epicatechin gallate (ECG) and (-)-epigallocatechin-3-gallate (EGCG) activate satellite cells by induction of Myf5 transcription factors. For satellite cell activation, Akt kinase was significantly induced after ECG treatment and ECG-induced satellite cell activation was blocked in the presence of Akt inhibitor. ECG also promotes myogenic differentiation through the induction of myogenic markers, including Myogenin and Muscle creatine kinase (MCK), in satellite and C2C12 myoblast cells. Finally, EGCG administration to mice significantly increased muscle fiber size for regeneration. Taken together, the results suggest that catechins stimulate muscle stem cell activation and differentiation for muscle regeneration. Copyright © 2017 Elsevier Inc. All rights reserved.
Electrical stimulation as a biomimicry tool for regulating muscle cell behavior

PubMed Central

Ahadian, Samad; Ostrovidov, Serge; Hosseini, Vahid; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

2013-01-01

There is a growing need to understand muscle cell behaviors and to engineer muscle tissues to replace defective tissues in the body. Despite a long history of the clinical use of electric fields for muscle tissues in vivo, electrical stimulation (ES) has recently gained significant attention as a powerful tool for regulating muscle cell behaviors in vitro. ES aims to mimic the electrical environment of electroactive muscle cells (e.g., cardiac or skeletal muscle cells) by helping to regulate cell-cell and cell-extracellular matrix (ECM) interactions. As a result, it can be used to enhance the alignment and differentiation of skeletal or cardiac muscle cells and to aid in engineering of functional muscle tissues. Additionally, ES can be used to control and monitor force generation and electrophysiological activity of muscle tissues for bio-actuation and drug-screening applications in a simple, high-throughput, and reproducible manner. In this review paper, we briefly describe the importance of ES in regulating muscle cell behaviors in vitro, as well as the major challenges and prospective potential associated with ES in the context of muscle tissue engineering. PMID:23823664
Electrical stimulation as a biomimicry tool for regulating muscle cell behavior.

PubMed

Ahadian, Samad; Ostrovidov, Serge; Hosseini, Vahid; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

2013-01-01

There is a growing need to understand muscle cell behaviors and to engineer muscle tissues to replace defective tissues in the body. Despite a long history of the clinical use of electric fields for muscle tissues in vivo, electrical stimulation (ES) has recently gained significant attention as a powerful tool for regulating muscle cell behaviors in vitro. ES aims to mimic the electrical environment of electroactive muscle cells (e.g., cardiac or skeletal muscle cells) by helping to regulate cell-cell and cell-extracellular matrix (ECM) interactions. As a result, it can be used to enhance the alignment and differentiation of skeletal or cardiac muscle cells and to aid in engineering of functional muscle tissues. Additionally, ES can be used to control and monitor force generation and electrophysiological activity of muscle tissues for bio-actuation and drug-screening applications in a simple, high-throughput, and reproducible manner. In this review paper, we briefly describe the importance of ES in regulating muscle cell behaviors in vitro, as well as the major challenges and prospective potential associated with ES in the context of muscle tissue engineering.
Stimulation of aortic smooth muscle cell mitogenesis by serotonin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nemecek, G.M.; Coughlin, S.R.; Handley, D.A.

1986-02-01

Bovine aortic smooth muscle cells in vitro responded to 1 nM to 10 ..mu..M serotonin with increased incorporation of (/sup 3/H)thymidine into DNA. The mitogenic effect of serotonin was half-maximal at 80 nM and maximal above 1 ..mu..M. At a concentration of 1 ..mu..M, serotonin stimulated smooth muscle cell mitogenesis to the same extent as human platelet-derived growth factor (PDGF) at 12 ng/ml. Tryptamine was approx. = 1/10th as potent as serotonin as a mitogen for smooth muscle cells. Other indoles that are structurally related to serotonin (D- and L-tryptophan, 5-hydroxy-L-tryptophan, N-acetyl-5-hydroxytryptamine, melatonin, 5-hydroxyindoleacetic acid, and 5-hydroxytryptophol) and quipazine weremore » inactive. The stimulatory effect of serotonin on smooth muscle cell DNA synthesis required prolonged (20-24 hr) exposure to the agonist and was attenuated in the presence of serotonin D receptor antagonists. When smooth muscle cells were incubated with submaximal concentrations of serotonin and PDGF, synergistic rather than additive mitogenic responses were observed. These data indicate that serotonin has a significant mitogenic effect on smooth muscle cells in vitro, which appears to be mediated by specific plasma membrane receptors.« less
Electrical Stimulation Decreases Coupling Efficiency Between Beta-Adrenergic Receptors and Cyclic AMP Production in Cultured Muscle Cells

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.

1999-01-01

Electrical stimulation of skeletal muscle cells in culture is an effective way to simulate the effects of muscle contraction and its effects on gene expression in muscle cells. Expression of the beta-adrenergic receptor and its coupling to cyclic AMP synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this project was to determine if electrical stimulation altered the beta-adrenergic response in muscle cells. Chicken skeletal muscle cells that had been grown for seven days in culture were subjected to electrical stimulation for an additional two days at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. At the end of this two-day stimulation period, beta-adrenergic receptor population was measured by the binding of tritium-labeled CGP-12177 to muscle cells, and coupling to cAMP synthesis was measured by Radioimmunoassay (RIA) after treating the cells for 10 min with the potent (beta)AR agonist, isoproterenol. The number of beta adrenergic receptors and the basal levels of intracellular cyclic AMP were not affected by electrical stimulation. However, the ability of these cells to synthesize cyclic AMP was reduced by approximately 50%. Thus, an enhanced level of contraction reduces the coupling efficiency of beta-adrenergic receptors for cyclic AMP production.
Effect of electrical stimulation on beta-adrenergic receptor population and cyclic amp production in chicken and rat skeletal muscle cell cultures

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Strietzel, C. J.

2000-01-01

Expression of the beta-adrenergic receptor (betaAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the betaAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the betaAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the betaAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.
Effect of Electrical Stimulation on Beta-Adrenergic Receptor Population and Cyclic AMP Production in Chicken and Rat Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Strietzel, Catherine J.

2000-01-01

Expression of the beta-adrenergic receptor (PAR) and its coupling to Adenosine 3'5' Cyclic Monophosphate (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the PAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture, were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the PAR population was not significantly affected by electrical stimulation; however, the ability, of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the PAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.
Effect of Electrical Stimulation on Beta-Adrenergic Receptor Population and Coupling Efficiency in Chicken and Rat Skeleton Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Strietzel, Catherine J.

1999-01-01

Expression of the beta-adrenergic receptor (bAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the bAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for seven days in culture were subjected to electrical stimulation for an additional two days at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the bAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. Thus, in chicken muscle cells an enhanced level of contraction reduced the coupling efficiency of bAR for cyclic AMP production by approximately 55% compared to controls. In contrast, the bAR population in rat muscle cells was increased by approximately 25% by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was also increased by almost two-fold. Thus, in rat muscle cells an enhanced level of contraction increased the coupling efficiency of bAR for cyclic AMP production by approximately 50% compared to controls. The basal levels of intracellular cyclic AMP in both rat muscle cells and chicken muscle cells were not affected by electrical stimulation.
Contractile Skeletal Muscle Cells Cultured with a Conducting Soft Wire for Effective, Selective Stimulation.

PubMed

Nagamine, Kuniaki; Sato, Hirotaka; Kai, Hiroyuki; Kaji, Hirokazu; Kanzaki, Makoto; Nishizawa, Matsuhiko

2018-02-02

Contractile skeletal muscle cells were cultured so as to wrap around an electrode wire to enable their selective stimulation even when they were co-cultured with other electrically-excitable cells. Since the electrode wire was composed of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and polyurethane (PU), which is soft and highly capacitive (~10 mF cm -2 ), non-faradaic electrical stimulation with charge/discharge currents could be applied to the surrounding cells without causing significant damage even for longer periods (more than a week). The advantage of this new culture system was demonstrated in the study of chemotactic interaction of monocytes and skeletal muscle cells via myokines.
Human skeletal muscle fibroblasts stimulate in vitro myogenesis and in vivo muscle regeneration.

PubMed

Mackey, Abigail L; Magnan, Mélanie; Chazaud, Bénédicte; Kjaer, Michael

2017-08-01

Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. The extent of cross-talk between fibroblasts, as the source of matrix protein, and satellite cells in humans is unknown. We studied this in human muscle biopsies and cell-culture studies. We observed a strong stimulation of myogenesis by human fibroblasts in cell culture. In biopsies collected 30 days after a muscle injury protocol, fibroblast number increased to four times control levels, where fibroblasts were found to be preferentially located immediately surrounding regenerating muscle fibres. These novel findings indicate an important role for fibroblasts in supporting the regeneration of muscle fibres, potentially through direct stimulation of satellite cell differentiation and fusion, and contribute to understanding of cell-cell cross-talk during physiological and pathological muscle remodelling. Accumulation of skeletal muscle extracellular matrix is an unfavourable characteristic of many muscle diseases, muscle injury and sarcopenia. In addition to the indispensable role satellite cells play in muscle regeneration, there is emerging evidence in rodents for a regulatory influence on fibroblast activity. However, the influence of fibroblasts on satellite cells and muscle regeneration in humans is unknown. The purpose of this study was to investigate this in vitro and during in vivo regeneration in humans. Following a muscle injury protocol in young healthy men (n = 7), the number of fibroblasts (TCF7L2+), satellite cells (Pax7+), differentiating myogenic cells (myogenin+) and regenerating fibres (neonatal/embryonic myosin+) was determined from biopsy cross-sections. Fibroblasts and myogenic precursor cells (MPCs) were also isolated from human skeletal muscle (n = 4) and co-cultured using different cell ratios, with the two cell populations either in direct contact with each other or separated by a permeable
Cytokine Response of Cultured Skeletal Muscle Cells Stimulated with Proinflammatory Factors Depends on Differentiation Stage

PubMed Central

Podbregar, Matej; Lainscak, Mitja; Prelovsek, Oja; Mars, Tomaz

2013-01-01

Myoblast proliferation and myotube formation are critical early events in skeletal muscle regeneration. The attending inflammation and cytokine signaling are involved in regulation of skeletal muscle cell proliferation and differentiation. Secretion of muscle-derived cytokines upon exposure to inflammatory factors may depend on the differentiation stage of regenerating muscle cells. Cultured human myoblasts and myotubes were exposed to 24-hour treatment with tumor necrosis factor (TNF)-α or lipopolysaccharide (LPS). Secretion of interleukin 6 (IL-6), a major muscle-derived cytokine, and interleukin 1 (IL-1), an important regulator of inflammatory response, was measured 24 hours after termination of TNF-α or LPS treatment. Myoblasts pretreated with TNF-α or LPS displayed robustly increased IL-6 secretion during the 24-hour period after removal of treatments, while IL-1 secretion remained unaltered. IL-6 secretion was also increased in myotubes, but the response was less pronounced compared with myoblasts. In contrast to myoblasts, IL-1 secretion was markedly stimulated in LPS-pretreated myotubes. We demonstrate that preceding exposure to inflammatory factors stimulates a prolonged upregulation of muscle-derived IL-6 and/or IL-1 in cultured skeletal muscle cells. Our findings also indicate that cytokine response to inflammatory factors in regenerating skeletal muscle partially depends on the differentiation stage of myogenic cells. PMID:23509435
The pathway to muscle fibrosis depends on myostatin stimulating the differentiation of fibro/adipogenic progenitor cells in chronic kidney disease

PubMed Central

Dong, Jiangling; Dong, Yanjun; Chen, Zihong; Mitch, William E.; Zhang, Liping

2016-01-01

Fibrosis in skeletal muscle develops after injury or in response to chronic kidney disease (CKD) but the origin of cells becoming fibrous tissue and the initiating and sustaining mechanisms causing muscle fibrosis are unclear. We have identified muscle fibro/adipogenic progenitor cells (FAPs) that potentially differentiate into adipose tissues or fibrosis. We also demonstrated that CKD stimulates myostatin production in muscle. Therefore, we tested whether CKD induces myostatin which stimulates fibrotic differentiation of FAPs leading to fibrosis in skeletal muscles. We isolated FAPs from mouse muscles and found that myostatin stimulates their proliferation and conversion into fibrocytes. In vivo, FAPs isolated from EGFP-transgenic mice (FAPs-EGFP) were transplanted into muscles of mice with CKD or into mouse muscles that were treated with myostatin. CKD or myostatin stimulated FAPs-EGFP proliferation in muscle and increased α-smooth muscle actin expression in FAP-EGFP cells. When myostatin was inhibited with a neutralizing peptibody (a chimeric peptide-Fc fusion protein), the FAP proliferation and muscle fibrosis induced by CKD were both suppressed. Knocking down Smad3 in cultured FAPs interrupted their conversion into fibrocytes indicating that myostatin directly converts FAPs into fibrocytes. Thus, counteracting myostatin may be a strategy for preventing the development of fibrosis in skeletal muscles of patients with CKD. PMID:27653838
The pathway to muscle fibrosis depends on myostatin stimulating the differentiation of fibro/adipogenic progenitor cells in chronic kidney disease.

PubMed

Dong, Jiangling; Dong, Yanjun; Chen, Zihong; Mitch, William E; Zhang, Liping

2017-01-01

Fibrosis in skeletal muscle develops after injury or in response to chronic kidney disease (CKD), but the origin of cells becoming fibrous tissue and the initiating and sustaining mechanisms causing muscle fibrosis are unclear. We identified muscle fibro/adipogenic progenitor cells (FAPs) that potentially differentiate into adipose tissues or fibrosis. We also demonstrated that CKD stimulates myostatin production in muscle. Therefore, we tested whether CKD induces myostatin, which stimulates fibrotic differentiation of FAPs leading to fibrosis in skeletal muscles. We isolated FAPs from mouse muscles and found that myostatin stimulates their proliferation and conversion into fibrocytes. In vivo, FAPs isolated from EGFP-transgenic mice (FAPs-EGFP) were transplanted into muscles of mice with CKD or into mouse muscles that were treated with myostatin. CKD or myostatin stimulated FAPs-EGFP proliferation in muscle and increased α-smooth muscle actin expression in FAP-EGFP cells. When myostatin was inhibited with a neutralizing peptibody (a chimeric peptide-Fc fusion protein), the FAP proliferation and muscle fibrosis induced by CKD were both suppressed. Knocking down Smad3 in cultured FAPs interrupted their conversion into fibrocytes, indicating that myostatin directly converts FAPs into fibrocytes. Thus, counteracting myostatin may be a strategy for preventing the development of fibrosis in skeletal muscles of patients with CKD. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.
Electrolysis stimulates creatine transport and transporter cell surface expression in incubated mouse skeletal muscle: potential role of ROS.

PubMed

Derave, Wim; Straumann, Nadine; Olek, Robert A; Hespel, Peter

2006-12-01

Electrical field stimulation of isolated, incubated rodent skeletal muscles is a frequently used model to study the effects of contractions on muscle metabolism. In this study, this model was used to investigate the effects of electrically stimulated contractions on creatine transport. Soleus and extensor digitorum longus muscles of male NMRI mice (35-50 g) were incubated in an oxygenated Krebs buffer between platinum electrodes. Muscles were exposed to [(14)C]creatine for 30 min after either 12 min of repeated tetanic isometric contractions (contractions) or electrical stimulation of only the buffer before incubation of the muscle (electrolysis). Electrolysis was also investigated in the presence of the reactive oxygen species (ROS) scavenging enzymes superoxide dismutase (SOD) and catalase. Both contractions and (to a lesser degree) electrolysis stimulated creatine transport severalfold over basal. The amount of electrolysis, but not contractile activity, induced (determined) creatine transport stimulation. Incubation with SOD and catalase at 100 and 200 U/ml decreased electrolysis-induced creatine transport by approximately 50 and approximately 100%, respectively. The electrolysis effects on creatine uptake were completely inhibited by beta-guanidino propionic acid, a competitive inhibitor of (creatine for) the creatine transporter (CRT), and were accompanied by increased cell surface expression of CRT. Muscle glucose transport was not affected by electrolysis. The present results indicate that electrical field stimulation of incubated mouse muscles, independently of contractions per se, stimulates creatine transport by a mechanism that depends on electrolysis-induced formation of ROS in the incubation buffer. The increased creatine uptake is paralleled by an increased cell surface expression of the creatine transporter.
Inflammatory cells in rat skeletal muscle are elevated after electrically stimulated contractions.

PubMed

McLoughlin, Thomas J; Mylona, Eleni; Hornberger, Troy A; Esser, Karyn A; Pizza, Francis X

2003-03-01

We determined the effect of muscle contractions resulting from high-frequency electrical stimulation (HFES) on inflammatory cells in rat tibialis anterior (TA), plantaris (Pln), and soleus (Sol) muscles at 6, 24, and 72 h post-HFES. A minimum of four and a maximum of seven rats were analyzed at each time point. HFES, applied to the sciatic nerve, caused the Sol and Pln to contract concentrically and the TA to contract eccentrically. Neutrophils were higher (P < 0.05) at 6 and 24 h after HFES in the Sol, Pln, and TA muscles relative to control muscles. ED1(+) macrophages in the Pln were elevated at 6 and 24 h after HFES and were also elevated in the Sol and TA after HFES relative to controls. ED2(+) macrophages in the Sol and TA were elevated at 24 and 72 h after HFES, respectively, and were also elevated in the Pln after HFES relative to controls. In contrast to the TA muscles, the Pln and Sol muscles showed no gross histological abnormalities. Collectively, these data indicate that both eccentric and concentric contractions can increase inflammatory cells in muscle, regardless of whether overt histological signs of injury are apparent.
Electrically Stimulated Adipose Stem Cells on Polypyrrole-Coated Scaffolds for Smooth Muscle Tissue Engineering.

PubMed

Björninen, Miina; Gilmore, Kerry; Pelto, Jani; Seppänen-Kaijansinkko, Riitta; Kellomäki, Minna; Miettinen, Susanna; Wallace, Gordon; Grijpma, Dirk; Haimi, Suvi

2017-04-01

We investigated the use of polypyrrole (PPy)-coated polymer scaffolds and electrical stimulation (ES) to differentiate adipose stem cells (ASCs) towards smooth muscle cells (SMCs). Since tissue engineering lacks robust and reusable 3D ES devices we developed a device that can deliver ES in a reliable, repeatable, and cost-efficient way in a 3D environment. Long pulse (1 ms) or short pulse (0.25 ms) biphasic electric current at a frequency of 10 Hz was applied to ASCs to study the effects of ES on ASC viability and differentiation towards SMCs on the PPy-coated scaffolds. PPy-coated scaffolds promoted proliferation and induced stronger calponin, myosin heavy chain (MHC) and smooth muscle actin (SMA) expression in ASCs compared to uncoated scaffolds. ES with 1 ms pulse width increased the number of viable cells by day 7 compared to controls and remained at similar levels to controls by day 14, whereas shorter pulses significantly decreased viability compared to the other groups. Both ES protocols supported smooth muscle expression markers. Our results indicate that electrical stimulation on PPy-coated scaffolds applied through the novel 3D ES device is a valid approach for vascular smooth muscle tissue engineering.
Acute molecular response of mouse hindlimb muscles to chronic stimulation.

PubMed

LaFramboise, W A; Jayaraman, R C; Bombach, K L; Ankrapp, D P; Krill-Burger, J M; Sciulli, C M; Petrosko, P; Wiseman, R W

2009-09-01

Stimulation of the mouse hindlimb via the sciatic nerve was performed for a 4-h period to investigate acute muscle gene activation in a model of muscle phenotype conversion. Initial force production (1.6 +/- 0.1 g/g body wt) declined 45% within 10 min and was maintained for the remainder of the experiment. Force returned to initial levels upon study completion. An immediate-early growth response was present in the extensor digitorum longus (EDL) muscle (FOS, JUN, activating transcription factor 3, and musculoaponeurotic fibrosarcoma oncogene) with a similar but attenuated pattern in the soleus muscle. Transcript profiles showed decreased fast fiber-specific mRNA (myosin heavy chains 2A and 2B, fast troponins T(3) and I, alpha-tropomyosin, muscle creatine kinase, and parvalbumin) and increased slow transcripts (myosin heavy chain-1beta/slow, troponin C slow, and tropomyosin 3y) in the EDL versus soleus muscles. Histological analysis of the EDL revealed glycogen depletion without inflammatory cell infiltration in stimulated versus control muscles, whereas ultrastructural analysis showed no evidence of myofiber damage after stimulation. Multiple fiber type-specific transcription factors (tea domain family member 1, nuclear factor of activated T cells 1, peroxisome proliferator-activated receptor-gamma coactivator-1alpha and -beta, circadian locomotor output cycles kaput, and hypoxia-inducible factor-1alpha) increased in the EDL along with transcription factors characteristic of embryogenesis (Kruppel-like factor 4; SRY box containing 17; transcription factor 15; PBX/knotted 1 homeobox 1; and embryonic lethal, abnormal vision). No established in vivo satellite cell markers or genes activated in our parallel experiments of satellite cell proliferation in vitro (cyclins A(2), B(2), C, and E(1) and MyoD) were differentially increased in the stimulated muscles. These results indicated that the molecular onset of fast to slow phenotype conversion occurred in the EDL within
Mifepristone enhances insulin-stimulated Akt phosphorylation and glucose uptake in skeletal muscle cells.

PubMed

Bernal-Sore, Izela; Navarro-Marquez, Mario; Osorio-Fuentealba, César; Díaz-Castro, Francisco; Del Campo, Andrea; Donoso-Barraza, Camila; Porras, Omar; Lavandero, Sergio; Troncoso, Rodrigo

2018-02-05

Mifepristone is the only FDA-approved drug for glycaemia control in patients with Cushing's syndrome and type 2 diabetes. Mifepristone also has beneficial effects in animal models of diabetes and patients with antipsychotic treatment-induced obesity. However, the mechanisms through which Mifepristone produces its beneficial effects are not completely elucidated. To determine the effects of mifepristone on insulin-stimulated glucose uptake on a model of L6 rat-derived skeletal muscle cells. Mifepristone enhanced insulin-dependent glucose uptake, GLUT4 translocation to the plasma membrane and Akt Ser 473 phosphorylation in L6 myotubes. In addition, mifepristone reduced oxygen consumption and ATP levels and increased AMPK Thr 172 phosphorylation. The knockdown of AMPK prevented the effects of mifepristone on insulin response. Mifepristone enhanced insulin-stimulated glucose uptake through a mechanism that involves a decrease in mitochondrial function and AMPK activation in skeletal muscle cells. Copyright © 2017 Elsevier B.V. All rights reserved.
Mast cell migration to Th2 stimulated airway smooth muscle from asthmatics

PubMed Central

Sutcliffe, A; Kaur, D; Page, S; Woodman, L; Armour, C L; Baraket, M; Bradding, P; Hughes, J M; Brightling, C E

2006-01-01

Background Mast cell microlocalisation within the airway smooth muscle (ASM) bundle is an important determinant of the asthmatic phenotype. We hypothesised that mast cells migrate towards ASM in response to ASM derived chemokines. Methods Primary ASM cultures from subjects with and without asthma were stimulated with interleukin (IL)‐1β, IL‐4, and IL‐13 alone and in combination. Mast cell chemotaxis towards these ASM supernatants was investigated, and the chemotaxins mediating migration by using specific blocking antibodies for stem cell factor (SCF) and the chemokine receptors CCR3, CXCR1, 3 and 4 as well as the Gi inhibitor pertussis toxin and the tyrosine kinase inhibitor genistein were defined. The concentrations of CCL11, CXCL8, CXCL10, TGF‐β, and SCF in the supernatants were measured and the effect of non‐asthmatic ASM supernatants on the mast cell chemotactic activity of asthmatic ASM was examined. Results Human lung mast cells and HMC‐1 cells migrated towards Th2 stimulated ASM from asthmatics but not non‐asthmatics. Mast cell migration was mediated through the combined activation of CCR3 and CXCR1. CCL11 and CXCL8 expression by ASM increased markedly after stimulation, but was similar in those with and without asthma. ASM supernatants from non‐asthmatics inhibited mast cell migration towards the asthmatic ASM supernatant. Conclusion Th2 stimulated ASM from asthmatics is chemotactic for mast cells. Non‐asthmatic ASM releases a mediator or mediators that inhibit mast cell migration towards stimulated asthmatic ASM. Specifically targeting mast cell migration into the ASM bundle may provide a novel treatment for asthma. PMID:16601090
Mechanical stimulation of skeletal muscle cells mitigates glucocorticoid-induced decreases in prostaglandin production and prostaglandin synthase activity

NASA Technical Reports Server (NTRS)

Chromiak, J. A.; Vandenburgh, H. H.

1994-01-01

The glucocorticoid dexamethasone (Dex) induces a decline in protein synthesis and protein content in tissue cultured, avian skeletal muscle cells, and this atrophy is attenuated by repetitive mechanical stretch. Since the prostaglandin synthesis inhibitor indomethacin mitigated this stretch attenuation of muscle atrophy, the effects of Dex and mechanical stretch on prostaglandin production and prostaglandin H synthase (PGHS) activity were examined. In static cultures, 10(-8) M Dex reduced PGF2 alpha production 55-65% and PGE2 production 84-90% after 24-72 h of incubation. Repetitive 10% stretch-relaxations of non-Dex-treated cultures increased PGF2 alpha efflux 41% at 24 h and 276% at 72 h, and increased PGE2 production 51% at 24 h and 236% at 72 h. Mechanical stimulation of Dex-treated cultures increased PGF2 alpha production 162% after 24 h, returning PGF2 alpha efflux to the level of non-Dex-treated cultures. At 72 h, stretch increased PGF2 alpha efflux 65% in Dex-treated cultures. Mechanical stimulation of Dex-treated cultures also increased PGE2 production at 24 h, but not at 72 h. Dex reduced PGHS activity in the muscle cultures by 70% after 8-24 h of incubation, and mechanical stimulation of the Dex-treated cultures increased PGHS activity by 98% after 24 h. Repetitive mechanical stimulation attenuates the catabolic effects of Dex on cultured skeletal muscle cells in part by mitigating the Dex-induced declines in PGHS activity and prostaglandin production.

21 CFR 890.5860 - Ultrasound and muscle stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep heat for selected medical conditions—(1) Identification. An ultrasound and muscle stimulator for use in...
21 CFR 890.5860 - Ultrasound and muscle stimulator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep heat for selected medical conditions—(1) Identification. An ultrasound and muscle stimulator for use in...
21 CFR 890.5860 - Ultrasound and muscle stimulator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep heat for selected medical conditions—(1) Identification. An ultrasound and muscle stimulator for use in...
21 CFR 890.5860 - Ultrasound and muscle stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep heat for selected medical conditions—(1) Identification. An ultrasound and muscle stimulator for use in...
21 CFR 890.5860 - Ultrasound and muscle stimulator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ultrasound and muscle stimulator. 890.5860 Section... Ultrasound and muscle stimulator. (a) Ultrasound and muscle stimulator for use in applying therapeutic deep heat for selected medical conditions—(1) Identification. An ultrasound and muscle stimulator for use in...
Mechanical stimulation improves tissue-engineered human skeletal muscle

NASA Technical Reports Server (NTRS)

Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

2002-01-01

Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.
Mesenchymal stem cells and myoblast differentiation under HGF and IGF-1 stimulation for 3D skeletal muscle tissue engineering.

PubMed

Witt, R; Weigand, A; Boos, A M; Cai, A; Dippold, D; Boccaccini, A R; Schubert, D W; Hardt, M; Lange, C; Arkudas, A; Horch, R E; Beier, J P

2017-02-28

Volumetric muscle loss caused by trauma or after tumour surgery exceeds the natural regeneration capacity of skeletal muscle. Hence, the future goal of tissue engineering (TE) is the replacement and repair of lost muscle tissue by newly generating skeletal muscle combining different cell sources, such as myoblasts and mesenchymal stem cells (MSCs), within a three-dimensional matrix. Latest research showed that seeding skeletal muscle cells on aligned constructs enhance the formation of myotubes as well as cell alignment and may provide a further step towards the clinical application of engineered skeletal muscle. In this study the myogenic differentiation potential of MSCs upon co-cultivation with myoblasts and under stimulation with hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) was evaluated. We further analysed the behaviour of MSC-myoblast co-cultures in different 3D matrices. Primary rat myoblasts and rat MSCs were mono- and co-cultivated for 2, 7 or 14 days. The effect of different concentrations of HGF and IGF-1 alone, as well as in combination, on myogenic differentiation was analysed using microscopy, multicolour flow cytometry and real-time PCR. Furthermore, the influence of different three-dimensional culture models, such as fibrin, fibrin-collagen-I gels and parallel aligned electrospun poly-ε-caprolacton collagen-I nanofibers, on myogenic differentiation was analysed. MSCs could be successfully differentiated into the myogenic lineage both in mono- and in co-cultures independent of HGF and IGF-1 stimulation by expressing desmin, myocyte enhancer factor 2, myosin heavy chain 2 and alpha-sarcomeric actinin. An increased expression of different myogenic key markers could be observed under HGF and IGF-1 stimulation. Even though, stimulation with HGF/IGF-1 does not seem essential for sufficient myogenic differentiation. Three-dimensional cultivation in fibrin-collagen-I gels induced higher levels of myogenic differentiation
Surface-distributed low-frequency asynchronous stimulation delays fatigue of stimulated muscles.

PubMed

Maneski, Lana Z Popović; Malešević, Nebojša M; Savić, Andrej M; Keller, Thierry; Popović, Dejan B

2013-12-01

One important reason why functional electrical stimulation (FES) has not gained widespread clinical use is the limitation imposed by rapid muscle fatigue due to non-physiological activation of the stimulated muscles. We aimed to show that asynchronous low-pulse-rate (LPR) electrical stimulation applied by multipad surface electrodes greatly postpones the occurrence of muscle fatigue compared with conventional stimulation (high pulse rate, HPR). We compared the produced force vs. time of the forearm muscles responsible for finger flexion in 2 stimulation protocols, LPR (fL = 10 Hz) and HPR (fH = 40 Hz). Surface-distributed low-frequency asynchronous stimulation (sDLFAS) doubles the time interval before the onset of fatigue (104 ± 80%) compared with conventional synchronous stimulation. Combining the performance of multipad electrodes (increased selectivity and facilitated positioning) with sDLFAS (decreased fatigue) can improve many FES applications in both the lower and upper extremities. Copyright © 2013 Wiley Periodicals, Inc.
Stimulation of the BKCa channel in cultured smooth muscle cells of human trachea by magnolol

PubMed Central

Wu, S; Chen, C; Li, H; Lo, Y; Chen, S; Chiang, H

2002-01-01

Background: Magnolol, a compound isolated from the cortex of Magnolia officinalis, has been found to possess anti-allergic and anti-asthmatic activity. Methods: The effect of magnolol on ionic currents was studied in cultured smooth muscle cells of human trachea with the aid of the patch clamp technique. Results: In whole cell current recordings magnolol reversibly increased the amplitude of K+ outward currents. The increase in outward current caused by magnolol was sensitive to inhibition by iberiotoxin (200 nM) or paxilline (1 µM) but not by glibenclamide (10 µM). In inside out patches, magnolol added to the bath did not modify single channel conductance but effectively enhanced the activity of large conductance Ca2+ activated K+ (BKCa) channels. Magnolol increased the probability of these channel openings in a concentration dependent manner with an EC50 value of 1.5 µM. The magnolol stimulated increase in the probability of channels opening was independent of internal Ca2+. The application of magnolol also shifted the activation curve of BKCa channels to less positive membrane potentials. The change in the kinetic behaviour of BKCa channels caused by magnolol in these cells is the result of an increase in dissociation and gating constants. Conclusions: These results provide evidence that, in addition to the presence of antioxidative activity, magnolol is potent in stimulating BKCa channel activity in tracheal smooth muscle cells. The direct stimulation of these BKCa channels by magnolol may contribute to the underlying mechanism by which it acts as an anti-asthmatic compound. PMID:11809993
Neuromuscular Electrical Stimulation for Skeletal Muscle Function

PubMed Central

Doucet, Barbara M.; Lam, Amy; Griffin, Lisa

2012-01-01

Lack of neural innervation due to neurological damage renders muscle unable to produce force. Use of electrical stimulation is a medium in which investigators have tried to find a way to restore movement and the ability to perform activities of daily living. Different methods of applying electrical current to modify neuromuscular activity are electrical stimulation (ES), neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and functional electrical stimulation (FES). This review covers the aspects of electrical stimulation used for rehabilitation and functional purposes. Discussed are the various parameters of electrical stimulation, including frequency, pulse width/duration, duty cycle, intensity/amplitude, ramp time, pulse pattern, program duration, program frequency, and muscle group activated, and how they affect fatigue in the stimulated muscle. PMID:22737049
The Effect of Electrical Stimulation in Improving Muscle Tone (Clinical)

NASA Astrophysics Data System (ADS)

Azman, M. F.; Azman, A. W.

2017-11-01

Electrical stimulation (ES) and also known as neuromuscular electrical stimulation (NMES) and transcutaneous electrical stimulation (TES) involves the use of electrical current to stimulate the nerves or nerve endings that innervate muscle beneath the skin. Electrical stimulation may be applied superficially on the skin (transcutaneously) or directly into a muscle or muscles (intramuscularly) for the primary purpose of enhancing muscle function. The basic theoretical premise is that if the peripheral nerve can be stimulated, the resulting excitation impulse will be transmitted along the nerve to the motor endplates in the muscle, producing a muscle contraction. In this work, the effect of mere electrical stimulation to the muscle bulk and strength are tested. This paper explains how electrical stimulation can affect the muscle bulk, muscle size, muscle tone, muscle atrophy and muscle strength. The experiment and data collection are performed on 5 subjects and the results obtained are analyzed. This research aims to understand the full potential of electrical stimulation and identifying its possible benefits or disadvantages to the muscle properties. The results indicated that electrical stimulation alone able to improve muscle properties but with certain limits and precautions which might be useful in rehabilitation programme.
Interdigitated array of Pt electrodes for electrical stimulation and engineering of aligned muscle tissue.

PubMed

Ahadian, Samad; Ramón-Azcón, Javier; Ostrovidov, Serge; Camci-Unal, Gulden; Hosseini, Vahid; Kaji, Hirokazu; Ino, Kosuke; Shiku, Hitoshi; Khademhosseini, Ali; Matsue, Tomokazu

2012-09-21

Engineered skeletal muscle tissues could be useful for applications in tissue engineering, drug screening, and bio-robotics. It is well-known that skeletal muscle cells are able to differentiate under electrical stimulation (ES), with an increase in myosin production, along with the formation of myofibers and contractile proteins. In this study, we describe the use of an interdigitated array of electrodes as a novel platform to electrically stimulate engineered muscle tissues. The resulting muscle myofibers were analyzed and quantified in terms of their myotube characteristics and gene expression. The engineered muscle tissues stimulated through the interdigitated array of electrodes demonstrated superior performance and maturation compared to the corresponding tissues stimulated through a conventional setup (i.e., through Pt wires in close proximity to the muscle tissue). In particular, the ES of muscle tissue (voltage 6 V, frequency 1 Hz and duration 10 ms for 1 day) through the interdigitated array of electrodes resulted in a higher degree of C2C12 myotube alignment (∼80%) as compared to ES using Pt wires (∼65%). In addition, higher amounts of C2C12 myotube coverage area, myotube length, muscle transcription factors and protein biomarkers were found for myotubes stimulated through the interdigitated array of electrodes compared to those stimulated using the Pt wires. Due to the wide array of potential applications of ES for two- and three-dimensional (2D and 3D) engineered tissues, the suggested platform could be employed for a variety of cell and tissue structures to more efficiently investigate their response to electrical fields.
The Effect of Paired Muscle Stimulation on Preparation for Movement.

PubMed

Brownjohn, Philip W; Blakemore, Rebekah L; Fox, Jonathan A; Shemmell, Jonathan

2018-06-07

Paired muscle stimulation is used clinically to facilitate the performance of motor tasks for individuals with motor dysfunction. However, the optimal temporal relationship between stimuli for enhancing movement remains unknown. We hypothesized that synchronous, muscle stimulation would increase the extent to which stimulated muscles are concurrently prepared for movement. We validated a measure of muscle-specific changes in corticomotor excitability prior to movement. We used this measure to examine the preparation of the first dorsal interosseous (FDI), abductor digiti minimi (ADM), abductor pollicis brevis (APB) muscles prior to voluntary muscle contractions before and after paired muscle stimulation at four interstimulus intervals (0, 5, 10, and 75 ms). Paired muscle stimulation increased premovement excitability in the stimulated FDI, but not in the ADM muscle. Interstimulus interval was not a significant factor in determining efficacy of the protocol. Paired stimulation, therefore, did not result in a functional association being formed between the stimulated muscles. Somatosensory potentials evoked by the muscle stimuli were small compared to those commonly elicited by stimulation of peripheral nerves, suggesting that the lack of functional association formation between muscles may be due to the small magnitude of afferent volleys from the stimulated muscles, particularly the ADM, reaching the cortex.
Chronic low-frequency stimulation transforms cat masticatory muscle fibers into jaw-slow fibers.

PubMed

Kang, Lucia H D; Hoh, Joseph F Y

2011-09-01

Cat masticatory muscle during regeneration expresses masticatory-specific myofibrillar proteins upon innervation by a fast muscle nerve but acquires the jaw-slow phenotype when innervated by a slow muscle nerve. Here, we test the hypothesis that chronic low-frequency stimulation simulating impulses from the slow nerve can result in masticatory-to-slow fiber-type transformation. In six cats, the temporalis muscle was continuously stimulated directly at 10 Hz for up to 12 weeks using a stimulator affixed to the skull. Stimulated muscles were analyzed by immunohistochemistry using, among others, monoclonal antibodies against masticatory-specific myosin heavy chain (MyHC), myosin binding protein-C, and tropomyosins. Under the electrodes, stimulation induced muscle regeneration, which generated slow fibers. Deep to the electrodes, at two to three weeks, two distinct populations of masticatory fibers began to express slow MyHC: 1) evenly distributed fibers that completely suppressed masticatory-specific proteins but transiently co-expressed fetal MyHCs, and 2) incompletely transformed fibers that express slow and masticatory but not fetal MyHCs. SDS-PAGE confirmed de novo expression of slow MyHC and β-tropomyosin in the stimulated muscles. We conclude that chronic low-frequency stimulation induces masticatory-to-slow fiber-type conversion. The two populations of transforming masticatory fibers may differ in their mode of activation or lineage of their myogenic cells.
Stimulation of Synthesis and Release of Brain-Derived Neurotropic Factor (BDNF) from Intestinal Smooth Muscle Cells by Substance P and Pituitary Adenylate Cyclase-Activating Peptide (PACAP)

PubMed Central

Al-Qudah, M.; Alkahtani, R.; Akbarali, H.I.; Murthy, K.S.; Grider, J.R.

2015-01-01

Background Brain-derived neurotrophic factor (BDNF) is a neurotrophin present in the intestine where it participates in survival and growth of enteric neurons, augmentation of enteric circuits, and stimulation of intestinal peristalsis and propulsion. Previous studies largely focused on the role of neural and mucosal BDNF. The expression and release of BDNF from intestinal smooth muscle and the interaction with enteric neuropeptides has not been studied in gut. Methods The expression and secretion of BDNF from smooth muscle cultured from rabbit longitudinal intestinal muscle in response to substance P and pituitary adenylate cyclase activating peptide (PACAP) was measured by western blot and ELISA. BDNF mRNA was measured by rt-PCR. Key Results The expression of BNDF protein and mRNA was greater in smooth muscle cells from the longitudinal muscle than from circular muscle layer. PACAP and substance P increased the expression of BDNF protein and mRNA in cultured longitudinal smooth muscle cells. PACAP and substance P also stimulated the secretion of BDNF from cultured longitudinal smooth muscle cells. Chelation of intracellular calcium with BAPTA prevented substance P-induced increase in BDNF mRNA and protein expression as well as substance P-induced secretion of BDNF. Conclusions & Inferences Neuropeptides known to be present in enteric neurons innervating the longitudinal layer increase the expression of BDNF mRNA and protein in smooth muscle cells and stimulate the release of BDNF. Considering the ability of BDNF to enhance smooth muscle contraction, this autocrine loop may partially explain the characteristic hypercontractility of longitudinal muscle in inflammatory bowel disease. PMID:26088546
Deciphering the role of a coleopteran steering muscle via free flight stimulation.

PubMed

Sato, Hirotaka; Vo Doan, Tat Thang; Kolev, Svetoslav; Huynh, Ngoc Anh; Zhang, Chao; Massey, Travis L; van Kleef, Joshua; Ikeda, Kazuo; Abbeel, Pieter; Maharbiz, Michel M

2015-03-16

Testing hypotheses of neuromuscular function during locomotion ideally requires the ability to record cellular responses and to stimulate the cells being investigated to observe downstream behaviors [1]. The inability to stimulate in free flight has been a long-standing hurdle for insect flight studies. The miniaturization of computation and communication technologies has delivered ultra-small, radio-enabled neuromuscular recorders and stimulators for untethered insects [2-8]. Published stimulation targets include the areas in brain potentially responsible for pattern generation in locomotion [5], the nerve chord for abdominal flexion [9], antennal muscles [2, 10], and the flight muscles (or their excitatory junctions) [7, 11-13]. However, neither fine nor graded control of turning has been demonstrated in free flight, and responses to the stimulation vary widely [2, 5, 7, 9]. Technological limitations have precluded hypotheses of function validation requiring exogenous stimulation during flight. We investigated the role of a muscle involved in wing articulation during flight in a coleopteran. We set out to identify muscles whose stimulation produced a graded turning in free flight, a feat that would enable fine steering control not previously demonstrated. We anticipated that gradation might arise either as a function of the phase of muscle firing relative to the wing stroke (as in the classic fly b1 muscle [14, 15] or the dorsal longitudinal and ventral muscles of moth [16]), or due to regulated tonic control, in which phase-independent summation of twitch responses produces varying amounts of force delivered to the wing linkages [15, 17, 18]. Copyright © 2015 Elsevier Ltd. All rights reserved.
PEDF-derived peptide promotes skeletal muscle regeneration through its mitogenic effect on muscle progenitor cells.

PubMed

Ho, Tsung-Chuan; Chiang, Yi-Pin; Chuang, Chih-Kuang; Chen, Show-Li; Hsieh, Jui-Wen; Lan, Yu-Wen; Tsao, Yeou-Ping

2015-08-01

In response injury, intrinsic repair mechanisms are activated in skeletal muscle to replace the damaged muscle fibers with new muscle fibers. The regeneration process starts with the proliferation of satellite cells to give rise to myoblasts, which subsequently differentiate terminally into myofibers. Here, we investigated the promotion effect of pigment epithelial-derived factor (PEDF) on muscle regeneration. We report that PEDF and a synthetic PEDF-derived short peptide (PSP; residues Ser(93)-Leu(112)) induce satellite cell proliferation in vitro and promote muscle regeneration in vivo. Extensively, soleus muscle necrosis was induced in rats by bupivacaine, and an injectable alginate gel was used to release the PSP in the injured muscle. PSP delivery was found to stimulate satellite cell proliferation in damaged muscle and enhance the growth of regenerating myofibers, with complete regeneration of normal muscle mass by 2 wk. In cell culture, PEDF/PSP stimulated C2C12 myoblast proliferation, together with a rise in cyclin D1 expression. PEDF induced the phosphorylation of ERK1/2, Akt, and STAT3 in C2C12 myoblasts. Blocking the activity of ERK, Akt, or STAT3 with pharmacological inhibitors attenuated the effects of PEDF/PSP on the induction of C2C12 cell proliferation and cyclin D1 expression. Moreover, 5-bromo-2'-deoxyuridine pulse-labeling demonstrated that PEDF/PSP stimulated primary rat satellite cell proliferation in myofibers in vitro. In summary, we report for the first time that PSP is capable of promoting the regeneration of skeletal muscle. The signaling mechanism involves the ERK, AKT, and STAT3 pathways. These results show the potential utility of this PEDF peptide for muscle regeneration. Copyright © 2015 the American Physiological Society.
Beneficial effect of mechanical stimulation on the regenerative potential of muscle-derived stem cells is lost by inhibiting vascular endothelial growth factor.

PubMed

Beckman, Sarah A; Chen, William C W; Tang, Ying; Proto, Jonathan D; Mlakar, Logan; Wang, Bing; Huard, Johnny

2013-08-01

We previously reported that mechanical stimulation increased the effectiveness of muscle-derived stem cells (MDSCs) for tissue repair. The objective of this study was to determine the importance of vascular endothelial growth factor (VEGF) on mechanically stimulated MDSCs in a murine model of muscle regeneration. MDSCs were transduced with retroviral vectors encoding the LacZ reporter gene (lacZ-MDSCs), the soluble VEGF receptor Flt1 (sFlt1-MDSCs), or a short hairpin RNA (shRNA) targeting messenger RNA of VEGF (shRNA_VEGF MDSCs). Cells were subjected to 24 hours of mechanical cyclic strain and immediately transplanted into the gastrocnemius muscles of mdx/scid mice. Two weeks after transplantation, angiogenesis, fibrosis, and regeneration were analyzed. There was an increase in angiogenesis in the muscles transplanted with mechanically stimulated lacZ-MDSCs compared with nonstimulated lacZ-MDSCs, sFlt1-MDSCs, and shRNA _VEGF MDSCs. Dystrophin-positive myofiber regeneration was significantly lower in the shRNA_VEGF-MDSC group compared with the lacZ-MDSC and sFlt1-MDSC groups. In vitro proliferation of MDSCs was not decreased by inhibition of VEGF; however, differentiation into myotubes and adhesion to collagen were significantly lower in the shRNA_VEGF-MDSC group compared with the lacZ-MDSC and sFlt1-MDSC groups. The beneficial effects of mechanical stimulation on MDSC-mediated muscle repair are lost by inhibiting VEGF.
Beneficial Effect of Mechanical Stimulation on the Regenerative Potential of Muscle-Derived Stem Cells Is Lost by Inhibiting Vascular Endothelial Growth Factor

PubMed Central

Beckman, Sarah A.; Chen, William C.W.; Tang, Ying; Proto, Jonathan D.; Mlakar, Logan; Wang, Bing; Huard, Johnny

2016-01-01

Objective We previously reported that mechanical stimulation increased the effectiveness of muscle-derived stem cells (MDSCs) for tissue repair. The objective of this study was to determine the importance of vascular endothelial growth factor (VEGF) on mechanically stimulated MDSCs in a murine model of muscle regeneration. Approach and Results MDSCs were transduced with retroviral vectors encoding the LacZ reporter gene (lacZ-MDSCs), the soluble VEGF receptor Flt1 (sFlt1-MDSCs), or a short hairpin RNA (shRNA) targeting messenger RNA of VEGF (shRNA_VEGF MDSCs). Cells were subjected to 24 hours of mechanical cyclic strain and immediately transplanted into the gastrocnemius muscles of mdx/scid mice. Two weeks after transplantation, angiogenesis, fibrosis, and regeneration were analyzed. There was an increase in angiogenesis in the muscles transplanted with mechanically stimulated lacZMDSCs compared with nonstimulated lacZ-MDSCs, sFlt1-MDSCs, and shRNA _VEGF MDSCs. Dystrophin-positive myofiber regeneration was significantly lower in the shRNA_VEGF-MDSC group compared with the lacZ-MDSC and sFlt1-MDSC groups. In vitro proliferation of MDSCs was not decreased by inhibition of VEGF; however, differentiation into myotubes and adhesion to collagen were significantly lower in the shRNA_VEGF-MDSC group compared with the lacZ-MDSC and sFlt1-MDSC groups. Conclusions The beneficial effects of mechanical stimulation on MDSC-mediated muscle repair are lost by inhibiting VEGF. PMID:23723372
An Electrical Muscle Stimulation Suit for Increasing Blood Pressure

DTIC Science & Technology

2008-09-01

an exploratory way in about 100 trials. Maximal indi- vidual stimulation intensity was selected to give a solid, tetanic muscle contraction without...therapy and in muscle strength training in athletes. However, if the electrical stimulation is too intense, the result will be muscle contraction pain...Each subject was instructed to have the investigator lower the intensity or stop the stimulation if muscle contraction pain was experienced

Muscle Stimulation Technology

NASA Technical Reports Server (NTRS)

1997-01-01

Under a Goddard Space Flight Center contract, Electrologic of America was able to refine the process of densely packing circuitry on personal computer boards, providing significant contributions to the closed-loop systems for the Remote Manipulator System Simulator. The microcircuitry work was then applied to the StimMaster FES Ergometer, an exercise device used to stimulate muscles suffering from paralysis. The electrical stimulation equipment was developed exclusively for V-Care Health Systems, Inc. Product still commercially available as of March 2002.
Cultured smooth muscle cells of the human vesical sphincter are more sensitive to histamine than are detrusor smooth muscle cells.

PubMed

Neuhaus, Jochen; Oberbach, Andreas; Schwalenberg, Thilo; Stolzenburg, Jens-Uwe

2006-05-01

To compare histamine receptor expression in cultured smooth muscle cells from the human detrusor and internal sphincter using receptor-specific agonists. Smooth muscle cells from the bladder dome and internal sphincter were cultured from 5 male patients undergoing cystectomy for bladder cancer therapy. Calcium transients in cells stimulated with carbachol, histamine, histamine receptor 1 (H1R)-specific heptanecarboxamide (HTMT), dimaprit (H2R), and R-(alpha)-methylhistamine (H3R) were measured by calcium imaging. Histamine receptor proteins were detected by Western blot analysis and immunocytochemistry. H1R, H2R, and H3R expression was found in tissue and cultured cells. Carbachol stimulated equal numbers of detrusor and sphincter cells (60% and 51%, respectively). Histamine stimulated significantly more cells than carbachol in detrusor (100%) and sphincter (99.34%) cells. Calcium responses to carbachol in detrusor and sphincter cells were comparable and did not differ from those to histamine in detrusor cells. However, histamine and specific agonists stimulated more sphincter cells than did carbachol (P <0.001), and the calcium increase was greater in sphincter cells than in detrusor cells. Single cell analysis revealed comparable H2R responses in detrusor and sphincter cells, but H1R and H3R-mediated calcium reactions were significantly greater in sphincter cells. Histamine very effectively induces calcium release in smooth muscle cells. In sphincter cells, histamine is even more effective than carbachol regarding the number of reacting cells and the intracellular calcium increase. Some of the variability in the outcome of antihistaminic interstitial cystitis therapies might be caused by the ineffectiveness of the chosen antihistaminic or unintentional weakening of sphincteric function.
Muscle fiber type specific induction of slow myosin heavy chain 2 gene expression by electrical stimulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crew, Jennifer R.; Falzari, Kanakeshwari; DiMario, Joseph X., E-mail: joseph.dimario@rosalindfranklin.edu

Vertebrate skeletal muscle fiber types are defined by a broad array of differentially expressed contractile and metabolic protein genes. The mechanisms that establish and maintain these different fiber types vary throughout development and with changing functional demand. Chicken skeletal muscle fibers can be generally categorized as fast and fast/slow based on expression of the slow myosin heavy chain 2 (MyHC2) gene in fast/slow muscle fibers. To investigate the cellular and molecular mechanisms that control fiber type formation in secondary or fetal muscle fibers, myoblasts from the fast pectoralis major (PM) and fast/slow medial adductor (MA) muscles were isolated, allowed tomore » differentiate in vitro, and electrically stimulated. MA muscle fibers were induced to express the slow MyHC2 gene by electrical stimulation, whereas PM muscle fibers did not express the slow MyHC2 gene under identical stimulation conditions. However, PM muscle fibers did express the slow MyHC2 gene when electrical stimulation was combined with inhibition of inositol triphosphate receptor (IP3R) activity. Electrical stimulation was sufficient to increase nuclear localization of expressed nuclear-factor-of-activated-T-cells (NFAT), NFAT-mediated transcription, and slow MyHC2 promoter activity in MA muscle fibers. In contrast, both electrical stimulation and inhibitors of IP3R activity were required for these effects in PM muscle fibers. Electrical stimulation also increased levels of peroxisome-proliferator-activated receptor-{gamma} co-activator-1 (PGC-1{alpha}) protein in PM and MA muscle fibers. These results indicate that MA muscle fibers can be induced by electrical stimulation to express the slow MyHC2 gene and that fast PM muscle fibers are refractory to stimulation-induced slow MyHC2 gene expression due to fast PM muscle fiber specific cellular mechanisms involving IP3R activity.« less
Muscle velocity recovery cycles: effects of repetitive stimulation on two muscles.

PubMed

Boërio, Delphine; Z'Graggen, Werner J; Tan, S Veronica; Guetg, Andri; Ackermann, Karin; Bostock, Hugh

2012-07-01

We sought to characterize the excitability properties of tibialis anterior (TA) and brachioradialis (BR) muscles at rest and during electrically induced muscle activation in normal subjects. Two centers recruited 10 subjects each. Multi-fiber velocity recovery cycles (VRCs) were recorded from TA (both centers) and BR (one center). VRCs were assessed at rest and during repetitive stimulation (intermittent 20 Hz for 6 min). Changes in latency and peak amplitude of the muscle action potential induced by a frequency ramp to 30 Hz were also characterized. Excitability properties recorded from TA were very similar between centers. Repetitive stimulation generated marked excitability changes, which were similar between TA and BR. Standardized tests of muscle VRCs and responses to repetitive stimulation can provide consistent measures of membrane function and may encourage their wider use in clinical neurophysiology to investigate the pathophysiology of neuromuscular disorders. Copyright © 2012 Wiley Periodicals, Inc.
Endothelin‐1 suppresses insulin‐stimulated Akt phosphorylation and glucose uptake via GPCR kinase 2 in skeletal muscle cells

PubMed Central

Hoshi, Akimasa; Harada, Takuya; Higa, Tsunaki; Karki, Sarita; Terada, Koji; Higashi, Tsunehito; Mai, Yosuke; Nepal, Prabha; Mazaki, Yuichi; Miwa, Soichi

2016-01-01

Background and Purpose Endothelin‐1 (ET‐1) reduces insulin‐stimulated glucose uptake in skeletal muscle, inducing insulin resistance. Here, we have determined the molecular mechanisms underlying negative regulation by ET‐1 of insulin signalling. Experimental Approach We used the rat L6 skeletal muscle cells fully differentiated into myotubes. Changes in the phosphorylation of Akt was assessed by Western blotting. Effects of ET‐1 on insulin‐stimulated glucose uptake was assessed with [3H]‐2‐deoxy‐d‐glucose ([3H]2‐DG). The C‐terminus region of GPCR kinase 2 (GRK2‐ct), a dominant negative GRK2, was overexpressed in L6 cells using adenovirus‐mediated gene transfer. GRK2 expression was suppressed by transfection of the corresponding short‐interfering RNA (siRNA). Key Results In L6 myotubes, insulin elicited sustained Akt phosphorylation at Thr308 and Ser473, which was suppressed by ET‐1. The inhibitory effects of ET‐1 were prevented by treatment with a selective ETA receptor antagonist and a Gq protein inhibitor, overexpression of GRK2‐ct and knockdown of GRK2. Insulin increased [3H]2‐DG uptake rate in a concentration‐dependent manner. ET‐1 noncompetitively antagonized insulin‐stimulated [3H]2‐DG uptake. Blockade of ETA receptors, overexpression of GRK2‐ct and knockdown of GRK2 prevented the ET‐1‐induced suppression of insulin‐stimulated [3H]2‐DG uptake. In L6 myotubes overexpressing FLAG‐tagged GRK2, ET‐1 facilitated the interaction of endogenous Akt with FLAG‐GRK2. Conclusions and Implications Activation of ETA receptors with ET‐1 suppressed insulin‐induced Akt phosphorylation at Thr308 and Ser473 and [3H]2‐DG uptake in a GRK2‐dependent manner in skeletal muscle cells. These findings suggest that ETA receptors and GRK2 are potential targets for overcoming insulin resistance. PMID:26660861
Contractile activity of human skeletal muscle cells prevents insulin resistance by inhibiting pro-inflammatory signalling pathways.

PubMed

Lambernd, S; Taube, A; Schober, A; Platzbecker, B; Görgens, S W; Schlich, R; Jeruschke, K; Weiss, J; Eckardt, K; Eckel, J

2012-04-01

Obesity is closely associated with muscle insulin resistance and is a major risk factor for the pathogenesis of type 2 diabetes. Regular physical activity not only prevents obesity, but also considerably improves insulin sensitivity and skeletal muscle metabolism. We sought to establish and characterise an in vitro model of human skeletal muscle contraction, with a view to directly studying the signalling pathways and mechanisms that are involved in the beneficial effects of muscle activity. Contracting human skeletal muscle cell cultures were established by applying electrical pulse stimulation. To induce insulin resistance, skeletal muscle cells were incubated with human adipocyte-derived conditioned medium, monocyte chemotactic protein (MCP)-1 and chemerin. Similarly to in exercising skeletal muscle in vivo, electrical pulse stimulation induced contractile activity in human skeletal muscle cells, combined with the formation of sarcomeres, activation of AMP-activated protein kinase (AMPK) and increased IL-6 secretion. Insulin-stimulated glucose uptake was substantially elevated in contracting cells compared with control. The incubation of skeletal muscle cells with adipocyte-conditioned media, chemerin and MCP-1 significantly reduced the insulin-stimulated phosphorylation of Akt. This effect was abrogated by concomitant pulse stimulation of the cells. Additionally, pro-inflammatory signalling by adipocyte-derived factors was completely prevented by electrical pulse stimulation of the myotubes. We showed that the effects of electrical pulse stimulation on skeletal muscle cells were similar to the effect of exercise on skeletal muscle in vivo in terms of enhanced AMPK activation and IL-6 secretion. In our model, muscle contractile activity eliminates insulin resistance by blocking pro-inflammatory signalling pathways. This novel model therefore provides a unique tool for investigating the molecular mechanisms that mediate the beneficial effects of muscle
A Nerve Clamp Electrode Design for Indirect Stimulation of Skeletal Muscle

DTIC Science & Technology

2010-10-01

neurons. This device enables stimulation of muscle contraction indirectly as opposed to contraction from direct muscle stimulation. The electrode is able...to stimulate indirect muscle contraction when tested on ex vivo preparations from rodent phrenic nerve-hemidiaphragm muscle in similar fashion to...unsuccessful in stimulating indirect muscle contraction . Therefore, this novel electrode is useful for physiological assessment of nerve agents and
Mimicking muscle activity with electrical stimulation

NASA Astrophysics Data System (ADS)

Johnson, Lise A.; Fuglevand, Andrew J.

2011-02-01

Functional electrical stimulation is a rehabilitation technology that can restore some degree of motor function in individuals who have sustained a spinal cord injury or stroke. One way to identify the spatio-temporal patterns of muscle stimulation needed to elicit complex upper limb movements is to use electromyographic (EMG) activity recorded from able-bodied subjects as a template for electrical stimulation. However, this requires a transfer function to convert the recorded (or predicted) EMG signals into an appropriate pattern of electrical stimulation. Here we develop a generalized transfer function that maps EMG activity into a stimulation pattern that modulates muscle output by varying both the pulse frequency and the pulse amplitude. We show that the stimulation patterns produced by this transfer function mimic the active state measured by EMG insofar as they reproduce with good fidelity the complex patterns of joint torque and joint displacement.
Fiber transformation and replacement in low-frequency stimulated rabbit fast-twitch muscles.

PubMed

Schuler, M; Pette, D

1996-08-01

The fast-to-slow conversion of rabbit skeletal muscles by chronic low-frequency (10 Hz, 12 h daily) stimulation involves (1) sequential fast-to-slow fiber-type transitions in the order of type IID-->type IIA-->type I, and (2) the replacement of deteriorating fast-twitch glycolytic fibers by new fibers derived from satellite cells and myotubes. These two processes were analyzed in 30- and 60-day stimulated extensor digitorum longus and tibialis anterior muscles. Fast-to-slow transforming fibers were identified by myofibrillar actomyosin histochemistry as type C fibers and immunohistochemically by their reaction with monoclonal antibodies specific to slow and fast myosin heavy chain isoforms. In situ hybridization of mRNA specific to the myosin heavy chain I isoform identified all fibers expressing slow myosin, i.e., type I and C fibers. The fraction of transforming fibers ranged between 35% and 50% in 30-day stimulated muscles. The percentage of type I fibers (20%) was threefold elevated in extensor digitorum longus muscle, but unaltered (3.5%) in tibialis anterior muscle, suggesting that fast-to-slow fiber conversion was more advanced in the former than in the latter. Fiber replacement was indicated by the finding that the fiber populations of both muscles contained 15% myotubes or small fibers with central nuclei. In situ hybridization revealed that myotubes and small regenerating fibers uniformly expressed myosin heavy chain I mRNA. Similarly, high percentages of slow-myosin-expressing myotubes and small fibers were found in 60-day stimulated muscles.
Leucine facilitates the insulin-stimulated glucose uptake and insulin signaling in skeletal muscle cells: involving mTORC1 and mTORC2.

PubMed

Liu, Hui; Liu, Rui; Xiong, Yufang; Li, Xiang; Wang, Xiaolei; Ma, Yan; Guo, Huailan; Hao, Liping; Yao, Ping; Liu, Liegang; Wang, Di; Yang, Xuefeng

2014-08-01

Leucine, a branched-chain amino acid, has been shown to promote glucose uptake and increase insulin sensitivity in skeletal muscle, but the exact mechanism remains unestablished. We addressed this issue in cultured skeletal muscle cells in this study. Our results showed that leucine alone did not have an effect on glucose uptake or phosphorylation of protein kinase B (AKT), but facilitated the insulin-induced glucose uptake and AKT phosphorylation. The insulin-stimulated glucose uptake and AKT phosphorylation were inhibited by the phosphatidylinositol 3-kinase inhibitor, wortmannin, but the inhibition was partially reversed by leucine. The inhibitor of mammalian target of rapamycin complex 1 (mTORC1), rapamycin, had no effect on the insulin-stimulated glucose uptake, but eliminated the facilitating effect of leucine in the insulin-stimulated glucose uptake and AKT phosphorylation. In addition, leucine facilitation of the insulin-induced AKT phosphorylation was neutralized by knocking down the core component of the mammalian target of rapamycin complex 2 (mTORC2) with specific siRNA. Together, these findings show that leucine can facilitate the insulin-induced insulin signaling and glucose uptake in skeletal muscle cells through both mTORC1 and mTORC2, implicating the potential importance of this amino acid in glucose homeostasis and providing new mechanistic insights.
Ketoisocaproic acid, a metabolite of leucine, suppresses insulin-stimulated glucose transport in skeletal muscle cells in a BCAT2-dependent manner

PubMed Central

Moghei, Mahshid; Tavajohi-Fini, Pegah; Beatty, Brendan

2016-01-01

Although leucine has many positive effects on metabolism in multiple tissues, elevated levels of this amino acid and the other branched-chain amino acids (BCAAs) and their metabolites are implicated in obesity and insulin resistance. While some controversies exist about the direct effect of leucine on insulin action in skeletal muscle, little is known about the direct effect of BCAA metabolites. Here, we first showed that the inhibitory effect of leucine on insulin-stimulated glucose transport in L6 myotubes was dampened when other amino acids were present, due in part to a 140% stimulation of basal glucose transport (P < 0.05). Importantly, we also showed that α-ketoisocaproic acid (KIC), an obligatory metabolite of leucine, stimulated mTORC1 signaling but suppressed insulin-stimulated glucose transport (−34%, P < 0.05) in an mTORC1-dependent manner. The effect of KIC on insulin-stimulated glucose transport was abrogated in cells depleted of branched-chain aminotransferase 2 (BCAT2), the enzyme that catalyzes the reversible transamination of KIC to leucine. We conclude that although KIC can modulate muscle glucose metabolism, this effect is likely a result of its transamination back to leucine. Therefore, limiting the availability of leucine, rather than those of its metabolites, to skeletal muscle may be more critical in the management of insulin resistance and its sequelae. PMID:27488662
Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1

PubMed Central

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-01-01

An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30–50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40–50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30–40% in tension developing muscle but did not affect contraction-stimulated glucose transport in muscles in which force development was prevented. Our findings suggest that Rac1 and the actin cytoskeleton regulate stretch-stimulated glucose transport and that Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. Key
Muscle satellite cells adopt divergent fates

PubMed Central

Zammit, Peter S.; Golding, Jon P.; Nagata, Yosuke; Hudon, Valérie; Partridge, Terence A.; Beauchamp, Jonathan R.

2004-01-01

Growth, repair, and regeneration of adult skeletal muscle depends on the persistence of satellite cells: muscle stem cells resident beneath the basal lamina that surrounds each myofiber. However, how the satellite cell compartment is maintained is unclear. Here, we use cultured myofibers to model muscle regeneration and show that satellite cells adopt divergent fates. Quiescent satellite cells are synchronously activated to coexpress the transcription factors Pax7 and MyoD. Most then proliferate, down-regulate Pax7, and differentiate. In contrast, other proliferating cells maintain Pax7 but lose MyoD and withdraw from immediate differentiation. These cells are typically located in clusters, together with Pax7−ve progeny destined for differentiation. Some of the Pax7+ve/MyoD−ve cells then leave the cell cycle, thus regaining the quiescent satellite cell phenotype. Significantly, noncycling cells contained within a cluster can be stimulated to proliferate again. These observations suggest that satellite cells either differentiate or switch from terminal myogenesis to maintain the satellite cell pool. PMID:15277541
Effects of electrical muscle stimulation on oxygen consumption.

PubMed

Hayter, Tina L; Coombes, Jeff S; Knez, Wade L; Brancato, Tania L

2005-02-01

Electrical muscle stimulation (EMS) devices are being marketed as weight/ fat loss devices throughout the world. Commercially available stimulators have the ability to evoke muscle contractions that may affect caloric expenditure while the device is being used. The aim of this study was to test the effects of two different EMS devices (Abtronic and Feminique) on oxygen consumption at rest. Subjects arrived for testing after an overnight fast, had the devices fitted, and then positioned supine with expired air measured to determine oxygen consumption. After a 10-minute acclimation period, oxygen consumption was measured for 20 minutes with the device switched off (resting) then 20 minutes with the device switched on (stimulated). There were no significant differences (p > 0.05) in oxygen consumption between the resting and stimulated periods with either the Abtronic (mean +/- SD; resting, 3.40 +/- 0.44; stimulated, 3.45 +/- 0.53 ml of O(2).kg(-1).min(-1)) or the Feminique (resting, 3.73 +/- 0.45; stimulated, 3.75 +/- 0.46 ml of O(2).kg(-1).min(-1)). In summary, the EMS devices tested had no effect on oxygen consumption during muscle stimulation.
Concept Developed for an Implanted Stimulated Muscle-Powered Piezoelectric Generator

NASA Technical Reports Server (NTRS)

Lewandowski, Beth; Kilgore, Kevin; Ercegovic, David; Gustafson, Kenneth

2005-01-01

Implanted electronic devices are typically powered by batteries or transcutaneous power transmission. Batteries must be replaced or recharged, and transcutaneous power sources burden the patient or subject with external equipment prone to failure. A completely self-sustaining implanted power source would alleviate these limitations. Skeletal muscle provides an available autologous power source containing native chemical energy that produces power in excess of the requirements for muscle activation by motor nerve stimulation. A concept has been developed to convert stimulated skeletal muscle power into electrical energy (see the preceding illustration). We propose to connect a piezoelectric generator between a muscle tendon and bone. Electrically stimulated muscle contractions would exert force on the piezoelectric generator, charging a storage circuit that would be used to power the stimulator and other devices.
Biceps brachii muscle oxygenation in electrical muscle stimulation.

PubMed

Muthalib, Makii; Jubeau, Marc; Millet, Guillaume Y; Maffiuletti, Nicola A; Ferrari, Marco; Nosaka, Kazunori

2010-09-01

The purpose of this study was to compare between electrical muscle stimulation (EMS) and maximal voluntary (VOL) isometric contractions of the elbow flexors for changes in biceps brachii muscle oxygenation (tissue oxygenation index, TOI) and haemodynamics (total haemoglobin volume, tHb = oxygenated-Hb + deoxygenated-Hb) determined by near-infrared spectroscopy (NIRS). The biceps brachii muscle of 10 healthy men (23-39 years) was electrically stimulated at high frequency (75 Hz) via surface electrodes to evoke 50 intermittent (4-s contraction, 15-s relaxation) isometric contractions at maximum tolerated current level (EMS session). The contralateral arm performed 50 intermittent (4-s contraction, 15-s relaxation) maximal voluntary isometric contractions (VOL session) in a counterbalanced order separated by 2-3 weeks. Results indicated that although the torque produced during EMS was approximately 50% of VOL (P<0.05), there was no significant difference in the changes in TOI amplitude or TOI slope between EMS and VOL over the 50 contractions. However, the TOI amplitude divided by peak torque was approximately 50% lower for EMS than VOL (P<0.05), which indicates EMS was less efficient than VOL. This seems likely because of the difference in the muscles involved in the force production between conditions. Mean decrease in tHb amplitude during the contraction phases was significantly (P<0.05) greater for EMS than VOL from the 10th contraction onwards, suggesting that the muscle blood volume was lower in EMS than VOL. It is concluded that local oxygen demand of the biceps brachii sampled by NIRS is similar between VOL and EMS.
Stretch-stimulated glucose transport in skeletal muscle is regulated by Rac1.

PubMed

Sylow, Lykke; Møller, Lisbeth L V; Kleinert, Maximilian; Richter, Erik A; Jensen, Thomas E

2015-02-01

Rac1 regulates stretch-stimulated (i.e. mechanical stress) glucose transport in muscle. Actin depolymerization decreases stretch-induced glucose transport in skeletal muscle. Rac1 is a required part of the mechanical stress-component of the contraction-stimulus to glucose transport in skeletal muscle. An alternative to the canonical insulin signalling pathway for glucose transport is muscle contraction/exercise. Mechanical stress is an integrated part of the muscle contraction/relaxation cycle, and passive stretch stimulates muscle glucose transport. However, the signalling mechanism regulating stretch-stimulated glucose transport is not well understood. We recently reported that the actin cytoskeleton regulating GTPase, Rac1, was activated in mouse muscle in response to stretching. Rac1 is a regulator of contraction- and insulin-stimulated glucose transport, however, its role in stretch-stimulated glucose transport and signalling is unknown. We therefore investigated whether stretch-induced glucose transport in skeletal muscle required Rac1 and the actin cytoskeleton. We used muscle-specific inducible Rac1 knockout mice as well as pharmacological inhibitors of Rac1 and the actin cytoskeleton in isolated soleus and extensor digitorum longus muscles. In addition, the role of Rac1 in contraction-stimulated glucose transport during conditions without mechanical load on the muscles was evaluated in loosely hanging muscles and muscles in which cross-bridge formation was blocked by the myosin ATPase inhibitors BTS and Blebbistatin. Knockout as well as pharmacological inhibition of Rac1 reduced stretch-stimulated glucose transport by 30-50% in soleus and extensor digitorum longus muscle. The actin depolymerizing agent latrunculin B similarly decreased glucose transport in response to stretching by 40-50%. Rac1 inhibition reduced contraction-stimulated glucose transport by 30-40% in tension developing muscle but did not affect contraction-stimulated glucose transport in
Mechanical stimulation of skeletal muscle mitigates glucocorticoid induced decreases in prostaglandin synthesis

NASA Technical Reports Server (NTRS)

Chromiak, Joseph A.; Vandenburgh, Herman H.

1993-01-01

The glucocorticoid dexamethasone (Dex) induces a decline in protein synthesis and protein content of tissue cultured, avian skeletal muscle cells, and this atrophy is attenuated by repetitive mechanical stretch. Since the prostaglandin synthesis inhibitor indomethacin mitigated this stretch attenuation of muscle atrophy, the role of prostaglandins as growth modulators in these processes was examined. Dex at 10(exp -8) M reduced PGF(sub 2(alpha)) production 55 percent - 65 percent and PGE(sub 2) production 84 - 90 percent after 24 - 72 h of incubation in static cultures. Repetitive 10 percent stretch-relaxations of the non-Dex treated cultures increased PGF(sub 2(alpha)) efflux 41 percent at 24 h and 276 percent at 72 h and increased PGE(sub 2) production 51 percent at 24 h and 236 percent at 72 h. Mechanical stimulation of Dex treated cultures increased PGF(sub 2(alpha)) production 162 percent after 24 h, thus returning PGF(sub 2(alpha)) efflux to the level of non-Dex treated cultures. At 72 h, stretch increased PGF(sub 2(alpha)) efflux 65 percent in Dex treated cultures, but PGF(sub 2(alpha)) production was 45-84 percent less than non-Dex treated cultures. Mechanical stimulation of Dex treated cultures increased PGE(sub 2) production at 24 h, but not at 72 h. Dex reduced prostaglandin H synthase (PGHS) activity in the muscle cultures by 70 percent after 8 - 24 h of incubation, and mechanical stimulation increased PGHS activity of the Dex treated cultures by 98 percent. It is concluded that repetitive mechanical stimulation attenuates the catabolic effects of Dex on cultured skeletal muscle cells in part by reversing the Dex-induced declines in PGHS activity and prostaglandin production.
Method to Reduce Muscle Fatigue During Transcutaneous Neuromuscular Electrical Stimulation in Major Knee and Ankle Muscle Groups.

PubMed

Sayenko, Dimitry G; Nguyen, Robert; Hirabayashi, Tomoyo; Popovic, Milos R; Masani, Kei

2015-09-01

A critical limitation with transcutaneous neuromuscular electrical stimulation as a rehabilitative approach is the rapid onset of muscle fatigue during repeated contractions. We have developed a method called spatially distributed sequential stimulation (SDSS) to reduce muscle fatigue by distributing the center of electrical field over a wide area within a single stimulation site, using an array of surface electrodes. To extend the previous findings and to prove feasibility of the method by exploring the fatigue-reducing ability of SDSS for lower limb muscle groups in the able-bodied population, as well as in individuals with spinal cord injury (SCI). SDSS was delivered through 4 active electrodes applied to the knee extensors and flexors, plantarflexors, and dorsiflexors, sending a stimulation pulse to each electrode one after another with 90° phase shift between successive electrodes. Isometric ankle torque was measured during fatiguing stimulations using SDSS and conventional single active electrode stimulation lasting 2 minutes. We demonstrated greater fatigue-reducing ability of SDSS compared with the conventional protocol, as revealed by larger values of fatigue index and/or torque peak mean in all muscles except knee flexors of able-bodied individuals, and in all muscles tested in individuals with SCI. Our study has revealed improvements in fatigue tolerance during transcutaneous neuromuscular electrical stimulation using SDSS, a stimulation strategy that alternates activation of subcompartments of muscles. The SDSS protocol can provide greater stimulation times with less decrement in mechanical output compared with the conventional protocol. © The Author(s) 2014.
Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.

PubMed

Okuno, Yukako; Takahashi, Ryoichi; Sewa, Yoko; Ohse, Hirotaka; Imura, Shigeyuki; Tomita, Kazuhide

2017-03-01

[Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.

Myogenic Maturation by Optical-Training in Cultured Skeletal Muscle Cells.

PubMed

Asano, Toshifumi; Ishizuka, Toru; Yawo, Hiromu

2017-01-01

Optogenetic techniques are powerful tools for manipulating biological processes in identified cells using light under high temporal and spatial resolutions. Here, we describe an optogenetic training strategy to promote morphological maturation and functional development of skeletal muscle cells in vitro. Optical stimulation with a rhythmical frequency facilitates specific structural alignment of sarcomeric proteins. Optical stimulation also depolarizes the membrane potential, and induces contractile responses in synchrony with the given pattern of light pulses. These results suggest that optogenetic techniques can be employed to manipulate activity-dependent processes during myogenic development and control contraction of photosensitive skeletal muscle cells with high temporal and special precision.
Matching initial torque with different stimulation parameters influences skeletal muscle fatigue.

PubMed

Bickel, C Scott; Gregory, Chris M; Azuero, Andres

2012-01-01

A fundamental barrier to using electrical stimulation in the clinical setting is an inability to maintain torque production secondary to muscle fatigue. Electrical stimulation parameters are manipulated to influence muscle torque production, and they may also influence fatigability during repetitive stimulation. Our purpose was to determine the response of the quadriceps femoris to three different fatigue protocols using the same initial torque obtained by altering stimulator parameter settings. Participants underwent fatigue protocols in which either pulse frequency (lowHz), pulse duration (lowPD), or voltage (lowV) was manipulated to obtain an initial torque that equaled 25% of maximum voluntary isometric contraction. Muscle soreness was reported on a visual analog scale 48 h after each fatigue test. The lowHz protocol resulted in the least fatigue (25% +/- 14%); the lowPD (50% +/- 13%) and lowV (48% +/- 14%) protocols had similar levels of fatigue. The lowHz protocol resulted in significantly less muscle soreness than the higher frequency protocols. Stimulation protocols that use a lower frequency coupled with long pulse durations and high voltages result in lesser amounts of muscle fatigue and perceived soreness. The identification of optimal stimulation patterns to maximize muscle performance will reduce the effect of muscle fatigue and potentially improve clinical efficacy.
Local myogenic pulp-derived cell injection enhances craniofacial muscle regeneration in vivo.

PubMed

Jung, J E; Song, M J; Shin, S; Choi, Y J; Kim, K H; Chung, C J

2017-02-01

To enhance myogenic differentiation in pulp cells isolated from extracted premolars by epigenetic modification using a DNA demethylation agent, 5-aza-2'-deoxycytidine (5-Aza), and to evaluate the potent stimulatory effect of 5-Aza-treated pulp cell injection for craniofacial muscle regeneration in vivo. Pulp cells were isolated from premolars extracted for orthodontic purposes from four adults (age range, 18-22.1 years). Levels of myogenic differentiation and functional contraction response in vitro were compared between pulp cells with or without pre-treatment of 5-Aza. Changes in muscle regeneration in response to green fluorescent protein (GFP)-labelled myogenic pulp cell injection in vivo were evaluated using a cardiotoxin (CTX)-induced muscle injury model of the gastrocnemius as well as the masseter muscle in mice. Pre-treatment of 5-Aza in pulp cells stimulated myotube formation, myogenic differentiation in terms of desmin and myogenin expression, and the level of collagen gel contraction. The local injection of 5-Aza pre-treated myogenic pulp cells was engrafted into the host tissue and indicated signs of enhanced muscle regeneration in both the gastrocnemius and the masseter muscles. The epigenetic modification of pulp cells from extracted premolars and the local injection of myogenic pulp cells may stimulate craniofacial muscles regeneration in vivo. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Murrayafoline A Induces a G0/G1-Phase Arrest in Platelet-Derived Growth Factor-Stimulated Vascular Smooth Muscle Cells

PubMed Central

Han, Joo-Hui; Kim, Yohan; Jung, Sang-Hyuk; Lee, Jung-Jin; Park, Hyun-Soo; Song, Gyu-Yong; Cuong, Nguyen Manh; Kim, Young Ho

2015-01-01

The increased potential for vascular smooth muscle cell (VSMC) growth is a key abnormality in the development of atherosclerosis and post-angioplasty restenosis. Abnormally high activity of platelet-derived growth factor (PDGF) is believed to play a central role in the etiology of these pathophysiological situations. Here, we investigated the anti-proliferative effects and possible mechanism(s) of murrayafoline A, a carbazole alkaloid isolated from Glycosmis stenocarpa Guillamin (Rutaceae), on PDGF-BB-stimulated VSMCs. Murrayafoline A inhibited the PDGF-BB-stimulated proliferation of VSMCs in a concentration-dependent manner, as measured using a non-radioactive colorimetric WST-1 assay and direct cell counting. Furthermore, murrayafoline A suppressed the PDGF-BB-stimulated progression through G0/G1 to S phase of the cell cycle, as measured by [3H]-thymidine incorporation assay and cell cycle progression analysis. This anti-proliferative action of murrayafoline A, arresting cell cycle progression at G0/G1 phase in PDGF-BB-stimulated VSMCs, was mediated via down-regulation of the expression of cyclin D1, cyclin E, cyclin-dependent kinase (CDK)2, CDK4, and proliferating cell nuclear antigen (PCNA), and the phosphorylation of retinoblastoma protein (pRb). These results indicate that murrayafoline A may be useful in preventing the progression of vascular complications such as restenosis after percutaneous transluminal coronary angioplasty and atherosclerosis. PMID:26330754
AMP-activated Protein Kinase Stimulates Warburg-like Glycolysis and Activation of Satellite Cells during Muscle Regeneration*

PubMed Central

Fu, Xing; Zhu, Mei-Jun; Dodson, Mike V.; Du, Min

2015-01-01

Satellite cells are the major myogenic stem cells residing inside skeletal muscle and are indispensable for muscle regeneration. Satellite cells remain largely quiescent but are rapidly activated in response to muscle injury, and the derived myogenic cells then fuse to repair damaged muscle fibers or form new muscle fibers. However, mechanisms eliciting metabolic activation, an inseparable step for satellite cell activation following muscle injury, have not been defined. We found that a noncanonical Sonic Hedgehog (Shh) pathway is rapidly activated in response to muscle injury, which activates AMPK and induces a Warburg-like glycolysis in satellite cells. AMPKα1 is the dominant AMPKα isoform expressed in satellite cells, and AMPKα1 deficiency in satellite cells impairs their activation and myogenic differentiation during muscle regeneration. Drugs activating noncanonical Shh promote proliferation of satellite cells, which is abolished because of satellite cell-specific AMPKα1 knock-out. Taken together, AMPKα1 is a critical mediator linking noncanonical Shh pathway to Warburg-like glycolysis in satellite cells, which is required for satellite activation and muscle regeneration. PMID:26370082
Kinematic MRI study of upper-airway biomechanics using electrical muscle stimulation

NASA Astrophysics Data System (ADS)

Brennick, Michael J.; Margulies, Susan S.; Ford, John C.; Gefter, Warren B.; Pack, Allan I.

1997-05-01

We have developed a new and powerful method to study the movement and function of upper airway muscles. Our method is to use direct electrical stimulation of individual upper airway muscles, while performing state of the art high resolution magnetic resonance imaging (MRI). We have adapted a paralyzed isolated UA cat model so that positive or negative static pressure in the UA can be controlled at specific levels while electrical muscle stimulation is applied during MRI. With these techniques we can assess the effect of muscle stimulation on airway cross-sectional area compliance and soft tissue motion. We are reporting the preliminary results and MRI techniques which have enabled us to examine changes in airway dimensions which result form electrical stimulation of specific upper airway dilator muscles. The results of this study will be relevant to the development of new clinical treatments for obstructive sleep apnea by providing new information as to exactly how upper airway muscles function to dilate the upper airway and the strength of stimulation required to prevent the airway obstruction when overall muscle tone may not be sufficient to maintain regular breathing.
Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

PubMed

Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

2009-01-01

Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels.
IGF-I Stimulates Cooperative Interaction between the IGF-I Receptor and CSK Homologous Kinase that Regulates SHPS-1 Phosphorylation in Vascular Smooth Muscle Cells

PubMed Central

Radhakrishnan, Yashwanth; Shen, Xinchun; Maile, Laura A.; Xi, Gang

2011-01-01

IGF-I plays an important role in smooth muscle cell proliferation and migration. In vascular smooth muscle cells cultured in 25 mm glucose, IGF-I stimulated a significant increase in Src homology 2 domain containing protein tyrosine phosphatase substrate-1 (SHPS-1) phosphorylation compared with 5 mm glucose and this increase was required for smooth muscle cell proliferation. A proteome-wide screen revealed that carboxyl-terminal SRC kinase homologous kinase (CTK) bound directly to phosphotyrosines in the SHPS-1 cytoplasmic domain. Because the kinase(s) that phosphorylates these tyrosines in response to IGF-I is unknown, we determined the roles of IGF-I receptor (IGF-IR) and CTK in mediating SHPS-1 phosphorylation. After IGF-I stimulation, CTK was recruited to IGF-IR and subsequently to phospho-SHPS-1. Expression of an IGF-IR mutant that eliminated CTK binding reduced CTK transfer to SHPS-1, SHPS-1 phosphorylation, and cell proliferation. IGF-IR phosphorylated SHPS-1, which provided a binding site for CTK. CTK recruitment to SHPS-1 resulted in a further enhancement of SHPS-1 phosphorylation. CTK knockdown also impaired IGF-I-stimulated SHPS-1 phosphorylation and downstream signaling. Analysis of specific tyrosines showed that mutation of tyrosines 428/452 in SHPS-1 to phenylalanine reduced SHPS-1 phosphorylation but allowed CTK binding. In contrast, the mutation of tyrosines 469/495 inhibited IGF-IR-mediated the phosphorylation of SHPS-1 and CTK binding, suggesting that IGF-IR phosphorylated Y469/495, allowing CTK binding, and that CTK subsequently phosphorylated Y428/452. Based on the above findings, we conclude that after IGF-I stimulation, CTK is recruited to IGF-IR and its recruitment facilitates CTK's subsequent association with phospho-SHPS-1. This results in the enhanced CTK transfer to SHPS-1, and the two kinases then fully phosphorylate SHPS-1, which is necessary for IGF-I stimulated cellular proliferation. PMID:21799000
In vivo sup 31 P-NMR spectroscopy of chronically stimulated canine skeletal muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, B.J. III; McCully, A.K.; Subramanian, H.V.

1988-02-01

Chronic stimulation converts skeletal muscle of mixed fiber type to a uniform muscle made up of type I, fatigue-resistant fibers. Here, the bioenergetic correlates of fatigue resistance in conditioned canine latissimus dorsi are assessed with in vivo phosphorus-31 nuclear magnetic resonance ({sup 31}P-NMR) spectroscopy. After chronic electrical stimulation, five dogs underwent {sup 31}P-NMR spectroscopic and isometric tension measurements on conditioned and contralateral control muscle during stimulation for 200, 300, 500, and 800 ms of an 1,100-ms duty cycle. With stimulation, phosphocreatine (PCr) fell proportional to the degree of stimulation in both conditioned and control muscle but fell significantly less inmore » conditioned muscle at all the least intense stimulation period (200 ms). Isometric tension, expressed as a tension time index per gram muscle, was significantly greater in the conditioned muscle at the two longest stimulation periods. The overall small change in PCr and the lack of a plateau in tension observed in the conditioned muscle are similar to that seen in cardiac muscle during increased energy demand. This study indicates that the conditioned muscle's markedly enhanced resistance to fatigue is in part the result of its increased capacity for oxidative phosphorylation.« less
ROS Production via P2Y1-PKC-NOX2 Is Triggered by Extracellular ATP after Electrical Stimulation of Skeletal Muscle Cells.

PubMed

Díaz-Vegas, Alexis; Campos, Cristian A; Contreras-Ferrat, Ariel; Casas, Mariana; Buvinic, Sonja; Jaimovich, Enrique; Espinosa, Alejandra

2015-01-01

During exercise, skeletal muscle produces reactive oxygen species (ROS) via NADPH oxidase (NOX2) while inducing cellular adaptations associated with contractile activity. The signals involved in this mechanism are still a matter of study. ATP is released from skeletal muscle during electrical stimulation and can autocrinely signal through purinergic receptors; we searched for an influence of this signal in ROS production. The aim of this work was to characterize ROS production induced by electrical stimulation and extracellular ATP. ROS production was measured using two alternative probes; chloromethyl-2,7- dichlorodihydrofluorescein diacetate or electroporation to express the hydrogen peroxide-sensitive protein Hyper. Electrical stimulation (ES) triggered a transient ROS increase in muscle fibers which was mimicked by extracellular ATP and was prevented by both carbenoxolone and suramin; antagonists of pannexin channel and purinergic receptors respectively. In addition, transient ROS increase was prevented by apyrase, an ecto-nucleotidase. MRS2365, a P2Y1 receptor agonist, induced a large signal while UTPyS (P2Y2 agonist) elicited a much smaller signal, similar to the one seen when using ATP plus MRS2179, an antagonist of P2Y1. Protein kinase C (PKC) inhibitors also blocked ES-induced ROS production. Our results indicate that physiological levels of electrical stimulation induce ROS production in skeletal muscle cells through release of extracellular ATP and activation of P2Y1 receptors. Use of selective NOX2 and PKC inhibitors suggests that ROS production induced by ES or extracellular ATP is mediated by NOX2 activated by PKC.
ROS Production via P2Y1-PKC-NOX2 Is Triggered by Extracellular ATP after Electrical Stimulation of Skeletal Muscle Cells

PubMed Central

Díaz-Vegas, Alexis; Campos, Cristian A.; Contreras-Ferrat, Ariel; Casas, Mariana; Buvinic, Sonja; Jaimovich, Enrique; Espinosa, Alejandra

2015-01-01

During exercise, skeletal muscle produces reactive oxygen species (ROS) via NADPH oxidase (NOX2) while inducing cellular adaptations associated with contractile activity. The signals involved in this mechanism are still a matter of study. ATP is released from skeletal muscle during electrical stimulation and can autocrinely signal through purinergic receptors; we searched for an influence of this signal in ROS production. The aim of this work was to characterize ROS production induced by electrical stimulation and extracellular ATP. ROS production was measured using two alternative probes; chloromethyl-2,7- dichlorodihydrofluorescein diacetate or electroporation to express the hydrogen peroxide-sensitive protein Hyper. Electrical stimulation (ES) triggered a transient ROS increase in muscle fibers which was mimicked by extracellular ATP and was prevented by both carbenoxolone and suramin; antagonists of pannexin channel and purinergic receptors respectively. In addition, transient ROS increase was prevented by apyrase, an ecto-nucleotidase. MRS2365, a P2Y1 receptor agonist, induced a large signal while UTPyS (P2Y2 agonist) elicited a much smaller signal, similar to the one seen when using ATP plus MRS2179, an antagonist of P2Y1. Protein kinase C (PKC) inhibitors also blocked ES-induced ROS production. Our results indicate that physiological levels of electrical stimulation induce ROS production in skeletal muscle cells through release of extracellular ATP and activation of P2Y1 receptors. Use of selective NOX2 and PKC inhibitors suggests that ROS production induced by ES or extracellular ATP is mediated by NOX2 activated by PKC. PMID:26053483
Growth of arterioles in chronically stimulated adult rat skeletal muscle.

PubMed

Hansen-Smith, F; Egginton, S; Hudlicka, O

1998-01-01

The purpose of this study was to test the hypothesis that capillary growth induced by chronic electrical stimulation of skeletal muscle is accompanied by the growth of small arterioles. Lower limb flexor muscles of Sprague-Dawley rats were stimulated by electrodes implanted in the vicinity of the peroneal nerve at 10 Hz for 8 h/d for 2 and 7 days. Cryostat sections from the proximal, middle, and distal regions of the extensor digitorum longus muscle (EDL) were fluorescently immunolabeled with alpha-smooth muscle actin (alpha SMA) and myosin heavy chain (MHC) to identify mature (alpha SMA and MHC-positive) and immature (alpha SMA-positive, MHC-negative) arterioles. The fluorescent derivative of the lectin Griffonia simplicifolia I (GSI) was used to identify all microvessels, including arterioles, capillaries, and venules. The number of vessels positive for GSI or alpha SMA surrounding muscle fibers was similar in all three muscle regions (proximal, middle, distal). The mean values +/- SEM for GSI-positive vessels from all regions were similar in control (4.3 +/- 0.07) and 2-day stimulated (4.7 +/- 0.08) but higher in 7-day stimulated muscles (6.7 +/- 0.1, p < 0.05), thus confirming the previous findings on capillary growth. A similar increase was found in the number of alpha SMA positive vessels < or = 10 microns outer diameter (1.3 +/- 0.09 versus 0.4 +/- 0.03 around muscle fibers in controls). The density of terminal arterioles (< or = 10 microns) was slightly but not significantly higher after 2 days of stimulation (19.5 +/- 4 versus 15.6 +/- 2 profiles/mm2 in control muscles) and significantly higher after 7 days (33 +/- 7). While a similar increase was observed in the density of preterminal arterioles > 10 microns (17 +/- 3 control, 22 +/- 3 at 2 days and 40 +/- 5 at 7 days), the density of MHC-positive vessels muscles stimulated for 7 days was unchanged. Seven-day stimulated muscle also had a fivefold higher density of microvessel profiles < or = 10 microns
21 CFR 890.5850 - Powered muscle stimulator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Powered muscle stimulator. 890.5850 Section 890.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5850 Powered muscle...
21 CFR 890.5850 - Powered muscle stimulator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered muscle stimulator. 890.5850 Section 890.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5850 Powered muscle...
21 CFR 890.5850 - Powered muscle stimulator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Powered muscle stimulator. 890.5850 Section 890.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5850 Powered muscle...
21 CFR 890.5850 - Powered muscle stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Powered muscle stimulator. 890.5850 Section 890.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5850 Powered muscle...
21 CFR 890.5850 - Powered muscle stimulator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Powered muscle stimulator. 890.5850 Section 890.5850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5850 Powered muscle...
Taurine supplementation increases skeletal muscle force production and protects muscle function during and after high-frequency in vitro stimulation.

PubMed

Goodman, Craig A; Horvath, Deanna; Stathis, Christos; Mori, Trevor; Croft, Kevin; Murphy, Robyn M; Hayes, Alan

2009-07-01

Recent studies report that depletion and repletion of muscle taurine (Tau) to endogenous levels affects skeletal muscle contractility in vitro. In this study, muscle Tau content was raised above endogenous levels by supplementing male Sprague-Dawley rats with 2.5% (wt/vol) Tau in drinking water for 2 wk, after which extensor digitorum longus (EDL) muscles were examined for in vitro contractile properties, fatigue resistance, and recovery from fatigue after two different high-frequency stimulation bouts. Tau supplementation increased muscle Tau content by approximately 40% and isometric twitch force by 19%, shifted the force-frequency relationship upward and to the left, increased specific force by 4.2%, and increased muscle calsequestrin protein content by 49%. Force at the end of a 10-s (100 Hz) continuous tetanic stimulation was 6% greater than controls, while force at the end of the 3-min intermittent high-frequency stimulation bout was significantly higher than controls, with a 12% greater area under the force curve. For 1 h after the 10-s continuous stimulation, tetanic force in Tau-supplemented muscles remained relatively stable while control muscle force gradually deteriorated. After the 3-min intermittent bout, tetanic force continued to slowly recover over the next 1 h, while control muscle force again began to decline. Tau supplementation attenuated F(2)-isoprostane production (a sensitive indicator of reactive oxygen species-induced lipid peroxidation) during the 3-min intermittent stimulation bout. Finally, Tau transporter protein expression was not altered by the Tau supplementation. Our results demonstrate that raising Tau content above endogenous levels increases twitch and subtetanic and specific force in rat fast-twitch skeletal muscle. Also, we demonstrate that raising Tau protects muscle function during high-frequency in vitro stimulation and the ensuing recovery period and helps reduce oxidative stress during prolonged stimulation.
Response of the urethral and intracorporeal pressures to cavernosus muscle stimulation: role of the muscles in erection and ejaculation.

PubMed

Shafik, A

1995-07-01

The role of the bulbocavernosus (BC) and ischiocavernosus (IC) muscles in erection and ejaculation was studied. The response of the urethral and intracorporeal pressure to cavernosus muscle stimulation was evaluated in 18 male volunteers (mean age, 36.6 years). A two-channel microtip catheter was placed in the prostatic and bulbous urethra. Muscle stimulation was done by two needle electrodes inserted into the BC and IC muscles. BC muscle stimulation caused an increase in the pressure of the bulbous urethra (P < 0.001) and corpus spongiosum (P < 0.01) and an insignificant change in the prostatic and pendulous urethral and corpus cavernosal pressures (difference not significant). IC muscle stimulation effected an increase in the corpus cavernosal pressure (P < 0.001) without changing the urethral pressure (difference not significant). The BC muscle contracts rhythmically at orgasm and this might help to eject the semen from the posterior to the anterior urethra. It is apparent that the muscle has minimal or no role in erection. IC muscle may have a role in erection by increasing the intracavernosal pressure. It seems that it has no role in ejaculation. BC may be considered the "muscle of ejaculation," and IC the "muscle of erection."
Stimulation of synthesis and release of brain-derived neurotropic factor from intestinal smooth muscle cells by substance P and pituitary adenylate cyclase-activating peptide.

PubMed

Al-Qudah, M; Alkahtani, R; Akbarali, H I; Murthy, K S; Grider, J R

2015-08-01

Brain-derived neurotrophic factor (BDNF) is a neurotrophin present in the intestine where it participates in survival and growth of enteric neurons, augmentation of enteric circuits, and stimulation of intestinal peristalsis and propulsion. Previous studies largely focused on the role of neural and mucosal BDNF. The expression and release of BDNF from intestinal smooth muscle and the interaction with enteric neuropeptides has not been studied in gut. The expression and secretion of BDNF from smooth muscle cultured from the rabbit intestinal longitudinal muscle layer in response to substance P (SP) and pituitary adenylate cyclase-activating peptide (PACAP) was measured by western blot and enzyme-linked immunosorbent assay. BDNF mRNA was measured by reverse-transcription polymerase chain reaction. The expression of BNDF protein and mRNA was greater in smooth muscle cells (SMCs) from the longitudinal muscle than from circular muscle layer. PACAP and SP increased the expression of BDNF protein and mRNA in cultured longitudinal SMCs. PACAP and SP also stimulated the secretion of BDNF from cultured longitudinal SMCs. Chelation of intracellular calcium with BAPTA (1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid) prevented SP-induced increase in BDNF mRNA and protein expression and SP-induced secretion of BDNF. Neuropeptides known to be present in enteric neurons innervating the longitudinal layer increase the expression of BDNF mRNA and protein in SMCs and stimulate the release of BDNF. Considering the ability of BDNF to enhance smooth muscle contraction, this autocrine loop may partially explain the characteristic hypercontractility of longitudinal muscle in inflammatory bowel disease. © 2015 John Wiley & Sons Ltd.

In vivo stimulation of oestrogen receptor α increases insulin-stimulated skeletal muscle glucose uptake

PubMed Central

Gorres, Brittany K; Bomhoff, Gregory L; Morris, Jill K; Geiger, Paige C

2011-01-01

Abstract Previous studies suggest oestrogen receptor α (ERα) is involved in oestrogen-mediated regulation of glucose metabolism and is critical for maintenance of whole body insulin action. Despite this, the effect of direct ERα modulation in insulin-responsive tissues is unknown. The purpose of the current study was to determine the impact of ERα activation, using the ER subtype-selective ligand propylpyrazoletriyl (PPT), on skeletal muscle glucose uptake. Two-month-old female Sprague–Dawley rats, ovariectomized for 1 week, were given subcutaneous injections of PPT (10 mg kg−1), oestradiol benzoate (EB; 20 μg kg−1), the ERβ agonist diarylpropionitrile (DPN, 10 mg kg−1) or vehicle every 24 h for 3 days. On the fourth day, insulin-stimulated skeletal muscle glucose uptake was measured in vitro and insulin signalling intermediates were assessed via Western blotting. Activation of ERα with PPT resulted in increased insulin-stimulated glucose uptake into the slow-twitch soleus and fast-twitch extensor digitorum longus (EDL) muscles, activation of insulin signalling intermediates (as measured by phospho-Akt (pAkt) and pAkt substrate (PAS)) and phosphorylation of AMP-activated protein kinase (AMPK). GLUT4 protein was increased only in the EDL muscle. Rats treated with EB or DPN for 3 days did not show an increase in insulin-stimulated skeletal muscle glucose uptake compared to vehicle-treated animals. These new findings reveal that direct activation of ERα positively mediates glucose uptake and insulin action in skeletal muscle. Evidence that oestrogens and ERα stimulate glucose uptake has important implications for understanding mechanisms of glucose homeostasis, particularly in postmenopausal women. PMID:21486807
MEAT SCIENCE AND MUSCLE BIOLOGY SYMPOSIUM--mechanism of growth hormone stimulation of skeletal muscle growth in cattle.

PubMed

Jiang, H; Ge, X

2014-01-01

Growth hormone, also called somatotropin (ST), is a polypeptide hormone produced by the anterior pituitary. The major functions of GH include stimulating bone and skeletal muscle growth, lipolysis, milk production, and expression of the IGF-I gene in the liver. Based on these functions, recombinant bovine ST (bST) and recombinant porcine ST (pST) have been used to improve milk production in dairy cows and lean tissue growth in pigs, respectively. However, despite these applications, the mechanisms of action of GH are not fully understood. Indeed, there has been a lot of controversy over the role of liver-derived circulating IGF-I and locally produced IGF-I in mediating the growth-stimulatory effect of GH during the last 15 yr. It is in this context that we have conducted studies to further understand how GH stimulates skeletal muscle growth in cattle. Our results do not support a role of skeletal muscle-derived IGF-I in GH-stimulated skeletal muscle growth in cattle. Our results indicate that GH stimulates skeletal muscle growth in cattle, in part, by stimulating protein synthesis in muscle through a GH receptor-mediated, IGF-I-independent mechanism. In this review, besides discussing these results, we also argue that liver-derived circulating IGF-I should be still considered as the major mechanism that mediates the growth-stimulatory effect of GH on skeletal muscle in cattle and other domestic animals.
Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage.

PubMed

Fogt, Donovan L; Pan, Shujia; Lee, Sukho; Ding, Zhenping; Scrimgeour, Angus; Lawrence, John C; Ivy, John L

2004-03-01

Insulin-stimulated muscle glucose uptake is inversely associated with the muscle glycogen concentration. To investigate whether this association is a cause and effect relationship, we compared insulin-stimulated muscle glucose uptake in noncontracted and postcontracted muscle of GSL3-transgenic and wild-type mice. GSL3-transgenic mice overexpress a constitutively active form of glycogen synthase, which results in an abundant storage of muscle glycogen. Muscle contraction was elicited by in situ electrical stimulation of the sciatic nerve. Right gastrocnemii from GSL3-transgenic and wild-type mice were subjected to 30 min of electrical stimulation followed by hindlimb perfusion of both hindlimbs. Thirty minutes of contraction significantly reduced muscle glycogen concentration in wild-type (49%) and transgenic (27%) mice, although transgenic mice retained 168.8 +/- 20.5 micromol/g glycogen compared with 17.7 +/- 2.6 micromol/g glycogen for wild-type mice. Muscle of transgenic and wild-type mice demonstrated similar pre- (3.6 +/- 0.3 and 3.9 +/- 0.6 micromol.g(-1).h(-1) for transgenic and wild-type, respectively) and postcontraction (7.9 +/- 0.4 and 7.0 +/- 0.4 micromol.g(-1).h(-1) for transgenic and wild-type, respectively) insulin-stimulated glucose uptakes. However, the [14C]glucose incorporated into glycogen was greater in noncontracted (151%) and postcontracted (157%) transgenic muscle vs. muscle of corresponding wild-type mice. These results indicate that glycogen synthase activity is not rate limiting for insulin-stimulated glucose uptake in skeletal muscle and that the inverse relationship between muscle glycogen and insulin-stimulated glucose uptake is an association, not a cause and effect relationship.
Electrical Stimulation of Coleopteran Muscle for Initiating Flight.

PubMed

Choo, Hao Yu; Li, Yao; Cao, Feng; Sato, Hirotaka

2016-01-01

Some researchers have long been interested in reconstructing natural insects into steerable robots or vehicles. However, until recently, these so-called cyborg insects, biobots, or living machines existed only in science fiction. Owing to recent advances in nano/micro manufacturing, data processing, and anatomical and physiological biology, we can now stimulate living insects to induce user-desired motor actions and behaviors. To improve the practicality and applicability of airborne cyborg insects, a reliable and controllable flight initiation protocol is required. This study demonstrates an electrical stimulation protocol that initiates flight in a beetle (Mecynorrhina torquata, Coleoptera). A reliable stimulation protocol was determined by analyzing a pair of dorsal longitudinal muscles (DLMs), flight muscles that oscillate the wings. DLM stimulation has achieved with a high success rate (> 90%), rapid response time (< 1.0 s), and small variation (< 0.33 s; indicating little habituation). Notably, the stimulation of DLMs caused no crucial damage to the free flight ability. In contrast, stimulation of optic lobes, which was earlier demonstrated as a successful flight initiation protocol, destabilized the beetle in flight. Thus, DLM stimulation is a promising secure protocol for inducing flight in cyborg insects or biobots.
Electrical Stimulation of Coleopteran Muscle for Initiating Flight

PubMed Central

Choo, Hao Yu; Li, Yao; Cao, Feng; Sato, Hirotaka

2016-01-01

Some researchers have long been interested in reconstructing natural insects into steerable robots or vehicles. However, until recently, these so-called cyborg insects, biobots, or living machines existed only in science fiction. Owing to recent advances in nano/micro manufacturing, data processing, and anatomical and physiological biology, we can now stimulate living insects to induce user-desired motor actions and behaviors. To improve the practicality and applicability of airborne cyborg insects, a reliable and controllable flight initiation protocol is required. This study demonstrates an electrical stimulation protocol that initiates flight in a beetle (Mecynorrhina torquata, Coleoptera). A reliable stimulation protocol was determined by analyzing a pair of dorsal longitudinal muscles (DLMs), flight muscles that oscillate the wings. DLM stimulation has achieved with a high success rate (> 90%), rapid response time (< 1.0 s), and small variation (< 0.33 s; indicating little habituation). Notably, the stimulation of DLMs caused no crucial damage to the free flight ability. In contrast, stimulation of optic lobes, which was earlier demonstrated as a successful flight initiation protocol, destabilized the beetle in flight. Thus, DLM stimulation is a promising secure protocol for inducing flight in cyborg insects or biobots. PMID:27050093
Partial fast-to-slow conversion of regenerating rat fast-twitch muscle by chronic low-frequency stimulation.

PubMed

Pette, Dirk; Sketelj, Janez; Skorjanc, Dejan; Leisner, Elmi; Traub, Irmtrud; Bajrović, Fajko

2002-01-01

Chronic low-frequency stimulation (CLFS) of rat fast-twitch muscles induces sequential transitions in myosin heavy chain (MHC) expression from MHCIIb --> MHCIId/x --> MHCIIa. However, the 'final' step of the fast-to-slow transition, i.e., the upregulation of MHCI, has been observed only after extremely long stimulation periods. Assuming that fibre degeneration/regeneration might be involved in the upregulation of slow myosin, we investigated the effects of CLFS on extensor digitorum longus (EDL) muscles regenerating after bupivacaine-induced fibre necrosis. Normal, non-regenerating muscles responded to both 30- and 60-day CLFS with fast MHC isoform transitions (MHCIIb --> MHCIId --> MHCIIa) and only slight increases in MHCI. CLFS of regenerating EDL muscles caused similar transitions among the fast isoforms but, in addition, caused significant increases in MHCI (to approximately 30% relative concentration). Stimulation periods of 30 and 60 days induced similar changes in the regenerating bupivacaine-treated muscles, indicating that the upregulation of slow myosin was restricted to regenerating fibres, but only during an early stage of regeneration. These results suggest that satellite cells and/or regenerating fast rat muscle fibres are capable of switching directly to a slow program under the influence of CLFS and, therefore, appear to be more malleable than adult fibres.
Urethral sphincters response to cavernosus muscles stimulation with identification of cavernoso-urethral reflex.

PubMed

Shafik, A; Shafik, A A; Shafik, I; el-Sibai, O

2005-01-01

The functional activity of the urethral sphincters during cavernosus muscles' contraction at coitus has been poorly addressed in the literature. We investigated the hypothesis that cavernosus muscles' contraction affects reflex contraction of the urethral sphincters to guard against semen reflux into the urinary bladder or urine leakage from the bladder during orgasm and ejaculation. The electromyographic (EMG) response of the external (EUS) and internal (IUS) urethral sphincters to ischio- (ICM) and bulbo- (BCM) cavernosus muscle stimulation was studied in 15 healthy volunteers (9 men, 6 women, age 39.3 +/- 8.2 SD years). An electrode was applied to each of ICM and BCM (stimulating electrodes) and the 2 urethral sphincters (recording electrodes). The test was repeated after individual anesthetization of the urethral sphincters and the 2 cavernosus muscles, and after using saline instead of lidocaine. Upon stimulation of each of the 2 cavernosus muscles, the EUS and IUS recorded increased EMG activity. Repeated cavernosus muscles' stimulation evoked the urethral sphincteric response without fatigue. The urethral sphincters did not respond to stimulation of the anesthetized cavernosus muscles nor did the anesthetized urethral sphincters respond to cavernosus muscle stimulation. Saline infiltration instead of lidocaine did not affect the urethral sphincteric response to cavernosal muscle stimulation. Results were reproducible. Cavernosus muscles' contraction is suggested to effect EUS and IUS contraction. This action seems to be reflex and mediated through the 'cavernoso-urethral reflex.' Urethral sphincters contraction upon cavernosus muscles contraction during sexual intercourse presumably prevents urine leak from the urinary bladder to urethra, prevents retrograde ejaculation, and propels ejaculate from the posterior to the penile urethra. The cavernoso-urethral reflex can act a diagnostic tool in the investigations of patients with ejaculatory disorders.
[Effect of biological electric stimulation on free muscle transfer].

PubMed

Yuang, F; Guan, W; Cao, Y

1997-01-01

The rectus femoris muscles of rabbits were used as muscle model. The electrical stimulation which resembled the normal motor-unit activity was used to observe its effects on free transferred muscle. After three months, the moist muscle weight (MW), its maximum cross-section area, its contractility and its histochemical characteristics were examined. The results showed that the function and morphology of the muscles were well preserved. These findings might encourage its clinical application.
Overexpression of Striated Muscle Activator of Rho Signaling (STARS) Increases C2C12 Skeletal Muscle Cell Differentiation.

PubMed

Wallace, Marita A; Della Gatta, Paul A; Ahmad Mir, Bilal; Kowalski, Greg M; Kloehn, Joachim; McConville, Malcom J; Russell, Aaron P; Lamon, Séverine

2016-01-01

Skeletal muscle growth and regeneration depend on the activation of satellite cells, which leads to myocyte proliferation, differentiation and fusion with existing muscle fibers. Skeletal muscle cell proliferation and differentiation are tightly coordinated by a continuum of molecular signaling pathways. The striated muscle activator of Rho signaling (STARS) is an actin binding protein that regulates the transcription of genes involved in muscle cell growth, structure and function via the stimulation of actin polymerization and activation of serum-response factor (SRF) signaling. STARS mediates cell proliferation in smooth and cardiac muscle models; however, whether STARS overexpression enhances cell proliferation and differentiation has not been investigated in skeletal muscle cells. We demonstrate for the first time that STARS overexpression enhances differentiation but not proliferation in C2C12 mouse skeletal muscle cells. Increased differentiation was associated with an increase in the gene levels of the myogenic differentiation markers Ckm, Ckmt2 and Myh4, the differentiation factor Igf2 and the myogenic regulatory factors (MRFs) Myf5 and Myf6. Exposing C2C12 cells to CCG-1423, a pharmacological inhibitor of SRF preventing the nuclear translocation of its co-factor MRTF-A, had no effect on myotube differentiation rate, suggesting that STARS regulates differentiation via a MRTF-A independent mechanism. These findings position STARS as an important regulator of skeletal muscle growth and regeneration.
Evoked EMG-based torque prediction under muscle fatigue in implanted neural stimulation

NASA Astrophysics Data System (ADS)

Hayashibe, Mitsuhiro; Zhang, Qin; Guiraud, David; Fattal, Charles

2011-10-01

In patients with complete spinal cord injury, fatigue occurs rapidly and there is no proprioceptive feedback regarding the current muscle condition. Therefore, it is essential to monitor the muscle state and assess the expected muscle response to improve the current FES system toward adaptive force/torque control in the presence of muscle fatigue. Our team implanted neural and epimysial electrodes in a complete paraplegic patient in 1999. We carried out a case study, in the specific case of implanted stimulation, in order to verify the corresponding torque prediction based on stimulus evoked EMG (eEMG) when muscle fatigue is occurring during electrical stimulation. Indeed, in implanted stimulation, the relationship between stimulation parameters and output torques is more stable than external stimulation in which the electrode location strongly affects the quality of the recruitment. Thus, the assumption that changes in the stimulation-torque relationship would be mainly due to muscle fatigue can be made reasonably. The eEMG was proved to be correlated to the generated torque during the continuous stimulation while the frequency of eEMG also decreased during fatigue. The median frequency showed a similar variation trend to the mean absolute value of eEMG. Torque prediction during fatigue-inducing tests was performed based on eEMG in model cross-validation where the model was identified using recruitment test data. The torque prediction, apart from the potentiation period, showed acceptable tracking performances that would enable us to perform adaptive closed-loop control through implanted neural stimulation in the future.
A muscle stem cell for every muscle: variability of satellite cell biology among different muscle groups

PubMed Central

Randolph, Matthew E.; Pavlath, Grace K.

2015-01-01

The human body contains approximately 640 individual skeletal muscles. Despite the fact that all of these muscles are composed of striated muscle tissue, the biology of these muscles and their associated muscle stem cell populations are quite diverse. Skeletal muscles are affected differentially by various muscular dystrophies (MDs), such that certain genetic mutations specifically alter muscle function in only a subset of muscles. Additionally, defective muscle stem cells have been implicated in the pathology of some MDs. The biology of muscle stem cells varies depending on the muscles with which they are associated. Here we review the biology of skeletal muscle stem cell populations of eight different muscle groups. Understanding the biological variation of skeletal muscles and their resident stem cells could provide valuable insight into mechanisms underlying the susceptibility of certain muscles to myopathic disease. PMID:26500547
Inhibition of muscarinic-stimulated polyphosphoinositide hydrolysis and Ca2+ mobilization in cat iris sphincter smooth muscle cells by cAMP-elevating agents.

PubMed

Ding, K H; Husain, S; Akhtar, R A; Isales, C M; Abdel-Latif, A A

1997-09-01

The effects of carbachol (CCh) on inositol 1,4,5-trisphosphate (IP3) production and intracellular calcium ([Ca2+]i) mobilization, and their regulation by cAMP-elevating agents were investigated in SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells. CCh produced time- and dose-dependent increases in IP3 production; the t1/2 and EC50 values were 68 s and 0.5 microM, respectively. The muscarinic agonist provoked a transient increase in [Ca2+]i which reached maximum within 77 s, and increased [Ca2+]i mobilization in a concentration-dependent manner with an EC50 of 1.4 microM. Thapsigargin, a Ca(2+)-pump inhibitor, caused a rapid rise in [Ca2+]i and subsequent addition of CCh was without effect. Both CCh-induced IP3 production and CCh-induced [Ca2+]i mobilization were more potently antagonized by 4-DAMP, an M3 muscarinic receptor antagonist, than by pirenzepine, an M1 receptor antagonist, suggesting that both responses are mediated through the M3 receptor subtype. Treatment of the cells with U73122, a phospholipase C (PLC) inhibitor, resulted in a concentration-dependent decrease in both CCh-stimulated IP3 production and [Ca2+]i mobilization. These data indicate close correlation between enhanced IP3 production and [Ca2+]i mobilization in these smooth muscle cells and suggest that the CCh-stimulated increase in [Ca2+]i could be mediated through increased IP3 production. Isoproterenol (ISO) inhibited CCh-induced IP3 production (IC50 = 80 nM) and [Ca2+]i mobilization (IC50 = 0.17 microM) in a concentration-dependent manner. Microsomal fractions isolated from SV-CISM-2 cells contained phospholipase C (PLC) which was stimulated by CCh (10 microM) and GTP gamma S (0.1 microM). Pretreatment of the cells with ISO or forskolin, 5 microM each, produced membrane fractions in which CCh-stimulated PLC activity was significantly attenuated. Furthermore, when microsomal fractions isolated from SV-CISM-2 cells were phosphorylated with Protein kinase A (PKA), the CCh
Tongue muscle plasticity following hypoglossal nerve stimulation in aged rats

PubMed Central

Connor, Nadine P.; Russell, John A.; Jackson, Michelle A.; Kletzien, Heidi; Wang, Hao; Schaser, Allison J.; Leverson, Glen E.; Zealear, David L.

2012-01-01

Introduction Age-related decreases in tongue muscle mass and strength have been reported. It may be possible to prevent age-related tongue muscle changes using neuromuscular electrical stimulation (NMES). Our hypothesis was that alterations in muscle contractile properties and myosin heavy chain composition would be found following NMES. Methods Fifty-four young, middle-aged and old Fischer 344/Brown Norway rats were included. Twenty-four rats underwent bilateral electrical stimulation of the hypoglossal nerves for 8 weeks and were compared with control or sham rats. Muscle contractile properties and myosin heavy chain (MHC) in the genioglossus (GG), styloglossus (SG) and hyoglossus (HG) muscles were examined. Results In comparison with unstimulated control rats, we found reduced muscle fatigue, increased contraction and half decay times and increased twitch and tetanic tension. Increased Type I MHC was found, except for GG in old and middle-aged rats. Discussion Transitions in tongue muscle contractile properties and phenotype were found following NMES. PMID:23169566
Nonparametric Model of Smooth Muscle Force Production During Electrical Stimulation.

PubMed

Cole, Marc; Eikenberry, Steffen; Kato, Takahide; Sandler, Roman A; Yamashiro, Stanley M; Marmarelis, Vasilis Z

2017-03-01

A nonparametric model of smooth muscle tension response to electrical stimulation was estimated using the Laguerre expansion technique of nonlinear system kernel estimation. The experimental data consisted of force responses of smooth muscle to energy-matched alternating single pulse and burst current stimuli. The burst stimuli led to at least a 10-fold increase in peak force in smooth muscle from Mytilus edulis, despite the constant energy constraint. A linear model did not fit the data. However, a second-order model fit the data accurately, so the higher-order models were not required to fit the data. Results showed that smooth muscle force response is not linearly related to the stimulation power.
Longitudinal growth of skeletal myotubes in vitro in a new horizontal mechanical cell stimulator

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Karlisch, Patricia

1989-01-01

A tissue-culture model system for growing skeletal-muscle cells under more dynamic conditions than found in normal tissue-culture environments is described. A computerized device presented allows mechanical stimulation of the cell's substratum by 300 to 400 pct in length in the horizontal plane. Cell growth rates and skeletal-muscle organogenesis are stimulated in this in vitro system. It is noted that longitudinal myotube growth observed is accompanied by increased rates of cell proliferation and myoblast fusion. Prestretching the collagen-coated substratum before cell plating is shown to lead to increased cell proliferation, myotube orientation, and longitudinal myotube growth. The effects of substratum stretching on myogenesis in the model system are also assessed and attributed to alterations in the cell's extracellular matrix.
Cisapride stimulates contraction of idiopathic megacolonic smooth muscle in cats.

PubMed

Hasler, A H; Washabau, R J

1997-01-01

We have previously shown that cisapride, a substituted piperidinyl benzamide, stimulates contraction of healthy feline colonic smooth muscle. The purpose of the present investigation was to determine the effect of cisapride on feline idiopathic megacolonic smooth muscle function. Longitudinal smooth muscle strips from ascending and descending colon were obtained from cats with idiopathic megacolon, suspended in a 1.5 mM Ca(2+)-HEPES buffer solution (37 degrees C, 100% O2, pH 7.4), attached to isometric force transducers, and stretched to optimal muscle length (Lo). Control responses were obtained at each muscle site with acetylcholine (10(-8) to 10(-4) M), substance P (10(-11) to 10(-7) M), or potassium chloride (10 to 80 mM). Muscles were then stimulated with cumulative (10(-9) to 10(-6) M) doses of cisapride in the absence or presence of tetrodotoxin (10(-6) M) and atropine (10(-6) M), or in a 0 calcium HEPES buffer solution. In cats with idiopathic megacolon, cisapride stimulated contractions of longitudinal smooth muscle from both the ascending and the descending colon. Cisapride-induced contractions were similar in magnitude to those induced by substance P and acetylcholine in the ascending colon, but were less than those observed in the descending colon. Cisapride-induced contractions in megacolonic smooth muscle were only partially inhibited by tetrodotoxin and atropine, but were virtually abolished by removal of extracellular calcium. We concluded that cisapride-induced contractions of feline megacolonic smooth muscle are largely smooth muscle mediated and dependent on influx of extracellular calcium. Cisapride-induced contractions in megacolonic smooth muscle are only partially dependent on enteric cholinergic nerves. Thus, cisapride may be useful in the treatment of cats with idiopathic megacolon.
Bone Marrow Stromal Cells Generate Muscle Cells and Repair Muscle Degeneration

NASA Astrophysics Data System (ADS)

Dezawa, Mari; Ishikawa, Hiroto; Itokazu, Yutaka; Yoshihara, Tomoyuki; Hoshino, Mikio; Takeda, Shin-ichi; Ide, Chizuka; Nabeshima, Yo-ichi

2005-07-01

Bone marrow stromal cells (MSCs) have great potential as therapeutic agents. We report a method for inducing skeletal muscle lineage cells from human and rat general adherent MSCs with an efficiency of 89%. Induced cells differentiated into muscle fibers upon transplantation into degenerated muscles of rats and mdx-nude mice. The induced population contained Pax7-positive cells that contributed to subsequent regeneration of muscle upon repetitive damage without additional transplantation of cells. These MSCs represent a more ready supply of myogenic cells than do the rare myogenic stem cells normally found in muscle and bone marrow.
Muscle electrical stimulation improves neurovascular control and exercise tolerance in hospitalised advanced heart failure patients.

PubMed

Groehs, Raphaela V; Antunes-Correa, Ligia M; Nobre, Thais S; Alves, Maria-Janieire Nn; Rondon, Maria Urbana Pb; Barreto, Antônio Carlos Pereira; Negrão, Carlos E

2016-10-01

We investigated the effects of muscle functional electrical stimulation on muscle sympathetic nerve activity and muscle blood flow, and, in addition, exercise tolerance in hospitalised patients for stabilisation of heart failure. Thirty patients hospitalised for treatment of decompensated heart failure, class IV New York Heart Association and ejection fraction ≤ 30% were consecutively randomly assigned into two groups: functional electrical stimulation (n = 15; 54 ± 2 years) and control (n = 15; 49 ± 2 years). Muscle sympathetic nerve activity was directly recorded via microneurography and blood flow by venous occlusion plethysmography. Heart rate and blood pressure were evaluated on a beat-to-beat basis (Finometer), exercise tolerance by 6-minute walk test, quadriceps muscle strength by a dynamometer and quality of life by Minnesota questionnaire. Functional electrical stimulation consisted of stimulating the lower limbs at 10 Hz frequency, 150 ms pulse width and 70 mA intensity for 60 minutes/day for 8-10 consecutive days. The control group underwent electrical stimulation at an intensity of < 20 mA. Baseline characteristics were similar between groups, except age that was higher and C-reactive protein and forearm blood flow that were smaller in the functional electrical stimulation group. Functional electrical stimulation significantly decreased muscle sympathetic nerve activity and increased muscle blood flow and muscle strength. No changes were found in the control group. Walking distance and quality of life increased in both groups. However, these changes were greater in the functional electrical stimulation group. Functional electrical stimulation improves muscle sympathetic nerve activity and vasoconstriction and increases exercise tolerance, muscle strength and quality of life in hospitalised heart failure patients. These findings suggest that functional electrical stimulation may be useful to hospitalised patients with
Potential of M-Wave Elicited by Double Pulse for Muscle Fatigue Evaluation in Intermittent Muscle Activation by Functional Electrical Stimulation for Motor Rehabilitation

PubMed Central

Miura, Naoto; Watanabe, Takashi

2016-01-01

Clinical studies on application of functional electrical stimulation (FES) to motor rehabilitation have been increasing. However, muscle fatigue appears early in the course of repetitive movement production training by FES. Although M-wave variables were suggested to be reliable indices of muscle fatigue in long lasting constant electrical stimulation under the isometric condition, the ability of M-wave needs more studies under intermittent stimulation condition, because the intervals between electrical stimulations help recovery of muscle activation level. In this paper, M-waves elicited by double pulses were examined in muscle fatigue evaluation during repetitive movements considering rehabilitation training with surface electrical stimulation. M-waves were measured under the two conditions of repetitive stimulation: knee extension force production under the isometric condition and the dynamic movement condition by knee joint angle control. Amplitude of M-wave elicited by the 2nd pulse of a double pulse decreased during muscle fatigue in both measurement conditions, while the change in M-waves elicited by single pulses in a stimulation burst was not relevant to muscle fatigue in repeated activation with stimulation interval of 1 s. Fatigue index obtained from M-waves elicited by 2nd pulses was suggested to provide good estimation of muscle fatigue during repetitive movements with FES. PMID:27110556
Induction of cortical plasticity for reciprocal muscles by paired associative stimulation

PubMed Central

Suzuki, Makoto; Kirimoto, Hikari; Sugawara, Kazuhiro; Watanabe, Makoto; Shimizu, Shinobu; Ishizaka, Ikuyo; Yamada, Sumio; Matsunaga, Atsuhiko; Fukuda, Michinari; Onishi, Hideaki

2014-01-01

Background Paired associative stimulation (PAS) is widely used to induce plasticity in the human motor cortex. Although reciprocal inhibition of antagonist muscles plays a fundamental role in human movements, change in cortical circuits for reciprocal muscles by PAS is unknown. Methods We investigated change in cortical plasticity for reciprocal muscles during PAS. PAS consisted of 200 pairs of peripheral electric stimulation of the right median nerve at the wrist at a frequency of 0.25 Hz followed by transcranial magnetic stimulation of the left M1 at the midpoint between the center of gravities of the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles. Measures of motor cortical excitability included resting motor threshold (RMT), GABAA-mediated short-interval intracortical inhibition (SICI), and GABAB-mediated long-interval intracortical inhibition (LICI). Results Motor evoked potential amplitude-conditioned LICI for the FCR muscle was significantly decreased after PAS (P = 0.020), whereas that for the ECR muscle was significantly increased (P = 0.033). Changes in RMT and SICI for the FCR and ECR muscles were not significantly different before and after PAS. Corticospinal excitability for both reciprocal muscles was increased during PAS, but GABAB-mediated cortical inhibitory functions for the agonist and antagonist muscles were reciprocally altered after PAS. Conclusion These results implied that the cortical excitability for reciprocal muscles including GABAB-ergic inhibitory systems within human M1 could be differently altered by PAS. PMID:25365805

Motor evoked responses from the thigh muscles to the stimulation of the upper limb nerves in patients with late poliomyelitis.

PubMed

Ertekin, Cumhur; On, Arzu Yagiz; Kirazli, Yeşim; Kurt, Tülay; Gürgör, Nevin

2002-04-01

To demonstrate a clear-cut M response recorded from the severely affected thigh muscles to the stimulation of the upper limb nerves in a serial of patients with late poliomyelitis. Fifteen patients with late poliomyelitis, 7 patients with spinal cord disorders and 11 control subjects were included. Evoked muscle responses were investigated in quadriceps femoris and/or thigh adductor muscles to the stimulation of the brachial plexus, median and ulnar nerves. Evoked muscle responses were obtained from the thigh muscles in all 12 late polio patients with proximal lower extremity involvement. The response could not be recorded from the thigh muscles neither in the 3 polio patients with upper extremity involvement nor in the healthy control subjects and in patients with other spinal cord disorders of anterior horn cell. It is proposed that the electrical stimulation of the arm nerves produce interlimb descending muscle responses in the severely affected atrophic thigh muscles of the patients with late polio. This finding suggests that there might be a focal and/or specific loss of inhibitory interneurons between injured and normal motor neurons and increased facilitatory synaptic action at the end of long propriospinal descending fibers in the case of late poliomyelitis.
Selective and graded recruitment of cat hamstring muscles with intrafascicular stimulation.

PubMed

Dowden, Brett R; Wilder, Andrew M; Hiatt, Scott D; Normann, Richard A; Brown, Nicholas A T; Clark, Gregory A

2009-12-01

The muscles of the hamstring group can produce different combinations of hip and knee torque. Thus, the ability to activate the different hamstring muscles selectively is of particular importance in eliciting functional movements such as stance and gait in a person with spinal cord injury. We investigated the ability of intrafascicular stimulation of the muscular branch of the sciatic nerve to recruit the feline hamstring muscles in a selective and graded fashion. A Utah Slanted Electrode Array, consisting of 100 penetrating microelectrodes, was implanted into the muscular branch of the sciatic nerve in six cats. Muscle twitches were evoked in the three compartments of biceps femoris (anterior, middle, and posterior), as well as semitendinosus and semimembranosus, using pulse-width modulated constant-voltage pulses. The resultant compound muscle action potentials were recorded using intramuscular fine-wire electrodes. 74% of the electrodes per implant were able to evoke a threshold response in these muscles, and these electrodes were evenly distributed among the instrumented muscles. Of the five muscles instrumented, on average 2.5 could be selectively activated to 90% of maximum EMG, and 3.5 could be selectively activated to 50% of maximum EMG. The muscles were recruited selectively with a mean stimulus dynamic range of 4.14 +/- 5.05 dB between threshold and either spillover to another muscle or a plateau in the response. This selective and graded activation afforded by intrafascicular stimulation of the muscular branch of the sciatic nerve suggests that it is a potentially useful stimulation paradigm for eliciting distinct forces in the hamstring muscle group in motor neuroprosthetic applications.
Kinesthetic illusions attenuate experimental muscle pain, as do muscle and cutaneous stimulation.

PubMed

Gay, André; Aimonetti, Jean-Marc; Roll, Jean-Pierre; Ribot-Ciscar, Edith

2015-07-30

In the present study, muscle pain was induced experimentally in healthy subjects by administrating hypertonic saline injections into the tibialis anterior (TA) muscle. We first aimed at comparing the analgesic effects of mechanical vibration applied to either cutaneous or muscle receptors of the TA or to both types simultaneously. Secondly, pain alleviation was compared in subjects in whom muscle tendon vibration evoked kinesthetic illusions of the ankle joint. Muscle tendon vibration, which primarily activated muscle receptors, reduced pain intensity by 30% (p<0.01). In addition, tangential skin vibration reduced pain intensity by 33% (p<0.01), primarily by activating cutaneous receptors. Concurrently stimulating both sensory channels induced stronger analgesic effects (-51%, p<0.01), as shown by the lower levels of electrodermal activity. The strongest analgesic effects of the vibration-induced muscle inputs occurred when illusory movements were perceived (-38%, p=0.01). The results suggest that both cutaneous and muscle sensory feedback reduce muscle pain, most likely via segmental and supraspinal processes. Further clinical trials are needed to investigate these new methods of muscle pain relief. Copyright © 2015 Elsevier B.V. All rights reserved.
Stem cell antigen-1 in skeletal muscle function.

PubMed

Bernstein, Harold S; Samad, Tahmina; Cholsiripunlert, Sompob; Khalifian, Saami; Gong, Wenhui; Ritner, Carissa; Aurigui, Julian; Ling, Vivian; Wilschut, Karlijn J; Bennett, Stephen; Hoffman, Julien; Oishi, Peter

2013-08-15

Stem cell antigen-1 (Sca-1) is a member of the Ly-6 multigene family encoding highly homologous, glycosyl-phosphatidylinositol-anchored membrane proteins. Sca-1 is expressed on muscle-derived stem cells and myogenic precursors recruited to sites of muscle injury. We previously reported that inhibition of Sca-1 expression stimulated myoblast proliferation in vitro and regulated the tempo of muscle repair in vivo. Despite its function in myoblast expansion during muscle repair, a role for Sca-1 in normal, post-natal muscle has not been thoroughly investigated. We systematically compared Sca-1-/- (KO) and Sca-1+/+ (WT) mice and hindlimb muscles to elucidate the tissue, contractile, and functional effects of Sca-1 in young and aging animals. Comparison of muscle volume, fibrosis, myofiber cross-sectional area, and Pax7+ myoblast number showed little differences between ages or genotypes. Exercise protocols, however, demonstrated decreased stamina in KO versus WT mice, with young KO mice achieving results similar to aging WT animals. In addition, KO mice did not improve with practice, while WT animals demonstrated conditioning over time. Surprisingly, myomechanical analysis of isolated muscles showed that KO young muscle generated more force and experienced less fatigue. However, KO muscle also demonstrated incomplete relaxation with fatigue. These findings suggest that Sca-1 is necessary for muscle conditioning with exercise, and that deficient conditioning in Sca-1 KO animals becomes more pronounced with age.
Endothelial cell stimulating angiogenesis factor.

PubMed

Weiss, J B; McLaughlin, B

1998-04-01

Endothelial cell stimulating angiogenesis factor (ESAF) is a small (> 1000 Da) dialysable non-peptide molecule with potent angiogenic activity. ESAF activates the major pro-matrix metalloproteinases and also uniquely reactivates the complex of these active enzymes with their tissue inhibitors resulting in both active enzyme and inhibitor. These actions may be pivotal in its role as an angiogenic factor. ESAF is primarily involved in angiogenic conditions where inflammatory cells are not evident such as foetal bone growth and electrically stimulated skeletal muscles and proliferative retinopathy. However, high levels also occur in actively growing human intracranial tumours but it is not noticeably elevated in rheumatoid arthritic synovial fluid. Its extreme potency and low molecular mass make its structural determination difficult. Possible therapeutic applications would be in the treatment of ischaemic ulcers, acceleration of fracture repair, infertility and more modestly in the correction of baldness. Analogues of ESAF could be of value in treating angiogenic diseases such as psoriasis and proliferative retinopathy.
Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy

PubMed Central

Fry, Christopher S.; Lee, Jonah D.; Jackson, Janna R.; Kirby, Tyler J.; Stasko, Shawn A.; Liu, Honglu; Dupont-Versteegden, Esther E.; McCarthy, John J.; Peterson, Charlotte A.

2014-01-01

Our aim in the current study was to determine the necessity of satellite cells for long-term muscle growth and maintenance. We utilized a transgenic Pax7-DTA mouse model, allowing for the conditional depletion of > 90% of satellite cells with tamoxifen treatment. Synergist ablation surgery, where removal of synergist muscles places functional overload on the plantaris, was used to stimulate robust hypertrophy. Following 8 wk of overload, satellite cell-depleted muscle demonstrated an accumulation of extracellular matrix (ECM) and fibroblast expansion that resulted in reduced specific force of the plantaris. Although the early growth response was normal, an attenuation of hypertrophy measured by both muscle wet weight and fiber cross-sectional area occurred in satellite cell-depleted muscle. Isolated primary myogenic progenitor cells (MPCs) negatively regulated fibroblast ECM mRNA expression in vitro, suggesting a novel role for activated satellite cells/MPCs in muscle adaptation. These results provide evidence that satellite cells regulate the muscle environment during growth.—Fry, C. S., Lee, J. D., Jackson, J. R., Kirby, T. J., Stasko, S. A., Liu, H., Dupont-Versteegden, E. E., McCarthy, J. J., Peterson, C. A. Regulation of the muscle fiber microenvironment by activated satellite cells during hypertrophy. PMID:24376025
Implantable power generation system utilizing muscle contractions excited by electrical stimulation.

PubMed

Sahara, Genta; Hijikata, Wataru; Tomioka, Kota; Shinshi, Tadahiko

2016-06-01

An implantable power generation system driven by muscle contractions for supplying power to active implantable medical devices, such as pacemakers and neurostimulators, is proposed. In this system, a muscle is intentionally contracted by an electrical stimulation in accordance with the demands of the active implantable medical device for electrical power. The proposed system, which comprises a small electromagnetic induction generator, electrodes with an electrical circuit for stimulation and a transmission device to convert the linear motion of the muscle contractions into rotational motion for the magneto rotor, generates electrical energy. In an ex vivo demonstration using the gastrocnemius muscle of a toad, which was 28 mm in length and weighed 1.3 g, the electrical energy generated by the prototype exceeded the energy consumed for electrical stimulation, with the net power being 111 µW. It was demonstrated that the proposed implantable power generation system has the potential to replace implantable batteries for active implantable medical devices. © IMechE 2016.
Pelvic floor muscle exercise by biofeedback and electrical stimulation to reinforce the pelvic floor muscle after normal delivery.

PubMed

Lee, In Sook; Choi, Euy Soon

2006-12-01

This study was conducted to investigate the effectiveness of pelvic floor muscle exercise using biofeedback and electrical stimulation after normal delivery. The subjects of this study were 49 (experimental group: 25, control group: 24) postpartum women who passed 6 weeks after normal delivery without complication of pregnancy, delivery and postpartum. The experimental group was applied to the pelvic muscle enforcement program by biofeedback and electrical stimulation for 30 minutes per session, twice a week for 6 weeks, after then self-exercise of pelvic floor muscle was done 50-60 repetition per session, 3 times a day for 6 weeks. Maximum pressure of pelvic floor muscle contraction (MPPFMC), average pressure of pelvic floor muscle contraction (APPFMC), duration time of pelvic floor muscle contraction (DTPFMC) and the subjective lower urinary symptoms were measured by digital perineometer and Bristol Female Urinary Symptom Questionnaire and compared between two groups prior to trial, at the end of treatment and 6 weeks after treatment. The results of this study indicated that MPPFMC, APPFMC, DTPFMC were significantly increased and subjective lower urinary symptoms were significantly decreased after treatment in the experimental group than in the control group. This study suggested that the pelvic floor muscle exercise using biofeedback and electrical stimulation might be a safer and more effective program for reinforcing pelvic floor muscle after normal delivery.
Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Shansky, Janet; Karlisch, Patricia; Solerssi, Rosa Lopez

1991-01-01

Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins E2 and F2(alpha) which regulate protein turnover rates and muscle cell growth. Mechnical stimulation significantly increases the breakdown rate of (3)H-arachidonic acid labelled phospholipids, releasing free (3)H-arachidonic acid, and the rate-limiting precursor of prostaglandin synthesis. Mechanical stimulation also significantly increases (3)H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-2-(3)H inositol labelled phospholipids. Phospholipase A2, phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are activated by stretch. The lipase inhibitors bromophenacylbromide and RHC80267 together reduce stretch-induced prostaglandin production by 73-83 percent. The stretch-induced increases in prostaglandin production, (3)H-arachidonic acid labelled phospholipid breakdown, and (3)H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-2-(3)H inositol labelled phospholipids are dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and prostaglandins through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.
Mechanical stimulation of skeletal muscle generates lipid-related second messengers by phospholipase activation

NASA Technical Reports Server (NTRS)

Vandenburgh, H. H.; Shansky, J.; Karlisch, P.; Solerssi, R. L.

1993-01-01

Repetitive mechanical stimulation of cultured avian skeletal muscle increases the synthesis of prostaglandins (PG) E2 and F2 alpha which regulate protein turnover rates and muscle cell growth. These stretch-induced PG increases are reduced in low extracellular calcium medium and by specific phospholipase inhibitors. Mechanical stimulation increases the breakdown rate of 3H-arachidonic acid labelled phospholipids, releasing free 3H-arachidonic acid, the rate-limiting precursor of PG synthesis. Mechanical stimulation also increases 3H-arachidonic acid labelled diacylglycerol formation and intracellular levels of inositol phosphates from myo-[2-3H]inositol labelled phospholipids. Phospholipase A2 (PLA2), phosphatidylinositol-specific phospholipase C (PLC), and phospholipase D (PLD) are all activated by stretch. The stretch-induced increases in PG production, 3H-arachidonic acid labelled phospholipid breakdown, and 3H-arachidonic acid labelled diacylglycerol formation occur independently of cellular electrical activity (tetrodotoxin insensitive) whereas the formation of inositol phosphates from myo-[2-3H]inositol labelled phospholipids is dependent on cellular electrical activity. These results indicate that mechanical stimulation increases the lipid-related second messengers arachidonic acid, diacylglycerol, and PG through activation of specific phospholipases such as PLA2 and PLD, but not by activation of phosphatidylinositol-specific PLC.
Pairing Voluntary Movement and Muscle-Located Electrical Stimulation Increases Cortical Excitability

PubMed Central

Jochumsen, Mads; Niazi, Imran K.; Signal, Nada; Nedergaard, Rasmus W.; Holt, Kelly; Haavik, Heidi; Taylor, Denise

2016-01-01

Learning new motor skills has been correlated with increased cortical excitability. In this study, different location of electrical stimulation (ES), nerve, or muscle, was paired with voluntary movement to investigate if ES paired with voluntary movement (a) would increase the excitability of cortical projections to tibialis anterior and (b) if stimulation location mattered. Cortical excitability changes were quantified using motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) at varying intensities during four conditions. Twelve healthy subjects performed 50 dorsiflexions at the ankle during nerve or muscle ES at motor threshold (MTh). ES alone was delivered 50 times and the movement was performed 50 times. A significant increase in the excitability from pre- to post-intervention (P = 0.0061) and pre- to 30 min post-intervention (P = 0.017) measurements was observed when voluntary movement was paired with muscle ES located at tibialis anterior. An increase of 50 ± 57 and 28 ± 54% in the maximum MEPs was obtained for voluntary movement paired with muscle-located and nerve-located ES, respectively. The maximum MEPs for voluntary movement alone and muscle-located ES alone were −5 ± 28 and 2 ± 42%, respectively. Pairing voluntary movement with muscle-located ES increases excitability of corticospinal projections of tibialis anterior in healthy participants. This finding suggests that active participation during muscle-located ES protocols increases cortical excitability to a greater extent than stimulation alone. The next stage of this research is to investigate the effect in people with stroke. The results may have implications for motor recovery in patients with motor impairments following neurological injury. PMID:27733823
Proliferation of smooth muscle cells stimulated by Porphyromonas gingivalis is inhibited by apple polyphenol.

PubMed

Inaba, Hiroaki; Tagashira, Motoyuki; Kanda, Tomomasa; Amano, Atsuo

2011-11-01

Porphyromonas gingivalis (Pg) is thought to be involved in the progression of occlusive arterial lesions, whereas vascular smooth muscle cell (SMC) proliferation is considered to be involved in occlusive arterial disease. We previously showed that bacteremia caused by Pg infection induced proliferation of mouse aortic SMCs. Furthermore, human SMCs stimulated with human plasma incubated with Pg showed a marked transformation from the contractile to proliferative phenotype. In the present study, we examine the involvement of Pg gingipains and fimbriae in induction of the SMC transformation and proliferation, and effective inhibitors. Pg strains including gingipain- and fimbria-null mutants were incubated in human plasma, after which the bacteria were removed and the supernatants were added to cultured SMCs. To evaluate the effects of inhibitors, Pg organisms were incubated in plasma in the presence of apple polyphenol (AP), epigallocatechin gallate, KYT-1 (Arg-gingipain inhibitor), and KYT-36 (Lys-gingipain inhibitor). Plasma supernatants from wild-type and fimbria-mutant cultures markedly stimulated cellular proliferation, whereas those containing gingipain-null mutants showed negligible effects. SMC proliferation was also induced by plasma treated with trypsin. Furthermore, plasma supernatants cultured in the presence of KYT-1/KYT-36 and AP showed significant inhibitory effects on SMC proliferation, whereas cultures with epigallocatechin gallate did not. Our results suggest that Pg gingipains are involved in the induction of SMC transformation and proliferation, whereas this was inhibited by AP.
Verification of an optimized stimulation point on the abdominal wall for transcutaneous neuromuscular electrical stimulation for activation of deep lumbar stabilizing muscles.

PubMed

Baek, Seung Ok; Cho, Hee Kyung; Jung, Gil Su; Son, Su Min; Cho, Yun Woo; Ahn, Sang Ho

2014-09-01

Transcutaneous neuromuscular electrical stimulation (NMES) can stimulate contractions in deep lumbar stabilizing muscles. An optimal protocol has not been devised for the activation of these muscles by NMES, and information is lacking regarding an optimal stimulation point on the abdominal wall. The goal was to determine a single optimized stimulation point on the abdominal wall for transcutaneous NMES for the activation of deep lumbar stabilizing muscles. Ultrasound images of the spinal stabilizing muscles were captured during NMES at three sites on the lateral abdominal wall. After an optimal location for the placement of the electrodes was determined, changes in the thickness of the lumbar multifidus (LM) were measured during NMES. Three stimulation points were investigated using 20 healthy physically active male volunteers. A reference point R, 1 cm superior to the iliac crest along the midaxillary line, was used. Three study points were used: stimulation point S1 was located 2 cm superior and 2 cm medial to the anterior superior iliac spine, stimulation point S3 was 2 cm below the lowest rib along the same sagittal plane as S1, and stimulation point S2 was midway between S1 and S3. Sessions were conducted stimulating at S1, S2, or S3 using R for reference. Real-time ultrasound imaging (RUSI) of the abdominal muscles was captured during each stimulation session. In addition, RUSI images were captured of the LM during stimulation at S1. Thickness, as measured by RUSI, of the transverse abdominis (TrA), obliquus internus, and obliquus externus was greater during NMES than at rest for all three study points (p<.05). Transverse abdominis was significantly stimulated more by NMES at S1 than at the other points (p<.05). The LM thickness was also significantly greater during NMES at S1 than at rest (p<.05). Neuromuscular electrical stimulation at S1 optimally activated deep spinal stabilizing muscles, TrA and LM, as evidenced by RUSI. The authors recommend this
Induction of functional tissue-engineered skeletal muscle constructs by defined electrical stimulation.

PubMed

Ito, Akira; Yamamoto, Yasunori; Sato, Masanori; Ikeda, Kazushi; Yamamoto, Masahiro; Fujita, Hideaki; Nagamori, Eiji; Kawabe, Yoshinori; Kamihira, Masamichi

2014-04-24

Electrical impulses are necessary for proper in vivo skeletal muscle development. To fabricate functional skeletal muscle tissues in vitro, recapitulation of the in vivo niche, including physical stimuli, is crucial. Here, we report a technique to engineer skeletal muscle tissues in vitro by electrical pulse stimulation (EPS). Electrically excitable tissue-engineered skeletal muscle constructs were stimulated with continuous electrical pulses of 0.3 V/mm amplitude, 4 ms width, and 1 Hz frequency, resulting in a 4.5-fold increase in force at day 14. In myogenic differentiation culture, the percentage of peak twitch force (%Pt) was determined as the load on the tissue constructs during the artificial exercise induced by continuous EPS. We optimized the stimulation protocol, wherein the tissues were first subjected to 24.5%Pt, which was increased to 50-60%Pt as the tissues developed. This technique may be a useful approach to fabricate tissue-engineered functional skeletal muscle constructs.
A 310-bp minimal promoter mediates smooth muscle cell-specific expression of telokin.

PubMed

Smith, A F; Bigsby, R M; Word, R A; Herring, B P

1998-05-01

A cell-specific promoter located in an intron of the smooth muscle myosin light chain kinase gene directs transcription of telokin exclusively in smooth muscle cells. Transgenic mice were generated in which a 310-bp rabbit telokin promoter fragment, extending from -163 to +147, was used to drive expression of simian virus 40 large T antigen. Smooth muscle-specific expression of the T-antigen transgene paralleled that of the endogenous telokin gene in all smooth muscle tissues except uterus. The 310-bp promoter fragment resulted in very low levels of transgene expression in uterus; in contrast, a transgene driven by a 2.4-kb fragment (-2250 to +147) resulted in high levels of transgene expression in uterine smooth muscle. Telokin expression levels correlate with the estrogen status of human myometrial tissues, suggesting that deletion of an estrogen response element (ERE) may account for the low levels of transgene expression driven by the 310-bp rabbit telokin promoter in uterine smooth muscle. Experiments in A10 smooth muscle cells directly showed that reporter gene expression driven by the 2.4-kb, but not 310-bp, promoter fragment could be stimulated two- to threefold by estrogen. This stimulation was mediated through an ERE located between -1447 and -1474. Addition of the ERE to the 310-bp fragment restored estrogen responsiveness in A10 cells. These data demonstrate that in addition to a minimal 310-bp proximal promoter at least one distal cis-acting regulatory element is required for telokin expression in uterine smooth muscle. The distal element may include an ERE between -1447 and -1474.
Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation.

PubMed

Koo, Bon Hyeock; Yi, Bong Gu; Wang, Wi Kwang; Ko, In Young; Hoe, Kwang Lae; Kwon, Young Guen; Won, Moo Ho; Kim, Young Myeong; Lim, Hyun Kyo; Ryoo, Sungwoo

2018-05-01

Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms. Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin. Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation. Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation. © Copyright: Yonsei University College of Medicine 2018.
Arginase Inhibition Suppresses Native Low-Density Lipoprotein-Stimulated Vascular Smooth Muscle Cell Proliferation by NADPH Oxidase Inactivation

PubMed Central

Wang, Wi-Kwang; Ko, In-Young; Hoe, Kwang-Lae; Kwon, Young-Guen; Won, Moo-Ho; Kim, Young-Myeong

2018-01-01

Purpose Vascular smooth muscle cell (VSMC) proliferation induced by native low-density lipoprotein (nLDL) stimulation is dependent on superoxide production from activated NADPH oxidase. The present study aimed to investigate whether the novel arginase inhibitor limonin could suppress nLDL-induced VSMC proliferation and to examine related mechanisms. Materials and Methods Isolated VSMCs from rat aortas were treated with nLDL, and cell proliferation was measured by WST-1 and BrdU assays. NADPH oxidase activation was evaluated by lucigenin-induced chemiluminescence, and phosphorylation of protein kinase C (PKC) βII and extracellular signal-regulated kinase (ERK) 1/2 was determined by western blot analysis. Mitochondrial reactive oxygen species (ROS) generation was assessed using MitoSOX-red, and intracellular L-arginine concentrations were determined by high-performance liquid chromatography (HPLC) in the presence or absence of limonin. Results Limonin inhibited arginase I and II activity in the uncompetitive mode, and prevented nLDL-induced VSMC proliferation in a p21Waf1/Cip1-dependent manner without affecting arginase protein levels. Limonin blocked PKCβII phosphorylation, but not ERK1/2 phosphorylation, and translocation of p47phox to the membrane was decreased, as was superoxide production in nLDL-stimulated VSMCs. Moreover, mitochondrial ROS generation was increased by nLDL stimulation and blocked by preincubation with limonin. Mitochondrial ROS production was responsible for the phosphorylation of PKCβII. HPLC analysis showed that arginase inhibition with limonin increases intracellular L-arginine concentrations, but decreases polyamine concentrations. L-Arginine treatment prevented PKCβII phosphorylation without affecting ERK1/2 phosphorylation. Conclusion Increased L-arginine levels following limonin-dependent arginase inhibition prohibited NADPH oxidase activation in a PKCβII-dependent manner, and blocked nLDL-stimulated VSMC proliferation. PMID
In Vivo Demonstration of a Self-Sustaining, Implantable, Stimulated-Muscle-Powered Piezoelectric Generator Prototype

PubMed Central

Lewandowski, B. E.; Kilgore, K. L.; Gustafson, K. J.

2010-01-01

An implantable, stimulated-muscle-powered piezoelectric active energy harvesting generator was previously designed to exploit the fact that the mechanical output power of muscle is substantially greater than the electrical power necessary to stimulate the muscle’s motor nerve. We reduced to practice the concept by building a prototype generator and stimulator. We demonstrated its feasibility in vivo, using rabbit quadriceps to drive the generator. The generated power was sufficient for self-sustaining operation of the stimulator and additional harnessed power was dissipated through a load resistor. The prototype generator was developed and the power generating capabilities were tested with a mechanical muscle analog. In vivo generated power matched the mechanical muscle analog, verifying its usefulness as a test-bed for generator development. Generator output power was dependent on the muscle stimulation parameters. Simulations and in vivo testing demonstrated that for a fixed number of stimuli/minute, two stimuli applied at a high frequency generated greater power than single stimuli or tetanic contractions. Larger muscles and circuitry improvements are expected to increase available power. An implanted, self-replenishing power source has the potential to augment implanted battery or transcutaneously powered electronic medical devices. PMID:19657742
Regulation of autophagy in human skeletal muscle: effects of exercise, exercise training and insulin stimulation

PubMed Central

Fritzen, Andreas M.; Madsen, Agnete B.; Kleinert, Maximilian; Treebak, Jonas T.; Lundsgaard, Anne‐Marie; Jensen, Thomas E.; Richter, Erik A.; Wojtaszewski, Jørgen; Kiens, Bente

2016-01-01

Key points Regulation of autophagy in human muscle in many aspects differs from the majority of previous reports based on studies in cell systems and rodent muscle.An acute bout of exercise and insulin stimulation reduce human muscle autophagosome content.An acute bout of exercise regulates autophagy by a local contraction‐induced mechanism.Exercise training increases the capacity for formation of autophagosomes in human muscle.AMPK activation during exercise seems insufficient to regulate autophagosome content in muscle, while mTORC1 signalling via ULK1 probably mediates the autophagy‐inhibiting effect of insulin. Abstract Studies in rodent muscle suggest that autophagy is regulated by acute exercise, exercise training and insulin stimulation. However, little is known about the regulation of autophagy in human skeletal muscle. Here we investigate the autophagic response to acute one‐legged exercise, one‐legged exercise training and subsequent insulin stimulation in exercised and non‐exercised human muscle. Acute one‐legged exercise decreased (P<0.01) lipidation of microtubule‐associated protein 1A/1B‐light chain 3 (LC3) (∼50%) and the LC3‐II/LC3‐I ratio (∼60%) indicating that content of autophagosomes decreases with exercise in human muscle. The decrease in LC3‐II/LC3‐I ratio did not correlate with activation of 5′AMP activated protein kinase (AMPK) trimer complexes in human muscle. Consistently, pharmacological AMPK activation with 5‐aminoimidazole‐4‐carboxamide riboside (AICAR) in mouse muscle did not affect the LC3‐II/LC3‐I ratio. Four hours after exercise, insulin further reduced (P<0.01) the LC3‐II/LC3‐I ratio (∼80%) in muscle of the exercised and non‐exercised leg in humans. This coincided with increased Ser‐757 phosphorylation of Unc51 like kinase 1 (ULK1), which is suggested as a mammalian target of rapamycin complex 1 (mTORC1) target. Accordingly, inhibition of mTOR signalling in mouse muscle prevented the
Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

Neutral sphingomyelinase-3 mediates TNF-stimulated oxidant activity in skeletal muscle.

PubMed

Moylan, Jennifer S; Smith, Jeffrey D; Wolf Horrell, Erin M; McLean, Julie B; Deevska, Gergana M; Bonnell, Mark R; Nikolova-Karakashian, Mariana N; Reid, Michael B

2014-01-01

Sphingolipid and oxidant signaling affect glucose uptake, atrophy, and force production of skeletal muscle similarly and both are stimulated by tumor necrosis factor (TNF), suggesting a connection between systems. Sphingolipid signaling is initiated by neutral sphingomyelinase (nSMase), a family of agonist-activated effector enzymes. Northern blot analyses suggest that nSMase3 may be a striated muscle-specific nSMase. The present study tested the hypothesis that nSMase3 protein is expressed in skeletal muscle and functions to regulate TNF-stimulated oxidant production. We demonstrate constitutive nSMase activity in skeletal muscles of healthy mice and humans and in differentiated C2C12 myotubes. nSMase3 (Smpd4 gene) mRNA is highly expressed in muscle. An nSMase3 protein doublet (88 and 85 kD) is derived from alternative mRNA splicing of exon 11. The proteins partition differently. The full-length 88 kD isoform (nSMase3a) fractionates with membrane proteins that are resistant to detergent extraction; the 85 kD isoform lacking exon 11 (nSMase3b) is more readily extracted and fractionates with detergent soluble membrane proteins; neither variant is detected in the cytosol. By immunofluorescence microscopy, nSMase3 resides in both internal and sarcolemmal membranes. Finally, myotube nSMase activity and cytosolic oxidant activity are stimulated by TNF. Both if these responses are inhibited by nSMase3 knockdown. These findings identify nSMase3 as an intermediate that links TNF receptor activation, sphingolipid signaling, and skeletal muscle oxidant production. Our data show that nSMase3 acts as a signaling nSMase in skeletal muscle that is essential for TNF-stimulated oxidant activity.
21 CFR 890.1850 - Diagnostic muscle stimulator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Diagnostic muscle stimulator. 890.1850 Section 890.1850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1850 Diagnostic...
21 CFR 890.1850 - Diagnostic muscle stimulator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Diagnostic muscle stimulator. 890.1850 Section 890.1850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1850 Diagnostic...
21 CFR 890.1850 - Diagnostic muscle stimulator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Diagnostic muscle stimulator. 890.1850 Section 890.1850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1850 Diagnostic...
21 CFR 890.1850 - Diagnostic muscle stimulator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Diagnostic muscle stimulator. 890.1850 Section 890.1850 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1850 Diagnostic...
Arginase inhibition reduces interleukin-1β-stimulated vascular smooth muscle cell proliferation by increasing nitric oxide synthase-dependent nitric oxide production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Jeongyeon; Ryoo, Sungwoo, E-mail: ryoosw08@kangwon.ac.kr

2013-06-07

Highlights: •Arginase inhibition suppressed proliferation of IL-1β-stimulated VSMCs in dose-dependent manner. •NO production from IL-1β-induced iNOS expression was augmented by arginase inhibition, reducing VSMC proliferation. •Incubation with cGMP analogues abolished IL-1β-dependent proliferation of VSMCs. -- Abstract: We investigated whether arginase inhibition suppressed interleukin (IL)-1β-stimulated proliferation in vascular smooth muscle cells (VSMCs) and the possible mechanisms involved. IL-1β stimulation increased VSMC proliferation, while the arginase inhibitor BEC and transfection of the antisense (AS) oligonucleotide against arginase I decreased VSMC proliferation and was associated with increased protein content of the cell cycle regulator p21Waf1/Cip1. IL-1β incubation induced inducible nitric oxide synthase (iNOS)more » mRNA expression and protein levels in a dose-dependent manner, but did not affect arginase I and II expression. Consistent with this data, IL-1β stimulation resulted in increase in NO production that was significantly augmented by arginase inhibition. The specific iNOS inhibitor 1400W abolished IL-1β-mediated NO production and further accentuated IL-1β-stimulated cell proliferation. Incubation with NO donors GSNO and DETA/NO in the presence of IL-1β abolished VSMCs proliferation and increased p21Waf1/Cip1 protein content. Furthermore, incubation with the cGMP analogue 8-Br-cGMP prevented IL-1β-induced VSMCs proliferation. In conclusion, arginase inhibition augmented iNOS-dependent NO production that resulted in suppression of IL-1β-induced VSMCs proliferation in a cGMP-dependent manner.« less
Potential of laryngeal muscle regeneration using induced pluripotent stem cell-derived skeletal muscle cells.

PubMed

Dirja, Bayu Tirta; Yoshie, Susumu; Ikeda, Masakazu; Imaizumi, Mitsuyoshi; Nakamura, Ryosuke; Otsuki, Koshi; Nomoto, Yukio; Wada, Ikuo; Hazama, Akihiro; Omori, Koichi

2016-01-01

Conclusion Induced pluripotent stem (iPS) cells may be a new potential cell source for laryngeal muscle regeneration in the treatment of vocal fold atrophy after recurrent laryngeal nerve paralysis. Objectives Unilateral vocal fold paralysis can lead to degeneration, atrophy, and loss of force of the thyroarytenoid muscle. At present, there are some treatments such as thyroplasty, arytenoid adduction, and vocal fold injection. However, such treatments cannot restore reduced mass of the thyroarytenoid muscle. iPS cells have been recognized as supplying a potential resource for cell transplantation. The aim of this study was to assess the effectiveness of the use of iPS cells for the regeneration of laryngeal muscle through the evaluation of both in vitro and in vivo experiments. Methods Skeletal muscle cells were generated from tdTomato-labeled iPS cells using embryoid body formation. Differentiation into skeletal muscle cells was analyzed by gene expression and immunocytochemistry. The tdTomato-labeled iPS cell-derived skeletal muscle cells were transplanted into the left atrophied thyroarytenoid muscle. To evaluate the engraftment of these cells after transplantation, immunohistochemistry was performed. Results The tdTomato-labeled iPS cells were successfully differentiated into skeletal muscle cells through an in vitro experiment. These cells survived in the atrophied thyroarytenoid muscle after transplantation.
Hydrogen peroxide stimulates ubiquitin-conjugating activity and expression of genes for specific E2 and E3 proteins in skeletal muscle myotubes

NASA Technical Reports Server (NTRS)

Li, Yi-Ping; Chen, Yuling; Li, Andrew S.; Reid, Michael B.

2003-01-01

Reactive oxygen species (ROS) are thought to promote muscle atrophy in chronic wasting diseases, but the underlying mechanism has not been determined. Here we show that H2O2 stimulates ubiquitin conjugation to muscle proteins through transcriptional regulation of the enzymes (E2 and E3 proteins) that conjugate ubiquitin to muscle proteins. Incubation of C2C12 myotubes with 100 microM H2O2 increased the rate of 125I-labeled ubiquitin conjugation to muscle proteins in whole cell extracts. This response required at least 4-h exposure to H2O2 and persisted for at least 24 h. Preincubating myotubes with cycloheximide or actinomycin D blocked H2O2 stimulation of ubiquitin-conjugating activity, suggesting that gene transcription is required. Northern blot analyses revealed that H2O2 upregulates expression of specific E3 and E2 proteins that are thought to regulate muscle catabolism, including atrogin1/MAFbx, MuRF1, and E214k. These results suggest that ROS stimulate protein catabolism in skeletal muscle by upregulating the ubiquitin conjugation system.
Contributions to muscle force and EMG by combined neural excitation and electrical stimulation

NASA Astrophysics Data System (ADS)

Crago, Patrick E.; Makowski, Nathaniel S.; Cole, Natalie M.

2014-10-01

Objective. Stimulation of muscle for research or clinical interventions is often superimposed on ongoing physiological activity without a quantitative understanding of the impact of the stimulation on the net muscle activity and the physiological response. Experimental studies show that total force during stimulation is less than the sum of the isolated voluntary and stimulated forces, but the occlusion mechanism is not understood. Approach. We develop a model of efferent motor activity elicited by superimposing stimulation during a physiologically activated contraction. The model combines action potential interactions due to collision block, source resetting, and refractory periods with previously published models of physiological motor unit recruitment, rate modulation, force production, and EMG generation in human first dorsal interosseous muscle to investigate the mechanisms and effectiveness of stimulation on the net muscle force and EMG. Main results. Stimulation during a physiological contraction demonstrates partial occlusion of force and the neural component of the EMG, due to action potential interactions in motor units activated by both sources. Depending on neural and stimulation firing rates as well as on force-frequency properties, individual motor unit forces can be greater, smaller, or unchanged by the stimulation. In contrast, voluntary motor unit EMG potentials in simultaneously stimulated motor units show progressive occlusion with increasing stimulus rate. The simulations predict that occlusion would be decreased by a reverse stimulation recruitment order. Significance. The results are consistent with and provide a mechanistic interpretation of previously published experimental evidence of force occlusion. The models also predict two effects that have not been reported previously—voluntary EMG occlusion and the advantages of a proximal stimulation site. This study provides a basis for the rational design of both future experiments and clinical
Contributions to muscle force and EMG by combined neural excitation and electrical stimulation

PubMed Central

Crago, Patrick E; Makowski, Nathaniel S; Cole, Natalie M

2014-01-01

Objective Stimulation of muscle for research or clinical interventions is often superimposed on ongoing physiological activity, without a quantitative understanding of the impact of the stimulation on the net muscle activity and the physiological response. Experimental studies show that total force during stimulation is less than the sum of the isolated voluntary and stimulated forces, but the occlusion mechanism is not understood. Approach We develop a model of efferent motor activity elicited by superimposing stimulation during a physiologically activated contraction. The model combines action potential interactions due to collision block, source resetting, and refractory periods with previously published models of physiological motor unit recruitment, rate modulation, force production, and EMG generation in human first dorsal interosseous muscle to investigate the mechanisms and effectiveness of stimulation on the net muscle force and EMG. Main Results Stimulation during a physiological contraction demonstrates partial occlusion of force and the neural component of the EMG, due to action potential interactions in motor units activated by both sources. Depending on neural and stimulation firing rates as well as on force-frequency properties, individual motor unit forces can be greater, smaller, or unchanged by the stimulation. In contrast, voluntary motor unit EMG potentials in simultaneously stimulated motor units show progressive occlusion with increasing stimulus rate. The simulations predict that occlusion would be decreased by a reverse stimulation recruitment order. Significance The results are consistent with and provide a mechanistic interpretation of previously published experimental evidence of force occlusion. The models also predict two effects that have not been reported previously - voluntary EMG occlusion and the advantages of a proximal stimulation site. This study provides a basis for the rational design of both future experiments and clinical
Electrical Stimulation Promotes Cardiac Differentiation of Human Induced Pluripotent Stem Cells

PubMed Central

Hernández, Damián; Millard, Rodney; Sivakumaran, Priyadharshini; Wong, Raymond C. B.; Crombie, Duncan E.; Hewitt, Alex W.; Liang, Helena; Hung, Sandy S. C.; Pébay, Alice; Shepherd, Robert K.; Dusting, Gregory J.; Lim, Shiang Y.

2016-01-01

Background. Human induced pluripotent stem cells (iPSCs) are an attractive source of cardiomyocytes for cardiac repair and regeneration. In this study, we aim to determine whether acute electrical stimulation of human iPSCs can promote their differentiation to cardiomyocytes. Methods. Human iPSCs were differentiated to cardiac cells by forming embryoid bodies (EBs) for 5 days. EBs were then subjected to brief electrical stimulation and plated down for 14 days. Results. In iPS(Foreskin)-2 cell line, brief electrical stimulation at 65 mV/mm or 200 mV/mm for 5 min significantly increased the percentage of beating EBs present by day 14 after plating. Acute electrical stimulation also significantly increased the cardiac gene expression of ACTC1, TNNT2, MYH7, and MYL7. However, the cardiogenic effect of electrical stimulation was not reproducible in another iPS cell line, CERA007c6. Beating EBs from control and electrically stimulated groups expressed various cardiac-specific transcription factors and contractile muscle markers. Beating EBs were also shown to cycle calcium and were responsive to the chronotropic agents, isoproterenol and carbamylcholine, in a concentration-dependent manner. Conclusions. Our results demonstrate that brief electrical stimulation can promote cardiac differentiation of human iPS cells. The cardiogenic effect of brief electrical stimulation is dependent on the cell line used. PMID:26788064
"Fast" and "slow" muscle fibres in hindlimb muscles of adult rats regenerate from intrinsically different satellite cells.

PubMed

Kalhovde, J M; Jerkovic, R; Sefland, I; Cordonnier, C; Calabria, E; Schiaffino, S; Lømo, T

2005-02-01

Myosin heavy chain (MyHC) expression was examined in regenerating fast extensor digitorum longus (EDL) and slow soleus (SOL) muscles of adult rats. Myotoxic bupivacaine was injected into SOL and EDL and the muscles were either denervated or neuromuscularly blocked by tetrodotoxin (TTX) on the sciatic nerve. Three to 10 or 30 days later, denervated SOL or EDL, or innervated but neuromuscularly blocked EDL received a slow 20 Hz stimulus pattern through electrodes implanted on the muscles or along the fibular nerve to EDL below the TTX block. In addition, denervated SOL and EDL received a fast 100 Hz stimulus pattern. Denervated EDL and SOL stimulated with the same slow stimulus pattern expressed different amounts of type 1 MyHC protein (8% versus 35% at 10 days, 13% versus 87% at 30 days). Stimulated denervated and stimulated innervated (TTX blocked) EDL expressed the same amounts of type 1, 2A, 2X and 2B MyHC proteins. Cross-sections treated for in situ hybridization and immunocytochemistry showed expression of type 1 MyHC in all SOL fibres but only in some scattered single or smaller groups of fibres in EDL. The results suggest that muscle fibres regenerate from intrinsically different satellite cells in EDL and SOL and within EDL. However, induction by different extrinsic factors arising in extracellular matrix or from muscle position and usage in the limb has not been excluded. No evidence for nerve-derived trophic influences was obtained.
Assessing viability of extracorporeal preserved muscle transplants using external field stimulation: a novel tool to improve methods prolonging bridge-to-transplantation time

PubMed Central

Taeger, Christian D.; Friedrich, Oliver; Dragu, Adrian; Weigand, Annika; Hobe, Frieder; Drechsler, Caroline; Geppert, Carol I.; Arkudas, Andreas; Münch, Frank; Buchholz, Rainer; Pollmann, Charlotte; Schramm, Axel; Birkholz, Torsten; Horch, Raymund E.; Präbst, Konstantin

2015-01-01

Preventing ischemia-related cell damage is a priority when preserving tissue for transplantation. Perfusion protocols have been established for a variety of applications and proven to be superior to procedures used in clinical routine. Extracorporeal perfusion of muscle tissue though cumbersome is highly desirable since it is highly susceptible to ischemia-related damage. To show the efficacy of different perfusion protocols external field stimulation can be used to immediately visualize improvement or deterioration of the tissue during active and running perfusion protocols. This method has been used to show the superiority of extracorporeal perfusion using porcine rectus abdominis muscles perfused with heparinized saline solution. Perfused muscles showed statistically significant higher ability to exert force compared to nonperfused ones. These findings can be confirmed using Annexin V as marker for cell damage, perfusion of muscle tissue limits damage significantly compared to nonperfused tissue. The combination of extracorporeal perfusion and external field stimulation may improve organ conservation research. PMID:26145230
Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone

DTIC Science & Technology

2016-10-01

AWARD NUMBER: W81XWH-14-2-0190 TITLE: Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone PRINCIPAL...including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and...2015 - 29 Sep 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone
Lymphatic Muscle Cells in Rat Mesenteric Lymphatic Vessels of Various Ages

PubMed Central

Bridenbaugh, Eric A.; Nizamutdinova, Irina Tsoy; Jupiter, Daniel; Nagai, Takashi; Thangaswamy, Sangeetha; Chatterjee, Victor

2013-01-01

Abstract Background Recent studies on aging-associated changes in mesenteric lymph flow in situ demonstrated predominance of the severe negative chronotropic effect of aging on the contractility of aged mesenteric lymphatic vessels (MLV). At the same time, contraction amplitude of the aged vessels was only slightly diminished by aging and can be rapidly stimulated within 5–15 minutes. However, the detailed quantitative evaluation of potential aging-associated changes in muscle cells investiture in MLV has never been performed. Methods and Results In this study we, for the first time, performed detailed evaluation of muscle cells investiture in MLV in reference to the position of lymphatic valve in different zones of lymphangion within various age groups (3-mo, 9-mo and 24-mo Fischer-344 rats). Using visual and quantitative analyses of the images of MLV immunohistochemically labeled for actin, we confirmed that the zones located close upstream (pre-valve zones) and above lymphatic valves (valve zones) possess the lowest investiture of lymphatic muscle cells. Most of the high muscle cells investiture zones exist downstream to the lymphatic valve (post-valve zones). The muscle cells investiture of these zones is not affected by aging, while pre-valve and valve zones demonstrate significant aging-associated decrease in muscle cells investiture. Conclusions The low muscle cells investiture zones in lymphatic vessels consist of predominantly longitudinally oriented muscle cells which are positioned in pre-valve and valve zones and connect adjacent lymphangions. These cells may provide important functional impact on the biomechanics of the lymphatic valve gating and electrical coupling between lymphangions, while their aging-associated changes may delimit adaptive reserves of aged lymphatic vessels. PMID:23531183
Neuromuscular electrical stimulation prior to presleep protein feeding stimulates the use of protein-derived amino acids for overnight muscle protein synthesis.

PubMed

Dirks, Marlou L; Groen, Bart B L; Franssen, Rinske; van Kranenburg, Janneau; van Loon, Luc J C

2017-01-01

Short periods of muscle disuse result in substantial skeletal muscle atrophy. Recently, we showed that both neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. In this study, we test our hypothesis that NMES can augment the use of presleep protein-derived amino acids for overnight muscle protein synthesis in older men. Twenty healthy, older [69 ± 1 (SE) yr] men were subjected to 24 h of bed rest, starting at 8:00 AM. In the evening, volunteers were subjected to 70-min 1-legged NMES, while the other leg served as nonstimulated control (CON). Immediately following NMES, 40 g of intrinsically l-[1- 13 C]-phenylalanine labeled protein was ingested prior to sleep. Blood samples were taken throughout the night, and muscle biopsies were obtained from both legs in the evening and the following morning (8 h after protein ingestion) to assess dietary protein-derived l-[1- 13 C]-phenylalanine enrichments in myofibrillar protein. Plasma phenylalanine concentrations and plasma l-[1- 13 C]-phenylalanine enrichments increased significantly following protein ingestion and remained elevated for up to 6 h after protein ingestion (P < 0.05). During overnight sleep, myofibrillar protein-bound l-[1- 13 C]-phenylalanine enrichments (MPE) increased to a greater extent in the stimulated compared with the control leg (0.0344 ± 0.0019 vs. 0.0297 ± 0.0016 MPE, respectively; P < 0.01), representing 18 ± 6% greater incorporation of presleep protein-derived amino acids in the NMES compared with CON leg. In conclusion, application of NMES prior to presleep protein feeding stimulates the use of dietary protein-derived amino acids for overnight muscle protein synthesis in older men. Neuromuscular electrical stimulation (NMES) as well as presleep dietary protein ingestion represent effective strategies to stimulate muscle protein synthesis rates. Here we demonstrate that in older
Increase in endothelial cell Ca2+ in response to mouse cremaster muscle contraction

PubMed Central

Duza, Tasmia; Sarelius, Ingrid H

2004-01-01

We addressed the role of endothelial cells (ECs) in metabolic dilatation of skeletal muscle arterioles in anaesthetized mice in situ. Electrical field stimulation was used to contract the cremaster muscle for 15 s at 30 Hz. Diameter was observed using bright field microscopy. In controls, muscle contraction produced a 15.7 ± 1.5 μm dilatation from a baseline of 17.4 ± 1.6 μm. Endothelial denudation (−EC) via intraluminal perfusion of air abolished this response (1.6 ± 1.2 μm in −EC, P < 0.05), identifying endothelium as the primary vascular cell type initiating the dilatation. To investigate the role of EC Ca2+ in metabolic dilatation, arteriolar ECs were loaded with Fluo-4 AM or BAPTA AM by intraluminal perfusion, after which blood flow was re-established. Ca2+ activity of individual ECs was monitored as a function of change from baseline fluorescence using confocal microscopy. In ECs, whole cell Ca2+ increased (>10%, P < 0.05) during muscle contraction, and localized Ca2+ transients were increased (>20%, P < 0.05) during the first minute after contraction. Chelation of EC Ca2+ abolished the dilatations in response to muscle contraction (1.1 ± 0.7 μm, P < 0.05). Inhibition of P1 purinergic receptors (with xanthine amine congener) did not alter the rate of onset of the dilatation (P > 0.05) but decreased its magnitude immediately post stimulation (7.1 ± 0.9 μm, P < 0.05) and during recovery. These findings demonstrate obligatory roles for endothelium and EC Ca2+ during metabolic dilatation in intact arterioles. Furthermore, they suggest that at least two separate pathways mediate the local response, one of which involves stimulation of endothelial P1 purinergic receptors via endogenous adenosine produced during muscle activity. PMID:14694141
Efficient generation of smooth muscle cells from adipose-derived stromal cells by 3D mechanical stimulation can substitute the use of growth factors in vascular tissue engineering.

PubMed

Parvizi, Mojtaba; Bolhuis-Versteeg, Lydia A M; Poot, André A; Harmsen, Martin C

2016-07-01

Occluding artery disease causes a high demand for bioartificial replacement vessels. We investigated the combined use of biodegradable and creep-free poly (1,3-trimethylene carbonate) (PTMC) with smooth muscle cells (SMC) derived by biochemical or mechanical stimulation of adipose tissue-derived stromal cells (ASC) to engineer bioartificial arteries. Biochemical induction of cultured ASC to SMC was done with TGF-β1 for 7d. Phenotype and function were assessed by qRT-PCR, immunodetection and collagen contraction assays. The influence of mechanical stimulation on non-differentiated and pre-differentiated ASC, loaded in porous tubular PTMC scaffolds, was assessed after culturing under pulsatile flow for 14d. Assays included qRT-PCR, production of extracellular matrix and scanning electron microscopy. ASC adhesion and TGF-β1-driven differentiation to contractile SMC on PTMC did not differ from tissue culture polystyrene controls. Mesenchymal and SMC markers were increased compared to controls. Interestingly, pre-differentiated ASC had only marginal higher contractility than controls. Moreover, in 3D PTMC scaffolds, mechanical stimulation yielded well-aligned ASC-derived SMC which deposited ECM. Under the same conditions, pre-differentiated ASC-derived SMC maintained their SMC phenotype. Our results show that mechanical stimulation can replace TGF-β1 pre-stimulation to generate SMC from ASC and that pre-differentiated ASC keep their SMC phenotype with increased expression of SMC markers. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Intramuscular Transplantation and Survival of Freshly Isolated Bone Marrow Cells following Skeletal Muscle Ischemia-reperfusion Injury

DTIC Science & Technology

2013-01-01

2) in a rat I/R model, consis- tent with this time course of functional recovery, evidence of muscle fiber damage and regeneration was still present...Contractile function of the anterior crural muscles was assessed by measuring maximal isometric torque as a function of stimulation frequency (20Y200 Hz...from the direct conver- sion of bone marrowYderived cells to muscle fibers , the paracrine secretory effects of stem cells resident in bone marrow
Expression of an insulin-regulatable glucose carrier in muscle and fat endothelial cells

NASA Astrophysics Data System (ADS)

Vilaró, Senen; Palacín, Manuel; Pilch, Paul F.; Testar, Xavier; Zorzano, Antonio

1989-12-01

INSULIN rapidly stimulates glucose use in the major target tissues, muscle and fat, by modulating a tissue-specific glucose transporter isoform1-6. Access of glucose to the target tissue is restricted by endothelial cells which line the walls of nonfenestrated capillaries of fat and muscle7. Thus, we examined whether the capillary endothelial cells are actively involved in the modulation of glucose availability by these tissues. We report here the abundant expression of the muscle/fat glucose transporter isoform in endothelial cells, using an immunocytochemical analysis with a monoclonal antibody specific for this isoform1. This expression is restricted to endothelial cells from the major insulin target tissues, and it is not detected in brain and liver where insulin does not activate glucose transport. The expression of the muscle/fat transporter isoform in endothelial cells is significantly greater than in the neighbouring muscle and fat cells. Following administration of insulin to animals in vivo, there occurs a rapid increase in the number of muscle/fat transporters present in the lumenal plasma membrane of the capillary endothelial cells. These results document that insulin promotes the translocation of the muscle/fat glucose transporter in endothelial cells. It is therefore likely that endothelial cells play an important role in the regulation of glucose use by the major insulin target tissues in normal and diseased states.

Lysophosphatidic acid-induced ADAM12 expression mediates human adipose tissue-derived mesenchymal stem cell-stimulated tumor growth.

PubMed

Do, Eun Kyoung; Kim, Young Mi; Heo, Soon Chul; Kwon, Yang Woo; Shin, Sang Hun; Suh, Dong-Soo; Kim, Ki-Hyung; Yoon, Man-Soo; Kim, Jae Ho

2012-11-01

Lysophosphatidic acid (LPA) is involved in mesenchymal stem cell-stimulated tumor growth in vivo. However, the molecular mechanism by which mesenchymal stem cells promote tumorigenesis remains elusive. In the present study, we demonstrate that conditioned medium from A549 human lung adenocarcinoma cells (A549 CM) induced the expression of ADAM12, a disintegrin and metalloproteases family member, in human adipose tissue-derived mesenchymal stem cells (hASCs). A549 CM-stimulated ADAM12 expression was abrogated by pretreatment of hASCs with the LPA receptor 1 inhibitor Ki16425 or by small interfering RNA-mediated silencing of LPA receptor 1, suggesting a key role for the LPA-LPA receptor 1 signaling axis in A549 CM-stimulated ADAM12 expression. Silencing of ADAM12 expression using small interfering RNA or short hairpin RNA abrogated LPA-induced expression of both α-smooth muscle actin, a marker of carcinoma-associated fibroblasts, and ADAM12 in hASCs. Using a xenograft transplantation model of A549 cells, we demonstrated that silencing of ADAM12 inhibited the hASC-stimulated in vivo growth of A549 xenograft tumors and the differentiation of transplanted hASCs to α-smooth muscle actin-positive carcinoma-associated fibroblasts. LPA-conditioned medium from hASCs induced the adhesion of A549 cells and silencing of ADAM12 inhibited LPA-induced expression of extracellular matrix proteins, periostin and βig-h3, in hASCs and LPA-conditioned medium-stimulated adhesion of A549 cells. These results suggest a pivotal role for LPA-stimulated ADAM12 expression in tumor growth and the differentiation of hASCs to carcinoma-associated fibroblasts expressing α-smooth muscle actin, periostin, and βig-h3. Copyright © 2012 Elsevier Ltd. All rights reserved.
Specific growth stimulation of cultured smooth muscle cells from spontaneously hypertensive rats by platelet-derived growth factor A-chain homodimer.

PubMed Central

Resink, T J; Scott-Burden, T; Hahn, A W; Rouge, M; Hosang, M; Powell, J S; Bühler, F R

1990-01-01

Cultured vascular smooth muscle cells (VSMC)1 from spontaneously hypertensive rats (SHR) possess specific cell surface receptors for both homodimeric forms of platelet-derived growth factor (PDGF-AA and PDGF-BB), in contrast to cells from normotensive Wistar Kyoto (WKY) animals, which express receptors only for the B-chain form of PDGF. Stimulation of quiescent VSMC from SHR with PDGF-AA resulted in activation of S6-kinase and induction of phosphoinositide catabolism, as well as cellular proliferation when cultures were maintained for prolonged periods with daily supplementation of the growth factor. WKY-derived VSMC showed no response to PDGF-AA, which was consistent with their lack of specific receptors for this homodimer. The responsiveness of quiescent cells from SHR and WKY to the B-chain homodimer was similar. The enhanced growth responsiveness of SHR-derived cells to fetal calf serum, as compared with cells from their normotensive counterparts, may be accounted for in part by their expression of receptors for the AA homodimer of PDGF. PMID:1965150
Transcutaneous calf-muscle electro-stimulation: A prospective treatment for diabetic claudicants?

PubMed

Ellul, Christian; Gatt, Alfred

2016-11-01

First-line therapy for claudicants with diabetes include supervised exercise programmes to improve walking distance. However, exercise comes with a number of barriers and may be contraindicated in certain conditions. The aim of this study was to evaluate whether calf-muscle electro-stimulation improves claudication distance. A prospective, one-group, pretest-posttest study design was employed on 40 participants living with type 2 diabetes mellitus, peripheral artery disease (ankle-brachial pressure index < 0.90) and calf-muscle claudication. Calf-muscle electro-stimulation of varying frequencies (1-250 Hz) was applied on both ischaemic limbs (N = 80) for 1 h per day for 12 consecutive weeks. The absolute claudication distance was measured at baseline and following the intervention. The cohort (n = 40; 30 males; mean age = 71 years; mean ankle-brachial pressure index = 0.70) registered a mean baseline absolute claudication distance of 333.71 m (standard deviation = 208). Following 91.68 days (standard deviation = 6.23) of electrical stimulation, a significant mean increase of 137 m (standard deviation = 136) in the absolute claudication distance was registered (p = 0.000, Wilcoxon signed rank test). Electrical stimulation of varying low to high frequencies on ischaemic calf muscles significantly increased the maximal walking capacity in claudicants with type 2 diabetes. This therapeutic approach may be considered in patients with impaired exercise tolerance or as an adjunct treatment modality. © The Author(s) 2016.
Effects of a multichannel dynamic functional electrical stimulation system on hemiplegic gait and muscle forces

PubMed Central

Qian, Jing-guang; Rong, Ke; Qian, Zhenyun; Wen, Chen; Zhang, Songning

2015-01-01

[Purpose] The purpose of the study was to design and implement a multichannel dynamic functional electrical stimulation system and investigate acute effects of functional electrical stimulation of the tibialis anterior and rectus femoris on ankle and knee sagittal-plane kinematics and related muscle forces of hemiplegic gait. [Subjects and Methods] A multichannel dynamic electrical stimulation system was developed with 8-channel low frequency current generators. Eight male hemiplegic patients were trained for 4 weeks with electric stimulation of the tibia anterior and rectus femoris muscles during walking, which was coupled with active contraction. Kinematic data were collected, and muscle forces of the tibialis anterior and rectus femoris of the affected limbs were analyzed using a musculoskelatal modeling approach before and after training. A paired sample t-test was used to detect the differences between before and after training. [Results] The step length of the affected limb significantly increased after the stimulation was applied. The maximum dorsiflexion angle and maximum knee flexion angle of the affected limb were both increased significantly during stimulation. The maximum muscle forces of both the tibia anterior and rectus femoris increased significantly during stimulation compared with before functional electrical stimulation was applied. [Conclusion] This study established a functional electrical stimulation strategy based on hemiplegic gait analysis and musculoskeletal modeling. The multichannel functional electrical stimulation system successfully corrected foot drop and altered circumduction hemiplegic gait pattern. PMID:26696734
Release of “neurokinin” on nervous and electrical stimulation of a frog stomach muscle preparation

PubMed Central

Singh, I.

1964-01-01

Activation of a frog stomach muscle preparation by electrical stimulation of a vagus nerve or by direct stimulation released two polypeptides. One was destroyed by trypsin or chymotrypsin in about 10 min; the activity of the other was enhanced by trypsin for about 10 min, but was destroyed by chymotrypsin. Similar stimulation of dog stomach muscle did not release these polypeptides. Correspondingly, the transmission from vagus nerve to stomach muscle in the frog was resistant to atropine, but was blocked by atropine in the dog. PMID:14190475
Suppressive effect of formononetin on platelet-derived growth factor-BB-stimulated proliferation and migration of vascular smooth muscle cells

PubMed Central

Chen, Zhuo; Liu, Suixin; Cai, Ying; Xie, Kangling; Zhang, Wenliang; Dong, Lei; Liu, Yuan; Zheng, Fan; Dun, Yaoshan; Li, Ning

2016-01-01

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) has been implicated in intimal hyperplasia, atherosclerosis and restenosis following percutaneous coronary intervention. Formononetin, a phytoestrogen extracted from the root of Astragalus membranaceus, has been widely used in Chinese tradition medicine due to its protective effects against certain symptoms of cancer, hypertension, inflammation, hypoxia-induced cytotoxicity and ovariectomy-induced bone loss. However, the effect of formononetin on platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of VSMCs, as well as the underlying molecular mechanism, remains largely unclear. In the present study, treatment with formononetin significantly inhibited PDGF-BB-induced proliferation and migration of human VSMCs. Investigation into the underlying molecular mechanism revealed that the administration of formononetin suppressed PDGF-BB-stimulated switch of VSMCs to a proliferative phenotype. Furthermore, treatment with formononetin inhibited the PDGF-BB-induced upregulation of cell cycle-related proteins, matrix metalloproteinase (MMP2) and MMP9. In addition, the that administration of formononetin inhibited the phosphorylation of AKT induced by PDGF-BB in VSMCs. The present results suggest that formononetin has a suppressive effect on PDGF-BB-stimulated VSMCs proliferation and migration, which may occur partly via the inhibition of AKT signaling pathway. Therefore, formononetin may be useful for the treatment of intimal hyperplasia, atherosclerosis and restenosis. PMID:27588108
Suppressive effect of formononetin on platelet-derived growth factor-BB-stimulated proliferation and migration of vascular smooth muscle cells.

PubMed

Chen, Zhuo; Liu, Suixin; Cai, Ying; Xie, Kangling; Zhang, Wenliang; Dong, Lei; Liu, Yuan; Zheng, Fan; Dun, Yaoshan; Li, Ning

2016-09-01

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) has been implicated in intimal hyperplasia, atherosclerosis and restenosis following percutaneous coronary intervention. Formononetin, a phytoestrogen extracted from the root of Astragalus membranaceus , has been widely used in Chinese tradition medicine due to its protective effects against certain symptoms of cancer, hypertension, inflammation, hypoxia-induced cytotoxicity and ovariectomy-induced bone loss. However, the effect of formononetin on platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of VSMCs, as well as the underlying molecular mechanism, remains largely unclear. In the present study, treatment with formononetin significantly inhibited PDGF-BB-induced proliferation and migration of human VSMCs. Investigation into the underlying molecular mechanism revealed that the administration of formononetin suppressed PDGF-BB-stimulated switch of VSMCs to a proliferative phenotype. Furthermore, treatment with formononetin inhibited the PDGF-BB-induced upregulation of cell cycle-related proteins, matrix metalloproteinase (MMP2) and MMP9. In addition, the that administration of formononetin inhibited the phosphorylation of AKT induced by PDGF-BB in VSMCs. The present results suggest that formononetin has a suppressive effect on PDGF-BB-stimulated VSMCs proliferation and migration, which may occur partly via the inhibition of AKT signaling pathway. Therefore, formononetin may be useful for the treatment of intimal hyperplasia, atherosclerosis and restenosis.
The effect of long-term stimulation of fast muscles on their blood flow, metabolism and ability to withstand fatigue.

PubMed

Hudlická, O; Brown, M; Cotter, M; Smith, M; Vrbová, G

1977-06-08

Chronic stimulation of fast rabbit muscles (tibialis anterior, extensor digitorum longus and the peroneal muscle group) at a frequency naturally occurring in nerves to slow muscles increased their ability to withstand fatigue. Isometric tension decreased during a 10-min period of contractions at 4 Hz by 75% in control muscles, but only 55% in muscles chronically stimulated for 4 days, and 23% in muscles stimulated for 28 days. Chronic stimulation had little effect on resting blood flow, oxygen or glucose consumption. The output or consumption of lactate and free fatty acids (FFA) at rest were also unaffected. The glycogen content was regularly increased, and was apparent after only 2 days of stimulation. The activity of fatty acid activating enzyme was increased after 28 days. During a 10-min period of isometric contractions at 4 Hz, there was a markedly greater increase in blood flow and oxygen consumption in muscles stimulated for 14-28 days than in control muscles; lactic acid output was lower in muscles stimulated for 28 days, and the uptake of FFA was significantly higher. It is therefore suggested that muscles chronically stimulated for 14-28 days use fats as the main source of energy during isometric contractions. The predominantly oxidative metabolism is probably facilitated by the higher density of capillaries. The latter also enables more efficient delivery of oxygen, and therefore smaller fatiguability, already after 4 days of chronic stimulation.
Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagata, Yosuke, E-mail: cynagata@mail.ecc.u-tokyo.ac.jp; Ohashi, Kazuya; Wada, Eiji

2014-08-01

Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermalmore » growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor. - Highlights: • EGF in combination with insulin induces proliferation of quiescent C2C12 cells. • Sphingosine kinase activity increases when reserve cells are stimulated with EGF. • EGF-induced activation of reserve cells is dependent on sphingosine kinase and ERK. • The S1P receptor S1P2 is involved in EGF-induced reserve cell activation. • EGF-induced reserve cell activation is mediated by S1P and
25-hydroxycholecalciferol stimulation of muscle metabolism.

PubMed Central

Birge, S J; Haddad, J G

1975-01-01

Intact diaphragms from vitamin D-deficient rats were incubated in vitro with [3H]leucine. Oral administration of 10 mug (400 U) of cholecalciferol 7 h before incubation increased leucine incorporation into diaphragm muscle protein by 136% (P less than 0.001) of the preparation from untreated animals. Nephrectomy did not obliterate this response. ATP content of the diaphragm muscle was also enhanced 7 h after administration of the vitamin. At 4 h after administration of cholecalciferol, serum phosphorus concentration was reduced by 0.7 mg/100 ml (P less than 0.025) and the rate of inorganic 32PO4 accumulation by diaphragm muscle was increased by 18% (P less than 0.025) over the untreated animals. Increasing serum phosphate concentration of the vitamin D-deficient animals by dietary supplementation with phosphate for 3 days failed to significantly enhance leucine incorporation into protein. However, supplementation of the rachitogenic, vitamin D-deficient diet with phosphorus for 3 wk stimulated the growth of the animal and muscle ATP levels. This increase in growth and muscle ATP content attributed to the addition of phosphorus to the diet was less than the increase in growth and muscle ATP levels achieved by the addition of both phosphorus and vitamin D to the diet. To eliminate systemic effects of the vitamin, the epitrochlear muscle of the rat foreleg of vitamin D-depleted rats was maintained in tissue culture. Addition of 20 ng/ml of 25-hydroxycholecalciferol (25-OHD3) to the medium enhanced ATP content of the muscle and increased leucine incorporation into protein. Vitamin D3 at a concentration of 20 mug/ml and 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) at a concentration of 500 pg/ml were without effect. Analysis of muscle cytosol in sucrose density gradients revealed a protein fraction which specifically bound 25-OHD3 and which demonstrated a lesser affinity for 1,25-(OH)2D3. These studies suggest that 25-OHD3 may influence directly the intracellular
Myoelectric stimulation on peroneal muscles resists simulated ankle sprain motion.

PubMed

Fong, Daniel Tik-Pui; Chu, Vikki Wing-Shan; Chan, Kai-Ming

2012-07-26

The inadequate reaction time of the peroneal muscles in response to an incorrect foot contact event has been proposed as one of the etiological factors contributing to ankle joint inversion injury. Thus, the current study aimed to investigate the efficacy of a myoelectric stimulation applied to the peroneal muscles in the prevention of a simulated ankle inversion trauma. Ten healthy male subjects performed simulated inversion and supination tests on a pair of mechanical sprain simulators. An electrical signal was delivered to the peroneal muscles of the subjects through a pair of electrode pads. The start of the stimulus was synchronized with the drop of the sprain simulator's platform. In order to determine the maximum delay time which the stimulus could still resist the simulated ankle sprain motion, different delay time were test (0, 5, 10, and 15ms). Together with the control trial (no stimulus), there were 5 testing conditions for both simulated inversion and supination test. The effect was quantified by the drop in maximum ankle tilting angle and angular velocity, as determined by a motion analysis system with a standard laboratory procedure. Results showed that the myoelectric stimulation was effective in all conditions except the one with myoelectric stimulus delayed for 15ms in simulated supination test. It is concluded that myoelectric stimulation on peroneal muscles could resist an ankle spraining motion. Copyright © 2012 Elsevier Ltd. All rights reserved.
Smooth muscle architecture within cell-dense vascular tissues influences functional contractility.

PubMed

Win, Zaw; Vrla, Geoffrey D; Steucke, Kerianne E; Sevcik, Emily N; Hald, Eric S; Alford, Patrick W

2014-12-01

The role of vascular smooth muscle architecture in the function of healthy and dysfunctional vessels is poorly understood. We aimed at determining the relationship between vascular smooth muscle architecture and contractile output using engineered vascular tissues. We utilized microcontact printing and a microfluidic cell seeding technique to provide three different initial seeding conditions, with the aim of influencing the cellular architecture within the tissue. Cells seeded in each condition formed confluent and aligned tissues but within the tissues, the cellular architecture varied. Tissues with a more elongated cellular architecture had significantly elevated basal stress and produced more contractile stress in response to endothelin-1 stimulation. We also found a correlation between the contractile phenotype marker expression and the cellular architecture, contrary to our previous findings in non-confluent tissues. Taken with previous results, these data suggest that within cell-dense vascular tissues, smooth muscle contractility is strongly influenced by cell and tissue architectures.
Triiodothyronine Acutely Stimulates Glucose Transport into L6 Muscle Cells Without Increasing Surface GLUT4, GLUT1, or GLUT3

PubMed Central

Teixeira, Silvania Silva; Tamrakar, Akhilesh K.; Goulart-Silva, Francemilson; Serrano-Nascimento, Caroline; Klip, Amira

2012-01-01

Background Thyroid hormones (THs) act genomically to stimulate glucose transport by elevating glucose transporter (Slc2a) expression and glucose utilization by cells. However, nongenomic effects of THs are now emerging. Here, we assess how triiodothyronine (T3) acutely affects glucose transport and the content of GLUT4, GLUT1, and GLUT3 at the surface of muscle cells, and possible interactions between T3 and insulin action. Methods Differentiated L6 myotubes transfected with myc-tagged Slc2a4 (L6-GLUT4myc) or Slc2a1 (L6-GLUT1myc) and wild-type L6 myotubes were studied in the following conditions: control, hypothyroid (Tx), Tx plus T3, Tx plus insulin, and Tx plus insulin and T3. Results Glucose uptake and GLUT4 content at the cell surface decreased in the Tx group relative to controls. T3 treatment for 30 minutes increased glucose transport into L6-GLUT4myc cells without altering surface GLUT4 content, which increased only thereafter. The total amount of GLUT4 protein remained unchanged among the groups studied. The surface GLUT1 content of L6-GLUT1myc cells also remained unaltered after T3 treatment; however, in these cells glucose transport was not stimulated by T3. In wild-type L6 cells, although T3 treatment increased the total amount of GLUT3, it did not change the surface GLUT3 content. Moreover, within 30 minutes, T3 stimulation of glucose uptake was additive to that of insulin in L6-GLUT4myc cells. As expected, insulin elevated surface GLUT4 content and glucose uptake. However, interestingly, surface GLUT4 content remained unchanged or even dropped with T3 plus insulin. Conclusions These data reveal that T3 rapidly increases glucose uptake in L6-GLUT4myc cells, which, at least for 30 minutes, did not depend on an increment in GLUT4 at the cell surface yet potentiates insulin action. We propose that this rapid T3 effect involves activation of GLUT4 transporters at the cell surface, but cannot discount the involvement of an unknown GLUT. PMID:22663547
Acromiohumeral Distance During Neuromuscular Electrical Stimulation of the Lower Trapezius and Serratus Anterior Muscles in Healthy Participants.

PubMed

Bdaiwi, Alya H; Mackenzie, Tanya Anne; Herrington, Lee; Horsley, Ian; Cools, Ann M

2015-07-01

Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance. To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance. Controlled laboratory study. Human performance laboratory. Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened. Neuromuscular electrical stimulation of the LT and SA. Ultrasound measurement of the acromiohumeral distance. Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t(19) = -3.89, P = .004), SA muscle (t(19) = -7.67, P = .001), and combined LT and SA muscles (t(19) = -5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F(2,57) = 3.109, P = .08). Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance.
Leucine modulation of mitochondrial mass and oxygen consumption in skeletal muscle cells and adipocytes

PubMed Central

Sun, Xiaocun; Zemel, Michael B

2009-01-01

Background The effects of dairy on energy metabolism appear to be mediated, in part, by leucine and calcium which regulate both adipocyte and skeletal muscle energy metabolism. We recently demonstrated that leucine and calcitriol regulate fatty acid oxidation in skeletal muscle cells in vitro, with leucine promoting and calcitriol suppressing fatty acid oxidation. Moreover, leucine coordinately regulated adipocyte lipid metabolism to promote flux of lipid to skeletal muscle and regulate metabolic flexibility. We have now investigated the role of mitochondrial biogenesis in mediating these effects. Methods We tested the effect of leucine, calcitriol and calcium in regulation of mitochondrial mass using a fluorescence method and tested mitochondrial biogenesis regulatory genes as well mitochondrial component genes using real-time PCR. We also evaluated the effect of leucine on oxygen consumption with a modified perfusion system. Results Leucine (0.5 mM) increased mitochondrial mass by 30% and 53% in C2C12 myocytes and 3T3-L1 adipocytes, respectively, while calcitriol (10 nM) decreased mitochondrial abundance by 37% and 27% (p < 0.02). Leucine also stimulated mitochondrial biogenesis genes SIRT-1, PGC-1α and NRF-1 as well as mitochondrial component genes UCP3, COX, and NADH expression by 3–5 fold in C2C12 cells (p < 0.003). Adipocyte-conditioned medium reduced mitochondrial abundance (p < 0.001) and decreased UCP3 but increased PGC-1α expression in myocytes, suggesting a feedback stimulation of mitochondrial biogenesis. Similar data were observed in C2C12 myocytes co-cultured with adipocytes, with co-culture markedly suppressing mitochondrial abundance (p < 0.02). Leucine stimulated oxygen consumption in both C2C12 cells and adipocytes compared with either control or valine-treated cells. Transfection of C2C12 myocytes with SIRT-1 siRNA resulted in parallel suppression of SIRT-1 expression and leucine-induced stimulation of PGC-1α and NRF-1, indicating that SIRT
Classical and adaptive control of ex vivo skeletal muscle contractions using Functional Electrical Stimulation (FES)

PubMed Central

Shoemaker, Adam; Grange, Robert W.; Abaid, Nicole; Leonessa, Alexander

2017-01-01

Functional Electrical Stimulation is a promising approach to treat patients by stimulating the peripheral nerves and their corresponding motor neurons using electrical current. This technique helps maintain muscle mass and promote blood flow in the absence of a functioning nervous system. The goal of this work is to control muscle contractions from FES via three different algorithms and assess the most appropriate controller providing effective stimulation of the muscle. An open-loop system and a closed-loop system with three types of model-free feedback controllers were assessed for tracking control of skeletal muscle contractions: a Proportional-Integral (PI) controller, a Model Reference Adaptive Control algorithm, and an Adaptive Augmented PI system. Furthermore, a mathematical model of a muscle-mass-spring system was implemented in simulation to test the open-loop case and closed-loop controllers. These simulations were carried out and then validated through experiments ex vivo. The experiments included muscle contractions following four distinct trajectories: a step, sine, ramp, and square wave. Overall, the closed-loop controllers followed the stimulation trajectories set for all the simulated and tested muscles. When comparing the experimental outcomes of each controller, we concluded that the Adaptive Augmented PI algorithm provided the best closed-loop performance for speed of convergence and disturbance rejection. PMID:28273101
Secretion of Growth Hormone in Response to Muscle Sensory Nerve Stimulation

NASA Technical Reports Server (NTRS)

Grindeland, Richard E.; Roy, R. R.; Edgerton, V. R.; Gosselink, K. L.; Grossman, E. J.; Sawchenko, P. E.; Wade, Charles E. (Technical Monitor)

1994-01-01

Growth hormone (GH) secretion is stimulated by aerobic and resistive exercise and inhibited by exposure to actual or simulated (bedrest, hindlimb suspension) microgravity. Moreover, hypothalamic growth hormone-releasing factor (GRF) and preproGRF mRNA are markedly decreased in spaceflight rats. These observations suggest that reduced sensory input from inactive muscles may contribute to the reduced secretion of GH seen in "0 G". Thus, the aim of this study was to determine the effect of muscle sensory nerve stimulation on secretion of GH. Fed male Wistar rats (304 +/- 23 g) were anesthetized (pentobarbital) and the right peroneal (Pe), tibial (T), and sural (S) nerves were cut. Electrical stimulation of the distal (D) or proximal (P) ends of the nerves was implemented for 15 min. to mimic the EMG activity patterns of ankle extensor muscles of a rat walking 1.5 mph. The rats were bled by cardiac puncture and their anterior pituitaries collected. Pituitary and plasma bioactive (BGH) and immunoactive (IGH) GH were measured by bioassay and RIA.
Bio-inspired Hybrid Carbon Nanotube Muscles

NASA Astrophysics Data System (ADS)

Kim, Tae Hyeob; Kwon, Cheong Hoon; Lee, Changsun; An, Jieun; Phuong, Tam Thi Thanh; Park, Sun Hwa; Lima, Márcio D.; Baughman, Ray H.; Kang, Tong Mook; Kim, Seon Jeong

2016-05-01

There has been continuous progress in the development for biomedical engineering systems of hybrid muscle generated by combining skeletal muscle and artificial structure. The main factor affecting the actuation performance of hybrid muscle relies on the compatibility between living cells and their muscle scaffolds during cell culture. Here, we developed a hybrid muscle powered by C2C12 skeletal muscle cells based on the functionalized multi-walled carbon nanotubes (MWCNT) sheets coated with poly(3,4-ethylenedioxythiophene) (PEDOT) to achieve biomimetic actuation. This hydrophilic hybrid muscle is physically durable in solution and responds to electric field stimulation with flexible movement. Furthermore, the biomimetic actuation when controlled by electric field stimulation results in movement similar to that of the hornworm by patterned cell culture method. The contraction and relaxation behavior of the PEDOT/MWCNT-based hybrid muscle is similar to that of the single myotube movement, but has faster relaxation kinetics because of the shape-maintenance properties of the freestanding PEDOT/MWCNT sheets in solution. Our development provides the potential possibility for substantial innovation in the next generation of cell-based biohybrid microsystems.
The Mitotic and Metabolic Effects of Phosphatidic Acid in the Primary Muscle Cells of Turbot (Scophthalmus maximus).

PubMed

Wang, Tingting; Wang, Xuan; Zhou, Huihui; Jiang, Haowen; Mai, Kangsen; He, Gen

2018-01-01

Searching for nutraceuticals and understanding the underlying mechanism that promote fish growth is at high demand for aquaculture industry. In this study, the modulatory effects of soy phosphatidic acids (PA) on cell proliferation, nutrient sensing, and metabolic pathways were systematically examined in primary muscle cells of turbot ( Scophthalmus maximus ). PA was found to stimulate cell proliferation and promote G1/S phase transition through activation of target of rapamycin signaling pathway. The expression of myogenic regulatory factors, including myoD and follistatin , was upregulated, while that of myogenin and myostatin was downregulated by PA. Furthermore, PA increased intracellular free amino acid levels and enhanced protein synthesis, lipogenesis, and glycolysis, while suppressed amino acid degradation and lipolysis. PA also was found to increased cellular energy production through stimulated tricarboxylic acid cycle and oxidative phosphorylation. Our results identified PA as a potential nutraceutical that stimulates muscle cell proliferation and anabolism in fish.
Hyperforin stimulates intracellular calcium mobilisation and enhances extracellular acidification in DDT1-MF2 smooth muscle cells.

PubMed

Koch, E; Chatterjee, S S

2001-07-01

Hyperforin, an acylphloroglucinol derivative, is a major constituent of St. John's wort extract (Hypericum perforatum L.), which is used in treating depressive disorders. Hyperforin has been demonstrated as a modulator of several neuronal ion channels, and inhibits smooth-muscle contraction induced by various neurotransmitters. To evaluate the spasmolytic properties of hyperforin in more detail, we performed studies on the hamster vas deferens smooth muscle cell line DDT1-MF2. In a first series of experiments, we determined the effect of hyperforin on intracellular Ca2+ concentration ([Ca2+]i) using the fluorochrome fura-2. These investigations were supplemented in a second series of assays, where the effects on cellular metabolism were analysed by measuring the rate of extracellular release of acidic metabolites with the help of a microphysiometer. Hyperforin (0.3-10 microg/ml) caused a concentration-dependent elevation of [Ca2+]i and extracellular acidification rate (ECAR). Both of these effects were independent of extracellular Ca2+. To elucidate whether the increase of [Ca2+]i by hyperforin causes or results from its ECAR-stimulating properties, we used various pharmacological tools to reveal the sequence of events and the molecular mechanisms involved. Our results suggest that hyperforin induces release of Ca2+ from as yet unidentified sources. Since the ECAR stimulation was inhibited to a different extent by the intracellular Ca2+ chelator BAPTA as well as by inhibitors of plasmalemmal and mitochondrial Na+/Ca2+ exchange, but not by inhibitors of Na+/H+ antiport, the intracellular Ca2+ increase seems to be essential for this hyperforin effect. However, further studies are needed to establish the exact mode of action, and to deduce whether this aspect of hyperforin activity contributes to its antidepressant and neuroprotective effects.

Analysis of biological effects in human endothelial cells after stimulated microgravity

NASA Astrophysics Data System (ADS)

Min, Zhang; Sun, Yeqing; Xu, Dan

Space environment is characterized by strong radiation, ultra-high vacuum, weak magnetic field and microgravity. Among them, microgravity (10-4-10-6g) in space is different from gravity (1g) on earth, possibly causing visual disorders, muscle alterations, bone loss and dysfunction of cardiovascular systems. To study about microgravity environment, the most advanced rotary cell culture system (RCCS-1) was used to do stimulated microgravity (SMG) experiments in the ground. Up to now, most of studies focus on the biological effects under stimulated microgravity, but it is less known about the cellular response after stimulated microgravity. In the present study, we explored the subsequent effects of stimulated microgravity on human endothelial cells (HUVEC-C) after these cells were cultured on RCCS-1 for 48 hours. We co-cultured HUVEC-C cells with Hillex-microcarriers in 60-mm culture dishes for 24h, followed by transferring them to RCCS-1 so that cells remain to be the state of SMG. In parallel, HUVEC-C cells were co-cultured with microcarriers in the ground condition. We found that stimulated microgravity induced cytoskeleton remodeling, cell cycle G2/M arrest and cellular senescence, consistent with previous reports. To study the subsequent effects of stimulated microgravity, we make cells detach from microcarriers and observed various effects including cell growth, cell adhesion, cytoskeleton, cell cycle, apoptosis and senescence. The results showed that those cells undergoing stimulated microgravity appeared obvious growth inhibition, a transition from the decrease in cell adhesion ability and cytoskeleton remodeling within 24h to induction of apoptosis and senescence-like phenotype in the later time with slight changes in cell cycle. Analysis of protein expression in western blot demonstrated that apoptosis-related protein PTEN was up-regulated on the time-dependent pattern after stimulated microgravity, indicating that PTEN-PI3K-Akt pathway might play an
Effect of TPA on ion fluxes and DNA synthesis in vascular smooth muscle cells

PubMed Central

1985-01-01

Previous reports have suggested that phorbol esters can decrease the affinity of epidermal growth factor (EGF) for its cellular receptors. Investigations of the consequences of the interaction between phorbol esters and EGF, however, have been limited to EGF-stimulated Na/H exchange in A431 cells (Whitely, B., D. Cassel, Y.-X. Zuang, and L. Glaser, 1984, J. Cell Biol., 99:1162-1166). In the present study, the effect of the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) on EGF-stimulated ion transport and DNA synthesis was determined in cultured vascular smooth muscle cells (A7r5). It was found that TPA stimulated Na/H exchange when added alone (half-maximal stimulatory concentration, 25 nM). However, when cells were pretreated with TPA and then challenged with EGF, TPA significantly inhibited EGF-stimulated Na/H exchange (78%; half-maximal inhibition [Ki] at 2.5 nM). Subsequently the effects of TPA on Na/K/Cl co-transport were measured. TPA was observed to inhibit Na/K/Cl co-transport (half-maximal inhibitory concentration, 50 nM) and also to inhibit EGF-stimulated Na/K/Cl co-transport (100%; Ki at 5 nM). Finally, the effects of TPA on DNA synthesis were assessed. TPA had a modest stimulatory effect on DNA synthesis (half-maximal stimulatory concentration, 6 nM), but had a significant inhibitory effect on EGF-stimulated DNA synthesis (56%; Ki at 5 nM). These findings suggest that the inhibitory effect of TPA on EGF-receptor functions goes beyond previously reported effects on Na/H exchange in A431 cells and extends to EGF-stimulation of Na/K/Cl co- transport and DNA synthesis in vascular smooth muscle cells. PMID:2410432
Muscle Activation During Peripheral Nerve Field Stimulation Occurs Due to Recruitment of Efferent Nerve Fibers, Not Direct Muscle Activation.

PubMed

Frahm, Ken Steffen; Hennings, Kristian; Vera-Portocarrero, Louis; Wacnik, Paul W; Mørch, Carsten Dahl

2016-08-01

Peripheral nerve field stimulation (PNFS) is a potential treatment for chronic low-back pain. Pain relief using PNFS is dependent on activation of non-nociceptive Aβ-fibers. However, PNFS may also activate muscles, causing twitches and discomfort. In this study, we developed a mathematical model, to investigate the activation of sensory and motor nerves, as well as direct muscle fiber activation. The extracellular field was estimated using a finite element model based on the geometry of CT scanned lumbar vertebrae. The electrode was modeled as being implanted to a depth of 10-15 mm. Three implant directions were modeled; horizontally, vertically, and diagonally. Both single electrode and "between-lead" stimulation between contralateral electrodes were modeled. The extracellular field was combined with models of sensory Aβ-nerves, motor neurons and muscle fibers to estimate their activation thresholds. The model showed that sensory Aβ fibers could be activated with thresholds down to 0.563 V, and the lowest threshold for motor nerve activation was 7.19 V using between-lead stimulation with the cathode located closest to the nerves. All thresholds for direct muscle activation were above 500 V. The results suggest that direct muscle activation does not occur during PNFS, and concomitant motor and sensory nerve fiber activation are only likely to occur when using between-lead configuration. Thus, it may be relevant to investigate the location of the innervation zone of the low-back muscles prior to electrode implantation to avoid muscle activation. © 2016 International Neuromodulation Society.
NS-398, a selective COX-2 inhibitor, inhibits proliferation of IL-1{beta}-stimulated vascular smooth muscle cells by induction of {eta}{omicron}-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Hyoung Chul; Kim, Hee Sun; Lee, Kwang Youn

2008-11-28

We investigated whether NS-398, a selective inhibitor of COX-2, induces HO-1 in IL-1{beta}-stimulated vascular smooth muscle cells (VSMC). NS-398 reduced the production of PGE{sub 2} without modulation of expression of COX-2 in IL-1{beta}-stimulated VSMC. NS-398 increased HO-1 mRNA and protein in a dose-dependent manner, but inhibited proliferation of IL-1{beta}-stimulated VSMC. Furthermore, SnPPIX, a HO-1 inhibitor, reversed the effects of NS-398 on PGE{sub 2} production, suggesting that COX-2 activity can be affected by HO-1. Hemin, a HO-1 inducer, also reduced the production of PGE{sub 2} and proliferation of IL-1{beta}-stimulated VSMC. CORM-2, a CO-releasing molecule, but not bilirubin inhibited proliferation of IL-1{beta}-stimulatedmore » VSMC. NS-398 inhibited proliferation of IL-1{beta}-stimulated VSMC in a HbO{sub 2}-sensitive manner. In conclusion, NS-398 inhibits proliferation of IL-1{beta}-stimulated VSMC by HO-1-derived CO. Thus, NS-398 may facilitate the healing process of vessels in vascular inflammatory disorders such as atherosclerosis.« less
Mechanically induced alterations in cultured skeletal muscle growth

NASA Technical Reports Server (NTRS)

Vandenburgh, H. H.; Hatfaludy, S.; Karlisch, P.; Shansky, J.

1991-01-01

Model systems are available for mechanically stimulating cultured skeletal muscle cells by passive tensile forces which simulate those found in vivo. When applied to embryonic muscle cells in vitro these forces induce tissue organogenesis, metabolic adaptations, and muscle cell growth. The mechanical stimulation of muscle cell growth correlates with stretch-induced increases in the efflux of prostaglandins PGE2 and PGF2(alpha) in a time and frequency dependent manner. These prostaglandins act as mechanical 'second messengers' regulating skeletal muscle protein turnover rates. Since they also effect bone remodelling in response to tissue loading and unloading, secreted prostaglandins may serve as paracrine growth factors, coordinating the growth rates of muscle and bone in response to external mechanical forces. Cell culture model systems will supplement other models in understanding mechanical transduction processes at the molecular level.
Intramuscular Electrical Stimulation for Muscle Activation of the Tibialis Anterior After Surgical Repair: A Case Report.

PubMed

Hollis, Sharon; McClure, Philip

2017-12-01

Background Loss of voluntary activation of musculature can result in muscle weakness. External neuromuscular stimulation can be utilized to improve voluntary activation but is often poorly tolerated because of pain associated with required stimulus level. Intramuscular electrical stimulation requires much lower voltage and may be better tolerated, and therefore more effective at restoring voluntary muscle activation. Case Description A 71-year-old man sustained a rupture of the distal attachment of the tibialis anterior tendon. Thirty-two weeks after surgical repair, there was no palpable or visible tension development in the muscle belly or tendon. Dorsiflexion was dependent on toe extensors. Electrical stimulation applied via a dry needling placement in the muscle belly was utilized to induce an isometric contraction. Outcomes Five sessions of intramuscular electrical stimulation were delivered. By day 4 (second visit), the patient was able to dorsiflex without prominent use of the extensor hallucis longus. By day 6 (third visit), active-range-of-motion dorsiflexion with toes flexed increased 20° (-10° to 10°). Eighteen days after the initial treatment, the patient walked without his previous high-step gait pattern, and the tibialis anterior muscle test improved to withstanding moderate resistance (manual muscle test score, 4/5). Discussion The rapid change in muscle function observed suggests that intramuscular electrical stimulation may facilitate voluntary muscle activation. Level of Evidence Therapy, level 5. J Orthop Sports Phys Ther 2017;47(12):965-969. Epub 15 Oct 2017. doi:10.2519/jospt.2017.7368.
Satellite Cells and the Muscle Stem Cell Niche

PubMed Central

Yin, Hang; Price, Feodor

2013-01-01

Adult skeletal muscle in mammals is a stable tissue under normal circumstances but has remarkable ability to repair after injury. Skeletal muscle regeneration is a highly orchestrated process involving the activation of various cellular and molecular responses. As skeletal muscle stem cells, satellite cells play an indispensible role in this process. The self-renewing proliferation of satellite cells not only maintains the stem cell population but also provides numerous myogenic cells, which proliferate, differentiate, fuse, and lead to new myofiber formation and reconstitution of a functional contractile apparatus. The complex behavior of satellite cells during skeletal muscle regeneration is tightly regulated through the dynamic interplay between intrinsic factors within satellite cells and extrinsic factors constituting the muscle stem cell niche/microenvironment. For the last half century, the advance of molecular biology, cell biology, and genetics has greatly improved our understanding of skeletal muscle biology. Here, we review some recent advances, with focuses on functions of satellite cells and their niche during the process of skeletal muscle regeneration. PMID:23303905
(S)-[6]-Gingerol inhibits TGF-β-stimulated biglycan synthesis but not glycosaminoglycan hyperelongation in human vascular smooth muscle cells.

PubMed

Kamato, Danielle; Babaahmadi Rezaei, Hossein; Getachew, Robel; Thach, Lyna; Guidone, Daniel; Osman, Narin; Roufogalis, Basil; Duke, Colin C; Tran, Van Hoan; Zheng, Wenhua; Little, Peter J

2013-07-01

(S)-[6]-Gingerol is under investigation for a variety of therapeutic uses. Transforming growth factor (TGF)-β stimulates proteoglycan synthesis, leading to increased binding of low-density lipoproteins, which is the initiating step in atherosclerosis. We evaluated the effects of (S)-[6]-gingerol on these TGF-β-mediated proteoglycan changes to explore its potential as an anti-atherosclerotic agent. Purified (S)-[6]-gingerol was assessed for its effects on proteoglycan synthesis by [(35) S]-sulfate incorporation into glycosaminoglycan chains and [(35) S]-Met/Cys incorporation into proteoglycans and total proteins in human vascular smooth muscle cells. Biglycan level was assessed by real-time quantitative polymerase chain reactions and the effects of (S)-[6]-gingerol on TGF-β signalling by assessment of the phosphorylation of Smads and Akt by western blotting. (S)-[6]-Gingerol concentration-dependently inhibited TGF-β-stimulated proteoglycan core protein synthesis, and this was not secondary to inhibition of total protein synthesis. (S)-[6]-Gingerol inhibited biglycan mRNA expression. (S)-[6]-Gingerol did not inhibit TGF-β-stimulated glycosaminoglycan hyperelongation or phosphorylation of Smad 2, in either the carboxy terminal or linker region, or Akt phosphorylation. The activity of (S)-[6]-gingerol to inhibit TGF-β-stimulated biglycan synthesis suggests a potential role for ginger in the prevention of atherosclerosis or other lipid-binding diseases. The signalling studies indicate a novel site of action of (S)-[6]-gingerol in inhibiting TGF-β responses. © 2013 Royal Pharmaceutical Society.
Rapid fast to slow fiber transformation in response to chronic stimulation of immobilized muscles of the rabbit.

PubMed

Cotter, M; Phillips, P

1986-09-01

Limb immobilization causes muscle atrophy particularly of slow oxidative fibers which also suffer the greatest decrement in neural activation. In this study a fast muscle, tibialis anterior, was chronically stimulated using an activity pattern characteristic of nerve fibers to slow muscles to see whether or not this could prevent immobilization induced slow fiber atrophy. Four groups of rabbits were used: unoperated controls, stimulated (10 Hz, 8 h/day), immobilized (neutral position), and a stimulated plus immobilized group. The experimental period was 28 to 30 days or 44 to 50 days. Immobilization caused significant decrease in slow oxidative fiber area which was completely prevented by stimulation. In animals tested for the longer period there was 56% hypertrophy. In addition, the combination of stimulation and immobilization caused a two-fold increase in the number of slow oxidative fibers and greatly increased the proportion of intermediate fibers. Stimulation without immobilization had no effect. Slow fibers in stimulated immobilized muscles had a bimodal area distribution; the number of large fibers (mean area 7059 micron2) was the same as the number of slow oxidative fibers in contralateral muscles, suggesting that they were the preexisting slow fibers, and a small fiber population (mean area 3143 micron2) represented newly converted fast fibers. We conclude that slow muscle units benefit from restoration of activity by chronic stimulation. In addition, the combination of stimulation and immobilization accelerates fast to slow fiber conversion. We suggest that isometric conditions as well as enhanced glucocorticoid effects could account for these findings.
Selective stimulation of facial muscles with a penetrating electrode array in the feline model

PubMed Central

Sahyouni, Ronald; Bhatt, Jay; Djalilian, Hamid R.; Tang, William C.; Middlebrooks, John C.; Lin, Harrison W.

2017-01-01

Objective Permanent facial nerve injury is a difficult challenge for both patients and physicians given its potential for debilitating functional, cosmetic, and psychological sequelae. Although current surgical interventions have provided considerable advancements in facial nerve rehabilitation, they often fail to fully address all impairments. We aim to introduce an alternative approach to facial nerve rehabilitation. Study design Acute experiments in animals with normal facial function. Methods The study included three anesthetized cats. Four facial muscles (levator auris longus, orbicularis oculi, nasalis, and orbicularis oris) were monitored with a standard electromyographic (EMG) facial nerve monitoring system with needle electrodes. The main trunk of the facial nerve was exposed and a 16-channel penetrating electrode array was placed into the nerve. Electrical current pulses were delivered to each stimulating electrode individually. Elicited EMG voltage outputs were recorded for each muscle. Results Stimulation through individual channels selectively activated restricted nerve populations, resulting in selective contraction of individual muscles. Increasing stimulation current levels resulted in increasing EMG voltage responses. Typically, selective activation of two or more distinct muscles was successfully achieved via a single placement of the multi-channel electrode array by selection of appropriate stimulation channels. Conclusion We have established in the animal model the ability of a penetrating electrode array to selectively stimulate restricted fiber populations within the facial nerve and to selectively elicit contractions in specific muscles and regions of the face. These results show promise for the development of a facial nerve implant system. PMID:27312936
Functional magnetic stimulation of the abdominal muscles in humans.

PubMed

Polkey, M I; Luo, Y; Guleria, R; Hamnegård, C H; Green, M; Moxham, J

1999-08-01

Functional magnetic stimulation (FMS) of the thoracic nerve roots to simulate cough has been suggested as a treatment approach in patients unable to voluntarily activate the abdominal muscles. However, factors that could influence the efficacy of FMS in clinical use have not been evaluated. In the present investigation we studied train length, posture, and frequency to determine the optimal stimulation protocol. We also evaluated the use of a valve at the mouth to enhance glottic function and investigated whether lung volume at the time of stimulation would influence the tension generated by the abdominal muscles. Studies were performed using a Magstim rapid stimulator augmented by four booster packs in nine healthy subjects; we measured the change in gastric (DeltaPga(FMS)), esophageal (DeltaPes(FMS)), and mouth pressure and expiratory flow. With our apparatus pressure generation was maximized by having a train length of at least 300 ms and a frequency of 25 Hz. Posture and valve use were not important determinants of DeltaPga(FMS) or DeltaPes(FMS). Lung volume exerted only a minor influence on DeltaPga(FMS), but the ratio DeltaPes(FMS):DeltaPga(FMS) was increased at TLC compared with FRC. Expiratory flow was increased by adopting a seated posture and using an occlusion valve with an opening threshold close to the maximum DeltaPes(FMS) generated by the stimulus train; however, expiratory flow was susceptible to interference from glottic incoordination. Representative results (with train length 600 ms, 25 Hz, and 100% power, seated) were mean DeltaPga(FMS), 166 cm H(2)O; mean DeltaPes(FMS), 108 cm H(2)O; and mean expiratory flow, 311 L/min. We confirm that FMS of the abdominal muscles can generate a substantial positive intra-abdominal and intrathoracic pressure and, consequently, expiratory flow in normal subjects.
The Mitotic and Metabolic Effects of Phosphatidic Acid in the Primary Muscle Cells of Turbot (Scophthalmus maximus)

PubMed Central

Wang, Tingting; Wang, Xuan; Zhou, Huihui; Jiang, Haowen; Mai, Kangsen; He, Gen

2018-01-01

Searching for nutraceuticals and understanding the underlying mechanism that promote fish growth is at high demand for aquaculture industry. In this study, the modulatory effects of soy phosphatidic acids (PA) on cell proliferation, nutrient sensing, and metabolic pathways were systematically examined in primary muscle cells of turbot (Scophthalmus maximus). PA was found to stimulate cell proliferation and promote G1/S phase transition through activation of target of rapamycin signaling pathway. The expression of myogenic regulatory factors, including myoD and follistatin, was upregulated, while that of myogenin and myostatin was downregulated by PA. Furthermore, PA increased intracellular free amino acid levels and enhanced protein synthesis, lipogenesis, and glycolysis, while suppressed amino acid degradation and lipolysis. PA also was found to increased cellular energy production through stimulated tricarboxylic acid cycle and oxidative phosphorylation. Our results identified PA as a potential nutraceutical that stimulates muscle cell proliferation and anabolism in fish. PMID:29780359
Stretch-induced prostaglandins and protein turnover in cultured skeletal muscle

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Hatfaludy, Sophia; Sohar, Istvan; Shansky, Janet

1990-01-01

The purpose of the study is to determine whether mechanical stimulation of cultured muscle cells influences prostaglandin efflux rates and whether they are related to stretch-induced alterations in protein turnover rates. The materials and methods of the experiment, including cell cultures, mechanical stimulation, protein synthesis, and degradation assays are outlined, and emphasis is placed on the effect of short-term mechanical stimulation in basal medium prostaglandin efflux from cultured skeletal muscle and stretch-induced alterations in prostaglandins efflux in complete medium. The major finding of the study is that mechanical stimulation of tissue-cultured skeletal-muscle cells under conditions inducing skeletal-muscle hypertropy increases the efflux of PGE(2) and PGE(2-alpha) but not 6-keto-PGF(1-alpha), the prostacyclin product.
Low-Intensity Vibration as a Treatment for Traumatic Muscle Injury

DTIC Science & Technology

2017-08-01

stimulation has an anabolic effect on musculoskeletal tissues, and mechanical stimulation via LIV has been shown to accelerate bone regeneration. Our... bone marrow-derived cells (BMDC) in LIV-induced improvements in muscle healing. Third, we will identify specific cells that detect and transduce...muscle regeneration following traumatic injury. 2. Determine the role of bone marrow-derived cells (BMDC) in LIV-induced improvements in muscle
Haemodynamic responses in chronically painful, human trapezius muscle to cold pressor stimulation.

PubMed

Acero, C O; Kuboki, T; Maekawa, K; Yamashita, A; Clark, G T

1999-10-01

The aim was to compare haemodynamic responses in trapezius muscles to cold pressor stimulation in individuals with localized trapezius myalgia and asymptomatic controls. Nine males with chronic localized pain in the trapezius (mean age, 23.2 years) and nine male controls (mean age, 24.6 years) who had no medical history of migraine, hypertension or sustained pain in the trapezius region were investigated. Two experimental (cold pressor and mock) trials were performed in a randomly assigned sequence. In the cold pressor trial the participant's left foot and ankle were immersed in 4 degrees C cold water for 2 min; the mock trial was done without that stimulus. Blood volume was continuously recorded 1 min before, 2 min during, and 5 min after cold pressor stimulation using near-infrared spectroscopy. Each participant's blood-volume data were baseline-corrected and submitted to statistical analysis. Results showed that the individuals with muscle pain exhibited a significantly lower mean blood volume than the controls during cold pressor stimulation (p = 0.0367). Upon withdrawal of that stimulation, the mean blood volume in both groups fell below the baseline. These results suggest that individuals with chronic regional trapezius myalgia have less capacity to vasodilate this muscle during cold pressor stimulation than those without such myalgia. It is not yet known if this difference in the haemodynamic response is a cause or an effect of the myalgia.
Mapping of electrical muscle stimulation using MRI

NASA Technical Reports Server (NTRS)

Adams, Gregory R.; Harris, Robert T.; Woodard, Daniel; Dudley, Gary A.

1993-01-01

The pattern of muscle contractile activity elicited by electromyostimulation (EMS) was mapped and compared to the contractile-activity pattern produced by voluntary effort. This was done by examining the patterns and the extent of contrast shift, as indicated by T2 values, im magnetic resonance (MR) images after isometric activity of the left m. quadriceps of human subjects was elicited by EMS (1-sec train of 500-microsec sine wave pulses at 50 Hz) or voluntary effort. The results suggest that, whereas EMS stimulates the same fibers repeatedly, thereby increasing the metabolic demand and T2 values, the voluntary efforts are performed by more diffuse asynchronous activation of skeletal muscle even at forces up to 75 percent of maximal to maintain performance.
Alcohol impairs skeletal muscle protein synthesis and mTOR signaling in a time-dependent manner following electrically stimulated muscle contraction

PubMed Central

Lang, Charles H.

2014-01-01

Alcohol (EtOH) decreases protein synthesis and mammalian target of rapamycin (mTOR)-mediated signaling and blunts the anabolic response to growth factors in skeletal muscle. The purpose of the current investigation was to determine whether acute EtOH intoxication antagonizes the contraction-induced increase in protein synthesis and mTOR signaling in skeletal muscle. Fasted male mice were injected intraperitoneally with 3 g/kg EtOH or saline (control), and the right hindlimb was electrically stimulated (10 sets of 6 contractions). The gastrocnemius muscle complex was collected 30 min, 4 h, or 12 h after stimulation. EtOH decreased in vivo basal protein synthesis (PS) in the nonstimulated muscle compared with time-matched Controls at 30 min, 4 h, and 12 h. In Control, but not EtOH, PS was decreased 15% after 30 min. In contrast, PS was increased in Control 4 h poststimulation but remained unchanged in EtOH. Last, stimulation increased PS 10% in Control and EtOH at 12 h, even though the absolute rate remained reduced by EtOH. The stimulation-induced increase in the phosphorylation of S6K1 Thr421/Ser424 (20–52%), S6K1 Thr389 (45–57%), and its substrate rpS6 Ser240/244 (37–72%) was blunted by EtOH at 30 min, 4 h, and 12 h. Phosphorylation of 4E-BP1 Ser65 was also attenuated by EtOH (61%) at 4 h. Conversely, phosphorylation of extracellular signal-regulated kinase Thr202/Tyr204 was increased by stimulation in Control and EtOH mice at 30 min but only in Control at 4 h. Our data indicate that acute EtOH intoxication suppresses muscle protein synthesis for at least 12 h and greatly impairs contraction-induced changes in synthesis and mTOR signaling. PMID:25257868
Acromiohumeral Distance During Neuromuscular Electrical Stimulation of the Lower Trapezius and Serratus Anterior Muscles in Healthy Participants

PubMed Central

Bdaiwi, Alya H.; Mackenzie, Tanya Anne; Herrington, Lee; Horsley, Ian; Cools, Ann M.

2015-01-01

Context Compromise to the acromiohumeral distance has been reported in participants with subacromial impingement syndrome compared with healthy participants. In clinical practice, patients with subacromial shoulder impingement are given strengthening programs targeting the lower trapezius (LT) and serratus anterior (SA) muscles to increase scapular posterior tilt and upward rotation. We are the first to use neuromuscular electrical stimulation to stimulate these muscle groups and evaluate how the muscle contraction affects the acromiohumeral distance. Objective To investigate if electrical muscle stimulation of the LT and SA muscles, both separately and simultaneously, increases the acromiohumeral distance and to identify which muscle-group contraction or combination most influences the acromiohumeral distance. Design Controlled laboratory study. Setting Human performance laboratory. Patients or Other Participants Twenty participants (10 men and 10 women, age = 26.9 ± 8.0 years, body mass index = 23.8) were screened. Intervention(s) Neuromuscular electrical stimulation of the LT and SA. Main Outcome Measure(s) Ultrasound measurement of the acromiohumeral distance. Results Acromiohumeral distance increased during contraction via neuromuscular electrical stimulation of the LT muscle (t19 = −3.89, P = .004), SA muscle (t19 = −7.67, P = .001), and combined LT and SA muscles (t19 = −5.09, P = .001). We observed no differences in the increased acromiohumeral distance among the 3 procedures (F2,57 = 3.109, P = .08). Conclusions Our results supported the hypothesis that the muscle force couple around the scapula is important in rehabilitation and scapular control and influences acromiohumeral distance. PMID:25933249
Cardiac cycle-synchronized electrical muscle stimulator for lower limb training with the potential to reduce the heart's pumping workload

PubMed Central

Matsuse, Hiroo; Akimoto, Ryuji; Kamiya, Shiro; Moritani, Toshio; Sasaki, Motoki; Ishizaki, Yuta; Ohtsuka, Masanori; Nakayoshi, Takaharu; Ueno, Takafumi; Shiba, Naoto; Fukumoto, Yoshihiro

2017-01-01

Background The lower limb muscle may play an important role in decreasing the heart’s pumping workload. Aging and inactivity cause atrophy and weakness of the muscle, leading to a loss of the heart-assisting role. An electrical lower limb muscle stimulator can prevent atrophy and weakness more effectively than conventional resistance training; however, it has been reported to increase the heart’s pumping workload in some situations. Therefore, more effective tools should be developed. Methods We newly developed a cardiac cycle-synchronized electrical lower limb muscle stimulator by combining a commercially available electrocardiogram monitor and belt electrode skeletal muscle electrical stimulator, making it possible to achieve strong and wide but not painful muscle contractions. Then, we tested the stimulator in 11 healthy volunteers to determine whether the special equipment enabled lower limb muscle training without harming the hemodynamics using plethysmography and a percutaneous cardiac output analyzer. Results In 9 of 11 subjects, the stimulator generated diastolic augmentation waves on the dicrotic notches and end-diastolic pressure reduction waves on the plethysmogram waveforms of the brachial artery, showing analogous waveforms in the intra-aortic balloon pumping heart-assisting therapy. The heart rate, stroke volume, and cardiac output significantly increased during the stimulation. There was no change in the systolic or diastolic blood pressure during the stimulation. Conclusion Cardiac cycle-synchronized electrical muscle stimulation for the lower limbs may enable muscle training without harmfully influencing the hemodynamics and with a potential to reduce the heart’s pumping workload, suggesting a promising tool for effectively treating both locomotor and cardiovascular disorders. PMID:29117189
Muscle oxygenation of vastus lateralis and medialis muscles during alternating and pulsed current electrical stimulation.

PubMed

Aldayel, Abdulaziz; Muthalib, Makii; Jubeau, Marc; McGuigan, Michael; Nosaka, Kazunori

2011-05-01

This study compared between alternating and pulsed current electrical muscle stimulation (EMS) for muscle oxygenation and blood volume during isometric contractions. Nine healthy men (23-48 years) received alternating current EMS (2500 Hz) modulated at 75 Hz on the knee extensors of one leg, and pulsed current EMS (75 Hz) for the other leg separated by 2 weeks in a randomised, counter-balanced order. Pulse duration (400 μs), on-off ratio (5-15 s) and other stimulation parameters were matched between conditions and 30 isometric contractions were induced at the knee joint angle of 100° (0° full extension). Changes in tissue oxygenation index (∆TOI) and total hemoglobin volume (∆tHb) of vastus lateralis and medialis muscles over 30 contractions were assessed by a near-infrared spectroscopy, and were compared between conditions by a two-way repeated measures ANOVA. Peak torque produced during EMS increased over 30 contractions in response to the increase in the stimulation intensity for pulsed current, but not for the alternating current EMS. The torque during each isometric contraction was less stable in alternating than pulsed current EMS. The changes in ∆TOI amplitude during relaxation phases and ∆tHb amplitude were not significantly different between conditions. However, the decreases in ∆TOI amplitude during contraction phases from baseline were significantly (P < 0.05) greater for the pulsed current than alternating current from the 18th contraction (-15.6 ± 2.3 vs. -8.9 ± 1.8%) to 30th contraction (-10.7 ± 1.8 vs. -4.8 ± 1.5%). These results suggest that the muscles were less activated in the alternating current EMS when compared with the pulsed current EMS.

Evaluation of innate immune stimulating activity of polysaccharides using a silkworm (Bombyx mori) muscle contraction assay.

PubMed

Fujiyuki, T; Hamamoto, H; Ishii, K; Urai, M; Kataoka, K; Takeda, T; Shibata, S; Sekimizu, K

2012-04-01

In silkworm larvae, the mature form of paralytic peptide (PP), an insect cytokine, is produced from pro-PP in association with activation of innate immune responses, resulting in slow muscle contraction. We utilized this reaction, muscle contraction in silkworms coupled with innate immunity stimulation, to quantitatively measure the innate immune stimulating activity of various natural polysaccharides. β-Glucan of Gyrophora esculenta (GE-3), fucoidan from sporophyll of Undaria pinnatifida, and curldan induced silkworm muscle contraction. We further demonstrated that GE-3 had therapeutic effects on silkworms infected by baculovirus. Based on these findings, we propose that the silkworm muscle contraction assay is useful for screening substances that stimulate innate immunity before evaluating therapeutic effectiveness in mammals.
[Simulated uterus microenvironment induced human placental mesenchymal stem cells differentiation to uterus smooth muscle cells in vitro].

PubMed

Li, Chang-dong; Zhang, Wei-yuan; Yuan, Chun-li; Han, Li-ying

2008-12-09

To develop a new method to promote the differentiation of mesenchymal stem cells derived from human placenta (pMSC) to uterus smooth muscle cells (uSMC) in simulated uterus microenvironment. MSCs were isolated from human placenta, cultivated, and analyzed for their phenotype by flow cytometry. The multipotential differentiation of the pMSC was examined by chondrogenic, adipogenic, and osteogenetic induction. uSMC were isolated from uteri resected during operation and co-cultivated with the pMSC in a Transwell chamber simulating Two, 4, and 8 days later RT-PCR and Western blotting were used to detect the mRNA and protein expression of alpha-actin, calmodulin, and myosin heavy chains (MHC), the markers of smooth muscle differentiation at the early, middle, and late stages. On day 8 RT-PCR was used to detect the expression of estrogen receptor in these 2 groups of cells, then estrogen was used to stimulate these cells and the protein kinase C (PKC) activity was examined. The pMSC could be induced into adipocytes, osteocytes, and chondrocytes respectively. After co-culture with uSMC, the morphology of the pMSC changed closely into that of the uSMC, and MHC was expressed in the pMSC. Estrogen receptor was positive in both groups of cells. The PKC activity increased, especially in the cell membrane, after stimulation of estrogen. The postpartum human placenta can be used as an important and novel source of multipotent stem cells for tissue engineering and genetic engineering. Placental MSC have the potential to differentiate into smooth muscle cells under the simulated uterus microenvironment in vitro.
Altered ROS production, NF-κB activation and interleukin-6 gene expression induced by electrical stimulation in dystrophic mdx skeletal muscle cells.

PubMed

Henríquez-Olguín, Carlos; Altamirano, Francisco; Valladares, Denisse; López, José R; Allen, Paul D; Jaimovich, Enrique

2015-07-01

-κB activation and IL-6 expression. Exposure to lipopolysaccharide induced a dramatic increase in both NF-κB activation and IL-6 expression in both wt and mdx myotubes, suggesting that the altered IL-6 gene expression after electrical stimulation in mdx muscle cells is due to dysregulation of Ca2+ release and ROS production, both of which impinge on NF-κB signaling. IL-6 is a key metabolic modulator that is released by the skeletal muscle to coordinate a multi-systemic response (liver, muscle, and adipocytes) during physical exercise; the alteration of this response in dystrophic muscles may contribute to an abnormal response to contraction and exercise. Copyright © 2015. Published by Elsevier B.V.
Postfatigue potentiation of the paralyzed soleus muscle: evidence for adaptation with long-term electrical stimulation training

PubMed Central

Shields, Richard K.; Dudley-Javoroski, Shauna; Littmann, Andrew E.

2012-01-01

Understanding the torque output behavior of paralyzed muscle has important implications for the use of functional neuromuscular electrical stimulation systems. Postfatigue potentiation is an augmentation of peak muscle torque during repetitive activation after a fatigue protocol. The purposes of this study were 1) to quantify postfatigue potentiation in the acutely and chronically paralyzed soleus and 2) to determine the effect of long-term soleus electrical stimulation training on the potentiation characteristics of recently paralyzed soleus muscle. Five subjects with chronic paralysis (>2 yr) demonstrated significant postfatigue potentiation during a repetitive soleus activation protocol that induced low-frequency fatigue. Ten subjects with acute paralysis (<6 mo) demonstrated no torque potentiation in response to repetitive stimulation. Seven of these acute subjects completed 2 yr of home-based isometric soleus electrical stimulation training of one limb (compliance = 83%; 8,300 contractions/wk). With the early implementation of electrically stimulated training, potentiation characteristics of trained soleus muscles were preserved as in the acute postinjury state. In contrast, untrained limbs showed marked postfatigue potentiation at 2 yr after spinal cord injury (SCI). A single acute SCI subject who was followed longitudinally developed potentiation characteristics very similar to the untrained limbs of the training subjects. The results of the present investigation support that postfatigue potentiation is a characteristic of fast-fatigable muscle and can be prevented by timely neuromuscular electrical stimulation training. Potentiation is an important consideration in the design of functional electrical stimulation control systems for people with SCI. PMID:16575026
Postfatigue potentiation of the paralyzed soleus muscle: evidence for adaptation with long-term electrical stimulation training.

PubMed

Shields, Richard K; Dudley-Javoroski, Shauna; Littmann, Andrew E

2006-08-01

Understanding the torque output behavior of paralyzed muscle has important implications for the use of functional neuromuscular electrical stimulation systems. Postfatigue potentiation is an augmentation of peak muscle torque during repetitive activation after a fatigue protocol. The purposes of this study were 1) to quantify postfatigue potentiation in the acutely and chronically paralyzed soleus and 2) to determine the effect of long-term soleus electrical stimulation training on the potentiation characteristics of recently paralyzed soleus muscle. Five subjects with chronic paralysis (>2 yr) demonstrated significant postfatigue potentiation during a repetitive soleus activation protocol that induced low-frequency fatigue. Ten subjects with acute paralysis (<6 mo) demonstrated no torque potentiation in response to repetitive stimulation. Seven of these acute subjects completed 2 yr of home-based isometric soleus electrical stimulation training of one limb (compliance = 83%; 8,300 contractions/wk). With the early implementation of electrically stimulated training, potentiation characteristics of trained soleus muscles were preserved as in the acute postinjury state. In contrast, untrained limbs showed marked postfatigue potentiation at 2 yr after spinal cord injury (SCI). A single acute SCI subject who was followed longitudinally developed potentiation characteristics very similar to the untrained limbs of the training subjects. The results of the present investigation support that postfatigue potentiation is a characteristic of fast-fatigable muscle and can be prevented by timely neuromuscular electrical stimulation training. Potentiation is an important consideration in the design of functional electrical stimulation control systems for people with SCI.
Loss of myogenic potential and fusion capacity of muscle stem cells isolated from contractured muscle in children with cerebral palsy.

PubMed

Domenighetti, Andrea A; Mathewson, Margie A; Pichika, Rajeswari; Sibley, Lydia A; Zhao, Leyna; Chambers, Henry G; Lieber, Richard L

2018-04-25

Cerebral palsy (CP) is the most common cause of pediatric neurodevelopmental and physical disability in the United States. It is defined as a group of motor disorders caused by a non-progressive perinatal insult to the brain. While the brain lesion is non-progressive, there is a progressive, lifelong impact on skeletal muscles, which are shorter, spastic, and may develop debilitating contractures. Satellite cells are resident muscle stem cells that are indispensable for postnatal growth and regeneration of skeletal muscles. Here we measured the myogenic potential of satellite cells isolated from contractured muscles in children with CP. When compared to typically developing (TD) children, satellite cell-derived myoblasts from CP differentiated more slowly (Slope: 0.013{plus minus}0.013 CP vs. 0.091{plus minus}0.024 TD over 24 hours, P<0.001) and fused less (Fusion Index: 21.3{plus minus}8.6 CP vs. 81.3{plus minus}7.7 TD after 48 hours, P<0.001) after exposure to low-serum conditions that stimulated myotube formation. This impairment was associated with downregulation of several markers important for myoblast fusion and myotube formation, including DNA methylation-dependent inhibition of pro-myogenic Integrin Beta 1D (ITGB1D) protein expression levels (-50% at 42 hours), and ~25% loss of integrin-mediated FAK kinase phosphorylation. The cytidine analog 5-Azacytidine (5-AZA), a demethylating agent, restored ITGB1D levels and promoted myogenesis in CP cultures. Our data demonstrate that muscle contractures in CP are associated with loss of satellite cell myogenic potential that is dependent on DNA methylation patterns affecting expression of genetic programs associated with muscle stem cell differentiation and muscle fiber formation.
Electrical stimulation to the trigeminal proprioceptive fibres that innervate the mechanoreceptors in Müller's muscle induces involuntary reflex contraction of the frontalis muscles.

PubMed

Matsuo, Kiyoshi; Osada, Yoshiro; Ban, Ryokuya

2013-02-01

The levator and frontalis muscles lack interior muscle spindles, despite consisting of slow-twitch fibres that involuntarily sustain eyelid-opening and eyebrow-raising against gravity. To compensate for this anatomical defect, this study hypothetically proposes that initial voluntary contraction of the levator fast-twitch muscle fibres stretches the mechanoreceptors in Müller's muscle and evokes proprioception, which continuously induces reflex contraction of slow-twitch fibres of the levator and frontalis muscles. This study sought to determine whether unilateral transcutaneous electrical stimulation to the trigeminal proprioceptive fibres that innervate the mechanoreceptors in Müller's muscle could induce electromyographic responses in the frontalis muscles, with monitoring responses in the orbicularis oculi muscles. The study population included 27 normal subjects and 23 subjects with aponeurotic blepharoptosis, who displayed persistently raised eyebrows on primary gaze and light eyelid closure. The stimulation induced a short-latency response in the ipsilateral frontalis muscle of all subjects and long-latency responses in the bilateral frontalis muscles of normal subjects. However, it did not induce long-latency responses in the bilateral frontalis muscles of subjects with aponeurotic blepharoptosis. The orbicularis oculi muscles showed R1 and/or R2 responses. The stimulation might reach not only the proprioceptive fibres, but also other sensory fibres related to the blink or corneal reflex. The experimental system can provoke a monosynaptic short-latency response in the ipsilateral frontalis muscle, probably through the mesencephalic trigeminal proprioceptive neuron and the frontalis motor neuron, and polysynaptic long-latency responses in the bilateral frontalis muscles through an unknown pathway. The latter neural circuit appeared to be engaged by the circumstances of aponeurotic blepharoptosis.
Improved sphincter contractility after allogenic muscle-derived progenitor cell injection into the denervated rat urethra.

PubMed

Cannon, Tracy W; Lee, Ji Youl; Somogyi, George; Pruchnic, Ryan; Smith, Christopher P; Huard, Johnny; Chancellor, Michael B

2003-11-01

To study the physiologic outcome of allogenic transplant of muscle-derived progenitor cells (MDPCs) in the denervated female rat urethra. MDPCs were isolated from muscle biopsies of normal 6-week-old Sprague-Dawley rats and purified using the preplate technique. Sciatic nerve-transected rats were used as a model of stress urinary incontinence. The experimental group was divided into three subgroups: control, denervated plus 20 microL saline injection, and denervated plus allogenic MDPCs (1 to 1.5 x 10(6) cells) injection. Two weeks after injection, urethral muscle strips were prepared and underwent electrical field stimulation. The pharmacologic effects of d-tubocurare, phentolamine, and tetrodotoxin on the urethral strips were assessed by contractions induced by electrical field stimulation. The urethral tissues also underwent immunohistochemical staining for fast myosin heavy chain and CD4-activated lymphocytes. Urethral denervation resulted in a significant decrease of the maximal fast-twitch muscle contraction amplitude to only 8.77% of the normal urethra and partial impairment of smooth muscle contractility. Injection of MDPCs into the denervated sphincter significantly improved the fast-twitch muscle contraction amplitude to 87.02% of normal animals. Immunohistochemistry revealed a large amount of new skeletal muscle fiber formation at the injection site of the urethra with minimal inflammation. CD4 staining showed minimal lymphocyte infiltration around the MDPC injection sites. Urethral denervation resulted in near-total abolishment of the skeletal muscle and partial impairment of smooth muscle contractility. Allogenic MDPCs survived 2 weeks in sciatic nerve-transected urethra with minimal inflammation. This is the first report of the restoration of deficient urethral sphincter function through muscle-derived progenitor cell tissue engineering. MDPC-mediated cellular urethral myoplasty warrants additional investigation as a new method to treat stress urinary
PPARdelta inhibits IL-1beta-stimulated proliferation and migration of vascular smooth muscle cells via up-regulation of IL-1Ra.

PubMed

Kim, H J; Kim, M Y; Hwang, J S; Kim, H J; Lee, J H; Chang, K C; Kim, J-H; Han, C W; Kim, J-H; Seo, H G

2010-06-01

Activation of peroxisome proliferator-activated receptor (PPAR) delta by GW501516, a specific PPARdelta ligand, significantly inhibited interleukin (IL)-1beta-induced proliferation and migration of vascular smooth muscle cells (VSMCs). This effect of GW501516 was dependent on transforming growth factor-beta, and was mediated through the up-regulation of IL-1 receptor antagonist. The inhibitory effect of GW501516 on VSMC proliferation was associated with cell cycle arrest at the G1 to S phase transition, which was accompanied by the induction of p21 and p53 along with decreased cyclin-dependent kinase 4 expression. Inhibition of cell migration by GW501516 was associated with the down-regulation of matrix metalloproteinase (MMP)-2 and MMP-9 in IL-1beta-treated VSMCs. Inhibition of extracellular signal-regulated kinase significantly reduced the GW501516-mediated inhibition of IL-1beta-stimulated VSMC proliferation. These results suggest that PPARdelta plays an important role in the pathophysiology of diseases associated with the proliferation and migration of VSMCs.
Bioelectrical activity of limb muscles during cold shivering of stimulation of the vestibular apparatus

NASA Technical Reports Server (NTRS)

Kuzmina, G. I.

1980-01-01

The effects of caloric and electric stimulation of the vestibular receptors on the EMG activity of limb muslces in anesthetized cats during cold induced shivering involved flexor muscles alone. Both types of stimulation suppressed bioelectrical activity more effectively in the ipsilateral muscles. The suppression of shivering activity seems to be due to the increased inhibitory effect of descending labyrinth pathways on the function of flexor motoneurons.
Effect of neuromuscular electrical stimulation on facial muscle strength and oral function in stroke patients with facial palsy

PubMed Central

Choi, Jong-Bae

2016-01-01

[Purpose] The aim of this study was to investigate the effect of neuromuscular electrical stimulation on facial muscle strength and oral function in stroke patients with facial palsy. [Subjects and Methods] Nine subjects received the electrical stimulation and traditional dysphagia therapy. Electrical stimulation was applied to stimulate each subject’s facial muscles 30 minutes a day, 5 days a week, for 4 weeks. [Results] Subjects showed significant improvement in cheek and lip strength and oral function after the intervention. [Conclusion] This study demonstrates that electrical stimulation improves facial muscle strength and oral function in stroke patients with dysphagia. PMID:27799689
The effect of electrical muscle stimulation on the prevention of disuse muscle atrophy in patients with consciousness disturbance in the intensive care unit.

PubMed

Hirose, Tomoya; Shiozaki, Tadahiko; Shimizu, Kentaro; Mouri, Tomoyoshi; Noguchi, Kazuo; Ohnishi, Mitsuo; Shimazu, Takeshi

2013-08-01

Disuse atrophy of the lower limbs of patients with consciousness disturbance has often been recognized as "an unavoidable consequence," such that the mechanism was not investigated diligently. In this study, we examined the preventive effects of electrical muscle stimulation (EMS) against disuse atrophy of the lower limbs in patients in coma after stroke or traumatic brain injury in the intensive care unit. We evaluated changes in cross-sectional area of lower limb muscles weekly with computed tomography in 6 control group patients and 9 EMS group patients. Electrical muscle stimulation was performed daily from day 7 after admission. We evaluated the anterior thigh muscle compartment, posterior thigh muscle compartment, anterior leg muscle compartment, and posterior leg muscle compartment. In the control group, the decrease in cross-sectional area progressed in all compartments every week (P < .0001). Cross-sectional areas of all compartments at day 14 were significantly decreased in the control group compared with those in the EMS group at day 7 (P < .001). We were able to limit the rate of muscle atrophy as measured in the cross-sectional areas to within 4% during the period of EMS (days 7-42) in 5 patients. The difference between the control and the EMS groups was statistically significant (P < .001). Electrical muscle stimulation is effective in the prevention of disuse muscle atrophy in patients with consciousness disorder. Copyright © 2013 Elsevier Inc. All rights reserved.
Counteracting Muscle Atrophy using Galvanic Stimulation of the Vestibular System

NASA Technical Reports Server (NTRS)

Fox, Robert A.; Polyakov, Igor

1999-01-01

The unloading of weight bearing from antigravity muscles during space flight produces significant muscle atrophy and is one of the most serious health problems facing the space program. Various exercise regimens have been developed and used either alone or in combination with pharmacological techniques to ameliorate this atrophy, but no effective countermeasure exists for this problem. The research in this project was conducted to evaluate the potential use of vestibular galvanic stimulation (VGS) to prevent muscle atrophy resulting from unloading of weight bearing from antigravity muscles. This approach was developed based on two concepts related to the process of maintaining the status of the anti-gravity neuromuscular system. These two premises are: (1) The "tone," or bias on spinal motorneurons is affected by vestibular projections that contribute importantly to maintaining muscle health and status. (2) VGS can be used to modify the excitability, or 'tone' of motorneuron of antigravity muscles. Thus, the strategy is to use VGS to modify the gain of vestibular projections to antigravity muscles and thereby change the general status of these muscles.
Evaluation of the innate immune-stimulating activity of amazake using a silkworm muscle contraction assay.

PubMed

Maruki-Uchida, Hiroko; Sai, Masahiko; Sekimizu, Kazuhisa

2017-11-22

We evaluated the innate immune-stimulating activity of amazake using a silkworm muscle contraction assay. Sake cake, a raw material used to make amazake, had high innate immunity-stimulating activity, whereas rice malt, another raw material used to make amazake, did not, even after fermentation. These results suggest that the silkworm muscle contraction assay is a useful tool to screen foods with high innate immune-stimulating activity and that amazake made from sake cake has immunomodulatory potential.
Dietary obacunone supplementation stimulates muscle hypertrophy, and suppresses hyperglycemia and obesity through the TGR5 and PPARγ pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horiba, Taro, E-mail: thoriba@mail.kikkoman.co.jp; Katsukawa, Masahiro; Mita, Moeko

Obacunone is a limonoid that is predominantly found in Citrus. Although various biological activities of limonoids have been reported, little is known about the beneficial effects of obacunone on metabolic disorders. In the present study, we examined the effects of dietary obacunone supplementation on obese KKAy mice, to clarify the function of obacunone in metabolic regulation. Mice were pair-fed a normal diet either alone or supplemented with 0.1% w/w obacunone for 28 days. Compared with the control, obacunone-fed mice had lower glycosylated hemoglobin, blood glucose, and white adipose tissue weight, although there was no significant difference in body weight. Obacunonemore » treatment also significantly increased the weight of the gastrocnemius and quadriceps muscles. Reporter gene assays revealed that obacunone stimulated the transcriptional activity of the bile acids-specific G protein-coupled receptor, TGR5, in a dose-dependent manner. In addition, obacunone inhibited adipocyte differentiation in 3T3-L1 cells and antagonized ligand-stimulated peroxisome proliferator-activated receptor γ (PPARγ) transcriptional activity. These results suggest that obacunone stimulates muscle hypertrophy and prevents obesity and hyperglycemia, and that these beneficial effects are likely to be mediated through the activation of TGR5 and inhibition of PPARγ transcriptional activity. - Highlights: • Citrus limonoid obacunone prevents hyperglycemia in obese, diabetic KKAy mice. • Obacunone reduces fat content and stimulates muscle hypertrophy in KKAy mice. • Obacunone stimulates TGR5 transcriptional activities. • Obacunone antagonizes PPARγ and inhibits lipid accumulation in adipocytes.« less
Atrial natriuretic peptide provokes a dramatic increase in cyclic GMP formation and markedly inhibits muscarinic-stimulated Ca2+ mobilisation in SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells.

PubMed

Ding, K H; Ali, N; Abdel-Latif, A A

1999-02-01

We investigated the effects of cGMP-elevating agents, including atrial natriuretic peptide (ANP), C-type natriuretic peptide (CNP) and sodium nitroprusside (SNP), on cGMP accumulation and on carbachol (CCh)-stimulated intracellular calcium ([Ca2+]i) mobilisation in SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells and in primary cultured cat iris sphincter smooth muscle (CISM) cells. The stimulatory effects of the natriuretic peptides on cGMP production correlated well with their inhibitory effects on CCh-induced [Ca+1]i mobilisation, and these effects were significantly more pronounced in the SV-CISM-2 cells than in the CISM cells. Thus, ANP (1 microM) increased cGMP production in the SV-CISM-2 cells and CISM cells by 487- and 1.7-fold, respectively, and inhibited CCh-induced [Ca2+]i mobilisation by 95 and 3%, respectively. In the SV-CISM-2 cells, ANP and CNP dose dependently inhibited CCh-induced [Ca2+]i mobilisation with IC50 values of 156 and 412 nM, respectively, and dose dependently stimulated cGMP formation with EC50 values of 24 and 88 nM, respectively, suggesting that the inhibitory actions of the peptides are mediated through cGMP. Both ANP and CNP stimulated cGMP accumulation in a time-dependent manner. The potency of the cGMP-elevating agents were in the following order: ANP>CNP>SNP; these agents had no effect on cAMP accumulation. The inhibitory effects of the natriuretic peptides were mimicked by 8-Br-cGMP, a selective activator of cGMP-dependent protein kinase. LY83583, a soluble guanylyl cyclase inhibitor, significantly inhibited SNP-induced cGMP formation but had no effect on those of ANP and CNP. The basal activities of the guanylyl cyclase and the dissociation constant (Kd) and total receptor density (Bmax) values of the natriuretic peptide receptor for [125I]ANP binding were not significantly different between the two cell types. The cGMP system, as with the cAMP system, has a major inhibitory influence on the muscarinic
Vitamin K2 improves proliferation and migration of bovine skeletal muscle cells in vitro.

PubMed

Rønning, Sissel Beate; Pedersen, Mona Elisabeth; Berg, Ragnhild Stenberg; Kirkhus, Bente; Rødbotten, Rune

2018-01-01

Skeletal muscle function is highly dependent on the ability to regenerate, however, during ageing or disease, the proliferative capacity is reduced, leading to loss of muscle function. We have previously demonstrated the presence of vitamin K2 in bovine skeletal muscles, but whether vitamin K has a role in muscle regulation and function is unknown. In this study, we used primary bovine skeletal muscle cells, cultured in monolayers in vitro, to assess a potential effect of vitamin K2 (MK-4) during myogenesis of muscle cells. Cell viability experiments demonstrate that the amount of ATP produced by the cells was unchanged when MK-4 was added, indicating viable cells. Cytotoxicity analysis show that MK-4 reduced the lactate dehydrogenase (LDH) released into the media, suggesting that MK-4 was beneficial to the muscle cells. Cell migration, proliferation and differentiation was characterised after MK-4 incubation using wound scratch analysis, immunocytochemistry and real-time PCR analysis. Adding MK-4 to the cells led to an increased muscle proliferation, increased gene expression of the myogenic transcription factor myod as well as increased cell migration. In addition, we observed a reduction in the fusion index and relative gene expression of muscle differentiation markers, with fewer complex myotubes formed in MK-4 stimulated cells compared to control cells, indicating that the MK-4 plays a significant role during the early phases of muscle proliferation. Likewise, we see the same pattern for the relative gene expression of collagen 1A, showing increased gene expression in proliferating cells, and reduced expression in differentiating cells. Our results also suggest that MK-4 incubation affect low density lipoprotein receptor-related protein 1 (LRP1) and the low-density lipoprotein receptor (LDLR) with a peak in gene expression after 45 min of MK-4 incubation. Altogether, our experiments show that MK-4 has a positive effect on muscle cell migration and
Leucine supplementation stimulates protein synthesis and reduces degradation signal activation in muscle of newborn pigs during acute endotoxemia

USDA-ARS?s Scientific Manuscript database

Sepsis disrupts skeletal muscle proteostasis and mitigates the anabolic response to leucine (Leu) in muscle of mature animals. We have shown that Leu stimulates muscle protein synthesis (PS) in healthy neonatal piglets. To determine if supplemental Leu can stimulate PS and reduce protein degradation...
Can angiogenesis induced by chronic electrical stimulation enhance latissimus dorsi muscle flap survival for application in cardiomyoplasty?

PubMed

Overgoor, Max L E; Carroll, Sean M; Papanicolau, George; Carroll, Camilla M A; Ustüner, Tuncay E T; Stremel, Richard W; Anderson, Gary L; Franken, Ralph J P M; Kon, Moshe; Barker, John H

2003-01-01

In cardiomyoplasty, the latissimus dorsi muscle is lifted on its primary neurovascular pedicle and wrapped around a failing heart. After 2 weeks, it is trained for 6 weeks using chronic electrical stimulation, which transforms the latissimus dorsi muscle into a fatigue-resistant muscle that can contract in synchrony with the beating heart without tiring. In over 600 cardiomyoplasty procedures performed clinically to date, the outcomes have varied. Given the data obtained in animal experiments, the authors believe these variable outcomes are attributable to distal latissimus dorsi muscle flap necrosis. The aim of the present study was to investigate whether the chronic electrical stimulation training used to transform the latissimus dorsi muscle into fatigue-resistant muscle could also be used to induce angiogenesis, increase perfusion, and thus protect the latissimus dorsi muscle flap from distal necrosis. After 14 days of chronic electrical stimulation (10 Hz, 330 microsec, 4 to 6 V continuous, 8 hours/day) of the right or left latissimus dorsi muscle (randomly selected) in 11 rats, both latissimus dorsi muscles were lifted on their thoracodorsal pedicles and returned to their anatomical beds. Four days later, the resulting amount of distal flap necrosis was measured. Also, at predetermined time intervals throughout the experiment, muscle surface blood perfusion was measured using scanning laser Doppler flowmetry. Finally, latissimus dorsi muscles were excised in four additional stimulated rats, to measure angiogenesis (capillary-to-fiber ratio), fiber type (oxidative or glycolytic), and fiber size using histologic specimens. The authors found that chronic electrical stimulation (1) significantly (p < 0.05) increased angiogenesis (mean capillary-to-fiber ratio) by 82 percent and blood perfusion by 36 percent; (2) did not reduce the amount of distal flap necrosis compared with nonchronic electrical stimulation controls (29 +/- 5.3 percent versus 26.6 +/- 5
Changes in the size and synthetic activity of nuclear populations in chronically stimulated rabbit skeletal muscle.

PubMed Central

Joplin, R E; Franchi, L L; Salmons, S

1987-01-01

The adaptive response of mammalian fast-twitch skeletal muscle to long-term low-frequency stimulation involves coordinated changes in the expression of a large number of genes and an increase in the synthesis of proteins and nucleic acids. Morphological correlates of these changes were sought in a qualitative and quantitative study of nuclear populations that included autoradiography at both light and electron microscopic levels. Stimulation-induced changes in biosynthetic activity were found to be supported by increases in the numbers of both non-muscle and muscle nuclei, and myonuclear counts were significantly increased in relation to sarcoplasmic volume. Moreover, the chronically stimulated muscle fibres showed ultrastructural signs consistent with mobilisation of transcriptional and translational activity. Images Fig. 2 Fig. 4 (cont.) Fig. 4 Fig. 5 PMID:3503051

Mechanical forces and their second messengers in stimulating cell growth in vitro

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.

1992-01-01

Mechanical forces play an important role in modulating the growth of a number of different tissues including skeletal muscle, smooth muscle, cardiac muscle, bone, endothelium, epithelium, and lung. As interest increases in the molecular mechanisms by which mechanical forces are transduced into growth alterations, model systems are being developed to study these processes in tissue culture. This paper reviews the current methods available for mechanically stimulating tissue cultured cells. It then outlines some of the putative 'mechanogenic' second messengers involved in altering cell growth. Not surprisingly, many mechanogenic second messengers are the same as those involved in growth factor-induced cell growth. It is hypothesized that from an evolutionary standpoint, some second messenger systems may have initially evolved for unicellular organisms to respond to physical forces such as gravity and mechanical perturbation in their environment. As multicellular organisms came into existence, they appropriated these mechanogenic second messenger cascades for cellular regulation by growth factors.
Muscle-Specific Deletion of Rictor Impairs Insulin-Stimulated Glucose Transport and Enhances Basal Glycogen Synthase Activity▿

PubMed Central

Kumar, Anil; Harris, Thurl E.; Keller, Susanna R.; Choi, Kin M.; Magnuson, Mark A.; Lawrence, John C.

2008-01-01

Rictor is an essential component of mTOR (mammalian target of rapamycin) complex 2 (mTORC2), a kinase complex that phosphorylates Akt at Ser473 upon activation of phosphatidylinositol 3-kinase (PI-3 kinase). Since little is known about the role of either rictor or mTORC2 in PI-3 kinase-mediated physiological processes in adult animals, we generated muscle-specific rictor knockout mice. Muscle from male rictor knockout mice exhibited decreased insulin-stimulated glucose uptake, and the mice showed glucose intolerance. In muscle lacking rictor, the phosphorylation of Akt at Ser473 was reduced dramatically in response to insulin. Furthermore, insulin-stimulated phosphorylation of the Akt substrate AS160 at Thr642 was reduced in rictor knockout muscle, indicating a defect in insulin signaling to stimulate glucose transport. However, the phosphorylation of Akt at Thr308 was normal and sufficient to mediate the phosphorylation of glycogen synthase kinase 3 (GSK-3). Basal glycogen synthase activity in muscle lacking rictor was increased to that of insulin-stimulated controls. Consistent with this, we observed a decrease in basal levels of phosphorylated glycogen synthase at a GSK-3/protein phosphatase 1 (PP1)-regulated site in rictor knockout muscle. This change in glycogen synthase phosphorylation was associated with an increase in the catalytic activity of glycogen-associated PP1 but not increased GSK-3 inactivation. Thus, rictor in muscle tissue contributes to glucose homeostasis by positively regulating insulin-stimulated glucose uptake and negatively regulating basal glycogen synthase activity. PMID:17967879
A biological micro actuator: graded and closed-loop control of insect leg motion by electrical stimulation of muscles.

PubMed

Cao, Feng; Zhang, Chao; Vo Doan, Tat Thang; Li, Yao; Sangi, Daniyal Haider; Koh, Jie Sheng; Huynh, Ngoc Anh; Bin Aziz, Mohamed Fareez; Choo, Hao Yu; Ikeda, Kazuo; Abbeel, Pieter; Maharbiz, Michel M; Sato, Hirotaka

2014-01-01

In this study, a biological microactuator was demonstrated by closed-loop motion control of the front leg of an insect (Mecynorrhina torquata, beetle) via electrical stimulation of the leg muscles. The three antagonistic pairs of muscle groups in the front leg enabled the actuator to have three degrees of freedom: protraction/retraction, levation/depression, and extension/flexion. We observed that the threshold amplitude (voltage) required to elicit leg motions was approximately 1.0 V; thus, we fixed the stimulation amplitude at 1.5 V to ensure a muscle response. The leg motions were finely graded by alternation of the stimulation frequencies: higher stimulation frequencies elicited larger leg angular displacement. A closed-loop control system was then developed, where the stimulation frequency was the manipulated variable for leg-muscle stimulation (output from the final control element to the leg muscle) and the angular displacement of the leg motion was the system response. This closed-loop control system, with an optimized proportional gain and update time, regulated the leg to set at predetermined angular positions. The average electrical stimulation power consumption per muscle group was 148 µW. These findings related to and demonstrations of the leg motion control offer promise for the future development of a reliable, low-power, biological legged machine (i.e., an insect-machine hybrid legged robot).
Colour stability of bovine Longissimus and Psoas major muscle as affected by electrical stimulation and hot boning.

PubMed

van Laack, R L; Smulders, F J

1990-01-01

From eight electrically stimulated and eight non-stimulated cows the righthand-side longissimus and psoas major muscles were hot boned within 1 1 2 h post mortem, vacuum packaged and chilled and storred at 1±1°C. Immediately after slaughter, the lefthand carcass-sides were blast-chilled for 1 1 2 h and subsequently chilled at 1±1°C until the following day. After cold boning, the longissimus and psoas major muscle were packaged, chilled and stored as the hot boned muscles. After 12 days of storage, steaks, cut from the primals, were displayed at 1±1°C under continuous illumination (300-400 lx). Colour measurements after 0, 2 and 4 days of display revealed a significant (p<0·10) effect of time of boning on non-stimulated psoas major muscle (lower values for a (∗), b (∗) values, chroma and %R630-%R580). Significant effects of electrical stimulation were not observed. Changes in hue tended to be more pronounced when the meat had been stimulated. Changes in chroma were largest (p<0·10) is non-stimulated, hot boned psoas muscle. Analysis of variances showed that in the longissimus muscle significant effects (p<0·10) of time boning and electrical stimulation were present. The effect of time of boning was often influenced by the use of electrical stimulation. Changes in hue and chroma indicated that hot boned samples had a higher colour stability than cold boned controls, especially when the carcasses had not been stimulated electrically. The observed differences in colour stability were rather small in all treatment groups and are not expected to present any practical merchandising problem. Copyright © 1990. Published by Elsevier Ltd.
Electrical stimulation of transplanted motoneurons improves motor unit formation

PubMed Central

Liu, Yang; Grumbles, Robert M.

2014-01-01

Motoneurons die following spinal cord trauma and with neurological disease. Intact axons reinnervate nearby muscle fibers to compensate for the death of motoneurons, but when an entire motoneuron pool dies, there is complete denervation. To reduce denervation atrophy, we have reinnervated muscles in Fisher rats from local transplants of embryonic motoneurons in peripheral nerve. Since growth of axons from embryonic neurons is activity dependent, our aim was to test whether brief electrical stimulation of the neurons immediately after transplantation altered motor unit numbers and muscle properties 10 wk later. All surgical procedures and recordings were done in anesthetized animals. The muscle consequences of motoneuron death were mimicked by unilateral sciatic nerve section. One week later, 200,000 embryonic day 14 and 15 ventral spinal cord cells, purified for motoneurons, were injected into the tibial nerve 10–15 mm from the gastrocnemii muscles as the only neuron source for muscle reinnervation. The cells were stimulated immediately after transplantation for up to 1 h using protocols designed to examine differential effects due to pulse number, stimulation frequency, pattern, and duration. Electrical stimulation that included short rests and lasted for 1 h resulted in higher motor unit counts. Muscles with higher motor unit counts had more reinnervated fibers and were stronger. Denervated muscles had to be stimulated directly to evoke contractions. These results show that brief electrical stimulation of embryonic neurons, in vivo, has long-term effects on motor unit formation and muscle force. This muscle reinnervation provides the opportunity to use patterned electrical stimulation to produce functional movements. PMID:24848463
Nitric Oxide Stimulates Matrix Synthesis and Deposition by Adult Human Aortic Smooth Muscle Cells Within Three-Dimensional Cocultures

PubMed Central

Simmers, Phillip; Gishto, Arsela; Vyavahare, Narendra

2015-01-01

Vascular diseases are characterized by the over-proliferation and migration of aortic smooth muscle cells (SMCs), and degradation of extracellular matrix (ECM) within the vessel wall, leading to compromise in cell–cell and cell–matrix signaling pathways. Tissue engineering approaches to regulate SMC over-proliferation and enhance healthy ECM synthesis showed promise, but resulted in low crosslinking efficiency. Here, we report the benefits of exogenous nitric oxide (NO) cues, delivered from S-Nitrosoglutathione (GSNO), to cell proliferation and matrix deposition by adult human aortic SMCs (HA-SMCs) within three-dimensional (3D) biomimetic cocultures. A coculture platform with two adjacent, permeable 3D culture chambers was developed to enable paracrine signaling between vascular cells. HA-SMCs were cultured in these chambers within collagen hydrogels, either alone or in the presence of human aortic endothelial cells (HA-ECs) cocultures, and exogenously supplemented with varying GSNO dosages (0–100 nM) for 21 days. Results showed that EC cocultures stimulated SMC proliferation within GSNO-free cultures. With increasing GSNO concentration, HA-SMC proliferation decreased in the presence or absence of EC cocultures, while HA-EC proliferation increased. GSNO (100 nM) significantly enhanced the protein amounts synthesized by HA-SMCs, in the presence or absence of EC cocultures, while lower dosages (1–10 nM) offered marginal benefits. Multi-fold increases in the synthesis and deposition of elastin, glycosaminoglycans, hyaluronic acid, and lysyl oxidase crosslinking enzyme (LOX) were noted at higher GSNO dosages, and coculturing with ECs significantly furthered these trends. Similar increases in TIMP-1 and MMP-9 levels were noted within cocultures with increasing GSNO dosages. Such increases in matrix synthesis correlated with NO-stimulated increases in endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) expression within EC
Hierarchical signaling transduction of the immune and muscle cell crosstalk in muscle regeneration.

PubMed

Yang, Wenjun; Hu, Ping

2018-04-01

The muscle regeneration is a complicated bioprocess that involved in many cell types, including necrotic muscle cells, satellite cells, mesenchymal cells, pericytes, immune cells, and other cell types present at the injury site. Immune cells involved in both innate and adaptive immune responses regulate the progress of muscle regeneration. In this review, we discussed the roles of different immune cells in muscle regeneration. The immune cells regulate muscle regeneration through cytokine production, cell-cell contacts, and general immune environment regulation. We also describe the current known mechanism of how immune cells regulating muscle regeneration. Copyright © 2017. Published by Elsevier Inc.
Role of skeletal muscle mitochondrial density on exercise-stimulated lipid oxidation.

PubMed

Galgani, Jose E; Johannsen, Neil M; Bajpeyi, Sudip; Costford, Sheila R; Zhang, Zhengyu; Gupta, Alok K; Ravussin, Eric

2012-07-01

Reduced skeletal muscle mitochondrial density is proposed to lead to impaired muscle lipid oxidation and increased lipid accumulation in sedentary individuals. We assessed exercise-stimulated lipid oxidation by imposing a prolonged moderate-intensity exercise in men with variable skeletal muscle mitochondrial density as measured by citrate synthase (CS) activity. After a 2-day isoenergetic high-fat diet, lipid oxidation was measured before and during exercise (650 kcal at 50% VO(2)max) in 20 healthy men with either high (HI-CS = 24 ± 1; mean ± s.e.) or low (LO-CS = 17 ± 1 nmol/min/mg protein) muscle CS activity. Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Respiratory exchange data and blood samples were collected at rest and throughout the exercise. HI-CS subjects had higher VO(2)max (50 ± 1 vs. 44 ± 2 ml/kg fat free mass/min; P = 0.01), lower fasting respiratory quotient (RQ) (0.81 ± 0.01 vs. 0.85 ± 0.01; P = 0.04) and higher ex vivo muscle palmitate oxidation (866 ± 168 vs. 482 ± 78 nmol/h/mg muscle; P = 0.05) compared to LO-CS individuals. However, whole-body exercise-stimulated lipid oxidation (20 ± 2 g vs. 19 ± 1 g; P = 0.65) and plasma glucose, lactate, insulin, and catecholamine responses were similar between the two groups. In conclusion, in response to the same energy demand during a moderate prolonged exercise bout, reliance on lipid oxidation was similar in individuals with high and low skeletal muscle mitochondrial density. This data suggests that decreased muscle mitochondrial density may not necessarily impair reliance on lipid oxidation over the course of the day since it was normal under a high-lipid oxidative demand condition. Twenty-four-hour lipid oxidation and its relationship with mitochondrial density need to be assessed.
Early changes in fiber profile and capillary density in long-term stimulated muscles.

PubMed

Hudlická, O; Dodd, L; Renkin, E M; Gray, S D

1982-10-01

Predominantly fast skeletal muscles of rabbits [tibialis anterior (TA), extensor digitorum longus (EDL)] were stimulated at a frequency naturally occurring in nerves to slow muscles (10 Hz continuously) for 8 h/day for 2--4 days. Such stimulation is known to convert all glycolytic fibers to oxidative and to increase capillary density. Our aim was to study early stages of conversion to investigate the factors responsible for the changes. Staining of quick-frozen sections for myosin ATPase, succinic dehydrogenase, and alkaline phosphatase was used to study the distribution of different fiber types and to measure fiber cross-sectional areas, capillaries per square millimeter, and capillary-to-fiber ratios in each fiber category. TA but not EDL showed conversion of fast glycolytic to fast oxidative fibers after 2 days, more after 4 days of stimulation. In both muscles, the largest fast glycolytic fibers were diminished in number after stimulation. There was significant increase in total capillaries per square millimeter after 4 days and some increase after 2 days of stimulation. The increase in capillaries per square millimeter exceeded the increase in the number of fibers per square millimeter, and since there was no change in mean fiber area, the increase is attributed to capillary growth. In EDL, there was an increase in the number of capillaries supplying both fast glycolytic and fast oxidative fibers, suggesting that capillary growth precedes fiber type conversion. In TA, the number of capillaries supplying fast oxidative fibers was increased but that to fast glycolytic fibers, was not. This is consistent with capillary growth simultaneous with or following fiber conversion. In both TA and EDL the number of capillaries perfused after contraction was higher in stimulated muscles, suggesting that increased capillary flow contributed to capillary growth.
Muscle Satellite Cell Protein Teneurin‐4 Regulates Differentiation During Muscle Regeneration

PubMed Central

Ishii, Kana; Suzuki, Nobuharu; Mabuchi, Yo; Ito, Naoki; Kikura, Naomi; Fukada, So‐ichiro; Okano, Hideyuki; Takeda, Shin'ichi

2015-01-01

Abstract Satellite cells are maintained in an undifferentiated quiescent state, but during muscle regeneration they acquire an activated stage, and initiate to proliferate and differentiate as myoblasts. The transmembrane protein teneurin‐4 (Ten‐4) is specifically expressed in the quiescent satellite cells; however, its cellular and molecular functions remain unknown. We therefore aimed to elucidate the function of Ten‐4 in muscle satellite cells. In the tibialis anterior (TA) muscle of Ten‐4‐deficient mice, the number and the size of myofibers, as well as the population of satellite cells, were reduced with/without induction of muscle regeneration. Furthermore, we found an accelerated activation of satellite cells in the regenerated Ten‐4‐deficient TA muscle. The cell culture analysis using primary satellite cells showed that Ten‐4 suppressed the progression of myogenic differentiation. Together, our findings revealed that Ten‐4 functions as a crucial player in maintaining the quiescence of muscle satellite cells. Stem Cells 2015;33:3017–3027 PMID:26013034
Intraoperative muscle electrical stimulation for accurate positioning of the temporalis muscle tendon during dynamic, one-stage lengthening temporalis myoplasty for facial and lip reanimation.

PubMed

Har-Shai, Yaron; Gil, Tamir; Metanes, Issa; Labbé, Daniel

2010-07-01

Facial paralysis is a significant functional and aesthetic handicap. Facial reanimation is performed either by two-stage microsurgical methods or by regional one-stage muscle pedicle flaps. Labbé has modified and improved the regional muscle pedicle transfer flaps for facial reanimation (i.e., the lengthening temporalis myoplasty procedure). This true myoplasty technique is capable of producing a coordinated, spontaneous, and symmetrical smile. An intraoperative electrical stimulation of the temporal muscle is proposed to simulate the smile of the paralyzed side on the surgical table. The intraoperative electrical stimulation of the temporalis muscle, employing direct percutaneous electrode needles or transcutaneous electrical stimulation electrodes, was utilized in 11 primary and four secondary cases with complete facial palsy. The duration of the facial paralysis was up to 12 years. Postoperative follow-up ranged from 3 to 12 months. The insertion points of the temporalis muscle tendon to the nasolabial fold, upper lip, and oral commissure had been changed according to the intraoperative muscle stimulation in six patients of the 11 primary cases (55 percent) and in all four secondary (revisional) cases. A coordinated, spontaneous, and symmetrical smile was achieved in all patients by 3 months after surgery by employing speech therapy and biofeedback. This adjunct intraoperative refinement provides crucial feedback for the surgeon in both primary and secondary facial palsy cases regarding the vector of action of the temporalis muscle and the accuracy of the anchoring points of its tendon, thus enhancing a more coordinated and symmetrical smile.
Defining the role of mesenchymal stromal cells on the regulation of matrix metalloproteinases in skeletal muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sassoli, Chiara; Nosi, Daniele; Tani, Alessia

Recent studies indicate that mesenchymal stromal cell (MSC) transplantation improves healing of injured and diseased skeletal muscle, although the mechanisms of benefit are poorly understood. In the present study, we investigated whether MSCs and/or their trophic factors were able to regulate matrix metalloproteinase (MMP) expression and activity in different cells of the muscle tissue. MSCs in co-culture with C2C12 cells or their conditioned medium (MSC-CM) up-regulated MMP-2 and MMP-9 expression and function in the myoblastic cells; these effects were concomitant with the down-regulation of the tissue inhibitor of metalloproteinases (TIMP)-1 and -2 and with increased cell motility. In the singlemore » muscle fiber experiments, MSC-CM administration increased MMP-2/9 expression in Pax-7{sup +} satellite cells and stimulated their mobilization, differentiation and fusion. The anti-fibrotic properties of MSC-CM involved also the regulation of MMPs by skeletal fibroblasts and the inhibition of their differentiation into myofibroblasts. The treatment with SB-3CT, a potent MMP inhibitor, prevented in these cells, the decrease of α-smooth actin and type-I collagen expression induced by MSC-CM, suggesting that MSC-CM could attenuate the fibrogenic response through mechanisms mediated by MMPs. Our results indicate that growth factors and cytokines released by these cells may modulate the fibrotic response and improve the endogenous mechanisms of muscle repair/regeneration. - Highlights: • MSC-CM contains paracrine factors that up-regulate MMP expression and function in different skeletal muscle cells. • MSC-CM promotes myoblast and satellite cell migration, proliferation and differentiation. • MSC-CM negatively interferes with fibroblast-myoblast transition in primary skeletal fibroblasts. • Paracrine factors from MSCs modulate the fibrotic response and improve the endogenous mechanisms of muscle regeneration.« less
Muscle satellite cell heterogeneity and self-renewal

PubMed Central

Motohashi, Norio; Asakura, Atsushi

2014-01-01

Adult skeletal muscle possesses extraordinary regeneration capacities. After muscle injury or exercise, large numbers of newly formed muscle fibers are generated within a week as a result of expansion and differentiation of a self-renewing pool of muscle stem cells termed muscle satellite cells. Normally, satellite cells are mitotically quiescent and reside beneath the basal lamina of muscle fibers. Upon regeneration, satellite cells are activated, and give rise to daughter myogenic precursor cells. After several rounds of proliferation, these myogenic precursor cells contribute to the formation of new muscle fibers. During cell division, a minor population of myogenic precursor cells returns to quiescent satellite cells as a self-renewal process. Currently, accumulating evidence has revealed the essential roles of satellite cells in muscle regeneration and the regulatory mechanisms, while it still remains to be elucidated how satellite cell self-renewal is molecularly regulated and how satellite cells are important in aging and diseased muscle. The number of satellite cells is decreased due to the changing niche during ageing, resulting in attenuation of muscle regeneration capacity. Additionally, in Duchenne muscular dystrophy (DMD) patients, the loss of satellite cell regenerative capacity and decreased satellite cell number due to continuous needs for satellite cells lead to progressive muscle weakness with chronic degeneration. Thus, it is necessary to replenish muscle satellite cells continuously. This review outlines recent findings regarding satellite cell heterogeneity, asymmetric division and molecular mechanisms in satellite cell self-renewal which is crucial for maintenance of satellite cells as a muscle stem cell pool throughout life. In addition, we discuss roles in the stem cell niche for satellite cell maintenance, as well as related cell therapies for approaching treatment of DMD. PMID:25364710
A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle.

PubMed

van Bolhuis, A I; Holsheimer, J; Savelberg, H H

2001-05-30

Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low intensity and long duration require minimal fatigue. The present study sought to apply a nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle. Two pulse generators were used, independently supplying short supramaximal cathodal stimulating pulses (0.5 ms) and long subthreshold cathodal inactivating pulses (1.5 s) to the sciatic nerve. Propagation of action potentials was selectively blocked in nerve fibres of different diameter by adjusting the strength of the inactivating current. A tensile-testing machine was used to gauge isometric muscle force of the plantaris and both heads of the gastrocnemius muscle. The order of motor-unit recruitment was estimated from twitch characteristics, i.e. peak force and relaxation time. The results showed prolonged relaxation at lower twitch peak forces as the intensity of the inactivating current increased, indicating a reduction of the number of large motor-units to force production. It is shown that the nerve stimulation method described is effective in mimicking physiological muscle control.
Neuromuscular electrical stimulation of the hindlimb muscles for movement therapy in a rodent model.

PubMed

Ichihara, Kazuhiko; Venkatasubramanian, Ganapriya; Abbas, James J; Jung, Ranu

2009-01-30

Neuromuscular electrical stimulation (NMES) can provide functional movements in people after central nervous system injury. The neuroplastic effects of long-term NMES-induced repetitive limb movement are not well understood. A rodent model of neurotrauma in which NMES can be implemented may be effective for such investigations. We present a rodent model for NMES of the flexor and extensor muscles of the hip, knee, and ankle hindlimb muscles. Custom fabricated intramuscular stimulating electrodes for rodents were implanted near identified motor points of targeted muscles in ten adult, female Long Evans rats. The effects of altering NMES pulse stimulation parameters were characterized using strength duration curves, isometric joint torque recruitment curves and joint angle measures. The data indicate that short pulse widths have the advantage of producing graded torque recruitment curves when current is used as the control parameter. A stimulus frequency of 75 Hz or more produces fused contractions. The data demonstrate ability to accurately implant the electrodes and obtain selective, graded, repeatable, strong muscle contractions. Knee and ankle angular excursions comparable to those obtained in normal treadmill walking in the same rodent species can be obtained by stimulating the target muscles. Joint torques (normalized to body weight) obtained were larger than those reported in the literature for small tailed therian mammals and for peak isometric ankle plantarflexion in a different rodent species. This model system could be used for investigations of NMES assisted hindlimb movement therapy.
Daily Electrical Muscle Stimulation Enhances Functional Recovery Following Nerve Transection and Repair in Rats.

PubMed

Willand, Michael P; Chiang, Cameron D; Zhang, Jennifer J; Kemp, Stephen W P; Borschel, Gregory H; Gordon, Tessa

2015-08-01

Incomplete recovery following surgical reconstruction of damaged peripheral nerves is common. Electrical muscle stimulation (EMS) to improve functional outcomes has not been effective in previous studies. To evaluate the efficacy of a new, clinically translatable EMS paradigm over a 3-month period following nerve transection and immediate repair. Rats were divided into 6 groups based on treatment (EMS or no treatment) and duration (1, 2, or 3 months). A tibial nerve transection injury was immediately repaired with 2 epineurial sutures. The right gastrocnemius muscle in all rats was implanted with intramuscular electrodes. In the EMS group, the muscle was electrically stimulated with 600 contractions per day, 5 days a week. Terminal measurements were made after 1, 2, or 3 months. Rats in the 3-month group were assessed weekly using skilled and overground locomotion tests. Neuromuscular junction reinnervation patterns were also examined. Muscles that received daily EMS had significantly greater numbers of reinnervated motor units with smaller average motor unit sizes. The majority of muscle endplates were reinnervated by a single axon arising from a nerve trunk with significantly fewer numbers of terminal sprouts in the EMS group, the numbers being small. Muscle mass and force were unchanged but EMS improved behavioral outcomes. Our results demonstrated that EMS using a moderate stimulation paradigm immediately following nerve transection and repair enhances electrophysiological and behavioral recovery. © The Author(s) 2014.
Growth Factors and Tension-Induced Skeletal Muscle Growth

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.

1994-01-01

The project investigated biochemical mechanisms to enhance skeletal muscle growth, and developed a computer based mechanical cell stimulator system. The biochemicals investigated in this study were insulin/(Insulin like Growth Factor) IGF-1 and Steroids. In order to analyze which growth factors are essential for stretch-induced muscle growth in vitro, we developed a defined, serum-free medium in which the differentiated, cultured avian muscle fibers could be maintained for extended periods of time. The defined medium (muscle maintenance medium, MM medium) maintains the nitrogen balance of the myofibers for 3 to 7 days, based on myofiber diameter measurements and myosin heavy chain content. Insulin and IGF-1, but not IGF-2, induced pronounced myofiber hypertrophy when added to this medium. In 5 to 7 days, muscle fiber diameters increase by 71 % to 98% compared to untreated controls. Mechanical stimulation of the avian muscle fibers in MM medium increased the sensitivity of the cells to insulin and IGF-1, based on a leftward shift of the insulin dose/response curve for protein synthesis rates. (54). We developed a ligand binding assay for IGF-1 binding proteins and found that the avian skeletal muscle cultures produced three major species of 31, 36 and 43 kD molecular weight (54) Stretch of the myofibers was found to have no significant effect on the efflux of IGF-1 binding proteins, but addition of exogenous collagen stimulated IGF-1 binding protein production 1.5 to 5 fold. Steroid hormones have a profound effect on muscle protein turnover rates in vivo, with the stress-related glucocorticoids inducing rapid skeletal muscle atrophy while androgenic steroids induce skeletal muscle growth. Exercise in humans and animals reduces the catabolic effects of glucocorticoids and may enhance the anabolic effects of androgenic steroids on skeletal muscle. In our continuing work on the involvement of exogenrus growth factors in stretch-induced avian skeletal muscle growth, we
Rapid desensitization of vasopressin-stimulated phosphatidylinositol 4,5-bisphosphate and phosphatidylcholine hydrolysis questions the role of these pathways in sustained diacylglycerol formation in A10 vascular-smooth-muscle cells.

PubMed

Plevin, R; Wakelam, M J

1992-08-01

The kinetics of vasopressin-stimulated PtdIns(4,5)P2 and phosphatidylcholine (PtdCho) hydrolysis in relation to sustained diacylglycerol (DAG) formation was investigated in A10 vascular-smooth-muscle cells in culture. Vasopressin stimulated a transient increase in Ins(1,4,5)P3 mass formation, which was mirrored by a decrease in PtdIns(4,5)P2 mass levels. Vasopressin stimulated sustained accumulation of total [3H]inositol phosphates ([3H]IP) in the presence of Li+; however, this was significantly decreased by adding a vasopressin-receptor antagonist at different times after initial stimulation. Vasopressin-stimulated phospholipase D (PLD) activity was found to be a transient phenomenon lasting approx. 2 min. Experiments involving agonist preincubation with subsequent addition of butanol confirmed that vasopressin-stimulated PLD activity was desensitized. Vasopressin stimulated an increase in formation of choline, but not of phosphocholine, suggesting that PLD was the major catalytic route of PtdCho hydrolysis in this cell line. The roles of choline and inositol phospholipid hydrolysis in the prolonged phase of DAG formation was examined by comparing vasopressin-stimulated changes in DAG levels in the presence of butanol, the protein kinase C inhibitor Ro-31-8220 or a V1a-receptor antagonist. Vasopressin-stimulated DAG formation was decreased by 40-50% in the presence of butanol between 1 and 10 min; however, during more prolonged stimulation butanol was without significant effect. In cells pretreated with Ro-31-8220, vasopressin-stimulated DAG formation was decreased by approx. 30% at 2 min, but was significantly potentiated at later times. This coincided with an enhancement of vasopressin-stimulated [3H]IP accumulation. In cells exposed to the V1a-receptor antagonist 5 min after addition of vasopressin, subsequent DAG formation was significantly decreased, indicating that sustained formation of DAG, like [3H]IP accumulation, was dependent on continual agonist
Hyperexcitability to electrical stimulation and accelerated muscle fatiguability of taut bands in rats.

PubMed

Wang, Yong-Hui; Yin, Ming-Jing; Fan, Zhen-Zhen; Arendt-Nielsen, Lars; Ge, Hong-You; Yue, Shou-Wei

2014-04-01

Myofascial trigger points contribute significantly to musculoskeletal pain and motor dysfunction and may be associated with accelerated muscle fatiguability. The aim of this study was to investigate the electrically induced force and fatigue characteristics of muscle taut bands in rats. Muscle taut bands were dissected out and subjected to trains of electrical stimulation. The electrical threshold intensity for muscle contraction and maximum contraction force (MCF), electrical intensity dependent fatigue and electrical frequency dependent fatigue characteristics were assessed in three different sessions (n=10 each) and compared with non-taut bands in the biceps femoris muscle. The threshold intensity for muscle contraction and MCF at the 10th, 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those of non-taut bands (all p<0.05). The MCF at the 15th and 20th intensity dependent fatigue stimuli of taut bands were significantly lower than those at the 1st and 5th stimuli (all p<0.01). The MCF in the frequency dependent fatigue test was significantly higher and the stimulus frequency that induced MCF was significantly lower for taut bands than for non-taut bands (both p<0.01). The present study demonstrates that the muscle taut band itself was more excitable to electrical stimulation and significantly less fatigue resistant than normal muscle fibres.
The Skeletal Muscle Satellite Cell

PubMed Central

2011-01-01

The skeletal muscle satellite cell was first described and named based on its anatomic location between the myofiber plasma and basement membranes. In 1961, two independent studies by Alexander Mauro and Bernard Katz provided the first electron microscopic descriptions of satellite cells in frog and rat muscles. These cells were soon detected in other vertebrates and acquired candidacy as the source of myogenic cells needed for myofiber growth and repair throughout life. Cultures of isolated myofibers and, subsequently, transplantation of single myofibers demonstrated that satellite cells were myogenic progenitors. More recently, satellite cells were redefined as myogenic stem cells given their ability to self-renew in addition to producing differentiated progeny. Identification of distinctively expressed molecular markers, in particular Pax7, has facilitated detection of satellite cells using light microscopy. Notwithstanding the remarkable progress made since the discovery of satellite cells, researchers have looked for alternative cells with myogenic capacity that can potentially be used for whole body cell-based therapy of skeletal muscle. Yet, new studies show that inducible ablation of satellite cells in adult muscle impairs myofiber regeneration. Thus, on the 50th anniversary since its discovery, the satellite cell’s indispensable role in muscle repair has been reaffirmed. PMID:22147605

Role of catechins on ET-1 induced stimulation of PLD and NADPH oxidase activities in pulmonary smooth muscle cells: Determination of the probable mechanism by molecular docking studies.

PubMed

Chakraborti, Sajal; Sarkar, Jaganmay; Bhuyan, Rajabrata; Chakraborti, Tapati

2017-12-05

Treatment of human pulmonary artery smooth muscle cells with ET-1 stimulated PLD and NADPH oxidase activities, which were inhibited upon pretreatment with bosentan (ET-1 receptor antagonist), FIPI (PLD inhibitor), apocynin (NADPH oxidase inhibitor) and EGCG & ECG (catechins having galloyl group), but not EGC & EC (catechins devoid of galloyl group). Herein, we determined the probable mechanism by which the galloyl group containing catechins inhibit ET-1 induced stimulation of PLD activity by molecular docking analyses based on our biochemical studies. ET-1 induced stimulation of PLD activity was inhibited by SecinH3 (inhibitor of cytohesin). Arf-6 and cytohesin-1 were associated in the cell membrane, which was not inhibited by the catechins during ET-1 treatment to the cells. However, EGCG and ECG inhibited binding of GTPγS with Arf-6 even in presence of cytohesin-1. The molecular docking analyses revealed that the galloyl group containing catechins (EGCG/ECG) with cytohesin1-Arf6GDP, but not the non-galloyl-containing catechins (EGC and EC), prevents GDP/GTP exchange in Arf-6 which seems to be an important mechanism for inhibition of ET-1 induced activation of PLD and subsequently increase in NADPH oxidase activities.
Calcium phosphate particles stimulate interleukin-1β release from human vascular smooth muscle cells: A role for spleen tyrosine kinase and exosome release.

PubMed

Dautova, Yana; Kapustin, Alexander N; Pappert, Kevin; Epple, Matthias; Okkenhaug, Hanneke; Cook, Simon J; Shanahan, Catherine M; Bootman, Martin D; Proudfoot, Diane

2018-02-01

Calcium phosphate (CaP) particle deposits are found in several inflammatory diseases including atherosclerosis and osteoarthritis. CaP, and other forms of crystals and particles, can promote inflammasome formation in macrophages leading to caspase-1 activation and secretion of mature interleukin-1β (IL-1β). Given the close association of small CaP particles with vascular smooth muscle cells (VSMCs) in atherosclerotic fibrous caps, we aimed to determine if CaP particles affected pro-inflammatory signalling in human VSMCs. Using ELISA to measure IL-1β release from VSMCs, we demonstrated that CaP particles stimulated IL-1β release from proliferating and senescent human VSMCs, but with substantially greater IL-1β release from senescent cells; this required caspase-1 activity but not LPS-priming of cells. Potential inflammasome agonists including ATP, nigericin and monosodium urate crystals did not stimulate IL-1β release from VSMCs. Western blot analysis demonstrated that CaP particles induced rapid activation of spleen tyrosine kinase (SYK) (increased phospho-Y525/526). The SYK inhibitor R406 reduced IL-1β release and caspase-1 activation in CaP particle-treated VSMCs, indicating that SYK activation occurs upstream of and is required for caspase-1 activation. In addition, IL-1β and caspase-1 colocalised in intracellular endosome-like vesicles and we detected IL-1β in exosomes isolated from VSMC media. Furthermore, CaP particle treatment stimulated exosome secretion by VSMCs in a SYK-dependent manner, while the exosome-release inhibitor spiroepoxide reduced IL-1β release. CaP particles stimulate SYK and caspase-1 activation in VSMCs, leading to the release of IL-1β, at least in part via exosomes. These novel findings in human VSMCs highlight the pro-inflammatory and pro-calcific potential of microcalcification. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
A new vibrator to stimulate muscle proprioceptors in fMRI.

PubMed

Montant, Marie; Romaiguère, Patricia; Roll, Jean-Pierre

2009-03-01

Studying cognitive brain functions by functional magnetic resonance imaging (fMRI) requires appropriate stimulation devices that do not interfere with the magnetic fields. Since the emergence of fMRI in the 90s, a number of stimulation devices have been developed for the visual and auditory modalities. Only few devices, however, have been developed for the somesthesic modality. Here, we present a vibration device for studying somesthesia that is compatible with high magnetic field environments and that can be used in fMRI machines. This device consists of a poly vinyl chloride (PVC) vibrator containing a wind turbine and of a pneumatic apparatus that controls 1-6 vibrators simultaneously. Just like classical electromagnetic vibrators, our device stimulates muscle mechanoreceptors (muscle spindles) and generates reliable illusions of movement. We provide the fMRI compatibility data (phantom test), the calibration curve (vibration frequency as a function of air flow), as well as the results of a kinesthetic test (perceived speed of the illusory movement as a function of vibration frequency). This device was used successfully in several brain imaging studies using both fMRI and magnetoencephalography.
Differential blockade of agonist- and depolarization-induced sup 45 Ca2+ influx in smooth muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallnoefer, A.C.; Cauvin, C.; Lategan, T.W.

1989-10-01

ATP stimulated {sup 45}Ca2+ influx in rat aortic smooth muscle cells in a concentration-dependent manner (EC50 = 3.6 +/- 0.5 X 10(-7) M). ADP and GTP were less effective than ATP in stimulating {sup 45}Ca2+ influx; AMP was weakly active and the adenosine agonist 5'-(N-ethyl-carboxamido)-adenosine (NECA) had no effect. ATP gamma S was about equieffective with ATP, whereas alpha,beta-methylene-ATP (APCPP) did not induce {sup 45}Ca2+ influx. Stimulation of {sup 45}Ca2+ influx by ATP was not abolished by the dihydropyridine Ca2+ channel antagonist darodipine (PY 108-068), which completely blocked depolarization-induced {sup 45}Ca2+ influx. Inorganic cations (La3+, Cd2+, Co2+, Ni2+, Mn2+, andmore » Mg2+) were able to inhibit both agonist- and depolarization-induced {sup 45}Ca2+ influx. Cd2+, however, was approximately 20 times more selective in blocking K+-stimulated than agonist-stimulated {sup 45}Ca2+ influx. These data indicate that ATP-stimulated Ca2+ influx in rat aortic smooth muscle cells is resistant to darodipine but is reduced by La3+, Cd2+, and other inorganic blockers of Ca2+ channels.« less
The effects of neuromuscular electrical stimulation at different frequencies on the activations of deep abdominal stabilizing muscles.

PubMed

Cho, Hee Kyung; Jung, Gil Su; Kim, Eun Hyuk; Cho, Yun Woo; Kim, Sang Woo; Ahn, Sang Ho

2016-01-01

Low back pain is associated with transversus abdominis (TrA) dysfunction. Recently, it was proposed that Neuromuscular Electrical Stimulation (NMES) could be used to stimulate deep abdominal muscle contractions and improve lumbopelvic stability. The purpose of this study was to determine the optimal stimulation frequency required during NMES for the activation of deep abdominal muscles. Twenty healthy volunteers between the ages of 24 and 32 were included. The portable research-stimulator was applied using a 10 second contraction time, and a 10 second resting time at 20 Hz, 50 Hz, and 80 Hz. Changes in muscle thicknesses were determined for the TrA, obliquus internus (OI), and obliquus externus (OE) by real time ultrasound imaging. Significant thickness increases in the TrA, OI, and OE were observed during NMES versus the resting state (p < 0.05). Of the frequencies examined, 50 Hz NMES produced the greatest increase in TrA thickness (1.33 fold as compared with 1.22 fold at 20 Hz and 1.21 fold at 80 Hz) (p < 0.05). Our results indicate that NMES can preferentially stimulate contractions in deep abdominal stabilizing muscles. Most importantly, 50 Hz NMES produced greater muscle thickness increases than 20 or 80 Hz.
Responses of enzymatically isolated mammalian vascular smooth muscle cells to pharmacological and electrical stimuli.

PubMed

DeFeo, T T; Morgan, K G

1985-05-01

A modified method for enzymatically isolating mammalian vascular smooth muscle cells has been developed and tested for ferret portal vein smooth muscle. This method produces a high proportion of fully relaxed cells and these cells appear to have normal pharmacological responsiveness. The ED50 values for both alpha stimulation and potassium depolarization are not significantly different in the isolated cells from those obtained from intact strips of ferret portal vein, suggesting that the enzymatic treatment does not destroy receptors or alter the electrical responsiveness of the cells. It was also possible to demonstrate a vasodilatory action of papaverine, nitroprusside and adenosine directly on the isolated cells indicating that the pathways involved are intact in the isolated cells. This method should be of considerable usefulness, particularly in combination with the new fluorescent indicators and cell sorter techniques which require isolated cells.
KCl cotransport regulation and protein kinase G in cultured vascular smooth muscle cells.

PubMed

Adragna, N C; Zhang, J; Di Fulvio, M; Lincoln, T M; Lauf, P K

2002-05-15

K-Cl cotransport is activated by vasodilators in erythrocytes and vascular smooth muscle cells and its regulation involves putative kinase/phosphatase cascades. N-ethylmaleimide (NEM) activates the system presumably by inhibiting a protein kinase. Nitrovasodilators relax smooth muscle via cGMP-dependent activation of protein kinase G (PKG), a regulator of membrane channels and transporters. We investigated whether PKG regulates K-Cl cotransport activity or mRNA expression in normal, PKG-deficient-vector-only-transfected (PKG-) and PKG-catalytic-domain-transfected (PKG+) rat aortic smooth muscle cells. K-Cl cotransport was calculated as the Cl-dependent Rb influx, and mRNA was determined by semiquantitative RT-PCR. Baseline K-Cl cotransport was higher in PKG+ than in PKG- cells (p <0.01). At 0.5 mM, NEM stimulated K-Cl cotransport by 5-fold in PKG- but not in PKG+ cells. However, NEM was more potent although less effective to activate K-Cl cotransport in normal (passage 1-3) and PKG+ than in PKG- cells. In PKG- cells, [(dihydroindenyl) oxy] alkanoic acid (300 mM) but not furosemide (1 mM) inhibited K-Cl cotransport. Furthermore, no difference in K-Cl cotransport mRNA expression was observed between these cells. In conclusion, this study shows that manipulation of PKG expression in vascular smooth muscle cells affects K-Cl cotransport activity and its activation by NEM.
Transcranial magnetic stimulation of the human brain: responses in muscles supplied by cranial nerves.

PubMed

Benecke, R; Meyer, B U; Schönle, P; Conrad, B

1988-01-01

The present investigation demonstrates that time-varying magnetic fields induced over the skull elicit distinct types of responses in muscles supplied by the cranial nerves both on the ipsilateral and the contralateral side. When the center of the copper coil was positioned 4 cm lateral to the vertex on a line from the vertex to the external auditory meatus, bilateral responses in the masseter, orbicularis oculi, mentalis, and sternocleidomastoideus muscles with a delay of about 10 to 14 ms after the stimulus occurred. Similar to the transcranially evoked muscle responses in hand muscles, the responses in the cranial muscles can be influenced in latency and amplitude by background excitation. It is concluded that these responses are induced by excitation of the face-associated motor cortex followed by multiple I-waves in the corticonuclear tract with both ipsilateral and contralateral projections to the corresponding motoneurones. Additionally, at higher stimulation strengths "short-latency" ipsilateral responses in muscles supplied by the trigeminal, facial, and accessory nerves occurred which we suggest are induced by direct stimulation of the peripheral cranial nerves in their intracisternal course. The present study confirms the bilateral projection of corticonuclear tracts in awake unanesthetised human subjects which has been observed by electrical stimulation on the exposed cortex during surgical procedures already decades ago. The present investigation will serve as a basis for the assessment of pathophysiological mechanisms involving the corticonuclear system or the peripheral cranial nerves in their proximal parts in awake humans.
Metformin ameliorates high uric acid-induced insulin resistance in skeletal muscle cells.

PubMed

Yuan, Huier; Hu, Yaqiu; Zhu, Yuzhang; Zhang, Yongneng; Luo, Chaohuan; Li, Zhi; Wen, Tengfei; Zhuang, Wanling; Zou, Jinfang; Hong, Liangli; Zhang, Xin; Hisatome, Ichiro; Yamamoto, Tetsuya; Cheng, Jidong

2017-03-05

Hyperuricemia occurs together with abnormal glucose metabolism and insulin resistance. Skeletal muscle is an important organ of glucose uptake, disposal, and storage. Metformin activates adenosine monophosphate-activated protein kinase (AMPK) to regulate insulin signaling and promote the translocation of glucose transporter type 4 (GLUT4), thereby stimulating glucose uptake to maintain energy balance. Our previous study showed that high uric acid (HUA) induced insulin resistance in skeletal muscle tissue. However, the mechanism of metformin ameliorating UA-induced insulin resistance in muscle cells is unknown and we aimed to determine it. In this study, differentiated C2C12 cells were exposed to UA (15 mg/dl), then reactive oxygen species (ROS) was detected with DCFH-DA and glucose uptake with 2-NBDG. The levels of phospho-insulin receptor substrate 1 (IRS1; Ser307), phospho-AKT (Ser473) and membrane GLUT4 were examined by western blot analysis. The impact of metformin on UA-induced insulin resistance was monitored by adding Compound C, an AMPK inhibitor, and LY294002, a PI3K/AKT inhibitor. Our data indicate that UA can increase ROS production, inhibit IRS1-AKT signaling and insulin-stimulated glucose uptake, and induce insulin resistance in C2C12 cells. Metformin can reverse this process by increasing intracellular glucose uptake and ameliorating UA-induced insulin resistance. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.
Zinc stimulates glucose oxidation and glycemic control by modulating the insulin signaling pathway in human and mouse skeletal muscle cell lines.

PubMed

Norouzi, Shaghayegh; Adulcikas, John; Sohal, Sukhwinder Singh; Myers, Stephen

2018-01-01

Zinc is a metal ion that is an essential cell signaling molecule. Highlighting this, zinc is an insulin mimetic, activating cellular pathways that regulate cellular homeostasis and physiological responses. Previous studies have linked dysfunctional zinc signaling with several disease states including cancer, obesity, cardiovascular disease and type 2 diabetes. The present study evaluated the insulin-like effects of zinc on cell signaling molecules including tyrosine, PRSA40, Akt, ERK1/2, SHP-2, GSK-3β and p38, and glucose oxidation in human and mouse skeletal muscle cells. Insulin and zinc independently led to the phosphorylation of these proteins over a 60-minute time course in both mouse and human skeletal muscle cells. Similarly, utilizing a protein array we identified that zinc could active the phosphorylation of p38, ERK1/2 and GSK-3B in human and ERK1/2 and GSK-3B in mouse skeletal muscle cells. Glucose oxidation assays were performed on skeletal muscle cells treated with insulin, zinc, or a combination of both and resulted in a significant induction of glucose consumption in mouse (p<0.01) and human (p<0.05) skeletal muscle cells when treated with zinc alone. Insulin, as expected, increased glucose oxidation in mouse (p<0.001) and human (0.001) skeletal muscle cells, however the combination of zinc and insulin did not augment glucose consumption in these cells. Zinc acts as an insulin mimetic, activating key molecules implicated in cell signaling to maintain glucose homeostasis in mouse and human skeletal muscle cells. Zinc is an important metal ion implicated in several biological processes. The role of zinc as an insulin memetic in activating key signaling molecules involved in glucose homeostasis could provide opportunities to utilize this ion therapeutically in treating disorders associated with dysfunctional zinc signaling.
Protein Kinase Cζ Mediates Insulin-induced Glucose Transport through Actin Remodeling in L6 Muscle Cells

PubMed Central

Liu, Li-Zhong; Zhao, Hai-Lu; Zuo, Jin; Ho, Stanley K.S.; Chan, Juliana C.N.; Meng, Yan; Fang, Fu-De; Tong, Peter C.Y.

2006-01-01

Protein kinase C (PKC) ζ has been implicated in insulin-induced glucose uptake in skeletal muscle cell, although the underlying mechanism remains unknown. In this study, we investigated the effect of PKCζ on actin remodeling and glucose transport in differentiated rat L6 muscle cells expressing myc-tagged glucose transporter 4 (GLUT4). On insulin stimulation, PKCζ translocated from low-density microsomes to plasma membrane accompanied by increase in GLUT4 translocation and glucose uptake. Z-scan confocal microscopy revealed a spatial colocalization of relocated PKCζ with the small GTPase Rac-1, actin, and GLUT4 after insulin stimulation. The insulin-mediated colocalization, PKCζ distribution, GLUT4 translocation, and glucose uptake were inhibited by wortmannin and cell-permeable PKCζ pseudosubstrate peptide. In stable transfected cells, overexpression of PKCζ caused an insulin-like effect on actin remodeling accompanied by a 2.1-fold increase in GLUT4 translocation and 1.7-fold increase in glucose uptake in the absence of insulin. The effects of PKCζ overexpression were abolished by cell-permeable PKCζ pseudosubstrate peptide, but not wortmannin. Transient transfection of constitutively active Rac-1 recruited PKCζ to new structures resembling actin remodeling, whereas dominant negative Rac-1 prevented the insulin-mediated PKCζ translocation. Together, these results suggest that PKCζ mediates insulin effect on glucose transport through actin remodeling in muscle cells. PMID:16525020
[Effect of substance P on the potassium and calcium currents of colonic smooth muscle cells].

PubMed

Tang, Qincai; Luo, Hesheng; Quan, Xiaojing; Fan, Han; Yu, Guang

2015-08-11

To investigate the effect of substance P(SP) on the spontaneous contractile activity of smooth muscle cells,the large-conductance calcium-activated potassium channel currents (IBKCa) and the L-type calcium channel currents (ICaL) in rat smooth muscle cells of the proximal colon. A total of 24 healthy male Wista rats were used in this test. The change of smooth muscle strips spontaneous contraction of rat proximal colon after adding SP was recorded by a physiological signal stystem (RM6240). The IBKCa and ICaL were measured via the whole cell patch-clamp technique. The longitudinal muscle contraction was obviously increased concentration-dependently after adding different concentrations of SP (10(-7)-10(-6) mol/L), so as the circular muscle while adding SP(10(-8)-10(-6) mol/L) (all P<0.05). Compared with the control group, IBKCa was decreased after adding SP(10(-6) mol/L). Under the stimulating voltage of 60 mV, the IBKCa current density was (11.71±1.65) pA/pF, which was significantly lower compared with the control group (14.42±2.89) pA/pF (P<0.05). The ICaL) was apparently increased. Under the stimulating voltage of 0 mV, the ICaL) currents density was (-5.04±0.67) pA/pF, compared with the control group (-4.25±0.46) pA/pF, which was significantly increased (P<0.01). SP can promote the spontaneous contractile activity of colon smooth muscle of rats in vitro.And SP decrease IBKCa representatively while apparently increase ICaL). That is probably one of the mechanism SP regulate the gastrointestinal motility.
Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue.

PubMed

Vromans, Maria; Faghri, Pouran

2017-12-05

This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1) identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC) at each ES frequency and 2) evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05). However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition) should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.
Decellularised skeletal muscles allow functional muscle regeneration by promoting host cell migration.

PubMed

Urciuolo, Anna; Urbani, Luca; Perin, Silvia; Maghsoudlou, Panagiotis; Scottoni, Federico; Gjinovci, Asllan; Collins-Hooper, Henry; Loukogeorgakis, Stavros; Tyraskis, Athanasios; Torelli, Silvia; Germinario, Elena; Fallas, Mario Enrique Alvarez; Julia-Vilella, Carla; Eaton, Simon; Blaauw, Bert; Patel, Ketan; De Coppi, Paolo

2018-05-30

Pathological conditions affecting skeletal muscle function may lead to irreversible volumetric muscle loss (VML). Therapeutic approaches involving acellular matrices represent an emerging and promising strategy to promote regeneration of skeletal muscle following injury. Here we investigated the ability of three different decellularised skeletal muscle scaffolds to support muscle regeneration in a xenogeneic immune-competent model of VML, in which the EDL muscle was surgically resected. All implanted acellular matrices, used to replace the resected muscles, were able to generate functional artificial muscles by promoting host myogenic cell migration and differentiation, as well as nervous fibres, vascular networks, and satellite cell (SC) homing. However, acellular tissue mainly composed of extracellular matrix (ECM) allowed better myofibre three-dimensional (3D) organization and the restoration of SC pool, when compared to scaffolds which also preserved muscular cytoskeletal structures. Finally, we showed that fibroblasts are indispensable to promote efficient migration and myogenesis by muscle stem cells across the scaffolds in vitro. This data strongly support the use of xenogeneic acellular muscles as device to treat VML conditions in absence of donor cell implementation, as well as in vitro model for studying cell interplay during myogenesis.
Satellite cells in human skeletal muscle plasticity

PubMed Central

Snijders, Tim; Nederveen, Joshua P.; McKay, Bryon R.; Joanisse, Sophie; Verdijk, Lex B.; van Loon, Luc J. C.; Parise, Gianni

2015-01-01

Skeletal muscle satellite cells are considered to play a crucial role in muscle fiber maintenance, repair and remodeling. Our knowledge of the role of satellite cells in muscle fiber adaptation has traditionally relied on in vitro cell and in vivo animal models. Over the past decade, a genuine effort has been made to translate these results to humans under physiological conditions. Findings from in vivo human studies suggest that satellite cells play a key role in skeletal muscle fiber repair/remodeling in response to exercise. Mounting evidence indicates that aging has a profound impact on the regulation of satellite cells in human skeletal muscle. Yet, the precise role of satellite cells in the development of muscle fiber atrophy with age remains unresolved. This review seeks to integrate recent results from in vivo human studies on satellite cell function in muscle fiber repair/remodeling in the wider context of satellite cell biology whose literature is largely based on animal and cell models. PMID:26557092
Recovery Effect of the Muscle Fatigue by the Magnetic Stimulation

NASA Astrophysics Data System (ADS)

Uchida, Kousuke; Nuruki, Atsuo; Tsujimura, Sei-Ichi; Tamari, Youzou; Yunokuchi, Kazutomo

The purpose of this study is to investigate the effect of magnetic stimulation for muscle fatigue. The six healthy subjects participated in the experiment with the repetition grasp using a hand dynamometer. The measurement of EMG (electromyography) and MMG (mechanomyography) is performed on the left forearm. All subjects performed MVC (maximum voluntary contraction), and repeated exercise in 80%MVC after the MVC measurement. The repetition task was entered when display muscular strength deteriorated. We used an EMG and MMG for the measurement of the muscle fatigue. Provided EMG and MMG waves were calculated integral calculus value (iEMG, and iMMG). The result of iEMG and iMMG were divided by muscular strength, because we calculate integral calculus value per the unit display muscular strength. The result of our study, we found recovery effect by the magnetic stimulation in voluntarily muscular strength and iEMG. However, we can not found in a figure of iMMG.
Therapeutic Angiogenesis via Solar Cell-Facilitated Electrical Stimulation.

PubMed

Jeong, Gun-Jae; Oh, Jin Young; Kim, Yeon-Ju; Bhang, Suk Ho; Jang, Hyeon-Ki; Han, Jin; Yoon, Jeong-Kee; Kwon, Sang-Mo; Lee, Tae Il; Kim, Byung-Soo

2017-11-08

Cell therapy has been suggested as a treatment modality for ischemic diseases, but the poor survival and engraftment of implanted cells limit its therapeutic efficacy. To overcome such limitation, we used electrical stimulation (ES) derived from a wearable solar cell for inducing angiogenesis in ischemic tissue. ES enhanced the secretion of angiogenic growth factors and the migration of mesenchymal stem cells (MSCs), myoblasts, endothelial progenitor cells, and endothelial cells in vitro. In a mouse ischemic hindlimb model, ES generated by a solar cell and applied to the ischemic region promoted migration of MSCs toward the ischemic site and upregulated expression of angiogenic paracrine factors (vascular endothelial, basic fibroblast, and hepatocyte growth factors; and stromal cell-derived factor-1α). Importantly, solar cell-generated ES promoted the formation of capillaries and arterioles at the ischemic region, attenuated muscle necrosis and fibrosis, and eventually prevented loss of the ischemic limb. Solar cell ES therapy showed higher angiogenic efficacy than conventional MSC therapy. This study shows the feasibility of using solar cell ES as a novel treatment for therapeutic angiogenesis.
Regulatory T cells and skeletal muscle regeneration.

PubMed

Schiaffino, Stefano; Pereira, Marcelo G; Ciciliot, Stefano; Rovere-Querini, Patrizia

2017-02-01

Skeletal muscle regeneration results from the activation and differentiation of myogenic stem cells, called satellite cells, located beneath the basal lamina of the muscle fibers. Inflammatory and immune cells have a crucial role in the regeneration process. Acute muscle injury causes an immediate transient wave of neutrophils followed by a more persistent infiltration of M1 (proinflammatory) and M2 (anti-inflammatory/proregenerative) macrophages. New studies show that injured muscle is also infiltrated by a specialized population of regulatory T (Treg) cells, which control both the inflammatory response, by promoting the M1-to-M2 switch, and the activation of satellite cells. Treg cells accumulate in injured muscle in response to specific cytokines, such as IL-33, and promote muscle growth by releasing growth factors, such as amphiregulin. Muscle repair during aging is impaired due to reduced number of Treg cells and can be enhanced by IL-33 supplementation. Migration of Treg cells could also contribute to explain the effect of heterochronic parabiosis, whereby muscle regeneration of aged mice can be improved by a parabiotically linked young partners. In mdx dystrophin-deficient mice, a model of human Duchenne muscular dystrophy, muscle injury, and inflammation is mitigated by expansion of the Treg-cell population but exacerbated by Treg-cell depletion. These findings support the notion that immunological mechanisms are not only essential in the response to pathogenic microbes and tumor cells but also have a wider homeostatic role in tissue repair, and open new perspectives for boosting muscle growth in chronic muscle disease and during aging. © 2016 Federation of European Biochemical Societies.
Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy*

PubMed Central

Woodall, Benjamin P.; Woodall, Meryl C.; Luongo, Timothy S.; Grisanti, Laurel A.; Tilley, Douglas G.; Elrod, John W.; Koch, Walter J.

2016-01-01

GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2fl/fl) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β2-adrenergic receptor (β2AR) agonist, was significantly enhanced in MLC-Cre:GRK2fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β2AR-induced hypertrophy. PMID:27566547
Skeletal Muscle-specific G Protein-coupled Receptor Kinase 2 Ablation Alters Isolated Skeletal Muscle Mechanics and Enhances Clenbuterol-stimulated Hypertrophy.

PubMed

Woodall, Benjamin P; Woodall, Meryl C; Luongo, Timothy S; Grisanti, Laurel A; Tilley, Douglas G; Elrod, John W; Koch, Walter J

2016-10-14

GRK2, a G protein-coupled receptor kinase, plays a critical role in cardiac physiology. Adrenergic receptors are the primary target for GRK2 activity in the heart; phosphorylation by GRK2 leads to desensitization of these receptors. As such, levels of GRK2 activity in the heart directly correlate with cardiac contractile function. Furthermore, increased expression of GRK2 after cardiac insult exacerbates injury and speeds progression to heart failure. Despite the importance of this kinase in both the physiology and pathophysiology of the heart, relatively little is known about the role of GRK2 in skeletal muscle function and disease. In this study we generated a novel skeletal muscle-specific GRK2 knock-out (KO) mouse (MLC-Cre:GRK2 fl/fl ) to gain a better understanding of the role of GRK2 in skeletal muscle physiology. In isolated muscle mechanics testing, GRK2 ablation caused a significant decrease in the specific force of contraction of the fast-twitch extensor digitorum longus muscle yet had no effect on the slow-twitch soleus muscle. Despite these effects in isolated muscle, exercise capacity was not altered in MLC-Cre:GRK2 fl/fl mice compared with wild-type controls. Skeletal muscle hypertrophy stimulated by clenbuterol, a β 2 -adrenergic receptor (β 2 AR) agonist, was significantly enhanced in MLC-Cre:GRK2 fl/fl mice; mechanistically, this seems to be due to increased clenbuterol-stimulated pro-hypertrophic Akt signaling in the GRK2 KO skeletal muscle. In summary, our study provides the first insights into the role of GRK2 in skeletal muscle physiology and points to a role for GRK2 as a modulator of contractile properties in skeletal muscle as well as β 2 AR-induced hypertrophy. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Stimulation with monochromatic green light during incubation alters satellite cell mitotic activity and gene expression in relation to embryonic and posthatch muscle growth of broiler chickens.

PubMed

Zhang, L; Zhang, H J; Wang, J; Wu, S G; Qiao, X; Yue, H Y; Yao, J H; Qi, G H

2014-01-01

Previous studies showed that monochromatic green light stimuli during embryogenesis accelerated posthatch body weight (BW) and pectoral muscle growth of broilers. In this experiment, we further investigated the morphological and molecular basis of this phenomenon. Fertile broiler eggs (Arbor Acres, n=880) were pre-weighed and randomly assigned to 1 of the 2 incubation treatment groups: (1) dark condition (control group), and (2) monochromatic green light group (560 nm). The monochromatic lighting systems sourced from light-emitting diode lamps and were equalized at the intensity of 15 lx at eggshell level. The dark condition was set as a commercial control from day 1 until hatching. After hatch, 120 male 1-day-old chicks from each group were housed under incandescent white light with an intensity of 30 lx at bird-head level. No effects of light stimuli during embryogenesis on hatching time, hatchability, hatching weight and bird mortality during the feeding trial period were observed in the present study. Compared with the dark condition, the BW, pectoral muscle weight and myofiber cross-sectional areas were significantly greater on 7-day-old chicks incubated under green light. Green light also increased the satellite cell mitotic activity of pectoral muscle on 1- and 3-day-old birds. In addition, green light upregulated MyoD, myogenin and myostatin mRNA expression in late embryos and/ or newly hatched chicks. These data suggest that stimulation with monochromatic green light during incubation promote muscle growth by enhancing proliferation and differentiation of satellite cells in late embryonic and newly hatched stages. Higher expression of myostatin may ultimately help prevent excessive proliferation and differentiation of satellite cells in birds incubated under green light.
Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.

2003-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate CAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of CAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of CAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of CAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of CAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of CAMP by either epinephrine or isoproterenol.
[Selective training of the vastus medialis muscle using electrical stimulator for chondromalacia patella].

PubMed

Guo, K; Ye, Q; Lin, J; Shen, J; Yang, X

1996-04-01

Chondromalacia patella is closely related with subluxation and tilt of patella, as well as with muscular atrophy of quadriceps, especially in vastus medialis muscle. 364 cases of chondromalacia patella were treated with selective training of the vastus medialis muscle using electrical stimulator in our hospital. 211 cases were followed up after treatment from 6 months to 3 years. Among them excellent and good results were seen in 130 cases (62%), fair results were seen in 69 cases (33%) and no change was seen in 12 cases (5%). Significant reduction of CA (P < 0.01) and LPA (P < 0.001) were observed in all these patients in comparison with their primary angle. We believe that the selective training of the vastus medialis muscle using electrical stimulator is one of the effective methods for the treatment of chondromalacia patella.
Acylated and unacylated ghrelin do not directly stimulate glucose transport in isolated rodent skeletal muscle.

PubMed

Cervone, Daniel T; Dyck, David J

2017-07-01

Emerging evidence implicates ghrelin, a gut-derived, orexigenic hormone, as a potential mediator of insulin-responsive peripheral tissue metabolism. However, in vitro and in vivo studies assessing ghrelin's direct influence on metabolism have been controversial, particularly due to confounding factors such as the secondary rise in growth hormone (GH) after ghrelin injection. Skeletal muscle is important in the insulin-stimulated clearance of glucose, and ghrelin's exponential rise prior to a meal could potentially facilitate this. This study was aimed at elucidating any direct stimulatory action that ghrelin may have on glucose transport and insulin signaling in isolated rat skeletal muscle, in the absence of confounding secondary factors. Oxidative soleus and glycolytic extensor digitorum longus skeletal muscles were isolated from male Sprague Dawley rats in the fed state and incubated with various concentrations of acylated and unacylated ghrelin in the presence or absence of insulin. Ghrelin did not stimulate glucose transport in either muscle type, with or without insulin. Moreover, GH had no acute, direct stimulatory effect on either basal or insulin-stimulated muscle glucose transport. In agreement with the lack of observed effect on glucose transport, ghrelin and GH also had no stimulatory effect on Ser 473 AKT or Thr 172 AMPK phosphorylation, two key signaling proteins involved in glucose transport. Furthermore, to our knowledge, we are among the first to show that ghrelin can act independent of its receptor and cause an increase in calmodulin-dependent protein kinase 2 (CaMKII) phosphorylation in glycolytic muscle, although this was not associated with an increase in glucose transport. We conclude that both acylated and unacylated ghrelin have no direct, acute influence on skeletal muscle glucose transport. Furthermore, the immediate rise in GH in response to ghrelin also does not appear to directly stimulate glucose transport in muscle. © 2017 The
Influence of peripheral magnetic stimulation of soleus muscle on H and M waves.

PubMed

Matsuda, Tadamitsu; Kurayama, Taichi; Tagami, Miki; Fujino, Yuji; Manji, Atsushi; Kusumoto, Yasuaki; Amimoto, Kazu

2018-05-01

[Purpose] This study evaluated the effects of repetitive peripheral magnetic stimulation of the soleus muscle on spinal cord and peripheral motor nerve excitability. [Subjects and Methods] Twelve healthy adults (mean age 22 years) who provided written informed consent were administered repetitive peripheral magnetic stimulation for 10 min. Pre-and post-stimulation latencies and amplitudes of H- and M-waves of the soleus muscle were measured using electromyography and compared using paired t-tests. [Results] Pre- and post-stimulation latencies (28.3 ± 3.3 vs. 29.1 ± 1.3 ms, respectively) and amplitudes (35.8 ± 1.3 vs. 35.8 ± 1.1 mV, respectively) of H-waves were similar. Pre-stimulation latencies of M-waves were significantly higher than post-stimulation latencies (6.1 ± 2.2 vs. 5.0 ± 0.9 ms, respectively), although pre- and post-stimulation amplitudes were similar (12.2 ± 1.4 vs. 12.2 ± 1.3 mV, respectively). Motor neuron excitability, based on the excitability of motor nerves and peripheral nerve action, was increased by M-waves following magnetic stimulation. [Conclusion] The lack of effect of magnetic stimulation on the amplitude and latency of the H-reflex suggests that magnetic stimulation did not activate sensory nerve synapses of α motor neurons in the spinal cord. However, because motor nerves were stimulated together with sensory nerves, the increased H-wave amplitude may have reflected changes in peripheral rather than in α motor nerves.
Effects of Electrical Stimulation on Skeletal Muscle of Old Sedentary People

PubMed Central

Mosole, Simone; Zampieri, Sandra; Furlan, Sandra; Carraro, Ugo; Löefler, Stefan; Kern, Helmut; Volpe, Pompeo

2018-01-01

Physical activity plays an important role in preventing muscle atrophy and chronic diseases in adults and in the elderly. Calcium (Ca2+) cycling and activation of specific molecular pathways are essential in contraction-induced muscle adaptation. This study attains human muscle sections and total homogenates prepared from biopsies obtained before (control) and after 9 weeks of training by electrical stimulation (ES) on a group of volunteers. The aim of the study was to investigate about the molecular mechanisms that support functional muscle improvement by ES. Evidences of kinase/phosphatase pathways activation after ES were obtained. Moreover, expression of Sarcalumenin, Calsequestrin and sarco/endoplasmic reticulum Ca2+-ATPase (Serca) isoforms was regulated by training. In conclusion, this work shows that neuromuscular ES applied to vastus lateralis muscle of sedentary seniors combines fiber remodeling with activation of Ca2+-Calmodulin molecular pathways and modulation of key Ca2+-handling proteins. PMID:29662923
Loss of niche-satellite cell interactions in syndecan-3 null mice alters muscle progenitor cell homeostasis improving muscle regeneration.

PubMed

Pisconti, Addolorata; Banks, Glen B; Babaeijandaghi, Farshad; Betta, Nicole Dalla; Rossi, Fabio M V; Chamberlain, Jeffrey S; Olwin, Bradley B

2016-01-01

The skeletal muscle stem cell niche provides an environment that maintains quiescent satellite cells, required for skeletal muscle homeostasis and regeneration. Syndecan-3, a transmembrane proteoglycan expressed in satellite cells, supports communication with the niche, providing cell interactions and signals to maintain quiescent satellite cells. Syndecan-3 ablation unexpectedly improves regeneration in repeatedly injured muscle and in dystrophic mice, accompanied by the persistence of sublaminar and interstitial, proliferating myoblasts. Additionally, muscle aging is improved in syndecan-3 null mice. Since syndecan-3 null myofiber-associated satellite cells downregulate Pax7 and migrate away from the niche more readily than wild type cells, syxndecan-3 appears to regulate satellite cell homeostasis and satellite cell homing to the niche. Manipulating syndecan-3 provides a promising target for development of therapies to enhance muscle regeneration in muscular dystrophies and in aged muscle.
Stimulation of abdominal and upper thoracic muscles with surface electrodes for respiration and cough: Acute studies in adult canines.

PubMed

Walter, James S; Posluszny, Joseph; Dieter, Raymond; Dieter, Robert S; Sayers, Scott; Iamsakul, Kiratipath; Staunton, Christine; Thomas, Donald; Rabbat, Mark; Singh, Sanjay

2018-05-01

To optimize maximal respiratory responses with surface stimulation over abdominal and upper thorax muscles and using a 12-Channel Neuroprosthetic Platform. Following instrumentation, six anesthetized adult canines were hyperventilated sufficiently to produce respiratory apnea. Six abdominal tests optimized electrode arrangements and stimulation parameters using bipolar sets of 4.5 cm square electrodes. Tests in the upper thorax optimized electrode locations, and forelimb moment was limited to slight-to-moderate. During combined muscle stimulation tests, the upper thoracic was followed immediately by abdominal stimulation. Finally, a model of glottal closure for cough was conducted with the goal of increased peak expiratory flow. Optimized stimulation of abdominal muscles included three sets of bilateral surface electrodes located 4.5 cm dorsal to the lateral line and from the 8 th intercostal space to caudal to the 13 th rib, 80 or 100 mA current, and 50 Hz stimulation frequency. The maximal expired volume was 343 ± 23 ml (n=3). Optimized upper thorax stimulation included a single bilateral set of electrodes located over the 2 nd interspace, 60 to 80 mA, and 50 Hz. The maximal inspired volume was 304 ± 54 ml (n=4). Sequential stimulation of the two muscles increased the volume to 600 ± 152 ml (n=2), and the glottal closure maneuver increased the flow. Studies in an adult canine model identified optimal surface stimulation methods for upper thorax and abdominal muscles to induce sufficient volumes for ventilation and cough. Further study with this neuroprosthetic platform is warranted.
Triptolide inhibits TGF-β1-induced cell proliferation in rat airway smooth muscle cells by suppressing Smad signaling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ming; Lv, Zhiqiang; Huang, Linjie

Background: We have reported that triptolide can inhibit airway remodeling in a murine model of asthma via TGF-β1/Smad signaling. In the present study, we aimed to investigate the effect of triptolide on airway smooth muscle cells (ASMCs) proliferation and the possible mechanism. Methods: Rat airway smooth muscle cells were cultured and made synchronized, then pretreated with different concentration of triptolide before stimulated by TGF-β1. Cell proliferation was evaluated by MTT assay. Flow cytometry was used to study the influence of triptolide on cell cycle and apoptosis. Signal proteins (Smad2, Smad3 and Smad7) were detected by western blotting analysis. Results: Triptolidemore » significantly inhibited TGF-β1-induced ASMC proliferation (P<0.05). The cell cycle was blocked at G1/S-interphase by triptolide dose dependently. No pro-apoptotic effects were detected under the concentration of triptolide we used. Western blotting analysis showed TGF-β1 induced Smad2 and Smad3 phosphorylation was inhibited by triptolide pretreatment, and the level of Smad7 was increased by triptolide pretreatment. Conclusions: Triptolide may function as an inhibitor of asthma airway remodeling by suppressing ASMCs proliferation via negative regulation of Smad signaling pathway. - Highlights: • In this study, rat airway smooth muscle cells were cultured and made synchronized. • Triptolide inhibited TGF-β1-induced airway smooth muscle cells proliferation. • Triptolide inhibited ASMCs proliferation via negative regulation of Smad signaling pathway.« less
The interrelation between aPKC and glucose uptake in the skeletal muscle during contraction and insulin stimulation.

PubMed

Santos, J M; Benite-Ribeiro, S A; Queiroz, G; Duarte, J A

2014-12-01

Contraction and insulin increase glucose uptake in skeletal muscle. While the insulin pathway, better characterized, requires activation of phosphoinositide 3-kinase (PI3K) and atypical protein kinase (aPKC), muscle contraction seems to share insulin-activated components to increase glucose uptake. This study aimed to investigate the interrelation between the pathway involved in glucose uptake evoked by insulin and muscle contraction. Isolated muscle of rats was treated with solvent (control), insulin, wortmannin (PI3K inhibitor) and the combination of insulin plus wortmannin. After treatment, muscles were electrically stimulated (contracted) or remained at rest. Glucose transporter 4 (GLUT4) localization, glucose uptake and phospho-aPKC (aPKC activated form) were assessed. Muscle contraction and insulin increased glucose uptake in all conditions when compared with controls not stimulating an effect that was accompanied by an increase in GLUT4 and of phospho-aPKC at the muscle membrane. Contracted muscles treated with insulin did not show additive effects on glucose uptake or aPKC activity compared with the response when these stimuli were applied alone. Inhibition of PI3K blocked insulin effect on glucose uptake and aPKC but not in the contractile response. Thus, muscle contraction seems to stimulate aPKC and glucose uptake independently of PI3K. Therefore, aPKC may be a convergence point and a rate limit step in the pathway by which, insulin and contraction, increase glucose uptake in skeletal muscle. Copyright © 2014 John Wiley & Sons, Ltd.
Role of cellular bioenergetics in smooth muscle cell proliferation induced by platelet-derived growth factor.

PubMed

Perez, Jessica; Hill, Bradford G; Benavides, Gloria A; Dranka, Brian P; Darley-Usmar, Victor M

2010-05-13

Abnormal smooth muscle cell proliferation is a hallmark of vascular disease. Although growth factors are known to contribute to cell hyperplasia, the changes in metabolism associated with this response, particularly mitochondrial respiration, remain unclear. Given the increased energy requirements for proliferation, we hypothesized that PDGF (platelet-derived growth factor) would stimulate glycolysis and mitochondrial respiration and that this elevated bioenergetic capacity is required for smooth muscle cell hyperplasia. To test this hypothesis, cell proliferation, glycolytic flux and mitochondrial oxygen consumption were measured after treatment of primary rat aortic VSMCs (vascular smooth muscle cells) with PDGF. PDGF increased basal and maximal rates of glycolytic flux and mitochondrial oxygen consumption; enhancement of these bioenergetic pathways led to a substantial increase in the mitochondrial reserve capacity. Interventions with the PI3K (phosphoinositide 3-kinase) inhibitor LY-294002 or the glycolysis inhibitor 2-deoxy-D-glucose abrogated PDGF-stimulated proliferation and prevented augmentation of glycolysis and mitochondrial reserve capacity. Similarly, when L-glucose was substituted for D-glucose, PDGF-dependent proliferation was abolished, as were changes in glycolysis and mitochondrial respiration. Interestingly, LDH (lactate dehydrogenase) protein levels and activity were significantly increased after PDGF treatment. Moreover, substitution of L-lactate for D-glucose was sufficient to increase mitochondrial reserve capacity and cell proliferation after treatment with PDGF; these effects were inhibited by the LDH inhibitor oxamate. These results suggest that glycolysis, by providing substrates that enhance the mitochondrial reserve capacity, plays an essential role in PDGF-induced cell proliferation, underscoring the integrated metabolic response required for proliferation of VSMCs in the diseased vasculature.
The role of CD27-CD70-mediated T cell co-stimulation in vasculogenesis, arteriogenesis and angiogenesis.

PubMed

Simons, K H; Aref, Z; Peters, H A B; Welten, S P; Nossent, A Y; Jukema, J W; Hamming, J F; Arens, R; de Vries, M R; Quax, P H A

2018-06-01

T cells have a distinctive role in neovascularization, which consists of arteriogenesis and angiogenesis under pathological conditions and vasculogenesis under physiological conditions. However, the role of co-stimulation in T cell activation in neovascularization has yet to be established. The aim of this study was to investigate the role T cell co-stimulation and inhibition in angiogenesis, arteriogenesis and vasculogenesis. Hind limb ischemia was induced by double ligation of the left femoral artery in mice and blood flow recovery was measured with Laser Doppler Perfusion Imaging in control, CD70 -/- , CD80/86 -/- , CD70/80/86 -/- and CTLA4 +/- mice. Blood flow recovery was significantly impaired in mice lacking CD70 compared to control mice, but was similar in CD80/86 -/- , CTLA4 +/- and control mice. Mice lacking CD70 showed impaired vasculogenesis, since the number of pre-existing collaterals was reduced as observed in the pia mater compared to control mice. In vitro an impaired capability of vascular smooth muscle cells (VSMC) to activate T cells was observed in VSMC lacking CD70. Furthermore, CD70 -/- , CD80/86 -/- and CD70/80/86 -/- mice showed reduced angiogenesis in the soleus muscle 10 days after ligation. Arteriogenesis was also decreased in CD70 -/- compared to control mice 10 and 28 days after surgery. The present study is the first to describe an important role for T cell activation via co-stimulation in angiogenesis, arteriogenesis and vasculogenesis, where the CD27-CD70 T cell co-stimulation pathway appears to be the most important co-stimulation pathway in pre-existing collateral formation and post-ischemic blood flow recovery, by arteriogenesis and angiogenesis. Copyright © 2018 Elsevier B.V. All rights reserved.
Group-level variations in motor representation areas of thenar and anterior tibial muscles: Navigated Transcranial Magnetic Stimulation Study.

PubMed

Niskanen, Eini; Julkunen, Petro; Säisänen, Laura; Vanninen, Ritva; Karjalainen, Pasi; Könönen, Mervi

2010-08-01

Navigated transcranial magnetic stimulation (TMS) can be used to stimulate functional cortical areas at precise anatomical location to induce measurable responses. The stimulation has commonly been focused on anatomically predefined motor areas: TMS of that area elicits a measurable muscle response, the motor evoked potential. In clinical pathologies, however, the well-known homunculus somatotopy theory may not be straightforward, and the representation area of the muscle is not fixed. Traditionally, the anatomical locations of TMS stimulations have not been reported at the group level in standard space. This study describes a methodology for group-level analysis by investigating the normal representation areas of thenar and anterior tibial muscle in the primary motor cortex. The optimal representation area for these muscles was mapped in 59 healthy right-handed subjects using navigated TMS. The coordinates of the optimal stimulation sites were then normalized into standard space to determine the representation areas of these muscles at the group-level in healthy subjects. Furthermore, 95% confidence interval ellipsoids were fitted into the optimal stimulation site clusters to define the variation between subjects in optimal stimulation sites. The variation was found to be highest in the anteroposterior direction along the superior margin of the precentral gyrus. These results provide important normative information for clinical studies assessing changes in the functional cortical areas because of plasticity of the brain. Furthermore, it is proposed that the presented methodology to study TMS locations at the group level on standard space will be a suitable tool for research purposes in population studies. 2010 Wiley-Liss, Inc.
Generation of Electrical Power from Stimulated Muscle Contractions Evaluated

NASA Technical Reports Server (NTRS)

Lewandowski, Beth; Kilgore, Kevin; Ercegovic, David B.

2004-01-01

This project is a collaborative effort between NASA Glenn Research Center's Revolutionary Aeropropulsion Concepts (RAC) Project, part of the NASA Aerospace Propulsion and Power Program of the Aerospace Technology Enterprise, and Case Western Reserve University's Cleveland Functional Electrical Stimulation (FES) Center. The RAC Project foresees implantable power requirements for future applications such as organically based sensor platforms and robotics that can interface with the human senses. One of the goals of the FES Center is to develop a totally implantable neural prosthesis. This goal is based on feedback from patients who would prefer a system with an internal power source over the currently used system with an external power source. The conversion system under investigation would transform the energy produced from a stimulated muscle contraction into electrical energy. We hypothesize that the output power of the system will be greater than the input power necessary to initiate, sustain, and control the electrical conversion system because of the stored potential energy of the muscle. If the system can be made biocompatible, durable, and with the potential for sustained use, then the biological power source will be a viable solution.
Altered responsiveness of the guinea-pig isolated ileum to smooth muscle stimulants and to electrical stimulation after in situ ischemia.

PubMed

Rodriguez, Rodolfo; Ventura-Martinez, Rosa; Santiago-Mejia, Jacinto; Avila-Costa, Maria R; Fortoul, Teresa I

2006-02-01

1. We evaluated changes in contractility of the guinea-pig isolated ileum, using intact segments and myenteric plexus-longitudinal muscle (MPLM) preparations, after several times (5-160 min) of ischemia in situ. 2. Intestinal ischemia was produced by clamping the superior mesenteric artery. Ischemic and nonischemic segments, obtained from the same guinea-pig, were mounted in organ baths containing Krebs-bicarbonate (K-B) solution, maintained at 37 degrees C and gassed with 95% O2/5% CO2. The preparations were allowed to equilibrate for 60 min under continuous superfusion of warm K-B solution and then electrically stimulated at 40 V (0.3 Hz, 3.0 ms). Thereafter, complete noncumulative concentration-response curves were constructed for acetylcholine (ACh), histamine (HIS), potassium chloride (KCl), and barium chloride (BaCl2). Mean Emax (maximal response) values were calculated for each drug. 3. Our study shows that alterations of chemically and electrically evoked contractions are dependent on ischemic periods. It also demonstrates that contractile responses of ischemic tissues to neurogenic stimulation decreases earlier and to a significantly greater extent than the non-nerve mediated responses of the intestinal smooth muscle. Contractile responses to smooth muscle stimulants were all similarly affected by ischemia. Electron microscopy images indicated necrotic neuronal death. The decrease in reactivity of ischemic tissues to electrical stimulation was ameliorated by dexrazoxane, an antioxidant agent. 4. We consider the guinea-pig isolated ileum as a useful model system to study the processes involved in neuronal ischemia, and we propose that the reduction in maximal responses to electrical stimulation is a useful parameter to study neuroprotection.
Optogenetic control of contractile function in skeletal muscle

PubMed Central

Bruegmann, Tobias; van Bremen, Tobias; Vogt, Christoph C.; Send, Thorsten; Fleischmann, Bernd K.; Sasse, Philipp

2015-01-01

Optogenetic stimulation allows activation of cells with high spatial and temporal precision. Here we show direct optogenetic stimulation of skeletal muscle from transgenic mice expressing the light-sensitive channel Channelrhodopsin-2 (ChR2). Largest tetanic contractions are observed with 5-ms light pulses at 30 Hz, resulting in 84% of the maximal force induced by electrical stimulation. We demonstrate the utility of this approach by selectively stimulating with a light guide individual intralaryngeal muscles in explanted larynges from ChR2-transgenic mice, which enables selective opening and closing of the vocal cords. Furthermore, systemic injection of adeno-associated virus into wild-type mice provides sufficient ChR2 expression for optogenetic opening of the vocal cords. Thus, direct optogenetic stimulation of skeletal muscle generates large force and provides the distinct advantage of localized and cell-type-specific activation. This technology could be useful for therapeutic purposes, such as restoring the mobility of the vocal cords in patients suffering from laryngeal paralysis. PMID:26035411
The role of satellite cells in muscle hypertrophy.

PubMed

Blaauw, Bert; Reggiani, Carlo

2014-02-01

The role of satellite cells in muscle hypertrophy has long been a debated issue. In the late 1980s it was shown that proteins remain close to the myonucleus responsible for its synthesis, giving rise to the idea of a nuclear domain. This, together with the observation that during various models of muscle hypertrophy there is an activation of the muscle stem cells, i.e. satellite cells, lead to the idea that satellite cell activation is required for muscle hypertrophy. Thus, satellite cells are not only responsible for muscle repair and regeneration, but also for hypertrophic growth. Further support for this line of thinking was obtained after studies showing that irradiation of skeletal muscle, and therefore elimination of all satellite cells, completely prevented overload-induced hypertrophy. Recently however, using different transgenic approaches, it has become clear that muscle hypertrophy can occur without a contribution of satellite cells, even though in most situations of muscle hypertrophy satellite cells are activated. In this review we will discuss the contribution of satellite cells, and other muscle-resident stem cells, to muscle hypertrophy both in mice as well as in humans.
The roles of muscle stem cells in muscle injury, atrophy and hypertrophy.

PubMed

Fukada, So-Ichiro

2018-05-01

Skeletal muscle is composed of multinuclear cells called myofibers. Muscular dystrophy (a genetic muscle disorder) induces instability in the cell membrane of myofibers and eventually causes myofibre damage. Non-genetic muscle disorders, including sarcopenia, diabetes, bedridden immobility and cancer cachexia, lead to atrophy of myofibres. In contrast, resistance training induces myofibre hypertrophy. Thus, myofibres exhibit a plasticity that is strongly affected by both intrinsic and extrinsic factors. There is no doubt that muscle stem cells (MuSCs, also known as muscle satellite cells) are indispensable for muscle repair/regeneration, but their contributions to atrophy and hypertrophy are still controversial. The present review focuses on the relevance of MuSCs to (i) muscle diseases and (ii) hypertrophy. Further, this review addresses fundamental questions about MuSCs to clarify the onset or progression of these diseases and which might lead to development of a MuSC-based therapy.
Skeletal muscle satellite cells

NASA Technical Reports Server (NTRS)

Schultz, E.; McCormick, K. M.

1994-01-01

Evidence now suggests that satellite cells constitute a class of myogenic cells that differ distinctly from other embryonic myoblasts. Satellite cells arise from somites and first appear as a distinct myoblast type well before birth. Satellite cells from different muscles cannot be functionally distinguished from one another and are able to provide nuclei to all fibers without regard to phenotype. Thus, it is difficult to ascribe any significant function to establishing or stabilizing fiber type, even during regeneration. Within a muscle, satellite cells exhibit marked heterogeneity with respect to their proliferative behavior. The satellite cell population on a fiber can be partitioned into those that function as stem cells and those which are readily available for fusion. Recent studies have shown that the cells are not simply spindle shaped, but are very diverse in their morphology and have multiple branches emanating from the poles of the cells. This finding is consistent with other studies indicating that the cells have the capacity for extensive migration within, and perhaps between, muscles. Complexity of cell shape usually reflects increased cytoplasmic volume and organelles including a well developed Golgi, and is usually associated with growing postnatal muscle or muscles undergoing some form of induced adaptive change or repair. The appearance of activated satellite cells suggests some function of the cells in the adaptive process through elaboration and secretion of a product. Significant advances have been made in determining the potential secretion products that satellite cells make. The manner in which satellite cell proliferative and fusion behavior is controlled has also been studied. There seems to be little doubt that cellcell coupling is not how satellite cells and myofibers communicate. Rather satellite cell regulation is through a number of potential growth factors that arise from a number of sources. Critical to the understanding of this form
Growth factor involvement in tension-induced skeletal muscle growth

NASA Technical Reports Server (NTRS)

Vandenburgh, H. H.

1987-01-01

Muscle tissue culture techniques were developed to grow skeletal myofibers which differentiate into more adult-like myofibers. Mechanical simulation studies of these muscle cells in a newly developed mechanical cell simulator can now be performed to study growth processes in skeletal muscle. Conditions in the mechanical cell simulator were defined where mechanical activity can either prevent muscle wasting or stimulate muscle growth. The role of endogenous and exogenous growth factors in tension-induced muscle growth is being investigated under the defined conditions of tissue culture.

Preliminary investigations on the effects of a Strongylus vulgaris larval extract, mononuclear factors and platelet factors on equine smooth muscle cells in vitro.

PubMed

Morgan, S J; Storts, R W; Stromberg, P C; Sowa, B A; Lay, J C

1989-01-01

Factors involved in the proliferation of equine vascular smooth muscle cells were studied in vitro. The most prominent proliferative responses in cultured vascular smooth muscle cells were induced by Strongylus vulgaris larval antigen extract (LAE) and platelet-derived factors. Less significant proliferative responses were obtained with conditioned media from S. vulgaris LAE stimulated and from unstimulated equine mononuclear leukocytes. Additionally, vascular smooth muscle cells exposed to S. vulgaris LAE developed numerous perinuclear vacuoles and were more spindle-shaped than control or smooth muscle cells exposed to other factors. Equine mononuclear leukocytes exposed to LAE developed prominent morphological changes, including enlargement, clumping and increased numbers of mitotic figures.
Mechanical Coupling of Smooth Muscle Cells Using Microengineered Substrates and Local Stimulation

NASA Astrophysics Data System (ADS)

Copeland, Craig; Hunter, David; Tung, Leslie; Chen, Christopher; Reich, Daniel

2013-03-01

Mechanical stresses directly affect many cellular processes, including signal transduction, growth, differentiation, and survival. Cells can themselves generate such stresses by activating myosin to contract the actin cytoskeleton, which in turn can regulate both cell-substrate and cell-cell interactions. We are studying mechanical forces at cell-cell and cell-substrate interactions using arrays of selectively patterned flexible PDMS microposts combined with the ability to apply local chemical stimulation. Micropipette ``spritzing'', a laminar flow technique, uses glass micropipettes mounted on a microscope stage to deliver drugs to controlled regions within a cellular construct while cell traction forces are recorded via the micropost array. The pipettes are controlled by micromanipulators allowing for rapid and precise movement across the array and the ability to treat multiple constructs within a sample. This technique allows for observing the propagation of a chemically induced mechanical stimulus through cell-cell and cell-substrate interactions. We have used this system to administer the acto-myosin inhibitors Blebbistatin and Y-27632 to single cells and observed the subsequent decrease in cell traction forces. Experiments using trypsin-EDTA have shown this system to be capable of single cell manipulation through removal of one cell within a pair configuration while leaving the other cell unaffected. This project is supported in part by NIH grant HL090747
Intercellular ultrafast Ca2+ wave in vascular smooth muscle cells: numerical and experimental study

NASA Astrophysics Data System (ADS)

Quijano, J. C.; Raynaud, F.; Nguyen, D.; Piacentini, N.; Meister, J. J.

2016-08-01

Vascular smooth muscle cells exhibit intercellular Ca2+ waves in response to local mechanical or KCl stimulation. Recently, a new type of intercellular Ca2+ wave was observed in vitro in a linear arrangement of smooth muscle cells. The intercellular wave was denominated ultrafast Ca2+ wave and it was suggested to be the result of the interplay between membrane potential and Ca2+ dynamics which depended on influx of extracellular Ca2+, cell membrane depolarization and its intercel- lular propagation. In the present study we measured experimentally the conduction velocity of the membrane depolarization and performed simulations of the ultrafast Ca2+ wave along coupled smooth muscle cells. Numerical results reproduced a wide spectrum of experimental observations, including Ca2+ wave velocity, electrotonic membrane depolarization along the network, effects of inhibitors and independence of the Ca2+ wave speed on the intracellular stores. The numerical data also provided new physiological insights suggesting ranges of crucial model parameters that may be altered experimentally and that could significantly affect wave kinetics allowing the modulation of the wave characteristics experimentally. Numerical and experimental results supported the hypothesis that the propagation of membrane depolarization acts as an intercellular messenger mediating intercellular ultrafast Ca2+ waves in smooth muscle cells.
Monocyte activation by smooth muscle cell-derived matrices.

PubMed

Kaufmann, J; Jorgensen, R W; Martin, B M; Franzblau, C

1990-12-01

Mononuclear phagocytes adhere to and penetrate the vessel wall endothelium and contact the subendothelial space prior to the development of the atherosclerotic plaque. In an attempt to model the early events of plaque development we used an elastin-rich, multicomponent, cell-derived matrix from neonatal rat aortic smooth muscle cells as a substratum for monocytes. Using this model, we show that human monocyte morphology and metabolism are markedly altered by the matrix substratum. When a mixed mononuclear cell population is seeded on matrix or plastic, only monocytes adhere to the matrix surface. In contrast, lymphocytes as well as monocytes adhere to the plastic surface. The matrix-adherent monocytes develop large intracellular granules and form extensive clusters of individual cells. Metabolically, these cells develop sodium fluoride resistant non-specific esterase activity and their media contain more growth factor activity and PGE2. Although total protein synthesis is equivalent in both cultures, the matrix contact induces an increase in specific proteins in the media. We also show that a purified alpha-elastin substratum induces some, but not all, of the monocyte changes seen when using the matrix substratum. Using the alpha-elastin substratum, there is selective adhesion of monocytes and increased growth factor activity, however, the cells are morphologically different from the matrix-adherent cells. Thus, the use of the smooth muscle cell-derived matrix, in conjunction with purified matrix components, serves as a model that can provide insight into the mechanisms of monocyte adhesion and stimulation by the matrix environment that exists in vivo. Such mechanisms may be particularly important in atherogenesis.
SIRT2 negatively regulates insulin resistance in C2C12 skeletal muscle cells.

PubMed

Arora, Amita; Dey, Chinmoy Sankar

2014-09-01

SIRT2 is primarily a cytoplasmic protein deacetylase and is abundantly expressed in metabolically active tissues like adipocytes and brain. However, its role, if any, in regulating insulin signaling in skeletal muscle cells, is not known. We have examined the role of SIRT2 in insulin-mediated glucose disposal in normal and insulin resistant C2C12 skeletal muscle cells in vitro. SIRT2 was over expressed in insulin resistant skeletal muscle cells. Pharmacological inhibition of SIRT2 increased insulin-stimulated glucose uptake and improved phosphorylation of Akt and GSK3β in insulin resistant cells. Knockdown of endogenous SIRT2 and over expression of catalytically-inactive SIRT2 mutant under insulin-resistant condition showed similar amelioration of insulin sensitivity. Our results suggest that down-regulation of SIRT2 improved insulin sensitivity in skeletal muscle cells under insulin-resistant condition. Previously it has been reported that down-regulation of SIRT1 and SIRT3 in C2C12 cells results in impairment of insulin signaling and induces insulin resistance. However, we have observed an altogether different role of SIRT2 in skeletal muscle. This implicates a differential regulation of insulin resistance by sirtuins which otherwise share a conserved catalytic domain. The study significantly directs towards future approaches in targeting inhibition of SIRT2 for therapeutic treatment of insulin resistance which is the major risk factor in Type 2 diabetes. Copyright © 2014 Elsevier B.V. All rights reserved.
Critical role of actin-associated proteins in smooth muscle contraction, cell proliferation, airway hyperresponsiveness and airway remodeling.

PubMed

Tang, Dale D

2015-10-30

Asthma is characterized by airway hyperresponsiveness and airway remodeling, which are largely attributed to increased airway smooth muscle contractility and cell proliferation. It is known that both chemical and mechanical stimulation regulates smooth muscle contraction. Recent studies suggest that contractile activation and mechanical stretch induce actin cytoskeletal remodeling in smooth muscle. However, the mechanisms that control actin cytoskeletal reorganization are not completely elucidated. This review summarizes our current understanding regarding how actin-associated proteins may regulate remodeling of the actin cytoskeleton in airway smooth muscle. In particular, there is accumulating evidence to suggest that Abelson tyrosine kinase (Abl) plays a critical role in regulating airway smooth muscle contraction and cell proliferation in vitro, and airway hyperresponsiveness and remodeling in vivo. These studies indicate that Abl may be a novel target for the development of new therapy to treat asthma.
Na+,K+-pump stimulation improves contractility in isolated muscles of mice with hyperkalemic periodic paralysis

PubMed Central

Nielsen, Ole Bækgaard; Clausen, Johannes D.; Pedersen, Thomas Holm; Hayward, Lawrence J.

2011-01-01

In patients with hyperkalemic periodic paralysis (HyperKPP), attacks of muscle weakness or paralysis are triggered by K+ ingestion or rest after exercise. Force can be restored by muscle work or treatment with β2-adrenoceptor agonists. A missense substitution corresponding to a mutation in the skeletal muscle voltage-gated Na+ channel (Nav1.4, Met1592Val) causing human HyperKPP was targeted into the mouse SCN4A gene (mutants). In soleus muscles prepared from these mutant mice, twitch, tetanic force, and endurance were markedly reduced compared with soleus from wild type (WT), reflecting impaired excitability. In mutant soleus, contractility was considerably more sensitive than WT soleus to inhibition by elevated [K+]o. In resting mutant soleus, tetrodotoxin (TTX)-suppressible 22Na uptake and [Na+]i were increased by 470 and 58%, respectively, and membrane potential was depolarized (by 16 mV, P < 0.0001) and repolarized by TTX. Na+,K+ pump–mediated 86Rb uptake was 83% larger than in WT. Salbutamol stimulated 86Rb uptake and reduced [Na+]i both in mutant and WT soleus. Stimulating Na+,K+ pumps with salbutamol restored force in mutant soleus and extensor digitorum longus (EDL). Increasing [Na+]i with monensin also restored force in soleus. In soleus, EDL, and tibialis anterior muscles of mutant mice, the content of Na+,K+ pumps was 28, 62, and 33% higher than in WT, respectively, possibly reflecting the stimulating effect of elevated [Na+]i on the synthesis of Na+,K+ pumps. The results confirm that the functional disorders of skeletal muscles in HyperKPP are secondary to increased Na+ influx and show that contractility can be restored by acute stimulation of the Na+,K+ pumps. Calcitonin gene-related peptide (CGRP) restored force in mutant soleus but caused no detectable increase in 86Rb uptake. Repeated excitation and capsaicin also restored contractility, possibly because of the release of endogenous CGRP from nerve endings in the isolated muscles. These
Muscle Stem Cells: A Model System for Adult Stem Cell Biology.

PubMed

Cornelison, Ddw; Perdiguero, Eusebio

2017-01-01

Skeletal muscle stem cells, originally termed satellite cells for their position adjacent to differentiated muscle fibers, are absolutely required for the process of skeletal muscle repair and regeneration. In the last decade, satellite cells have become one of the most studied adult stem cell systems and have emerged as a standard model not only in the field of stem cell-driven tissue regeneration but also in stem cell dysfunction and aging. Here, we provide background in the field and discuss recent advances in our understanding of muscle stem cell function and dysfunction, particularly in the case of aging, and the potential involvement of muscle stem cells in genetic diseases such as the muscular dystrophies.
Extracellular formation and uptake of adenosine during skeletal muscle contraction in the rat: role of adenosine transporters

PubMed Central

Lynge, J; Juel, C; Hellsten, Y

2001-01-01

The existence of adenosine transporters in plasma membrane giant vesicles from rat skeletal muscles and in primary skeletal muscle cell cultures was investigated. In addition, the contribution of intracellularly or extracellularly formed adenosine to the overall extracellular adenosine concentration during muscle contraction was determined in primary skeletal muscle cell cultures. In plasma membrane giant vesicles, the carrier-mediated adenosine transport demonstrated saturation kinetics with Km= 177 ± 36 μm and Vmax= 1.9 ± 0.2 nmol ml−1 s−1 (0.7 nmol (mg protein)−1 s−1). The existence of an adenosine transporter was further evidenced by the inhibition of the carrier-mediated adenosine transport in the presence of NBMPR (nitrobenzylthioinosine; 72 % inhibition) or dipyridamol (64 % inhibition; P < 0.05). In primary skeletal muscle cells, the rate of extracellular adenosine accumulation was 5-fold greater (P < 0.05) with electrical stimulation than without electrical stimulation. Addition of the adenosine transporter inhibitor NBMPR led to a 57 % larger (P < 0.05) rate of extracellular adenosine accumulation in the electro-stimulated muscle cells compared with control cells, demonstrating that adenosine is taken up by the skeletal muscle cells during contractions. Inhibition of ecto-5′-nucleotidase with AOPCP in electro-stimulated cells resulted in a 70 % lower (P < 0.05) rate of extracellular adenosine accumulation compared with control cells, indicating that adenosine to a large extent is formed in the extracellular space during contraction. The present study provides evidence for the existence of an NBMPR-sensitive adenosine transporter in rat skeletal muscle. Our data furthermore demonstrate that the increase in extracellular adenosine observed during electro-stimulation of skeletal muscle is due to production of adenosine in the extracellular space of skeletal muscle and that adenosine is taken up rather than released by the skeletal muscle cells
Three-dimensional co-culture of C2C12/PC12 cells improves skeletal muscle tissue formation and function.

PubMed

Ostrovidov, Serge; Ahadian, Samad; Ramon-Azcon, Javier; Hosseini, Vahid; Fujie, Toshinori; Parthiban, S Prakash; Shiku, Hitoshi; Matsue, Tomokazu; Kaji, Hirokazu; Ramalingam, Murugan; Bae, Hojae; Khademhosseini, Ali

2017-02-01

Engineered muscle tissues demonstrate properties far from native muscle tissue. Therefore, fabrication of muscle tissues with enhanced functionalities is required to enable their use in various applications. To improve the formation of mature muscle tissues with higher functionalities, we co-cultured C2C12 myoblasts and PC12 neural cells. While alignment of the myoblasts was obtained by culturing the cells in micropatterned methacrylated gelatin (GelMA) hydrogels, we studied the effects of the neural cells (PC12) on the formation and maturation of muscle tissues. Myoblasts cultured in the presence of neural cells showed improved differentiation, with enhanced myotube formation. Myotube alignment, length and coverage area were increased. In addition, the mRNA expression of muscle differentiation markers (Myf-5, myogenin, Mefc2, MLP), muscle maturation markers (MHC-IId/x, MHC-IIa, MHC-IIb, MHC-pn, α-actinin, sarcomeric actinin) and the neuromuscular markers (AChE, AChR-ε) were also upregulated. All these observations were amplified after further muscle tissue maturation under electrical stimulation. Our data suggest a synergistic effect on the C2C12 differentiation induced by PC12 cells, which could be useful for creating improved muscle tissue. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.
Interstitial Cells: Regulators of Smooth Muscle Function

PubMed Central

Sanders, Kenton M.; Ward, Sean M.; Koh, Sang Don

2014-01-01

Smooth muscles are complex tissues containing a variety of cells in addition to muscle cells. Interstitial cells of mesenchymal origin interact with and form electrical connectivity with smooth muscle cells in many organs, and these cells provide important regulatory functions. For example, in the gastrointestinal tract, interstitial cells of Cajal (ICC) and PDGFRα+ cells have been described, in detail, and represent distinct classes of cells with unique ultrastructure, molecular phenotypes, and functions. Smooth muscle cells are electrically coupled to ICC and PDGFRα+ cells, forming an integrated unit called the SIP syncytium. SIP cells express a variety of receptors and ion channels, and conductance changes in any type of SIP cell affect the excitability and responses of the syncytium. SIP cells are known to provide pacemaker activity, propagation pathways for slow waves, transduction of inputs from motor neurons, and mechanosensitivity. Loss of interstitial cells has been associated with motor disorders of the gut. Interstitial cells are also found in a variety of other smooth muscles; however, in most cases, the physiological and pathophysiological roles for these cells have not been clearly defined. This review describes structural, functional, and molecular features of interstitial cells and discusses their contributions in determining the behaviors of smooth muscle tissues. PMID:24987007
Phospholemman is not required for the acute stimulation of Na⁺-K⁺-ATPase α₂-activity during skeletal muscle fatigue.

PubMed

Manoharan, Palanikumar; Radzyukevich, Tatiana L; Hakim Javadi, Hesamedin; Stiner, Cory A; Landero Figueroa, Julio A; Lingrel, Jerry B; Heiny, Judith A

2015-12-15

The Na(+)-K(+)-ATPase α2-isoform in skeletal muscle is rapidly stimulated during muscle use and plays a critical role in fatigue resistance. The acute mechanisms that stimulate α2-activity are not completely known. This study examines whether phosphorylation of phospholemman (PLM/FXYD1), a regulatory subunit of Na(+)-K(+)-ATPase, plays a role in the acute stimulation of α2 in working muscles. Mice lacking PLM (PLM KO) have a normal content of the α2-subunit and show normal exercise capacity, in contrast to the greatly reduced exercise capacity of mice that lack α2 in the skeletal muscles. Nerve-evoked contractions in vivo did not induce a change in total PLM or PLM phosphorylated at Ser63 or Ser68, in either WT or PLM KO. Isolated muscles of PLM KO mice maintain contraction and resist fatigue as well as wild type (WT). Rb(+) transport by the α2-Na(+)-K(+)-ATPase is stimulated to the same extent in contracting WT and contracting PLM KO muscles. Phosphorylation of sarcolemmal membranes prepared from WT but not PLM KO skeletal muscles stimulates the activity of both α1 and α2 in a PLM-dependent manner. The stimulation occurs by an increase in Na(+) affinity without significant change in Vmax and is more effective for α1 than α2. These results demonstrate that phosphorylation of PLM is capable of stimulating the activity of both isozymes in skeletal muscle; however, contractile activity alone is not sufficient to induce PLM phosphorylation. Importantly, acute stimulation of α2, sufficient to support exercise and oppose fatigue, does not require PLM or its phosphorylation. Copyright © 2015 the American Physiological Society.
Electrical stimulation induces IL-6 in skeletal muscle through extracellular ATP by activating Ca(2+) signals and an IL-6 autocrine loop.

PubMed

Bustamante, Mario; Fernández-Verdejo, Rodrigo; Jaimovich, Enrique; Buvinic, Sonja

2014-04-15

Interleukin-6 (IL-6) is an important myokine that is highly expressed in skeletal muscle cells upon exercise. We assessed IL-6 expression in response to electrical stimulation (ES) or extracellular ATP as a known mediator of the excitation-transcription mechanism in skeletal muscle. We examined whether the canonical signaling cascade downstream of IL-6 (IL-6/JAK2/STAT3) also responds to muscle cell excitation, concluding that IL-6 influences its own expression through a positive loop. Either ES or exogenous ATP (100 μM) increased both IL-6 expression and p-STAT3 levels in rat myotubes, a process inhibited by 100 μM suramin and 2 U/ml apyrase. ATP also evoked IL-6 expression in both isolated skeletal fibers and extracts derived from whole FDB muscles. ATP increased IL-6 release up to 10-fold. STAT3 activation evoked by ATP was abolished by the JAK2 inhibitor HBC. Blockade of secreted IL-6 with a neutralizing antibody or preincubation with the STAT3 inhibitor VIII reduced STAT3 activation evoked by extracellular ATP by 70%. Inhibitor VIII also reduced by 70% IL-6 expression evoked by ATP, suggesting a positive IL-6 loop. In addition, ATP increased up to 60% the protein levels of SOCS3, a negative regulator of the IL-6 signaling pathway. On the other hand, intracellular calcium chelation or blockade of IP3-dependent calcium signals abolished STAT3 phosphorylation evoked by either extracellular ATP or ES. These results suggest that expression of IL-6 in stimulated skeletal muscle cells is mediated by extracellular ATP and nucleotide receptors, involving IP3-dependent calcium signals as an early step that triggers a positive IL-6 autocrine loop.
Amino acids augment muscle protein synthesis in neonatal pigs during acute endotoxemia by stimulating mTOR-dependent translation initiation

USDA-ARS?s Scientific Manuscript database

In skeletal muscle of adults, sepsis reduces protein synthesis by depressing translation initiation and induces resistance to branched-chain amino acid stimulation. Normal neonates maintain a high basal muscle protein synthesis rate that is sensitive to amino acid stimulation. In the present study...
Caffeine and contraction synergistically stimulate 5′-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle

PubMed Central

Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

2015-01-01

5′-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr172 phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser473 phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction. PMID:26471759
Combined use of bone marrow-derived mesenchymal stromal cells (BM-MSCs) and platelet rich plasma (PRP) stimulates proliferation and differentiation of myoblasts in vitro: new therapeutic perspectives for skeletal muscle repair/regeneration.

PubMed

Sassoli, Chiara; Vallone, Larissa; Tani, Alessia; Chellini, Flaminia; Nosi, Daniele; Zecchi-Orlandini, Sandra

2018-06-01

Satellite cell-mediated skeletal muscle repair/regeneration is compromised in cases of extended damage. Bone marrow mesenchymal stromal cells (BM-MSCs) hold promise for muscle healing but some criticisms hamper their clinical application, including the need to avoid animal serum contamination for expansion and the scarce survival after transplant. In this context, platelet-rich plasma (PRP) could offer advantages. Here, we compare the effects of PRP or standard culture media on C2C12 myoblast, satellite cell and BM-MSC viability, survival, proliferation and myogenic differentiation and evaluate PRP/BM-MSC combination effects in promoting myogenic differentiation. PRP induced an increase of mitochondrial activity and Ki67 expression comparable or even greater than that elicited by standard media and promoted AKT signaling activation in myoblasts and BM-MSCs and Notch-1 pathway activation in BM-MSCs. It stimulated MyoD, myogenin, α-sarcomeric actin and MMP-2 expression in myoblasts and satellite cell activation. Notably, PRP/BM-MSC combination was more effective than PRP alone. We found that BM-MSCs influenced myoblast responses through a paracrine activation of AKT signaling, contributing to shed light on BM-MSC action mechanisms. Our results suggest that PRP represents a good serum substitute for BM-MSC manipulation in vitro and could be beneficial towards transplanted cells in vivo. Moreover, it might influence muscle resident progenitors' fate, thus favoring the endogenous repair/regeneration mechanisms. Finally, within the limitations of an in vitro experimentation, this study provides an experimental background for considering the PRP/BM-MSC combination as a potential therapeutic tool for skeletal muscle damage, combining the beneficial effects of BM-MSCs and PRP on muscle tissue, while potentiating BM-MSC functionality.
Chronic stimulation of farnesoid X receptor impairs nitric oxide sensitivity of vascular smooth muscle.

PubMed

Kida, Taiki; Murata, Takahisa; Hori, Masatoshi; Ozaki, Hiroshi

2009-01-01

Farnesoid X receptor (FXR), a member of the nuclear receptor superfamily that is highly expressed in enterohepatic tissue, is implicated in bile acid, lipid, and glucose metabolisms. Although recent studies showed that FXR is also expressed in vascular endothelial cells and smooth muscle cells, its physiological and/or pathological roles in vasculature tissue remain unknown. The aim of this study is to examine the chronic effect of synthetic FXR agonist GW4064 on vascular contraction and endothelium-dependent relaxation using tissue culture procedure. In cultured rabbit mesenteric arteries, the treatment with 0.1-10 microM GW4064 for 7 days did not influence vascular contractility induced by high K(+) (15-65 mM), norepinephrine (0.1-100 microM), and endothelin-1 (0.1-100 nM). However, the chronic treatment with GW4064 (1-10 microM for 7 days) dose dependently impaired endothelium-dependent relaxation induced by substance P (0.1-30 nM). In hematoxylin-eosin cross sectioning and en face immunostaining, GW4064 had no effects on the morphology of endothelial and smooth muscle cells. In endothelium-denuded arteries treated with GW4064 (1-10 microM) for 7 days, 3 nM-100 microM sodium nitroprusside-induced vasorelaxation, but not membrane-permeable cGMP analog 8-bromoguanosine-cGMP (8-Br-cGMP; 1-100 microM)-induced vasorelaxation, was significantly impaired. In these GW4064-treated arteries, 1 muM sodium nitroprusside-induced intracellular cGMP elevations were impaired. In RT-PCR, any changes were detected in mRNA expression level of alpha(1)- and beta(1)-subunit of soluble guanylyl cyclase. These results suggest that chronic stimulation of FXR impairs endothelium-dependent relaxation, which is due to decreased sensitivity of smooth muscle cells to nitric oxide.
Replication of Muscle Cell Using Bioimprint

NASA Astrophysics Data System (ADS)

Samsuri, Fahmi; Mitchell, John S.; Alkaisi, Maan M.; Evans, John J.

2009-07-01

In our earlier study a heat-curable PDMS or a UV curable elastomer, was used as the replicating material to introduce Bioimprint methodology to facilitate cell imaging [1-2] But, replicating conditions for thermal polymerization is known to cause cell dehydration during curing. In this study, a new type of polymer was developed for use in living cell replica formation, and it was tested on human muscle cells. The cells were incubated and cultured according to standard biological culturing procedures, and they were grown for about 10 days. The replicas were then separated from the muscle cells and taken for analysis under an Atomic Force Microscope (AFM). The new polymer was designed to be biocompatible with higher resolution and fast curing process compared to other types of silicon-based organic polymers such as polydimethylsiloxane (PDMS). Muscle cell imprints were achieved and higher resolution images were able to show the micro structures of the muscle cells, including the cellular fibers and cell membranes. The AFM is able to image features at nanoscale resolution. This capacity enables a number of characteristics of biological cells to be visualized in a unique manner. Polymer and muscle cells preparations were developed at Hamilton, in collaboration between Plant and Food Research and the Department of Electrical and Computer Engineering, University of Canterbury. Tapping mode was used for the AFM image analysis as it has low tip-sample forces and non-destructive imaging capability. We will be presenting the bioimprinting processes of muscle cells, their AFM imaging and characterization of the newly developed polymer.
NADPH oxidase activation contributes to native low-density lipoprotein-induced proliferation of human aortic smooth muscle cells.

PubMed

Park, Il Hwan; Hwang, Hye Mi; Jeon, Byeong Hwa; Kwon, Hyung-Joo; Hoe, Kwang Lae; Kim, Young Myeong; Ryoo, Sungwoo

2015-06-12

Elevated plasma concentration of native low-density lipoprotein (nLDL) is associated with vascular smooth muscle cell (VSMC) activation and cardiovascular disease. We investigated the mechanisms of superoxide generation and its contribution to pathophysiological cell proliferation in response to nLDL stimulation. Lucigenin-induced chemiluminescence was used to measure nLDL-induced superoxide production in human aortic smooth muscle cells (hAoSMCs). Superoxide production was increased by nicotinamide adenine dinucleotide phosphate (NADPH) and decreased by NADPH oxidase inhibitors in nLDL-stimulated hAoSMC and hAoSMC homogenates, as well as in prepared membrane fractions. Extracellular signal-regulated kinase 1/2 (Erk1/2), protein kinase C-θ (PKCθ) and protein kinase C-β (PKCβ) were phosphorylated and maximally activated within 3 min of nLDL stimulation. Phosphorylated Erk1/2 mitogen-activated protein kinase, PKCθ and PKCβ stimulated interactions between p47phox and p22phox; these interactions were prevented by MEK and PKC inhibitors (PD98059 and calphostin C, respectively). These inhibitors decreased nLDL-dependent superoxide production and blocked translocation of p47phox to the membrane, as shown by epifluorescence imaging and cellular fractionation experiments. Proliferation assays showed that a small interfering RNA against p47phox, as well as superoxide scavenger and NADPH oxidase inhibitors, blocked nLDL-induced hAoSMC proliferation. The nLDL stimulation in deendothelialized aortic rings from C57BL/6J mice increased dihydroethidine fluorescence and induced p47phox translocation that was blocked by PD98059 or calphostin C. Isolated aortic SMCs from p47phox(-/-) mice (mAoSMCs) did not respond to nLDL stimulation. Furthermore, NADPH oxidase 1 (Nox1) was responsible for superoxide generation and cell proliferation in nLDL-stimulated hAoSMCs. These data demonstrated that NADPH oxidase activation contributed to cell proliferation in nLDL-stimulated hAoSMCs.
Activation of Cyclic AMP Synthesis by Full and Partial Beta-Adrenergic Receptor Agonists in Chicken Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Cureri, Peter A. (Technical Monitor)

2002-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Accordingly, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax concentrations were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. When cimaterol and clenbuterol were added to culture media at concentrations known to cause significant muscle hypertrophy in animals, there was no detectable effect on stimulation of cAMP synthesis. Finally, these same levels of cimaterol and clenbuterol did not antagonize the stimulation of cAMP by either epinephrine or isoproterenol.

Immunological Tolerance to Muscle Autoantigens Involves Peripheral Deletion of Autoreactive CD8+ T Cells

PubMed Central

Franck, Emilie; Bonneau, Carole; Jean, Laetitia; Henry, Jean-Paul; Lacoume, Yann; Salvetti, Anna; Boyer, Olivier; Adriouch, Sahil

2012-01-01

Muscle potentially represents the most abundant source of autoantigens of the body and can be targeted by a variety of severe autoimmune diseases. Yet, the mechanisms of immunological tolerance toward muscle autoantigens remain mostly unknown. We investigated this issue in transgenic SM-Ova mice that express an ovalbumin (Ova) neo-autoantigen specifically in skeletal muscle. We previously reported that antigen specific CD4+ T cell are immunologically ignorant to endogenous Ova in this model but can be stimulated upon immunization. In contrast, Ova-specific CD8+ T cells were suspected to be either unresponsive to Ova challenge or functionally defective. We now extend our investigations on the mechanisms governing CD8+ tolerance in SM-Ova mice. We show herein that Ova-specific CD8+ T cells are not detected upon challenge with strongly immunogenic Ova vaccines even after depletion of regulatory T cells. Ova-specific CD8+ T cells from OT-I mice adoptively transferred to SM-Ova mice started to proliferate in vivo, acquired CD69 and PD-1 but subsequently down-regulated Bcl-2 and disappeared from the periphery, suggesting a mechanism of peripheral deletion. Peripheral deletion of endogenous Ova-specific cells was formally demonstrated in chimeric SM-Ova mice engrafted with bone marrow cells containing T cell precursors from OT-I TCR-transgenic mice. Thus, the present findings demonstrate that immunological tolerance to muscle autoantigens involves peripheral deletion of autoreactive CD8+ T cells. PMID:22570714
Bisdemethoxycurcumin inhibits PDGF-induced vascular smooth muscle cell motility and proliferation

PubMed Central

Hua, Yinan; Dolence, Julia; Ramanan, Shalini; Ren, Jun; Nair, Sreejayan

2013-01-01

Scope A key event in the development of plaque in the arteries is the migration and proliferation of smooth muscle cells (SMCs) from the media to the intima of the blood vessel. This study was conducted to evaluate the effects of bisdemethoxycurcumin, a naturally occurring structural analog of curcumin, on PDGF-stimulated migration and proliferation of SMCs. Methods and results Demethoxycurcumin were synthesized by condensing vanillin and 4-hydroxybenzaldehyde. SMCs isolated from adult rat aorta were stimulated with PDGF in the presence or absence of curcumin or bisdemethoxycurcumin following which cell migration and proliferation were assessed by monolayer wound healing assay and [3H]-thymidine incorporation respectively. PDGF-induced phosphorylation of PDGF-receptor-β and its downstream effector Akt were assessed by Western blotting. Intracellular reactive oxygen species (ROS) was assessed using the fluorescent dye DCFDA. Bisdemethoxycurcumin elicited a concentration-dependent inhibition of PDGF-stimulated phosphorylation of PDGFR-β, Akt and Erk as well as the PDGF-stimulated SMC migration and proliferation. Bisdemethoxycurcumin was more potent than curcumin in inhibiting migration and proliferation and suppressing PDGF-signaling in SMCs. Both compounds were equipotent in inhibiting PDGF-stimulated intracellular ROS-generation. Conclusion Bisdemethoxycurcumin may be of potential use in the prevention or treatment of vascular disease. PMID:23554078
Increased adipogenicity of cells from regenerating skeletal muscle.

PubMed

Yamanouchi, Keitaro; Yada, Erica; Ishiguro, Naomi; Hosoyama, Tohru; Nishihara, Masugi

2006-09-10

Adipose tissue development is observed in some muscle pathologies, however, mechanisms that induce accumulation of this tissue as well as its cellular origin are unknown. The adipogenicity of cells from bupivacaine hydrochloride (BPVC)-treated and untreated muscle was compared in vitro. Culturing cells from both BPVC-treated and untreated muscles in adipogenic differentiation medium (ADM) for 10 days resulted in the appearance of mature adipocytes, but their number was 3.5-fold higher in cells from BPVC-treated muscle. Temporal expressions of PPARgamma and the presence of lipid droplets during adipogenic differentiation were examined. On day 2 of culture in ADM, only cells from BPVC-treated muscle were positive both for PPARgamma and lipid droplets. Pref-1 was expressed in cells from untreated muscle, whereas its expression was absent in cells from BPVC-treated muscle. In ADM, the presence of insulin, which negates an inhibitory effect of Pref-1 on adipogenic differentiation, was required for PPARgamma2 expression in cells from untreated muscle, but not for cells from BPVC-treated muscle. These results indicate that BPVC-induced degenerative/regenerative changes in muscle lead to increased adipogenicity of cells, and suggest that this increased adipogenicity not only involves an increase in the number of cells having adipogenic potential, but also contributes to the progression of these cells toward adipogenic differentiation.
Selective Expansion of Skeletal Muscle Stem Cells from Bulk Muscle Cells in Soft Three‐Dimensional Fibrin Gel

PubMed Central

Zhu, Pei; Zhou, Yalu; Wu, Furen; Hong, Yuanfan; Wang, Xin; Shekhawat, Gajendra; Mosenson, Jeffrey

2017-01-01

Abstract Muscle stem cells (MuSCs) exhibit robust myogenic potential in vivo, thus providing a promising curative treatment for muscle disorders. Ex vivo expansion of adult MuSCs is highly desired to achieve a therapeutic cell dose because of their scarcity in limited muscle biopsies. Sorting of pure MuSCs is generally required for all the current culture systems. Here we developed a soft three‐dimensional (3D) salmon fibrin gel culture system that can selectively expand mouse MuSCs from bulk skeletal muscle preparations without cell sorting and faithfully maintain their regenerative capacity in culture. Our study established a novel platform for convenient ex vivo expansion of MuSCs, thus greatly advancing stem cell‐based therapies for various muscle disorders. Stem Cells Translational Medicine 2017;6:1412–1423 PMID:28244269
Growth factor involvement in tension-induced skeletal muscle growth

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.

1993-01-01

Long-term manned space travel will require a better understanding of skeletal muscle atrophy which results from microgravity. Astronaut strength and dexterity must be maintained for normal mission operations and for emergency situations. Although exercise in space slows the rate of muscle loss, it does not prevent it. A biochemical understanding of how gravity/tension/exercise help to maintain muscle size by altering protein synthesis and/or degradation rate should ultimately allow pharmacological intervention to prevent muscle atrophy in microgravity. The overall objective is to examine some of the basic biochemical processes involved in tension-induced muscle growth. With an experimental in vitro system, the role of exogenous and endogenous muscle growth factors in mechanically stimulated muscle growth are examined. Differentiated avian skeletal myofibers can be 'exercised' in tissue culture using a newly developed dynamic mechanical cell stimulator device which simulates different muscle activity patterns. Patterns of mechanical activity which significantly affect muscle growth and metabolic characteristics were found. Both exogenous and endogenous growth factors are essential for tension-induced muscle growth. Exogenous growth factors found in serum, such as insulin, insulin-like growth factors, and steroids, are important regulators of muscle protein turnover rates and mechanically-induced muscle growth. Endogenous growth factors are synthesized and released into the culture medium when muscle cells are mechanically stimulated. At least one family of mechanically induced endogenous factors, the prostaglandins, help to regulate the rates of protein turnover in muscle cells. Endogenously synthesized IGF-1 is another. The interaction of muscle mechanical activity and these growth factors in the regulation of muscle protein turnover rates with our in vitro model system is studied.
Extracellular matrix components direct porcine muscle stem cell behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilschut, Karlijn J.; Haagsman, Henk P.; Roelen, Bernard A.J., E-mail: b.a.j.roelen@uu.nl

2010-02-01

In muscle tissue, extracellular matrix proteins, together with the vasculature system, muscle-residence cells and muscle fibers, create the niche for muscle stem cells. The niche is important in controlling proliferation and directing differentiation of muscle stem cells to sustain muscle tissue. Mimicking the extracellular muscle environment improves tools exploring the behavior of primary muscle cells. Optimizing cell culture conditions to maintain muscle commitment is important in stem cell-based studies concerning toxicology screening, ex vivo skeletal muscle tissue engineering and in the enhancement of clinical efficiency. We used the muscle extracellular matrix proteins collagen type I, fibronectin, laminin, and also gelatinmore » and Matrigel as surface coatings of tissue culture plastic to resemble the muscle extracellular matrix. Several important factors that determine myogenic commitment of the primary muscle cells were characterized by quantitative real-time RT-PCR and immunofluorescence. Adhesion of high PAX7 expressing satellite cells was improved if the cells were cultured on fibronectin or laminin coatings. Cells cultured on Matrigel and laminin coatings showed dominant integrin expression levels and exhibited an activated Wnt pathway. Under these conditions both stem cell proliferation and myogenic differentiation capacity were superior if compared to cells cultured on collagen type I, fibronectin and gelatin. In conclusion, Matrigel and laminin are the preferred coatings to sustain the proliferation and myogenic differentiation capacity of the primary porcine muscle stem cells, when cells are removed from their natural environment for in vitro culture.« less
Electrical Stimulation Followed by Mesenchymal Stem Cells Improves Anal Sphincter Anatomy and Function in a Rat Model at a Time Remote From Injury.

PubMed

Sun, Li; Yeh, Judy; Xie, Zhuojun; Kuang, Mei; Damaser, Margot S; Zutshi, Massarat

2016-05-01

We have explored cell-based therapy to aid anal sphincter repair, but a conditioning injury is required to direct stem cells to the site of injury because symptoms usually manifest at a time remote from injury. We aimed to investigate the effect of local electrical stimulation followed by mesenchymal stem cell delivery on anal sphincter regeneration at a time remote from injury. With the use of a rat model, electrical stimulation parameters and cell delivery route were selected based on in vivo cytokine expression and luciferase-labeled cell imaging of the anal sphincter complex. Three weeks after a partial anal sphincter excision, rats were randomly allocated to 4 groups based on different local interventions: no treatment, daily electrical stimulation for 3 days, daily stimulation for 3 days followed by stem cell injection on the third day, and daily electrical stimulation followed by stem cell injection on the first and third days. Histology-assessed anatomy and anal manometry evaluated physiology 4 weeks after intervention. The electrical stimulation parameters that significantly upregulated gene expression of homing cytokines also achieved mesenchymal stem cell retention when injected directly in the anal sphincter complex in comparison with intravascular and intraperitoneal injections. Four weeks after intervention, there was significantly more new muscle in the area of injury and significantly improved anal resting pressure in the group that received daily electrical stimulation for 3 days followed by a single injection of 1 million stem cells on the third day at the site of injury. This was a pilot study and therefore was not powered for functional outcome. In this rat injury model with optimized parameters, electrical stimulation with a single local mesenchymal stem cell injection administered 3 weeks after injury significantly improved both new muscle formation in the area of injury and anal sphincter pressures.
Biophysical Stimulation for Engineering Functional Skeletal Muscle.

PubMed

Somers, Sarah M; Spector, Alexander A; DiGirolamo, Douglas J; Grayson, Warren L

2017-08-01

Tissue engineering is a promising therapeutic strategy to regenerate skeletal muscle. However, ex vivo cultivation methods typically result in a low differentiation efficiency of stem cells as well as grafts that resemble the native tissues morphologically, but lack contractile function. The application of biomimetic tensile strain provides a potent stimulus for enhancing myogenic differentiation and engineering functional skeletal muscle grafts. We reviewed integrin-dependent mechanisms that potentially link mechanotransduction pathways to the upregulation of myogenic genes. Yet, gaps in our understanding make it challenging to use these pathways to theoretically determine optimal ex vivo strain regimens. A multitude of strain protocols have been applied to in vitro cultures for the cultivation of myogenic progenitors (adipose- and bone marrow-derived stem cells and satellite cells) and transformed murine myoblasts, C2C12s. Strain regimens are characterized by orientation, amplitude, and time-dependent factors (effective frequency, duration, and the rest period between successive strain cycles). Analysis of published data has identified possible minimum/maximum values for these parameters and suggests that uniaxial strains may be more potent than biaxial strains, possibly because they more closely mimic physiologic strain profiles. The application of these biophysical stimuli for engineering 3D skeletal muscle grafts is nontrivial and typically requires custom-designed bioreactors used in combination with biomaterial scaffolds. Consideration of the physical properties of these scaffolds is critical for effective transmission of the applied strains to encapsulated cells. Taken together, these studies demonstrate that biomimetic tensile strain generally results in improved myogenic outcomes in myogenic progenitors and differentiated myoblasts. However, for 3D systems, the optimization of the strain regimen may require the entire system including cells, biomaterials
Lysyl oxidase propeptide inhibits smooth muscle cell signaling and proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurtado, Paola A.; Vora, Siddharth; Sume, Siddika Selva

2008-02-01

Lysyl oxidase is required for the normal biosynthesis and maturation of collagen and elastin. It is expressed by vascular smooth muscle cells, and its increased expression has been previously found in atherosclerosis and in models of balloon angioplasty. The lysyl oxidase propeptide (LOX-PP) has more recently been found to have biological activity as a tumor suppressor, and it inhibits Erk1/2 Map kinase activation. We reasoned that LOX-PP may have functions in normal non-transformed cells. We, therefore, investigated its effects on smooth muscle cells, focusing on important biological processes mediated by Erk1/2-dependent signaling pathways including proliferation and matrix metalloproteinase-9 (MMP-9) expression.more » In addition, we investigated whether evidence for accumulation of LOX-PP could be found in vivo in a femoral artery injury model. Recombinant LOX-PP was expressed and purified, and was found to inhibit primary rat aorta smooth muscle cell proliferation and DNA synthesis by more than 50%. TNF-{alpha}-stimulated MMP-9 expression and Erk1/2 activation were both significantly inhibited by LOX-PP. Immunohistochemistry studies carried out with affinity purified anti-LOX-PP antibody showed that LOX-PP epitopes were expressed at elevated levels in vascular lesions of injured arteries. These novel data suggest that LOX-PP may provide a feedback control mechanism that serves to inhibit properties associated with the development of vascular pathology.« less
Chronic muscle stimulation improves muscle function and reverts the abnormal surface EMG pattern in Myotonic Dystrophy: a pilot study

PubMed Central

2013-01-01

Background To date, in Myotonic Dystrophy type 1 (DM1) the rehabilitative interventions have always been aimed at muscle strengthening, increasing of fatigue resistance and improving of aerobic metabolism efficiency whereas the electrical membrane fault has always been addressed pharmacologically. Neuromuscular electrical stimulation (NMES) is a useful therapeutic tool in sport medicine and in the rehabilitation of many clinical conditions characterized by motor impairment such as stroke, cerebral palsy and spinal cord injury. The aim of our pilot study was to evaluate the effects of chronic electrical stimulation both on functional and electrical properties of muscle in a small group of DM1 patients. Methods Five DM1 patients and one patient with Congenital Myotonia (CM) performed a home electrical stimulation of the tibialis anterior muscle lasting 15 days with a frequency of two daily sessions of 60 minutes each. Muscle strength was assessed according to the MRC scale (Medical Research Council) and functional tests (10 Meter Walking Test, 6 Minutes Walking Test and Timed Up and Go Test) were performed. We analyzed the average rectified value of sEMG signal amplitude (ARV) to characterize the sarcolemmal excitability. Results After the treatment an increase of muscle strength in those DM1 patients with a mild strength deficit was observed. In all subjects an improvement of 10MWT was recorded. Five patients improved their performance in the 6MWT. In TUG test 4 out of 6 patients showed a slight reduction in execution time. All patients reported a subjective improvement when walking. A complete recovery of the normal increasing ARV curve was observed in 4 out of 5 DM1 patients; the CM patient didn’t show modification of the ARV pattern. Conclusions NMES determined a clear-cut improvement of both the muscular weakness and the sarcolemmal excitability alteration in our small group of DM1 patients. Therefore this rehabilitative approach, if confirmed by further
Proteinase-activated receptor 4 stimulation-induced epithelial-mesenchymal transition in alveolar epithelial cells

PubMed Central

Ando, Seijitsu; Otani, Hitomi; Yagi, Yasuhiro; Kawai, Kenzo; Araki, Hiromasa; Fukuhara, Shirou; Inagaki, Chiyoko

2007-01-01

Background Proteinase-activated receptors (PARs; PAR1–4) that can be activated by serine proteinases such as thrombin and neutrophil catepsin G are known to contribute to the pathogenesis of various pulmonary diseases including fibrosis. Among these PARs, especially PAR4, a newly identified subtype, is highly expressed in the lung. Here, we examined whether PAR4 stimulation plays a role in the formation of fibrotic response in the lung, through alveolar epithelial-mesenchymal transition (EMT) which contributes to the increase in myofibroblast population. Methods EMT was assessed by measuring the changes in each specific cell markers, E-cadherin for epithelial cell, α-smooth muscle actin (α-SMA) for myofibroblast, using primary cultured mouse alveolar epithelial cells and human lung carcinoma-derived alveolar epithelial cell line (A549 cells). Results Stimulation of PAR with thrombin (1 U/ml) or a synthetic PAR4 agonist peptide (AYPGKF-NH2, 100 μM) for 72 h induced morphological changes from cobblestone-like structure to elongated shape in primary cultured alveolar epithelial cells and A549 cells. In immunocytochemical analyses of these cells, such PAR4 stimulation decreased E-cadherin-like immunoreactivity and increased α-SMA-like immunoreactivity, as observed with a typical EMT-inducer, tumor growth factor-β (TGF-β). Western blot analyses of PAR4-stimulated A549 cells also showed similar changes in expression of these EMT-related marker proteins. Such PAR4-mediated changes were attenuated by inhibitors of epidermal growth factor receptor (EGFR) kinase and Src. PAR4-mediated morphological changes in primary cultured alveolar epithelial cells were reduced in the presence of these inhibitors. PAR4 stimulation increased tyrosine phosphorylated EGFR or tyrosine phosphorylated Src level in A549 cells, and the former response being inhibited by Src inhibitor. Conclusion PAR4 stimulation of alveolar epithelial cells induced epithelial-mesenchymal transition (EMT
Effect of Electrical Stimulation of the Suprahyoid Muscles in Brain-Injured Patients with Dysphagia.

PubMed

Beom, Jaewon; Oh, Byung-Mo; Choi, Kyoung Hyo; Kim, Won; Song, Young Jin; You, Dae Sang; Kim, Sang Jun; Han, Tai Ryoon

2015-08-01

The purpose of this study is to determine whether neuromuscular electrical stimulation of the suprahyoid muscle is effective compared to that of the infrahyoid muscle in brain-injured patients with dysphagia. A total of 132 patients with stroke, traumatic brain injury, or brain tumor in 2 university hospitals were allocated to 2 groups: those who received electrical stimulation therapy (EST) on the suprahyoid muscles (SM group, n = 66) and those who received EST with one pair of electrodes on the suprahyoid muscle and the other pair on the infrahyoid muscle (SI group, n = 66). Patients received 11.2 ± 3.4 sessions of electrical stimulation in the SM group and 11.9 ± 3.4 sessions in the SI group. The functional dysphagia scale (FDS), swallow function score (SFS), supraglottic penetration, and subglottic aspiration were measured using videofluoroscopic swallowing study. FDS scores decreased from 42.0 ± 19.1 to 32.3 ± 17.8 in the SM group and from 44.8 ± 17.4 to 32.9 ± 18.8 in the SI group by per-protocol (PP) analysis, and those decreased from 41.2 ± 20.9 to 34.5 ± 20.3 in the SM group and from 44.3 ± 19.1 to 35.7 ± 20.5 in the SI group by intention-to-treat (ITT) analysis, after electrical stimulation (p < 0.001 for each). SFSs increased from 3.3 ± 1.8 to 4.2 ± 1.6 in the SM group and from 2.8 ± 1.8 to 4.0 ± 1.8 in the SI group by PP analysis, and those increased from 3.3 ± 1.6 to 3.9 ± 1.6 in the SM group and from 2.8 ± 1.9 to 3.6 ± 2.0 in the SI group by ITT analysis, after electrical stimulation (p < 0.001, respectively). However, changes in FDS scores, SFSs, penetration, and aspiration were comparable between the SM and the SI groups. The results suggest that both SM and SI therapies induced similar improvements in swallowing function in brain-injured patients.
Ceruloplasmin enhances smooth muscle cell- and endothelial cell-mediated low density lipoprotein oxidation by a superoxide-dependent mechanism

NASA Technical Reports Server (NTRS)

Mukhopadhyay, C. K.; Ehrenwald, E.; Fox, P. L.

1996-01-01

Cultured vascular smooth muscle cells (SMC) and endothelial cells (EC) stimulate low density lipoprotein (LDL) oxidation by free radical-mediated, transition metal-dependent mechanisms. The physiological source(s) of metal ions is not known; however, purified ceruloplasmin, a plasma protein containing 7 coppers, oxidizes LDL in vitro. We now show that ceruloplasmin also increases LDL oxidation by vascular cells. In metal ion-free medium, human ceruloplasmin increased bovine aortic SMC- and EC-mediated LDL oxidation by up to 30- and 15-fold, respectively. The maximal response was at 100-300 microg ceruloplasmin/ml, a level at or below the unevoked physiological plasma concentration. Oxidant activity was dependent on protein structure as a specific proteolytic cleavage or removal of one of the seven ceruloplasmin copper atoms inhibited activity. Three lines of evidence indicated a critical role for cellular superoxide (O2.) in ceruloplasmin-stimulated oxidation. First, the rate of production of O2. by cells correlated with their rates of LDL oxidation. Second, superoxide dismutase effectively blocked ceruloplasmin-stimulated oxidation by both cell types. Finally, O2. production by SMC quantitatively accounted for the observed rate of LDL oxidation. To show this, the course of O2. production by SMC was simulated by repeated addition of xanthine and xanthine oxidase to culture medium under cell-free conditions. Neither ceruloplasmin nor O2. alone increased LDL oxidation, but together they completely reconstituted the oxidation rate of ceruloplasmin-stimulated SMC. These results are the first to show that ceruloplasmin stimulates EC- and SMC-mediated oxidation of LDL and that cell-derived O2. accounts quantitatively for metal-dependent, free radical-initiated oxidation of LDL by these cells.
Pharmacological activation of AMPK and glucose uptake in cultured human skeletal muscle cells from patients with ME/CFS.

PubMed

Brown, Audrey E; Dibnah, Beth; Fisher, Emily; Newton, Julia L; Walker, Mark

2018-06-29

Skeletal muscle fatigue and post-exertional malaise are key symptoms of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (ME/CFS). We have previously shown that AMP-activated protein kinase (AMPK) activation and glucose uptake are impaired in primary human skeletal muscle cell cultures derived from patients with ME/CFS in response to electrical pulse stimulation (EPS), a method which induces contraction of muscle cells in vitro The aim of the present study was to assess if AMPK could be activated pharmacologically in ME/CFS. Primary skeletal muscle cell cultures from patients with ME/CFS and healthy controls were treated with either metformin or compound 991. AMPK activation was assessed by Western blot and glucose uptake measured. Both metformin and 991 treatment significantly increased AMPK activation and glucose uptake in muscle cell cultures from both controls and ME/CFS. Cellular ATP content was unaffected by treatment although ATP content was significantly decreased in ME/CFS compared with controls. Pharmacological activation of AMPK can improve glucose uptake in muscle cell cultures from patients with ME/CFS. This suggests that the failure of EPS to activate AMPK in these muscle cultures is due to a defect proximal to AMPK. Further work is required to delineate the defect and determine whether pharmacological activation of AMPK improves muscle function in patients with ME/CFS. © 2018 The Author(s).
Activation of particulate guanylate cyclase by adrenomedullin in cultured SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells.

PubMed

Ali, N; Yousufzai, S Y; Abdel-Latif, A A

2000-07-01

We investigated the effects of adrenomedullin (ADM) on cGMP production in cultured SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells. ADM increased cGMP accumulation in a time- and concentration- dependent manner. The peptide increased cGMP formation in the transformed cells by 405-fold as compared to 1. 6-fold in primary cultured CISM cells. The basal cGMP concentrations in both cell types were comparable. In addition, ADM increased cAMP accumulation in SV-CISM-2 cells and in primary cultured cells by 18. 9- and 5.8-fold, respectively. The ADM receptor antagonist, ADM(26-52), but not the atrial natriuretic peptide (ANP) receptor antagonist, anantin, inhibited ADM-induced cGMP formation. The phorbol ester, phorbol 12, 13-dibutyrate (PDBu), which inhibits particulate guanylate cyclases in smooth muscle, blocked ADM-stimulated cGMP accumulation. In contrast, inhibitors of the soluble guanylate cyclases, such as LY83583 and ODQ, and inhibitors of the nitric oxide cascade had little effect on ADM-stimulated cGMP production. The stimulatory effect of ADM on cGMP formation is due to activation of the guanylate cyclase system and not to a much reduced phosphodiesterase activity. ADM stimulated guanylate cyclase activity in membrane fractions isolated from SV-CISM-2 cells in a concentration-dependent manner with EC(50) value of 72 nM. Pertussis toxin, an activator of the G-protein, Gi, inhibited ADM-stimulated cGMP accumulation, whereas cholera toxin, a stimulator of the Gs G-protein and subsequently cAMP accumulation, had little effect. Pretreatment of the plasma membrane fraction with Gialpha antibody attenuated ADM-stimulated guanylate cyclase activity by 75%. We conclude that ADM increases intracellular cGMP levels in SV-CISM-2 cells through activation of the ADM receptor and subsequent stimulation of a Gi-mediated membrane-bound guanylate cyclase.
Common neural structures activated by epidural and transcutaneous lumbar spinal cord stimulation: Elicitation of posterior root-muscle reflexes

PubMed Central

Freundl, Brigitta; Binder, Heinrich; Minassian, Karen

2018-01-01

Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI) to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS) may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG) characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord—predominantly primary afferent fibers within multiple posterior roots—by both techniques and add to unraveling the basic mechanisms
Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability.

PubMed

Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 ( n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 ( n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability.
Presence and Absence of Muscle Contraction Elicited by Peripheral Nerve Electrical Stimulation Differentially Modulate Primary Motor Cortex Excitability

PubMed Central

Sasaki, Ryoki; Kotan, Shinichi; Nakagawa, Masaki; Miyaguchi, Shota; Kojima, Sho; Saito, Kei; Inukai, Yasuto; Onishi, Hideaki

2017-01-01

Modulation of cortical excitability by sensory inputs is a critical component of sensorimotor integration. Sensory afferents, including muscle and joint afferents, to somatosensory cortex (S1) modulate primary motor cortex (M1) excitability, but the effects of muscle and joint afferents specifically activated by muscle contraction are unknown. We compared motor evoked potentials (MEPs) following median nerve stimulation (MNS) above and below the contraction threshold based on the persistence of M-waves. Peripheral nerve electrical stimulation (PES) conditions, including right MNS at the wrist at 110% motor threshold (MT; 110% MNS condition), right MNS at the index finger (sensory digit nerve stimulation [DNS]) with stimulus intensity approximately 110% MNS (DNS condition), and right MNS at the wrist at 90% MT (90% MNS condition) were applied. PES was administered in a 4 s ON and 6 s OFF cycle for 20 min at 30 Hz. In Experiment 1 (n = 15), MEPs were recorded from the right abductor pollicis brevis (APB) before (baseline) and after PES. In Experiment 2 (n = 15), M- and F-waves were recorded from the right APB. Stimulation at 110% MNS at the wrist evoking muscle contraction increased MEP amplitudes after PES compared with those at baseline, whereas DNS at the index finger and 90% MNS at the wrist not evoking muscle contraction decreased MEP amplitudes after PES. M- and F-waves, which reflect spinal cord or muscular and neuromuscular junctions, did not change following PES. These results suggest that muscle contraction and concomitant muscle/joint afferent inputs specifically enhance M1 excitability. PMID:28392766
Functional heterogeneity of side population cells in skeletal muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uezumi, Akiyoshi; Ojima, Koichi; Fukada, So-ichiro

2006-03-17

Skeletal muscle regeneration has been exclusively attributed to myogenic precursors, satellite cells. A stem cell-rich fraction referred to as side population (SP) cells also resides in skeletal muscle, but its roles in muscle regeneration remain unclear. We found that muscle SP cells could be subdivided into three sub-fractions using CD31 and CD45 markers. The majority of SP cells in normal non-regenerating muscle expressed CD31 and had endothelial characteristics. However, CD31{sup -}CD45{sup -} SP cells, which are a minor subpopulation in normal muscle, actively proliferated upon muscle injury and expressed not only several regulatory genes for muscle regeneration but also somemore » mesenchymal lineage markers. CD31{sup -}CD45{sup -} SP cells showed the greatest myogenic potential among three SP sub-fractions, but indeed revealed mesenchymal potentials in vitro. These SP cells preferentially differentiated into myofibers after intramuscular transplantation in vivo. Our results revealed the heterogeneity of muscle SP cells and suggest that CD31{sup -}CD45{sup -} SP cells participate in muscle regeneration.« less
A pilot study of contralateral homonymous muscle activity simulated electrical stimulation in chronic hemiplegia.

PubMed

Osu, Rieko; Otaka, Yohei; Ushiba, Junichi; Sakata, Sachiko; Yamaguchi, Tomofumi; Fujiwara, Toshiyuki; Kondo, Kunitsugu; Liu, Meigen

2012-01-01

For the recovery of hemiparetic hand function, a therapy was developed called contralateral homonymous muscle activity stimulated electrical stimulation (CHASE), which combines electrical stimulation and bilateral movements, and its feasibility was studied in three chronic stroke patients with severe hand hemiparesis. Patients with a subcortical lesion were asked to extend their wrist and fingers bilaterally while an electromyogram (EMG) was recorded from the extensor carpi radialis (ECR) muscle in the unaffected hand. Electric stimulation was applied to the homonymous wrist and finger extensors of the affected side. The intensity of the electrical stimulation was computed based on the EMG and scaled so that the movements of the paretic hand looked similar to those of the unaffected side. The patients received 30-minutes of therapy per day for 2 weeks. Improvement in the active range of motion of wrist extension was observed for all patients. There was a decrease in the scores of modified Ashworth scale in the flexors. Fugl-Meyer assessment scores of motor function of the upper extremities improved in two of the patients. The results suggest a positive outcome can be obtained using the CHASE system for upper extremity rehabilitation of patients with severe hemiplegia.

AMP-Activated Protein Kinase Plays an Important Evolutionary Conserved Role in the Regulation of Glucose Metabolism in Fish Skeletal Muscle Cells

PubMed Central

Magnoni, Leonardo J.; Vraskou, Yoryia; Palstra, Arjan P.; Planas, Josep V.

2012-01-01

AMPK, a master metabolic switch, mediates the observed increase of glucose uptake in locomotory muscle of mammals during exercise. AMPK is activated by changes in the intracellular AMP∶ATP ratio when ATP consumption is stimulated by contractile activity but also by AICAR and metformin, compounds that increase glucose transport in mammalian muscle cells. However, the possible role of AMPK in the regulation of glucose metabolism in skeletal muscle has not been investigated in other vertebrates, including fish. In this study, we investigated the effects of AMPK activators on glucose uptake, AMPK activity, cell surface levels of trout GLUT4 and expression of GLUT1 and GLUT4 as well as the expression of enzymes regulating glucose disposal and PGC1α in trout myotubes derived from a primary muscle cell culture. We show that AICAR and metformin significantly stimulated glucose uptake (1.6 and 1.3 fold, respectively) and that Compound C completely abrogated the stimulatory effects of the AMPK activators on glucose uptake. The combination of insulin and AMPK activators did not result in additive nor synergistic effects on glucose uptake. Moreover, exposure of trout myotubes to AICAR and metformin resulted in an increase in AMPK activity (3.8 and 3 fold, respectively). We also provide evidence suggesting that stimulation of glucose uptake by AMPK activators in trout myotubes may take place, at least in part, by increasing the cell surface and mRNA levels of trout GLUT4. Finally, AICAR increased the mRNA levels of genes involved in glucose disposal (hexokinase, 6-phosphofructokinase, pyruvate kinase and citrate synthase) and mitochondrial biogenesis (PGC-1α) and did not affect glycogen content or glycogen synthase mRNA levels in trout myotubes. Therefore, we provide evidence, for the first time in non-mammalian vertebrates, suggesting a potentially important role of AMPK in stimulating glucose uptake and utilization in the skeletal muscle of fish. PMID:22359576
ROS-mediated decline in maximum Ca2+-activated force in rat skeletal muscle fibers following in vitro and in vivo stimulation.

PubMed

Dutka, Travis L; Verburg, Esther; Larkins, Noni; Hortemo, Kristin H; Lunde, Per K; Sejersted, Ole M; Lamb, Graham D

2012-01-01

We hypothesised that normal skeletal muscle stimulated intensely either in vitro or in situ would exhibit reactive oxygen species (ROS)-mediated contractile apparatus changes common to many pathophysiological conditions. Isolated soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat were bubbled with 95% O(2) and stimulated in vitro at 31°C to give isometric tetani (50 Hz for 0.5 s every 2 s) until maximum force declined to ≤30%. Skinned superficial slow-twitch fibers from the SOL muscles displayed a large reduction (∼41%) in maximum Ca(2+)-activated specific force (F(max)), with Ca(2+)-sensitivity unchanged. Fibers from EDL muscles were less affected. The decrease in F(max) in SOL fibers was evidently due to oxidation effects on cysteine residues because it was reversed if the reducing agent DTT was applied prior to activating the fiber. The GSH:GSSG ratio was ∼3-fold lower in the cytoplasm of superficial fibers from stimulated muscle compared to control, confirming increased oxidant levels. The presence of Tempol and L-NAME during in vitro stimulation prevented reduction in F(max). Skinned fibers from SOL muscles stimulated in vivo at 37°C with intact blood supply also displayed reduction in F(max), though to a much smaller extent (∼12%). Thus, fibers from muscles stimulated even with putatively adequate O(2) supply display a reversible oxidation-induced decrease in F(max) without change in Ca(2+)-sensitivity, consistent with action of peroxynitrite (or possibly superoxide) on cysteine residues of the contractile apparatus. Significantly, the changes closely resemble the contractile deficits observed in a range of pathophysiological conditions. These findings highlight how readily muscle experiences ROS-related deficits, and also point to potential difficulties when defining muscle performance and fatigue.
ROS-Mediated Decline in Maximum Ca2+-Activated Force in Rat Skeletal Muscle Fibers following In Vitro and In Vivo Stimulation

PubMed Central

Dutka, Travis L.; Verburg, Esther; Larkins, Noni; Hortemo, Kristin H.; Lunde, Per K.; Sejersted, Ole M.; Lamb, Graham D.

2012-01-01

We hypothesised that normal skeletal muscle stimulated intensely either in vitro or in situ would exhibit reactive oxygen species (ROS)-mediated contractile apparatus changes common to many pathophysiological conditions. Isolated soleus (SOL) and extensor digitorum longus (EDL) muscles of the rat were bubbled with 95% O2 and stimulated in vitro at 31°C to give isometric tetani (50 Hz for 0.5 s every 2 s) until maximum force declined to ≤30%. Skinned superficial slow-twitch fibers from the SOL muscles displayed a large reduction (∼41%) in maximum Ca2+-activated specific force (Fmax), with Ca2+-sensitivity unchanged. Fibers from EDL muscles were less affected. The decrease in Fmax in SOL fibers was evidently due to oxidation effects on cysteine residues because it was reversed if the reducing agent DTT was applied prior to activating the fiber. The GSH∶GSSG ratio was ∼3-fold lower in the cytoplasm of superficial fibers from stimulated muscle compared to control, confirming increased oxidant levels. The presence of Tempol and L-NAME during in vitro stimulation prevented reduction in Fmax. Skinned fibers from SOL muscles stimulated in vivo at 37°C with intact blood supply also displayed reduction in Fmax, though to a much smaller extent (∼12%). Thus, fibers from muscles stimulated even with putatively adequate O2 supply display a reversible oxidation-induced decrease in Fmax without change in Ca2+-sensitivity, consistent with action of peroxynitrite (or possibly superoxide) on cysteine residues of the contractile apparatus. Significantly, the changes closely resemble the contractile deficits observed in a range of pathophysiological conditions. These findings highlight how readily muscle experiences ROS-related deficits, and also point to potential difficulties when defining muscle performance and fatigue. PMID:22629297
Differences in end-point force trajectories elicited by electrical stimulation of individual human calf muscles

PubMed Central

Giordano, S B; Segal, R L; Abelew, T A

2009-01-01

The purpose of this study was to investigate the end-point force trajectories of the fibularis longus (FIB), lateral gastrocnemius (LG) and medial gastrocnemius (MG) muscles. Most information about individual muscle function has come from studies which use models based on electromyographic (EMG) recordings. In this study (N=20 subjects) we used electrical stimulation (20Hz) to elicit activity in individual muscles, recorded the end-point forces at the foot and verified the selectivity of stimulation by using magnetic resonance imaging. Unexpectedly, no significant differences were found between LG and MG force directions. Stimulation of LG and MG resulted in downward and medial or lateral forces depending on the subject. We found FIB end-point forces to be significantly different than those of LG and MG. In all subjects, stimulation of FIB resulted in downward and lateral forces. Based on our results, we suggest that there are multiple factors determining when and whether LG or MG will produce a medial or lateral force and FIB consistently plays a significant role in eversion/abduction and plantarflexion. We suggest that the inter-subject variability we found is not simply an artifact of experimental or technical error but is functionally relevant and should be addressed in future studies and models. PMID:20095454
The response of the cat anococcygeus muscle to nerve or drug stimulation and a comparison with the rat anococcygeus

PubMed Central

Gillespie, J.S.; McGrath, J.C.

1974-01-01

1 The cat anococcygeus muscle is shown to possess a dual innervation similar to the rat anococcygeus, with a motor adrenergic innervation and an inhibitory innervation whose transmitter is unknown. The pharmacological properties of the cat muscle were investigated and compared with those of the rat muscle. 2 The cat muscle contracts to noradrenaline, 5-hydroxytryptamine, tyramine, amphetamine, guanethidine, cocaine and lysergic acid diethylamide (LSD). The effects of noradrenaline and 5-hydroxytryptamine are blocked by phentolamine and methysergide respectively. 3 The cat anococcygeus is relaxed by acetylcholine, carbachol, isoprenaline, ATP, prostaglandins E1, E2 and F2α and vasopressin, all of which contract the rat muscle. The effects of acetylcholine and carbachol are blocked by atropine and those of isoprenaline by propranolol. 4 Field stimulation produces contraction of the cat anococcygeus, which is blocked by phentolamine and guanethidine but unaffected by hexamethonium, atropine or neostigmine. 5 In the presence of guanethidine (10-5 M), the tone of the muscle is raised and field stimulation produces relaxation of the muscle. These inhibitory responses are unaffected by phentolamine, hexamethonium, atropine or neostigmine. 6 Neostigmine potentiates the effects of acetylcholine, but not of carbachol in relaxing the cat anococcygeus and in contracting the rat anococcygeus, but has no effect on either motor or inhibitory responses to field stimulation. 7 Cold storage for up to eight days had little effect on either the motor response to noradrenaline or the motor or inhibitory response to field stimulation of the cat anococcygeus. Beyond eight days, the response to field stimulation diminishes more rapidly than the response to noradrenaline. PMID:4823462
R59949, a diacylglycerol kinase inhibitor, inhibits inducible nitric oxide production through decreasing transplasmalemmal L-arginine uptake in vascular smooth muscle cells.

PubMed

Shimomura, Tomoko; Nakano, Tomoyuki; Goto, Kaoru; Wakabayashi, Ichiro

2017-02-01

Although diacylglycerol kinase (DGK) is known to be expressed in vascular smooth muscle cell, its functional significance remains to be clarified. We hypothesized that DGK is involved in the pathway of cytokine-induced nitric oxide (NO) production in vascular smooth muscle cells. The purpose of this study was to investigate the effects of R59949, a diacylglycerol kinase inhibitor, on inducible nitric oxide production in vascular smooth muscle cell. Cultured rat aortic smooth muscle cells (RASMCs) were used to elucidate the effects of R59949 on basal and interleukin-1β (IL-1β)-induced NO production. The effects of R59949 on protein and mRNA expression of induced nitric oxide synthase (iNOS) and on transplasmalemmal L-arginine uptake were also evaluated using RASMCs. Treatment of RASMCs with R59949 (10 μM) inhibited IL-1β (10 ng/ml)-induced NO production but not basal NO production. Neither protein nor mRNA expression level of iNOS after stimulation with IL-1β was significantly affected by R59949. Estimated enzymatic activities of iNOS in RASMCs were comparable in the absence and presence of R59949. Stimulation of RASMCs with IL-1β caused a marked increase in transplasmalemmal L-arginine uptake into RASMCs. L-Arginine uptake in the presence of IL-1β was markedly inhibited by R59949, while basal L-arginine uptake was not significantly affected by R59949. Both IL-1β-induced NO production and L-arginine uptake were abolished in the presence of cycloheximide (1 μM). The results indicate that R59949 inhibits inducible NO production through decreasing transplasmalemmal L-arginine uptake. DGK is suggested to be involved in cytokine-stimulated L-arginine transport and regulate its intracellular concentration in vascular smooth muscle cell.
Defining the Contribution of AMP-activated Protein Kinase (AMPK) and Protein Kinase C (PKC) in Regulation of Glucose Uptake by Metformin in Skeletal Muscle Cells*

PubMed Central

Turban, Sophie; Stretton, Clare; Drouin, Olivier; Green, Charlotte J.; Watson, Maria L.; Gray, Alexander; Ross, Fiona; Lantier, Louise; Viollet, Benoit; Hardie, D. Grahame; Marette, Andre; Hundal, Harinder S.

2012-01-01

The importance of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) as effectors of metformin (Met) action on glucose uptake (GU) in skeletal muscle cells was investigated. GU in L6 myotubes was stimulated 2-fold following 16 h of Met treatment and acutely enhanced by insulin in an additive fashion. Insulin-stimulated GU was sensitive to PI3K inhibition, whereas that induced by Met was not. Met and its related biguanide, phenformin, stimulated AMPK activation/phosphorylation to a level comparable with that induced by the AMPK activator, 5-amino-1-β-d-ribofuranosyl-imidazole-4-carboxamide (AICAR). However, the increase in GU elicited by AICAR was significantly lower than that induced by either biguanide. Expression of a constitutively active AMPK mimicked the effects of AICAR on GU, whereas a dominant interfering AMPK or shRNA silencing of AMPK prevented AICAR-stimulated GU and Met-induced AMPK signaling but only repressed biguanide-stimulated GU by ∼20%. Consistent with this, analysis of GU in muscle cells from α1−/−/α2−/− AMPK-deficient mice revealed a significant retention of Met-stimulated GU, being reduced by ∼35% compared with that of wild type cells. Atypical PKCs (aPKCs) have been implicated in Met-stimulated GU, and in line with this, Met and phenformin induced activation/phosphorylation of aPKC in L6 myotubes. However, although cellular depletion of aPKC (>90%) led to loss in biguanide-induced aPKC phosphorylation, it had no effect on Met-stimulated GU, whereas inhibitors targeting novel/conventional PKCs caused a significant reduction in biguanide-induced GU. Our findings indicate that although Met activates AMPK, a significant component of Met-stimulated GU in muscle cells is mediated via an AMPK-independent mechanism that involves novel/conventional PKCs. PMID:22511782
Defining the contribution of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) in regulation of glucose uptake by metformin in skeletal muscle cells.

PubMed

Turban, Sophie; Stretton, Clare; Drouin, Olivier; Green, Charlotte J; Watson, Maria L; Gray, Alexander; Ross, Fiona; Lantier, Louise; Viollet, Benoit; Hardie, D Grahame; Marette, Andre; Hundal, Harinder S

2012-06-08

The importance of AMP-activated protein kinase (AMPK) and protein kinase C (PKC) as effectors of metformin (Met) action on glucose uptake (GU) in skeletal muscle cells was investigated. GU in L6 myotubes was stimulated 2-fold following 16 h of Met treatment and acutely enhanced by insulin in an additive fashion. Insulin-stimulated GU was sensitive to PI3K inhibition, whereas that induced by Met was not. Met and its related biguanide, phenformin, stimulated AMPK activation/phosphorylation to a level comparable with that induced by the AMPK activator, 5-amino-1-β-d-ribofuranosyl-imidazole-4-carboxamide (AICAR). However, the increase in GU elicited by AICAR was significantly lower than that induced by either biguanide. Expression of a constitutively active AMPK mimicked the effects of AICAR on GU, whereas a dominant interfering AMPK or shRNA silencing of AMPK prevented AICAR-stimulated GU and Met-induced AMPK signaling but only repressed biguanide-stimulated GU by ∼20%. Consistent with this, analysis of GU in muscle cells from α1(-/-)/α2(-/-) AMPK-deficient mice revealed a significant retention of Met-stimulated GU, being reduced by ∼35% compared with that of wild type cells. Atypical PKCs (aPKCs) have been implicated in Met-stimulated GU, and in line with this, Met and phenformin induced activation/phosphorylation of aPKC in L6 myotubes. However, although cellular depletion of aPKC (>90%) led to loss in biguanide-induced aPKC phosphorylation, it had no effect on Met-stimulated GU, whereas inhibitors targeting novel/conventional PKCs caused a significant reduction in biguanide-induced GU. Our findings indicate that although Met activates AMPK, a significant component of Met-stimulated GU in muscle cells is mediated via an AMPK-independent mechanism that involves novel/conventional PKCs.
21 CFR 884.5940 - Powered vaginal muscle stimulator for therapeutic use.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Powered vaginal muscle stimulator for therapeutic use. 884.5940 Section 884.5940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... for therapeutic use in increasing muscular tone and strength in the treatment of sexual dysfunction...
21 CFR 884.5940 - Powered vaginal muscle stimulator for therapeutic use.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Powered vaginal muscle stimulator for therapeutic use. 884.5940 Section 884.5940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... for therapeutic use in increasing muscular tone and strength in the treatment of sexual dysfunction...
21 CFR 884.5940 - Powered vaginal muscle stimulator for therapeutic use.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Powered vaginal muscle stimulator for therapeutic use. 884.5940 Section 884.5940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... for therapeutic use in increasing muscular tone and strength in the treatment of sexual dysfunction...
21 CFR 884.5940 - Powered vaginal muscle stimulator for therapeutic use.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Powered vaginal muscle stimulator for therapeutic use. 884.5940 Section 884.5940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... for therapeutic use in increasing muscular tone and strength in the treatment of sexual dysfunction...
21 CFR 884.5940 - Powered vaginal muscle stimulator for therapeutic use.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered vaginal muscle stimulator for therapeutic use. 884.5940 Section 884.5940 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND... for therapeutic use in increasing muscular tone and strength in the treatment of sexual dysfunction...
Inhibitory effects of HgCl2 on excitation-secretion coupling at the motor nerve terminal and excitation-contraction coupling in the muscle cell.

PubMed

Røed, A; Herlofson, B B

1994-12-01

1. Indirect and direct twitch (0.1-Hz) stimulation of the rat phrenic nerve-diaphragm disclosed that the inhibitory effect of HgCl2, 3.7 x 10(-5) M, on the neuromuscular transmission and in the muscle cell, was accelerated by 10-sec periods of 50-Hz tetanic stimulation every 10 min. This activity-dependent enhancement suggested an inhibitory mechanism of HgCl2 related to the development of fatigue, like membrane depolarization or decreased excitability, decreased availability of transmitter, or interference with the factors controlling excitation-secretion coupling of the nerve terminal, i.e. (Ca2+)0 or (Ca2+)i, and excitation-contraction coupling in the muscle cell, i.e., (Ca2+)i. 2. During both indirect and direct stimulation, HgCl2-induced inhibition was enhanced markedly by pretreatment with caffeine, which releases Ca2+ from endoplasmic and sarcoplasmic reticulum in the nerve terminal and muscle cell, respectively. This caffeine-induced enhancement was completely antagonized by dantrolene, which inhibits the caffeine-induced release. However, dantrolene alone did not antagonize the HgCl2-induced inhibition. 3. Since caffeine depletes the intracellular Ca2+ stores of the smooth endoplasmic reticulum, HgCl2 probably inhibits by binding to SH groups of transport proteins conveying the messenger function of (Ca2+)i. In the muscle cell this leads to inhibition of contraction. In the nerve terminal, an additional enhancement of the HgCl2-induced inhibition, by inhibiting reuptake of choline by TEA and tetanic stimulation, suggested that HgCl2 inhibited a (Ca2+)i signal necessary for this limiting factor in resynthesis of acetylcholine. 4. The (Ca2+)0 signal necessary for stimulus-induced release of acetylcholine was not affected by HgCl2. Hyperpolarization in K(+)-free solution antagonized the inhibitory effect of HgCl2 at indirect stimulation, and Ca(2+)-free solution enhanced the inhibitory effect at direct stimulation. K+ depolarization, membrane electric field
( sup 3 H)QNB binding and contraction of rabbit colonic smooth muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ringer, M.J.; Hyman, P.E.; Kao, H.W.

The authors used radioligand binding and studies of cell contraction to characterize muscarinic receptors on dispersed smooth muscle cells from rabbit proximal and distal colon. Cells obtained after serial incubations in collagenase were used to measure binding of tritiated quinuclidinyl benzilate (({sup 3}H)QNB). At 37{degree}C, specific ({sup 3}H)QNB binding was saturable and linearly related to cell number. Nonlinear regression analysis was used to determine the affinity of ({sup 3}H)QNB for its receptor. The IC{sub 50} for the muscarinic agonists bethanechol and oxotremorine were 80 and 0.57 {mu}M, respectively. Hill coefficients were 0.67 for both, suggesting more complex interaction involving receptorsmore » of different affinities. In studies of cell contraction, bethanechol stimulated a dose-dependent decrease in cell length with half the maximal contraction occurring at 100 pM. These results suggest that (1) contraction is mediated by binding of bethanechol to M{sub 2}-muscarinic receptors and that (2) there are a large number of spare receptors in colonic smooth muscle.« less
Electrical Stimulation of the Suprahyoid Muscles in Brain-injured Patients with Dysphagia: A Pilot Study

PubMed Central

Beom, Jaewon; Kim, Sang Jun

2011-01-01

Objective To investigate the therapeutic effects of repetitive electrical stimulation of the suprahyoid muscles in brain-injured patients with dysphagia. Method Twenty-eight brain-injured patients who showed reduced laryngeal elevation and supraglottic penetration or subglottic aspiration during a videofluoroscopic swallowing study (VFSS) were selected. The patients received either conventional dysphagia management (CDM) or CDM with repetitive electrical stimulation of the suprahyoid muscles (ESSM) for 4 weeks. The videofluoroscopic dysphagia scale (VDS) using the VFSS and American Speech-Language-Hearing Association National Outcome Measurement System (ASHA NOMS) swallowing scale (ASHA level) was used to determine swallowing function before and after treatment. Results VDS scores decreased from 29.8 to 17.9 in the ESSM group, and from 29.2 to 16.6 in the CDM group. However, there was no significant difference between the groups (p=0.796). Six patients (85.7%) in the ESSM group and 14 patients (66.7%) in the CDM group showed improvement according to the ASHA level with no significant difference between the ESSM and CDM groups (p=0.633). Conclusion Although repetitive neuromuscular electrical stimulation of the suprahyoid muscles did not further improve the swallowing function of dysphagia patients with reduced laryngeal elevation, more patients in the ESSM group showed improvement in the ASHA level than those in the CDM group. Further studies with concurrent controls and a larger sample group are required to fully establish the effects of repetitive neuromuscular electrical stimulation of the suprahyoid muscles in dysphagia patients. PMID:22506140
Th1 cytokine-induced syndecan-4 shedding by airway smooth muscle cells is dependent on mitogen-activated protein kinases.

PubMed

Tan, Xiahui; Khalil, Najwa; Tesarik, Candice; Vanapalli, Karunasri; Yaputra, Viki; Alkhouri, Hatem; Oliver, Brian G G; Armour, Carol L; Hughes, J Margaret

2012-04-01

In asthma, airway smooth muscle (ASM) chemokine secretion can induce mast cell recruitment into the airways. The functions of the mast cell chemoattractant CXCL10, and other chemokines, are regulated by binding to heparan sulphates such as syndecan-4. This study is the first demonstration that airway smooth muscle cells (ASMC) from people with and without asthma express and shed syndecan-4 under basal conditions. Syndecan-4 shedding was enhanced by stimulation for 24 h with the Th1 cytokines interleukin-1β (IL-1β) or tumor necrosis factor-α (TNF-α), but not interferon-γ (IFNγ), nor the Th2 cytokines IL-4 and IL-13. ASMC stimulation with IL-1β, TNF-α, and IFNγ (cytomix) induced the highest level of syndecan-4 shedding. Nonasthmatic and asthmatic ASM cell-associated syndecan-4 protein expression was also increased by TNF-α or cytomix at 4-8 h, with the highest levels detected in cytomix-stimulated asthmatic cells. Cell-associated syndecan-4 levels were decreased by 24 h, whereas shedding remained elevated at 24 h, consistent with newly synthesized syndecan-4 being shed. Inhibition of ASMC matrix metalloproteinase-2 did not prevent syndecan-4 shedding, whereas inhibition of ERK MAPK activation reduced shedding from cytomix-stimulated ASMC. Although ERK inhibition had no effect on syndecan-4 mRNA levels stimulated by cytomix, it did cause an increase in cell-associated syndecan-4 levels, consistent with the shedding being inhibited. In conclusion, ASMC produce and shed syndecan-4 and although this is increased by the Th1 cytokines, the MAPK ERK only regulates shedding. ASMC syndecan-4 production during Th1 inflammatory conditions may regulate chemokine activity and mast cell recruitment to the ASM in asthma.
The role of frequency in the effects of long-term intermittent stimulation of denervated slow-twitch muscle in the rat.

PubMed Central

Al-Amood, W S; Lewis, D M

1987-01-01

1. Rat soleus muscle was denervated by sciatic transection and electrically stimulated for periods of between 3 and 9 weeks with intermittent 1 s bursts of pulses. Most of the bursts were either repeated every 90 s and pulses within them had frequencies between 10 and 100 Hz, or had a frequency of 50 Hz and were repeated at intervals between 60 and 600 s. Comparisons were made with continuous stimulation at 10 Hz. 2. At the end of the period of stimulation, isometric twitches and tetani were measured and, in a proportion, also isotonic shortening velocity. 3. Isometric twitch duration (contraction and relaxation) decreased with time of stimulation. Very similar effects were seen in all animals in which intermittent stimulation had been used. There was a significant relationship between the change in twitch duration and the frequency used within the bursts of chronic stimulation, with slightly larger effects at frequencies of 40 and 60 Hz. The lowest burst repetition rate produced the largest effects. 4. It was confirmed that similar changes were found in denervated muscles that were not stimulated, although these changes were smaller and developed more slowly. 5. The extreme loss of tetanic tension induced in the muscle by denervation was reduced by chronic stimulation, with no significant difference between different regimes, although there were small differences which showed the same patterns of effectiveness described for twitch durations. 6. Continuous stimulation at 10 Hz maintained the twitch contraction and relaxation phases at the values found 3 weeks after denervation, that is it prevented secondary shortening of the twitch. Continuous stimulation reduced tension loss but was, perhaps, less effective than intermittent stimulation. 7. Twitch-tetanus ratio increased with denervation with little spontaneous reversal later. Stimulation at all frequencies reduced the ratio, but it did not reach normal values. 8. Isotonic shortening velocity was measured in many
Notch1 stimulation induces a vascularization switch with pericyte-like cell differentiation of glioblastoma stem cells.

PubMed

Guichet, Pierre-Olivier; Guelfi, Sophie; Teigell, Marisa; Hoppe, Liesa; Bakalara, Norbert; Bauchet, Luc; Duffau, Hugues; Lamszus, Katrin; Rothhut, Bernard; Hugnot, Jean-Philippe

2015-01-01

Glioblastoma multiforms (GBMs) are highly vascularized brain tumors containing a subpopulation of multipotent cancer stem cells. These cells closely interact with endothelial cells in neurovascular niches. In this study, we have uncovered a close link between the Notch1 pathway and the tumoral vascularization process of GBM stem cells. We observed that although the Notch1 receptor was activated, the typical target proteins (HES5, HEY1, and HEY2) were not or barely expressed in two explored GBM stem cell cultures. Notch1 signaling activation by expression of the intracellular form (NICD) in these cells was found to reduce their growth rate and migration, which was accompanied by the sharp reduction in neural stem cell transcription factor expression (ASCL1, OLIG2, and SOX2), while HEY1/2, KLF9, and SNAI2 transcription factors were upregulated. Expression of OLIG2 and growth were restored after termination of Notch1 stimulation. Remarkably, NICD expression induced the expression of pericyte cell markers (NG2, PDGFRβ, and α-smooth muscle actin [αSMA]) in GBM stem cells. This was paralleled with the induction of several angiogenesis-related factors most notably cytokines (heparin binding epidermal growth factor [HB-EGF], IL8, and PLGF), matrix metalloproteinases (MMP9), and adhesion proteins (vascular cell adhesion molecule 1 [VCAM1], intercellular adhesion molecule 1 [ICAM1], and integrin alpha 9 [ITGA9]). In xenotransplantation experiments, contrasting with the infiltrative and poorly vascularized tumors obtained with control GBM stem cells, Notch1 stimulation resulted in poorly disseminating but highly vascularized grafts containing large vessels with lumen. Notch1-stimulated GBM cells expressed pericyte cell markers and closely associated with endothelial cells. These results reveal an important role for the Notch1 pathway in regulating GBM stem cell plasticity and angiogenic properties. © 2014 AlphaMed Press.
Immortalization of cat iris sphincter smooth muscle cells by SV40 virus: growth, morphological, biochemical and pharmacological characteristics.

PubMed

Ocklind, A; Yousufzai, S Y; Ghosh, S; Coca-Prados, M; St Jernschantz, J; Abdel-Latif, A A

1995-11-01

The purpose of this study was to establish immortalized cell cultures of cat iris sphincter smooth muscle cells for a model investigating ocular receptors and their signal transduction pathways. Cultured cat iris sphincter muscle cells were immortalized by viral transformation with SV40 virus and the morphological and immunocytochemical properties of the normal and immortalized cells were investigated. The transformed cell clone, SV-CISM-2, was further characterized biochemically and pharmacologically. The normal muscle cells showed characteristics of smooth muscle cells, as judged by their growth and the presence of smooth muscle alpha-actin and desmin. After seven passages the normal cells ceased to proliferate. In contrast, the immortalized cells retained their proliferative ability for more than 220 population doublings over 55 passages. The transformation phenotype in these cells was confirmed by their expression of the large T-antigen, the incorporation of viral DNA into cellular DNA, growth in agarose and in low-serum medium, and complete loss of contact inhibition. The immortalized cells expressed smooth muscle alpha-actin, desmin and MLC protein. Biochemical and pharmacological studies on the SV-CISM cells revealed the presence of several functional receptors including muscarinic cholinergic, beta-adrenergic, peptidergic (substance P and endothelin). Platelet-activating factor, and prostaglandin (PG). Muscarinic stimulation of these cells resulted in: (a) a dose-dependent increase in the release of arachidonic acid (AA) and (PGs) and enhancement in the production of inositol trisphosphate (IP3); and (b) a substantial increase in MLC phosphorylation (118%), an indicator of smooth muscle contractility. The stimulatory effects of carbachol on these responses were completely blocked by atropine, a muscarinic receptor antagonist. This study constitutes the first successful immortalization of iris sphincter smooth muscle cells. The SV-CISM-2 cells can serve as

Study of muscle cell dedifferentiation after skeletal muscle injury of mice with a Cre-Lox system.

PubMed

Mu, Xiaodong; Peng, Hairong; Pan, Haiying; Huard, Johnny; Li, Yong

2011-02-03

Dedifferentiation of muscle cells in the tissue of mammals has yet to be observed. One of the challenges facing the study of skeletal muscle cell dedifferentiation is the availability of a reliable model that can confidentially distinguish differentiated cell populations of myotubes and non-fused mononuclear cells, including stem cells that can coexist within the population of cells being studied. In the current study, we created a Cre/Lox-β-galactosidase system, which can specifically tag differentiated multinuclear myotubes and myotube-generated mononuclear cells based on the activation of the marker gene, β-galactosidase. By using this system in an adult mouse model, we found that β-galactosidase positive mononuclear cells were generated from β-galactosidase positive multinuclear myofibers upon muscle injury. We also demonstrated that these mononuclear cells can develop into a variety of different muscle cell lineages, i.e., myoblasts, satellite cells, and muscle derived stem cells. These novel findings demonstrated, for the first time, that cellular dedifferentiation of skeletal muscle cells actually occurs in mammalian skeletal muscle following traumatic injury in vivo.
Three-dimensional contractile muscle tissue consisting of human skeletal myocyte cell line.

PubMed

Shima, Ai; Morimoto, Yuya; Sweeney, H Lee; Takeuchi, Shoji

2018-06-18

This paper describes a method to construct three-dimensional (3D) contractile human skeletal muscle tissues from a cell line. The 3D tissue was fabricated as a fiber-based structure and cultured for two weeks under tension by anchoring its both ends. While myotubes from the immortalized human skeletal myocytes used in this study never contracted in the conventional two-dimensional (2D) monolayer culture, myotubes in the 3D tissue showed spontaneous contraction at a high frequency and also reacted to the electrical stimulation. Immunofluorescence revealed that the myotubes in the 3D tissues had sarcomeres and expressed ryanodine receptor (RyR) and sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA). In addition, intracellular calcium oscillations in the myotubes in the 3D tissue were observed. These results indicated that the 3D culture enabled the myocyte cell line to reach a more highly matured state compared to 2D culture. Since contraction is the most significant feature of skeletal muscle, we believe that our 3D human muscle tissue with the contractile ability would be a useful tool for both basic biology research and drug discovery as one of the muscle-on-chips. Copyright © 2018. Published by Elsevier Inc.
Blood flow variation in human muscle during electrically stimulated exercise bouts.

PubMed

Vanderthommen, Marc; Depresseux, Jean-Claude; Dauchat, Luc; Degueldre, Christian; Croisier, Jean-Louis; Crielaard, Jean-Michel

2002-07-01

To evaluate, with a high spatial resolution, the blood flow variations in human skeletal muscle during neuromuscular electric stimulation (NMES) and hence to gain better understanding of the mechanisms of muscle spatial recruitment during NMES. One thigh was submitted to 3 stimulation bouts of different durations (S1=4min, S2=8min, S3=12min) with a workload corresponding to 10% of quadriceps maximal isometric voluntary torque. A cyclotron research center at a Belgian university. Ten healthy male volunteers. Not applicable. Participants were studied with positron emission tomography and H(2)(15)O. Tissue blood flow was evaluated during the last 4 minutes of each stimulation bout in multiple regions of interest (ROIs) selected in the transverse section of the stimulated thigh. Mean tissue blood flow was significantly lower during S1 (5.9+/-1.3mL. min(-1). 100g(-1)) than during S2 (10.6+/-3.4mL. min(-1). 100g(-1)) and S3 (11.6+/-3.7mL. min(-1). 100g(-1)) (P<.05). For each ROI, an arbitrary tissue blood flow activation level of 5mLmin(-1)100g(-1) was fixed. The mean percentage of activated ROIs reached 42.4%, 62.7%, and 63.6% during S1, S2, and S3, respectively. Between S1 and S3, the newly recruited ROIs were preferentially located far from the electrode. During NMES, new muscular regions situated far from the stimulation site are recruited. These recruitment mechanisms are particular and contrast with the recruitment of motor units seen during voluntary contraction. Copyright 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation
Pharmacological activation of PPARbeta/delta stimulates utrophin A expression in skeletal muscle fibers and restores sarcolemmal integrity in mature mdx mice.

PubMed

Miura, Pedro; Chakkalakal, Joe V; Boudreault, Louise; Bélanger, Guy; Hébert, Richard L; Renaud, Jean-Marc; Jasmin, Bernard J

2009-12-01

A therapeutic strategy to treat Duchenne muscular dystrophy (DMD) involves identifying compounds that can elevate utrophin A expression in muscle fibers of affected patients. The dystrophin homologue utrophin A can functionally substitute for dystrophin when its levels are enhanced in the mdx mouse model of DMD. Utrophin A expression in skeletal muscle is regulated by mechanisms that promote the slow myofiber program. Since activation of peroxisome proliferator-activated receptor (PPAR) beta/delta promotes the slow oxidative phenotype in skeletal muscle, we initiated studies to determine whether pharmacological activation of PPARbeta/delta provides functional benefits to the mdx mouse. GW501516, a PPARbeta/delta agonist, was found to stimulate utrophin A mRNA levels in C2C12 muscle cells through an element in the utrophin A promoter. Expression of PPARbeta/delta was greater in skeletal muscles of mdx versus wild-type mice. We treated 5-7-week-old mdx mice with GW501516 for 4 weeks. This treatment increased the percentage of muscle fibers expressing slower myosin heavy chain isoforms and stimulated utrophin A mRNA levels leading to its increased expression at the sarcolemma. Expression of alpha1-syntrophin and beta-dystroglycan was restored to the sarcolemma. Improvement of mdx sarcolemmal integrity was evidenced by decreased intracellular IgM staining and decreased in vivo Evans blue dye (EBD) uptake. GW501516 treatment also conferred protection against eccentric contraction (ECC)-induced damage of mdx skeletal muscles, as shown by a decreased contraction-induced force drop and reduction of dye uptake during ECC. These results demonstrate that pharmacological activation of PPARbeta/delta might provide functional benefits to DMD patients through enhancement of utrophin A expression.
Amino acids augment muscle protein synthesis in neonatal pigs during acute endotoxemia by stimulating mTOR-dependent translation initiation.

PubMed

Orellana, Renán A; Jeyapalan, Asumthia; Escobar, Jeffery; Frank, Jason W; Nguyen, Hanh V; Suryawan, Agus; Davis, Teresa A

2007-11-01

In skeletal muscle of adults, sepsis reduces protein synthesis by depressing translation initiation and induces resistance to branched-chain amino acid stimulation. Normal neonates maintain a high basal muscle protein synthesis rate that is sensitive to amino acid stimulation. In the present study, we determined the effect of amino acids on protein synthesis in skeletal muscle and other tissues in septic neonates. Overnight-fasted neonatal pigs were infused with endotoxin (LPS, 0 and 10 microg.kg(-1).h(-1)), whereas glucose and insulin were maintained at fasting levels; amino acids were clamped at fasting or fed levels. In the presence of fasting insulin and amino acids, LPS reduced protein synthesis in longissimus dorsi (LD) and gastrocnemius muscles and increased protein synthesis in the diaphragm, but had no effect in masseter and heart muscles. Increasing amino acids to fed levels accelerated muscle protein synthesis in LD, gastrocnemius, masseter, and diaphragm. LPS stimulated protein synthesis in liver, lung, spleen, pancreas, and kidney in fasted animals. Raising amino acids to fed levels increased protein synthesis in liver of controls, but not LPS-treated animals. The increase in muscle protein synthesis in response to amino acids was associated with increased mTOR, 4E-BP1, and S6K1 phosphorylation and eIF4G-eIF4E association in control and LPS-infused animals. These findings suggest that amino acids stimulate skeletal muscle protein synthesis during acute endotoxemia via mTOR-dependent ribosomal assembly despite reduced basal protein synthesis rates in neonatal pigs. However, provision of amino acids does not further enhance the LPS-induced increase in liver protein synthesis.
Tissue-specific stem cells: Lessons from the skeletal muscle satellite cell

PubMed Central

Brack, Andrew S.; Rando, Thomas A.

2012-01-01

In 1961, the satellite cell was first identified when electron microscopic examination of skeletal muscle demonstrated a cell wedged between the plasma membrane of the muscle fiber and the basement membrane. In recent years it has been conclusively demonstrated that the satellite cell is the primary cellular source for muscle regeneration and is equipped with the potential to self renew, thus functioning as a bone fide skeletal muscle stem cell (MuSC). As we move past the 50th anniversary of the satellite cell, we take this opportunity to discuss the current state of the art and dissect the unknowns in the MuSC field. PMID:22560074
Quantitative analysis of immune cell subset infiltration of supraspinatus muscle after severe rotator cuff injury.

PubMed

Krieger, J R; Tellier, L E; Ollukaren, M T; Temenoff, J S; Botchwey, E A

2017-06-01

Rotator cuff tears cause muscle degeneration that is characterized by myofiber atrophy, fatty infiltration, and fibrosis and is minimally responsive to current treatment options. The underlying pathogenesis of rotator cuff muscle degeneration remains to be elucidated, and increasing evidence implicates immune cell infiltration as a significant factor. Because immune cells are comprised of highly heterogeneous subpopulations that exert divergent effects on injured tissue, understanding trafficking and accumulation of immune subpopulations may hold the key to more effective therapies. The present study quantifies subpopulations of immune cells infiltrating the murine supraspinatus muscle after severe rotator cuff injury that includes tenotomy and denervation. Rotator cuff injury stimulates dramatic infiltration of mononuclear phagocytes, enriches mononuclear phagocytes in non-classical subpopulations, and enriches T lymphocytes in T H and T reg subpopulations. The combination of tenotomy plus denervation significantly increases mononuclear phagocyte infiltration, enriches macrophages in the non-classical subpopulation, and decreases T lymphocyte enrichment in T H cells compared to tenotomy alone. Depletion of circulating monocytes via liposomal clodronate accelerates supraspinatus atrophy after tenotomy and denervation. The study may aid rational design of immunologically smart therapies that harness immune cells to enhance outcomes after rotator cuff tears.
Direct comparison of progenitor cells derived from adipose, muscle, and bone marrow from wild-type or craniosynostotic rabbits

PubMed Central

GM, Cooper; EL, Lensie; JJ, Cray; MR, Bykowski; GE, DeCesare; MA, Smalley; MP, Mooney; PG, Campbell; JE, Losee

2010-01-01

Background Reports have identified cells capable of osteogenic differentiation in bone marrow, muscle, and adipose tissues, but there are few direct comparisons of these different cell-types. Also, few have investigated the potential connection between a tissue-specific pathology and cells derived from seemingly unrelated tissues. Here, we compare cells isolated from wild-type rabbits or rabbits with nonsyndromic craniosynostosis, defined as the premature fusion of one or more of the cranial sutures. Methods Cells were derived from bone marrow, adipose, and muscle of 10 day-old wild-type rabbits (WT; n=17) or from age-matched rabbits with familial nonsyndromic craniosynostosis (CS; n=18). Cells were stimulated with bone morphogenetic protein 4 (BMP4) and alkaline phosphatase expression and cell proliferation were assessed. Results In WT rabbits, cells derived from muscle had more alkaline phosphatase activity than cells derived from either adipose or bone marrow. The cells derived from CS rabbit bone marrow and muscle were significantly more osteogenic than WT. Adipose-derived cells demonstrated no significant differences. While muscle-derived cells were most osteogenic in WT rabbits, bone marrow-derived cells were most osteogenic in CS rabbits. Conclusions Results suggest that cells from different tissues have different potentials for differentiation. Furthermore, cells derived from rabbits with craniosynostosis were different from wild-type derived cells. Interestingly, cells derived from the craniosynostotic rabbits were not uniformly more responsive compared with wild-type cells, suggesting that specific tissue-derived cells may react differently in individuals with craniosynostosis. PMID:20871482
Assessment of abdominal muscle function in individuals with motor-complete spinal cord injury above T6 in response to transcranial magnetic stimulation.

PubMed

Bjerkefors, Anna; Squair, Jordan W; Chua, Romeo; Lam, Tania; Chen, Zhen; Carpenter, Mark G

2015-02-01

To use transcranial magnetic stimulation and electromyography to assess the potential for preserved function in the abdominal muscles in individuals classified with motor-complete spinal cord injury above T6. Five individuals with spinal cord injury (C5-T3) and 5 able-bodied individuals. Transcranial magnetic stimulation was delivered over the abdominal region of primary motor cortex during resting and sub-maximal (or attempted) contractions. Surface electromyography was used to record motor-evoked potentials as well as maximal voluntary (or attempted) contractions in the abdominal muscles and the diaphragm. Responses to transcranial magnetic stimulation in the abdominal muscles occurred in all spinal cord injury subjects. Latencies of muscle response onsets were similar in both groups; however, peak-to-peak amplitudes were smaller in the spinal cord injury group. During maximal voluntary (or attempted) contractions all spinal cord injury subjects were able to elicit electromyography activity above resting levels in more than one abdominal muscle across tasks. Individuals with motor-complete spinal cord injury above T6 were able to activate abdominal muscles in response to transcranial magnetic stimulation and during maximal voluntary (or attempted) contractions. The activation was induced directly through corticospinal pathways, and not indirectly by stretch reflex activations of the diaphragm. Transcranial magnetic stimulation and electromyography measurements provide a useful method to assess motor preservation of abdominal muscles in persons with spinal cord injury.
Muscle-Specific Vascular Endothelial Growth Factor Deletion Induces Muscle Capillary Rarefaction Creating Muscle Insulin Resistance

PubMed Central

Bonner, Jeffrey S.; Lantier, Louise; Hasenour, Clinton M.; James, Freyja D.; Bracy, Deanna P.; Wasserman, David H.

2013-01-01

Muscle insulin resistance is associated with a reduction in vascular endothelial growth factor (VEGF) action and muscle capillary density. We tested the hypothesis that muscle capillary rarefaction critically contributes to the etiology of muscle insulin resistance in chow-fed mice with skeletal and cardiac muscle VEGF deletion (mVEGF−/−) and wild-type littermates (mVEGF+/+) on a C57BL/6 background. The mVEGF−/− mice had an ∼60% and ∼50% decrease in capillaries in skeletal and cardiac muscle, respectively. The mVEGF−/− mice had augmented fasting glucose turnover. Insulin-stimulated whole-body glucose disappearance was blunted in mVEGF−/− mice. The reduced peripheral glucose utilization during insulin stimulation was due to diminished in vivo cardiac and skeletal muscle insulin action and signaling. The decreased insulin-stimulated muscle glucose uptake was independent of defects in insulin action at the myocyte, suggesting that the impairment in insulin-stimulated muscle glucose uptake was due to poor muscle perfusion. The deletion of VEGF in cardiac muscle did not affect cardiac output. These studies emphasize the importance for novel therapeutic approaches that target the vasculature in the treatment of insulin-resistant muscle. PMID:23002035
Skeletal muscle PLIN proteins, ATGL and CGI-58, interactions at rest and following stimulated contraction

PubMed Central

Ramos, Sofhia V.; Vandenboom, Rene; Roy, Brian D.; Peters, Sandra J.

2013-01-01

Evidence indicates that skeletal muscle lipid droplet-associated proteins (PLINs) regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN1 is thought to regulate lipolysis by directly interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to fully activate ATGL and initiate triglyceride breakdown. The absence of PLIN1 in skeletal muscle leads us to believe that other PLIN family members undertake this role. Our purpose was to examine interactions between PLIN2, PLIN3, and PLIN5, with ATGL and its coactivator CGI-58 at rest and following contraction. Isolated rat solei were incubated for 30 min at rest or during 30 min of intermittent tetanic stimulation [150-ms volleys at 60 Hz with a train rate of 20 tetani/min (25°C)] to maximally stimulate intramuscular lipid breakdown. Results show that the interaction between ATGL and CGI-58 increased 128% following contraction (P = 0.041). Further, ATGL interacts with PLIN2, PLIN3, and PLIN5 at rest and following contraction. The PLIN2-ATGL interaction decreased significantly by 21% following stimulation (P = 0.013). Both PLIN3 and PLIN5 coprecipitated with CGI-58 at rest and following contraction, while there was no detectable interaction between PLIN2 and CGI-58 in either condition. Therefore, our findings indicate that in skeletal muscle, during contraction-induced muscle lipolysis, ATGL and CGI-58 strongly associate and that the PLIN proteins work together to regulate lipolysis, in part, by preventing ATGL and CGI-58 interactions at rest. PMID:23408028
Myostatin genetic inactivation inhibits myogenesis by muscle-derived stem cells in vitro but not when implanted in the mdx mouse muscle

PubMed Central

2013-01-01

Introduction Stimulating the commitment of implanted dystrophin+ muscle-derived stem cells (MDSCs) into myogenic, as opposed to lipofibrogenic lineages, is a promising therapeutic strategy for Duchenne muscular dystrophy (DMD). Methods To examine whether counteracting myostatin, a negative regulator of muscle mass and a pro-lipofibrotic factor, would help this process, we compared the in vitro myogenic and fibrogenic capacity of MDSCs from wild-type (WT) and myostatin knockout (Mst KO) mice under various modulators, the expression of key stem cell and myogenic genes, and the capacity of these MDSCs to repair the injured gastrocnemius in aged dystrophic mdx mice with exacerbated lipofibrosis. Results Surprisingly, the potent in vitro myotube formation by WT MDSCs was refractory to modulators of myostatin expression or activity, and the Mst KO MDSCs failed to form myotubes under various conditions, despite both MDSC expressing Oct 4 and various stem cell genes and differentiating into nonmyogenic lineages. The genetic inactivation of myostatin in MDSCs was associated with silencing of critical genes for early myogenesis (Actc1, Acta1, and MyoD). WT MDSCs implanted into the injured gastrocnemius of aged mdx mice significantly improved myofiber repair and reduced fat deposition and, to a lesser extent, fibrosis. In contrast to their in vitro behavior, Mst KO MDSCs in vivo also significantly improved myofiber repair, but had few effects on lipofibrotic degeneration. Conclusions Although WT MDSCs are very myogenic in culture and stimulate muscle repair after injury in the aged mdx mouse, myostatin genetic inactivation blocks myotube formation in vitro, but the myogenic capacity is recovered in vivo under the influence of the myostatin+ host-tissue environment, presumably by reactivation of key genes originally silenced in the Mst KO MDSCs. PMID:23295128
Transplantated mesenchymal stem cells derived from embryonic stem cells promote muscle regeneration and accelerate functional recovery of injured skeletal muscle.

PubMed

Ninagawa, Nana Takenaka; Isobe, Eri; Hirayama, Yuri; Murakami, Rumi; Komatsu, Kazumi; Nagai, Masataka; Kobayashi, Mami; Kawabata, Yuka; Torihashi, Shigeko

2013-08-01

We previously established that mesenchymal stem cells originating from mouse embryonic stem (ES) cells (E-MSCs) showed markedly higher potential for differentiation into skeletal muscles in vitro than common mesenchymal stem cells (MSCs). Further, the E-MSCs exhibited a low risk for teratoma formation. Here we evaluate the potential of E-MSCs for differentiation into skeletal muscles in vivo and reveal the regeneration and functional recovery of injured muscle by transplantation. E-MSCs were transplanted into the tibialis anterior (TA) muscle 24 h following direct clamping. After transplantation, the myogenic differentiation of E-MSCs, TA muscle regeneration, and re-innervation were morphologically analyzed. In addition, footprints and gaits of each leg under spontaneous walking were measured by CatWalk XT, and motor functions of injured TA muscles were precisely analyzed. Results indicate that >60% of transplanted E-MSCs differentiated into skeletal muscles. The cross-sectional area of the injured TA muscles of E-MSC-transplanted animals increased earlier than that of control animals. E-MSCs also promotes re-innervation of the peripheral nerves of injured muscles. Concerning function of the TA muscles, we reveal that transplantation of E-MSCs promotes the recovery of muscles. This is the first report to demonstrate by analysis of spontaneous walking that transplanted cells can accelerate the functional recovery of injured muscles. Taken together, the results show that E-MSCs have a high potential for differentiation into skeletal muscles in vivo as well as in vitro. The transplantation of E-MSCs facilitated the functional recovery of injured muscles. Therefore, E-MSCs are an efficient cell source in transplantation.
Transplantated Mesenchymal Stem Cells Derived from Embryonic Stem Cells Promote Muscle Regeneration and Accelerate Functional Recovery of Injured Skeletal Muscle

PubMed Central

Ninagawa, Nana Takenaka; Isobe, Eri; Hirayama, Yuri; Murakami, Rumi; Komatsu, Kazumi; Nagai, Masataka; Kobayashi, Mami; Kawabata, Yuka

2013-01-01

Abstract We previously established that mesenchymal stem cells originating from mouse embryonic stem (ES) cells (E-MSCs) showed markedly higher potential for differentiation into skeletal muscles in vitro than common mesenchymal stem cells (MSCs). Further, the E-MSCs exhibited a low risk for teratoma formation. Here we evaluate the potential of E-MSCs for differentiation into skeletal muscles in vivo and reveal the regeneration and functional recovery of injured muscle by transplantation. E-MSCs were transplanted into the tibialis anterior (TA) muscle 24 h following direct clamping. After transplantation, the myogenic differentiation of E-MSCs, TA muscle regeneration, and re-innervation were morphologically analyzed. In addition, footprints and gaits of each leg under spontaneous walking were measured by CatWalk XT, and motor functions of injured TA muscles were precisely analyzed. Results indicate that >60% of transplanted E-MSCs differentiated into skeletal muscles. The cross-sectional area of the injured TA muscles of E-MSC–transplanted animals increased earlier than that of control animals. E-MSCs also promotes re-innervation of the peripheral nerves of injured muscles. Concerning function of the TA muscles, we reveal that transplantation of E-MSCs promotes the recovery of muscles. This is the first report to demonstrate by analysis of spontaneous walking that transplanted cells can accelerate the functional recovery of injured muscles. Taken together, the results show that E-MSCs have a high potential for differentiation into skeletal muscles in vivo as well as in vitro. The transplantation of E-MSCs facilitated the functional recovery of injured muscles. Therefore, E-MSCs are an efficient cell source in transplantation. PMID:23914336
3D Cell Printing of Functional Skeletal Muscle Constructs Using Skeletal Muscle-Derived Bioink.

PubMed

Choi, Yeong-Jin; Kim, Taek Gyoung; Jeong, Jonghyeon; Yi, Hee-Gyeong; Park, Ji Won; Hwang, Woonbong; Cho, Dong-Woo

2016-10-01

Engineered skeletal muscle tissues that mimic the structure and function of native muscle have been considered as an alternative strategy for the treatment of various muscular diseases and injuries. Here, it is demonstrated that 3D cell-printing of decellularized skeletal muscle extracellular matrix (mdECM)-based bioink facilitates the fabrication of functional skeletal muscle constructs. The cellular alignment and the shape of the tissue constructs are controlled by 3D cell-printing technology. mdECM bioink provides the 3D cell-printed muscle constructs with a myogenic environment that supports high viability and contractility as well as myotube formation, differentiation, and maturation. More interestingly, the preservation of agrin is confirmed in the mdECM, and significant increases in the formation of acetylcholine receptor clusters are exhibited in the 3D cell-printed muscle constructs. In conclusion, mdECM bioink and 3D cell-printing technology facilitate the mimicking of both the structural and functional properties of native muscle and hold great promise for producing clinically relevant engineered muscle for the treatment of muscular injuries. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Evoked EMG versus Muscle Torque during Fatiguing Functional Electrical Stimulation-Evoked Muscle Contractions and Short-Term Recovery in Individuals with Spinal Cord Injury

PubMed Central

Estigoni, Eduardo H.; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M.; Davis, Glen M.

2014-01-01

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery. PMID:25479324
Evoked EMG versus muscle torque during fatiguing functional electrical stimulation-evoked muscle contractions and short-term recovery in individuals with spinal cord injury.

PubMed

Estigoni, Eduardo H; Fornusek, Che; Hamzaid, Nur Azah; Hasnan, Nazirah; Smith, Richard M; Davis, Glen M

2014-12-03

This study investigated whether the relationship between muscle torque and m-waves remained constant after short recovery periods, between repeated intervals of isometric muscle contractions induced by functional electrical stimulation (FES). Eight subjects with spinal cord injury (SCI) were recruited for the study. All subjects had their quadriceps muscles group stimulated during three sessions of isometric contractions separated by 5 min of recovery. The evoked-electromyographic (eEMG) signals, as well as the produced torque, were synchronously acquired during the contractions and during short FES bursts applied during the recovery intervals. All analysed m-wave variables changed progressively throughout the three contractions, even though the same muscle torque was generated. The peak to peak amplitude (PtpA), and the m-wave area (Area) were significantly increased, while the time between the stimulus artefact and the positive peak (PosT) were substantially reduced when the muscles became fatigued. In addition, all m-wave variables recovered faster and to a greater extent than did torque after the recovery intervals. We concluded that rapid recovery intervals between FES-evoked exercise sessions can radically interfere in the use of m-waves as a proxy for torque estimation in individuals with SCI. This needs to be further investigated, in addition to seeking a better understanding of the mechanisms of muscle fatigue and recovery.
Thermal Mechanisms of Millimeter Wave Stimulation of Excitable Cells

PubMed Central

Shapiro, Mikhail G.; Priest, Michael F.; Siegel, Peter H.; Bezanilla, Francisco

2013-01-01

Interactions between millimeter waves (MMWs) and biological systems have received increasing attention due to the growing use of MMW radiation in technologies ranging from experimental medical devices to telecommunications and airport security. Studies have shown that MMW exposure alters cellular function, especially in neurons and muscles. However, the biophysical mechanisms underlying such effects are still poorly understood. Due to the high aqueous absorbance of MMW, thermal mechanisms are likely. However, nonthermal mechanisms based on resonance effects have also been postulated. We studied MMW stimulation in a simplified preparation comprising Xenopus laevis oocytes expressing proteins that underlie membrane excitability. Using electrophysiological recordings simultaneously with 60 GHz stimulation, we observed changes in the kinetics and activity levels of voltage-gated potassium and sodium channels and a sodium-potassium pump that are consistent with a thermal mechanism. Furthermore, we showed that MMW stimulation significantly increased the action potential firing rate in oocytes coexpressing voltage-gated sodium and potassium channels, as predicted by thermal terms in the Hodgkin-Huxley model of neurons. Our results suggest that MMW stimulation produces significant thermally mediated effects on excitable cells via basic thermodynamic mechanisms that must be taken into account in the study and use of MMW radiation in biological systems. PMID:23790370
The effect of subthalamic stimulation on viscoelastic stiffness of skeletal muscles in patients with Parkinson's disease.

PubMed

Rätsep, Tõnu; Asser, Toomas

2017-05-01

Myotonometric evaluation of viscoelastic stiffness of skeletal muscles has been proposed to document the effect of surgical or pharmacological treatment on rigidity in patients with Parkinson's disease. The aim of the study was to analyze the changes of viscoelastic stiffness induced by deep brain stimulation. Fifteen patients in an advanced stage of Parkinson's disease participated in the study. The study took place in the off-medication conditions after one night of drug withdrawal. The Unified Parkinson's Disease Rating Scale was used for clinical assessment of the disease. Myotonometry was used to measure viscoelastic stiffness in the resting muscles before and directly after passive wrist movements, commonly used for clinical evaluation of rigidity. The measurements were repeated during the stimulation-on and stimulation-off periods and compared with fifteen healthy control persons. The clinical scores for wrist rigidity improved from 3.0 (1-4) to 0.93 (0-2) (P<0.05) due to brain stimulation. The mean values of viscoelastic stiffness were similar before and after passive wrist movements, but the differences between the patients with high vs. low rigidity values (354.9 vs 310.2N/m; P<0.05) and in stimulation-off vs. stimulation-on conditions (342.7 vs 310.5N/m; P<0.05) were significant only if the measurements had been performed after passive wrist movements. Effective deep brain stimulation and increased rigidity can significantly change viscoelastic stiffness in the resting muscles in patients with Parkinson's disease, especially if evaluated after passive wrist movements. This paper supports the use of myotonometry for objective quantification of parkinsonian rigidity at rest. Copyright © 2017 Elsevier Ltd. All rights reserved.
Contraction of gut smooth muscle cells assessed by fluorescence imaging.

PubMed

Tokita, Yohei; Akiho, Hirotada; Nakamura, Kazuhiko; Ihara, Eikichi; Yamamoto, Masahiro

2015-03-01

Here we discuss the development of a novel cell imaging system for the evaluation of smooth muscle cell (SMC) contraction. SMCs were isolated from the circular and longitudinal muscular layers of mouse small intestine by enzymatic digestion. SMCs were stimulated by test agents, thereafter fixed in acrolein. Actin in fixed SMCs was stained with phalloidin and cell length was determined by measuring diameter at the large end of phalloidin-stained strings within the cells. The contractile response was taken as the decrease in the average length of a population of stimulated-SMCs. Various mediators and chemically identified compounds of daikenchuto (DKT), pharmaceutical-grade traditional Japanese prokinetics, were examined. Verification of the integrity of SMC morphology by phalloidin and DAPI staining and semi-automatic measurement of cell length using an imaging analyzer was a reliable method by which to quantify the contractile response. Serotonin, substance P, prostaglandin E2 and histamine induced SMC contraction in concentration-dependent manner. Two components of DKT, hydroxy-α-sanshool and hydroxy-β-sanshool, induced contraction of SMCs. We established a novel cell imaging technique to evaluate SMC contractility. This method may facilitate investigation into SMC activity and its role in gastrointestinal motility, and may assist in the discovery of new prokinetic agents. Copyright © 2015 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

The combined effects of transcutaneous electrical nerve stimulation (TENS) and stretching on muscle hardness and pressure pain threshold.

PubMed

Karasuno, Hiroshi; Ogihara, Hisayoshi; Morishita, Katsuyuki; Yokoi, Yuka; Fujiwara, Takayuki; Ogoma, Yoshiro; Abe, Koji

2016-04-01

[Purpose] This study aimed to clarify the immediate effects of a combined transcutaneous electrical nerve stimulation and stretching protocol. [Subjects] Fifteen healthy young males volunteered to participate in this study. The inclusion criterion was a straight leg raising range of motion of less than 70 degrees. [Methods] Subjects performed two protocols: 1) stretching (S group) of the medial hamstrings, and 2) tanscutaneous electrical nerve stimulation (100 Hz) with stretching (TS group). The TS group included a 20-minute electrical stimulation period followed by 10 minutes of stretching. The S group performed 10 minutes of stretching. Muscle hardness, pressure pain threshold, and straight leg raising range of motion were analyzed to evaluate the effects. The data were collected before transcutaneous electrical nerve stimulation (T1), before stretching (T2), immediately after stretching (T3), and 10 minutes after stretching (T4). [Results] Combined transcutaneous electrical nerve stimulation and stretching had significantly beneficial effects on muscle hardness, pressure pain threshold, and straight leg raising range of motion at T2, T3, and T4 compared with T1. [Conclusion] These results support the belief that transcutaneous electrical nerve stimulation combined with stretching is effective in reducing pain and decreasing muscle hardness, thus increasing range of motion.
Stimulation of Cortical Myosin Phosphorylation by p114RhoGEF Drives Cell Migration and Tumor Cell Invasion

PubMed Central

Zihni, Ceniz; Harris, Andrew R.; Bailly, Maryse; Charras, Guillaume T.; Balda, Maria S.; Matter, Karl

2012-01-01

Actinomyosin activity is an important driver of cell locomotion and has been shown to promote collective cell migration of epithelial sheets as well as single cell migration and tumor cell invasion. However, the molecular mechanisms underlying activation of cortical myosin to stimulate single cell movement, and the relationship between the mechanisms that drive single cell locomotion and those that mediate collective cell migration of epithelial sheets are incompletely understood. Here, we demonstrate that p114RhoGEF, an activator of RhoA that associates with non-muscle myosin IIA, regulates collective cell migration of epithelial sheets and tumor cell invasion. Depletion of p114RhoGEF resulted in specific spatial inhibition of myosin activation at cell-cell contacts in migrating epithelial sheets and the cortex of migrating single cells, but only affected double and not single phosphorylation of myosin light chain. In agreement, overall elasticity and contractility of the cells, processes that rely on persistent and more constant forces, were not affected, suggesting that p114RhoGEF mediates process-specific myosin activation. Locomotion was p114RhoGEF-dependent on Matrigel, which favors more roundish cells and amoeboid-like actinomyosin-driven movement, but not on fibronectin, which stimulates flatter cells and lamellipodia-driven, mesenchymal-like migration. Accordingly, depletion of p114RhoGEF led to reduced RhoA, but increased Rac activity. Invasion of 3D matrices was p114RhoGEF-dependent under conditions that do not require metalloproteinase activity, supporting a role of p114RhoGEF in myosin-dependent, amoeboid-like locomotion. Our data demonstrate that p114RhoGEF drives cortical myosin activation by stimulating myosin light chain double phosphorylation and, thereby, collective cell migration of epithelial sheets and amoeboid-like motility of tumor cells. PMID:23185572
MicroRNA-29a in Adult Muscle Stem Cells Controls Skeletal Muscle Regeneration During Injury and Exercise Downstream of Fibroblast Growth Factor-2.

PubMed

Galimov, Artur; Merry, Troy L; Luca, Edlira; Rushing, Elisabeth J; Mizbani, Amir; Turcekova, Katarina; Hartung, Angelika; Croce, Carlo M; Ristow, Michael; Krützfeldt, Jan

2016-03-01

The expansion of myogenic progenitors (MPs) in the adult muscle stem cell niche is critical for the regeneration of skeletal muscle. Activation of quiescent MPs depends on the dismantling of the basement membrane and increased access to growth factors such as fibroblast growth factor-2 (FGF2). Here, we demonstrate using microRNA (miRNA) profiling in mouse and human myoblasts that the capacity of FGF2 to stimulate myoblast proliferation is mediated by miR-29a. FGF2 induces miR-29a expression and inhibition of miR-29a using pharmacological or genetic deletion decreases myoblast proliferation. Next generation RNA sequencing from miR-29a knockout myoblasts (Pax7(CE/+) ; miR-29a(flox/flox) ) identified members of the basement membrane as the most abundant miR-29a targets. Using gain- and loss-of-function experiments, we confirm that miR-29a coordinately regulates Fbn1, Lamc1, Nid2, Col4a1, Hspg2 and Sparc in myoblasts in vitro and in MPs in vivo. Induction of FGF2 and miR-29a and downregulation of its target genes precedes muscle regeneration during cardiotoxin (CTX)-induced muscle injury. Importantly, MP-specific tamoxifen-induced deletion of miR-29a in adult skeletal muscle decreased the proliferation and formation of newly formed myofibers during both CTX-induced muscle injury and after a single bout of eccentric exercise. Our results identify a novel miRNA-based checkpoint of the basement membrane in the adult muscle stem cell niche. Strategies targeting miR-29a might provide useful clinical approaches to maintain muscle mass in disease states such as ageing that involve aberrant FGF2 signaling. © 2016 The Authors Stem Cells published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.
The comparative effects of aminoglycoside antibiotics and muscle relaxants on electrical field stimulation response in rat bladder smooth muscle.

PubMed

Min, Chang Ho; Min, Young Sil; Lee, Sang Joon; Sohn, Uy Dong

2016-06-01

It has been reported that several aminoglycoside antibiotics have a potential of prolonging the action of non-depolarizing muscle relaxants by drug interactions acting pre-synaptically to inhibit acetylcholine release, but antibiotics itself also have a strong effect on relaxing the smooth muscle. In this study, four antibiotics of aminoglycosides such as gentamicin, streptomycin, kanamycin and neomycin were compared with skeletal muscle relaxants baclofen, tubocurarine, pancuronium and succinylcholine, and a smooth muscle relaxant, papaverine. The muscle strips isolated from the rat bladder were stimulated with pulse trains of 40 V in amplitude and 10 s in duration, with pulse duration of 1 ms at the frequency of 1-8 Hz, at 1, 2, 4, 6, 8 Hz respectively. To test the effect of four antibiotics on bladder smooth muscle relaxation, each of them was treated cumulatively from 1 μM to 0.1 mM with an interval of 5 min. Among the four antibiotics, gentamicin and neomycin inhibited the EFS response. The skeletal muscle relaxants (baclofen, tubocurarine, pancuronium and succinylcholine) and inhibitory neurotransmitters (GABA and glycine) did not show any significant effect. However, papaverine, had a significant effect in the relaxation of the smooth muscle. It was suggested that the aminoglycoside antibiotics have inhibitory effect on the bladder smooth muscle.
Human dental pulp pluripotent-like stem cells promote wound healing and muscle regeneration.

PubMed

Martínez-Sarrà, Ester; Montori, Sheyla; Gil-Recio, Carlos; Núñez-Toldrà, Raquel; Costamagna, Domiziana; Rotini, Alessio; Atari, Maher; Luttun, Aernout; Sampaolesi, Maurilio

2017-07-27

Dental pulp represents an easily accessible autologous source of adult stem cells. A subset of these cells, named dental pulp pluripotent-like stem cells (DPPSC), shows high plasticity and can undergo multiple population doublings, making DPPSC an appealing tool for tissue repair or maintenance. DPPSC were harvested from the dental pulp of third molars extracted from young patients. Growth factors released by DPPSC were analysed using antibody arrays. Cells were cultured in specific differentiation media and their endothelial, smooth and skeletal muscle differentiation potential was evaluated. The therapeutic potential of DPPSC was tested in a wound healing mouse model and in two genetic mouse models of muscular dystrophy (Scid/mdx and Sgcb-null Rag2-null γc-null). DPPSC secreted several growth factors involved in angiogenesis and extracellular matrix deposition and improved vascularisation in all three murine models. Moreover, DPPSC stimulated re-epithelialisation and ameliorated collagen deposition and organisation in healing wounds. In dystrophic mice, DPPSC engrafted in the skeletal muscle of both dystrophic murine models and showed integration in muscular fibres and vessels. In addition, DPPSC treatment resulted in reduced fibrosis and collagen content, larger cross-sectional area of type II fast-glycolytic fibres and infiltration of higher numbers of proangiogenic CD206 + macrophages. Overall, DPPSC represent a potential source of stem cells to enhance the wound healing process and slow down dystrophic muscle degeneration.
Piezo1 in Smooth Muscle Cells Is Involved in Hypertension-Dependent Arterial Remodeling.

PubMed

Retailleau, Kevin; Duprat, Fabrice; Arhatte, Malika; Ranade, Sanjeev Sumant; Peyronnet, Rémi; Martins, Joana Raquel; Jodar, Martine; Moro, Céline; Offermanns, Stefan; Feng, Yuanyi; Demolombe, Sophie; Patel, Amanda; Honoré, Eric

2015-11-10

The mechanically activated non-selective cation channel Piezo1 is a determinant of vascular architecture during early development. Piezo1-deficient embryos die at midgestation with disorganized blood vessels. However, the role of stretch-activated ion channels (SACs) in arterial smooth muscle cells in the adult remains unknown. Here, we show that Piezo1 is highly expressed in myocytes of small-diameter arteries and that smooth-muscle-specific Piezo1 deletion fully impairs SAC activity. While Piezo1 is dispensable for the arterial myogenic tone, it is involved in the structural remodeling of small arteries. Increased Piezo1 opening has a trophic effect on resistance arteries, influencing both diameter and wall thickness in hypertension. Piezo1 mediates a rise in cytosolic calcium and stimulates activity of transglutaminases, cross-linking enzymes required for the remodeling of small arteries. In conclusion, we have established the connection between an early mechanosensitive process, involving Piezo1 in smooth muscle cells, and a clinically relevant arterial remodeling. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
Distributed stimulation increases force elicited with functional electrical stimulation

NASA Astrophysics Data System (ADS)

Buckmire, Alie J.; Lockwood, Danielle R.; Doane, Cynthia J.; Fuglevand, Andrew J.

2018-04-01

Objective. The maximum muscle forces that can be evoked using functional electrical stimulation (FES) are relatively modest. The reason for this weakness is not fully understood but could be partly related to the widespread distribution of motor nerve branches within muscle. As such, a single stimulating electrode (as is conventionally used) may be incapable of activating the entire array of motor axons supplying a muscle. Therefore, the objective of this study was to determine whether stimulating a muscle with more than one source of current could boost force above that achievable with a single source. Approach. We compared the maximum isometric forces that could be evoked in the anterior deltoid of anesthetized monkeys using one or two intramuscular electrodes. We also evaluated whether temporally interleaved stimulation between two electrodes might reduce fatigue during prolonged activity compared to synchronized stimulation through two electrodes. Main results. We found that dual electrode stimulation consistently produced greater force (~50% greater on average) than maximal stimulation with single electrodes. No differences, however, were found in the fatigue responses using interleaved versus synchronized stimulation. Significance. It seems reasonable to consider using multi-electrode stimulation to augment the force-generating capacity of muscles and thereby increase the utility of FES systems.
[Stimulation of proliferation by carnosine: cellular and transcriptome approaches].

PubMed

Vishniakova, Kh S; Babizhaev, M A; Aliper, A M; Buzdin, A A; Kudriavtseva, A V; Egorov, E E

2014-01-01

Concentration of endogenous dipeptide carnosine in human muscle tissue reaches tens of millimoles. For more than 100 years of research, a lot of data concerning carnosine functions were accumulated, among which anti-aging effects are regarded most important. Heire, effect of carnosine in cell cultures was studied. It has been found that apart from the known action--an increase of the Hayflick limit and morphological rejuvenation--carnosine stimulates cell division in colony-forming assays and in the course of transition of cells to the quiescent state. The analysis of the transcriptome showed that carnosine-induced changes are mainly related to positive regulation of the cell cycle at all levels, from the onset of the DNA synthesis to chromosome condensation. One can suppose that the revealed stimulation of the cell cycle account for the carnosine-induced rejuvenation processes and a high concentration ofcarnosine in muscle tissue is required for the muscle recovery (regeneration) after excess loads.
Metabolic alterations induced in cultured skeletal muscle by stretch-relaxation activity

NASA Technical Reports Server (NTRS)

Hatfaludy, Sophia; Shansky, Janet; Vandenburgh, Herman H.

1989-01-01

Muscle cells differentiated in vitro are repetitively stretched and relaxed in order to determine the presence of short- and long-term alterations occurring in glucose uptake and lactate efflux that are similar to the metabolic alterations occurring in stimulated organ-cultured muscle and in vivo skeletal muscle during the active state. It is observed that whereas mechanical stimulation increases these metabolic parameters within 4-6 h of starting activity, unstimulated basal rates in control cultures also increase during this period of time, and by 8 h, their rates have reached or exceeded the rates in continuously stimulated cells. Measurements of these parameters in media of different compositions show that activity-induced long-term alterations in the parameters occur independently of growth factors in serium and embryo extracts.
Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot

NASA Astrophysics Data System (ADS)

Layne, Charles S.; Forth, Katharine E.; Abercromby, Andrew F. J.

2005-05-01

Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.
Magnetic stimulation of the upper trapezius muscles in patients with migraine - A pilot study.

PubMed

Sollmann, Nico; Trepte-Freisleder, Florian; Albers, Lucia; Jung, Nikolai H; Mall, Volker; Meyer, Bernhard; Heinen, Florian; Krieg, Sandro M; Landgraf, Mirjam N

2016-11-01

Repetitive peripheral magnetic stimulation (rPMS) has been applied to musculoskeletal pain conditions. Since recent data show that migraine and tension-type headache (TTH) might be closely related to peripheral muscular pain in the neck and shoulder region (supporting the concept of the trigemino-cervical complex (TCC)), this pilot study explores the acceptance of rPMS to the upper trapezius muscles in migraine (partly in combination with TTH). We used rPMS to stimulate active myofascial trigger points (aTrPs) of the upper trapezius muscles in 20 young adults suffering from migraine. Acceptance was assessed by a standardized questionnaire, whereas self-rated effectiveness was evaluated by headache calendars and the Migraine Disability Assessment (MIDAS). Algometry was performed to explore the local effect of rPMS on the muscles. Acceptance of rPMS was shown in all subjects without any adverse events, and rPMS had a statistically significant impact on almost every parameter of the headache calendar and MIDAS. Among others, the number of migraine attacks (p < 0.001) and migraine intensity (p = 0.001) significantly decreased regarding pre- and post-stimulation assessments. Accordingly, 100.0% of subjects would repeat the stimulation, while 90.0% would recommend rPMS as a treatment option for migraine. rPMS might represent a promising tool to alleviate migraine symptoms within the context of myofascial pain. This might be due to stimulation-dependent modulation of the peripheral sensory effect within the TCC in migraine. However, sham-controlled studies with larger and more homogeneous cohorts are needed to prove a potential beneficial effect. Ethics Committee Registration Numbers: 356-14 and 447/14. Copyright © 2016 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.
Depressed tetanic contactile function cannot be compensated by increasing stimulating frequency in unloaded soleus muscle

NASA Astrophysics Data System (ADS)

Gao, Fang; Yu, Zhi-Bin

2005-08-01

The weightlessness-induced muscle atrophy is associated with a reduced force and power and with an increased fatigability [1]. In prolonged manned space missions, these alterations in skeletal muscles could limit the crew's ability to work in space and to rapidly egress in an emergency on return to Earth. In order to elucidate the underlying mechanisms of the increased fatigability in the atrophic skeletal muscle, we isolated the typically fast and slow muscle, extensor digitorum longus (EDL) and soleus (SOL), to observe the changes in maximal contraction tension, optimal stimulating frequency, and recovery features after fatigue in the intermittent tetanic contraction.
ANODAL TRANSCRANIAL DIRECT CURRENT STIMULATION (TDCS) INCREASES ISOMETRIC STRENGTH OF SHOULDER ROTATORS MUSCLES IN HANDBALL PLAYERS.

PubMed

Hazime, Fuad Ahmad; da Cunha, Ronaldo Alves; Soliaman, Renato Rozenblit; Romancini, Ana Clara Bezerra; Pochini, Alberto de Castro; Ejnisman, Benno; Baptista, Abrahão Fontes

2017-06-01

Weakness of the rotator cuff muscles can lead to imbalances in the strength of shoulder external and internal rotators, change the biomechanics of the glenohumeral joint and predispose an athlete to injury. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has demonstrated promising results in a variety of health conditions. However few studies addressed its potential approach in the realm of athletics. The purpose of this study was to investigate if transcranial direct current stimulation (tDCS) technique increases the isometric muscle strength of shoulder external and internal rotators in handball athletes. Randomized, double-blind, placebo-controlled, crossover study. Eight female handball players aged between 17 and 21 years (Mean=19.65; SD=2.55) with 7.1 ± 4.8 years of experience in training, participating in regional and national competitions were recruited. Maximal voluntary isometric contraction (MVIC) of shoulder external and internal rotator muscles was evaluated during and after 30 and 60 minutes post one session of anodal and sham current (2mA; 0.057mA/cm 2 ) with a one-week interval between stimulations. Compared to baseline, MVIC of shoulder external and internal rotators significantly increased after real but not sham tDCS. Between-group differences were observed for external and internal rotator muscles. Maximal voluntary isometric contraction of external rotation increased significantly during tDCS, and 30 and 60 minutes post-tDCS for real tDCS compared to that for sham tDCS. For internal rotation MVIC increased significantly during and 60 minutes post-tDCS. The results indicate that transcranial direct current stimulation temporarily increases maximal isometric contractions of the internal and external rotators of the shoulder in handball players. 2.
Leucine stimulates protein synthesis in skeletal muscle of neonatal pigs by enhancing mTORC1 activation

USDA-ARS?s Scientific Manuscript database

Skeletal muscle in the neonate grows at a rapid rate due in part to an enhanced sensitivity to the postprandial rise in amino acids, particularly leucine. To elucidate the molecular mechanism by which leucine stimulates protein synthesis in neonatal muscle, overnight-fasted 7-day-old piglets were tr...
Electrical Stimulation of Denervated Rat Skeletal Muscle Retards Capillary and Muscle Loss in Early Stages of Disuse Atrophy

PubMed Central

Nakagawa, Kouki; Hayao, Keishi; Yotani, Kengo; Ogita, Futoshi; Yamamoto, Noriaki; Onishi, Hideaki

2017-01-01

The purpose of the present study is to investigate the effects of low-frequency electrical muscle stimulation (ES) on the decrease in muscle mass, fiber size, capillary supply, and matrix metalloproteinase (MMP) immunoreactivity in the early stages of denervation-induced limb disuse. Direct ES was performed on the tibialis anterior muscle following denervation in seven-week-old male rats. The rats were divided into the following groups: control (CON), denervation (DN), and denervation with direct ES (DN + ES). Direct ES was performed at an intensity of 16 mA and a frequency of 10 Hz for 30 min per day, six days a week, for one week. We performed immunohistochemical staining to determine the expression of dystrophin, CD34, and MMP-2 in transverse sections of TA muscles. The weight, myofiber cross-sectional area (FCSA), and capillary-to-fiber (C/F) ratio of the tibialis anterior (TA) muscle were significantly reduced in the DN group compared to the control and DN + ES groups. The MMP-2 positive area was significantly greater in DN and DN + ES groups compared to the control group. These findings suggest beneficial effects of direct ES in reducing muscle atrophy and capillary regression without increasing MMP-2 immunoreactivity in the early stages of DN-induced muscle disuse in rat hind limbs. PMID:28497057
Activation of particulate guanylyl cyclase by endothelins in cultured SV-40 transformed cat iris sphincter smooth muscle cells.

PubMed

Ding, K H; Latimer, A J; Abdel-Latif, A A

1999-01-01

We investigated the effects of endothelins (ETs) on cGMP production in cultured SV-40 transformed cat iris sphincter smooth muscle (SV-CISM-2) cells. ET-3 increased cGMP formation in a concentration-dependent manner (EC50 = 98nM), which was 2.5 times higher than that of ET-1. The ET(B)receptor agonists sarafotoxin-S6c and IRL 1620 also increased cGMP production, mimicking the effects of the ETs. The ET(B) receptor antagonist BQ 788, but not the ET(A) receptor antagonist BQ610, dose-dependently blocked ET-3-stimulated cGMP formation (IC50=10nM). The phorbol ester, Phorbol 12, 13-dibutyrate (PDBu), which inhibits particulate guanylyl cyclase in smooth muscle, dose-dependently inhibited ET-3-stimulated cGMP accumulation (IC50=66nM). LY83583 and ODQ, inhibitors of soluble guanylyl cyclases, as well as inhibitors of the nitric oxide cascade and of intracellular Ca2+ elevation had no appreciable effect on ET-3-induced cGMP production. ET-3 markedly inhibited carbachol-induced intracellular Ca2+ mobilization. We conclude that ET-3 increases intracellular cGMP levels in SV-CISM-2 cells through activation of the ET(B) receptor subtype and subsequent stimulation of the membrane-bound guanylyl cyclase. Elevation of cGMP by ET and the subsequent inhibition of muscarinic stimulation of intracellular Ca2+ mobilization by the cyclic nucleotide could serve to modulate the contractile effects of Ca2+-mobilizing agonists in the iris sphincter smooth muscle.
Effect of neuromuscular electrical stimulation on motor cortex excitability upon release of tonic muscle contraction.

PubMed

Sugawara, Kenichi; Tanabe, Shigeo; Suzuki, Tomotaka; Higashi, Toshio

The aim of the present study was to investigate the neurophysiological triggers underlying muscle relaxation from the contracted state, and to examine the mechanisms involved in this process and their subsequent modification by neuromuscular electrical stimulation (NMES). Single-pulse transcranial magnetic stimulation (TMS) was used to produce motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) in 23 healthy participants, wherein motor cortex excitability was examined at the onset of voluntary muscle relaxation following a period of voluntary tonic muscle contraction. In addition, the effects of afferent input on motor cortex excitability, as produced by NMES during muscle contraction, were examined. In particular, two NMES intensities were used for analysis: 1.2 times the sensory threshold and 1.2 times the motor threshold (MT). Participants were directed to execute constant wrist extensions and to release muscle contraction in response to an auditory "GO" signal. MEPs were recorded from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles, and TMS was applied at three different time intervals (30, 60, and 90 ms) after the "GO" signal. Motor cortex excitability was greater during voluntary ECR and FCR relaxation using high-intensity NMES, and relaxation time was decreased. Each parameter differed significantly between 30 and 60 ms. Moreover, in both muscles, SICI was larger in the presence than in the absence of NMES. Therefore, the present findings suggest that terminating a muscle contraction triggers transient neurophysiological mechanisms that facilitate the NMES-induced modulation of cortical motor excitability in the period prior to muscle relaxation. High-intensity NMES might facilitate motor cortical excitability as a function of increased inhibitory intracortical activity, and therefore serve as a transient trigger for the relaxation of prime mover muscles in a therapeutic context.
A REVIEW OF ELECTRICAL STIMULATION AND ITS EFFECT ON LINGUAL, LABIAL AND BUCCAL MUSCLE STRENGTH.

PubMed

Safi, Mohammed F; Wright-Harp, Wilhelmina; Lucker, Jay R; Payne, Joan C; Harris, Ovetta

2014-11-01

Lingual, labial and buccal weakness (LLBW) is a widespread consequence of several neurological insults. LLBW impact on oral motor functions such as speech production and swallowing is well documented in the literature. Therefore, it is important for the speech-language pathologists to have access to evidence-based approaches for treatment. Thus, it is imperative that the speech-language pathology field search for effective treatment approaches and explore new treatment modalities that can improve therapy outcomes. One relatively new modality in this field is neuromuscular electrical stimulation (NMES). The purpose of this paper is fivefold: (a) to provide an overview of the general effects of NMES on skeletal muscles; (b) to review the effect of NMES on orofacial musculature evaluating the potential appropriateness of NMES for use in strengthening lingual, labial and buccal muscles; (c) to identify future directions for research with consideration of its potential role in improving speech intelligibility and the oral preparatory phase of swallowing in patients with oral motor weakness; (d) to provide a brief anatomic and physiologic bases of LLBW; (e) to provide background information for orofacial myologists who may encounter individuals with LLBW. NMES is a modality that is commonly used in physical therapy and occupational therapy fields that assists in treating several motor and sensory muscular disorders including muscular weakness. The literature reviewed demonstrate that very limited data related to the use of NMES on orofacial muscles exist despite the fact that these muscles can be easily accessed by electrical stimulation from the surface. This review of the research using electrical stimulation of muscles highlights the need for experimental treatment studies that investigate the effect of NMES on orofacial weakness.
Sonic hedgehog acts cell-autonomously on muscle precursor cells to generate limb muscle diversity

PubMed Central

Anderson, Claire; Williams, Victoria C.; Moyon, Benjamin; Daubas, Philippe; Tajbakhsh, Shahragim; Buckingham, Margaret E.; Shiroishi, Toshihiko; Hughes, Simon M.; Borycki, Anne-Gaëlle

2012-01-01

How muscle diversity is generated in the vertebrate body is poorly understood. In the limb, dorsal and ventral muscle masses constitute the first myogenic diversification, as each gives rise to distinct muscles. Myogenesis initiates after muscle precursor cells (MPCs) have migrated from the somites to the limb bud and populated the prospective muscle masses. Here, we show that Sonic hedgehog (Shh) from the zone of polarizing activity (ZPA) drives myogenesis specifically within the ventral muscle mass. Shh directly induces ventral MPCs to initiate Myf5 transcription and myogenesis through essential Gli-binding sites located in the Myf5 limb enhancer. In the absence of Shh signaling, myogenesis is delayed, MPCs fail to migrate distally, and ventral paw muscles fail to form. Thus, Shh production in the limb ZPA is essential for the spatiotemporal control of myogenesis and coordinates muscle and skeletal development by acting directly to regulate the formation of specific ventral muscles. PMID:22987640
Brain and muscle Arnt-like 1 promotes skeletal muscle regeneration through satellite cell expansion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, Somik; Yin, Hongshan; Department of Cardiovascular Medicine, Third Affiliated Hospital, Hebei Medical University, Shijiazhuang 050051, Hebei

Circadian clock is an evolutionarily conserved timing mechanism governing diverse biological processes and the skeletal muscle possesses intrinsic functional clocks. Interestingly, although the essential clock transcription activator, Brain and muscle Arnt-like 1 (Bmal1), participates in maintenance of muscle mass, little is known regarding its role in muscle growth and repair. In this report, we investigate the in vivo function of Bmal1 in skeletal muscle regeneration using two muscle injury models. Bmal1 is highly up-regulated by cardiotoxin injury, and its genetic ablation significantly impairs regeneration with markedly suppressed new myofiber formation and attenuated myogenic induction. A similarly defective regenerative response ismore » observed in Bmal1-null mice as compared to wild-type controls upon freeze injury. Lack of satellite cell expansion accounts for the regeneration defect, as Bmal1{sup −/−} mice display significantly lower satellite cell number with nearly abolished induction of the satellite cell marker, Pax7. Furthermore, satellite cell-derived primary myoblasts devoid of Bmal1 display reduced growth and proliferation ex vivo. Collectively, our results demonstrate, for the first time, that Bmal1 is an integral component of the pro-myogenic response that is required for muscle repair. This mechanism may underlie its role in preserving adult muscle mass and could be targeted therapeutically to prevent muscle-wasting diseases. - Highlights: • Bmal1 is highly inducible by muscle injury and myogenic stimuli. • Genetic ablation of Bmal1 significantly impairs muscle regeneration. • Bmal1 promotes satellite cell expansion during muscle regeneration. • Bmal1-deficient primary myoblasts display attenuated growth and proliferation.« less

Angiotensin II Stimulates Protein Kinase D–Dependent Histone Deacetylase 5 Phosphorylation and Nuclear Export Leading to Vascular Smooth Muscle Cell Hypertrophy

PubMed Central

Xu, Xiangbin; Ha, Chang-Hoon; Wong, Chelsea; Wang, Weiye; Hausser, Angelika; Pfizenmaier, Klaus; Olson, Eric N.; McKinsey, Timothy A.; Jin, Zheng-Gen

2014-01-01

Background Angiotensin II (Ang II) induces the phenotypic modulation and hypertrophy of vascular smooth muscle cells (VSMCs), which is implicated in the pathogenesis of hypertension, atherosclerosis, and diabetes. In this study, we tested the hypothesis that histone deacetylases 5 (HDAC5) and its signal pathway play a role in Ang II–induced VSMC hypertrophy. Methods and Results VSMCs were isolated from the thoracic aortas of male Sprague-Dawley rats and treated with Ang II. We found that Ang II rapidly stimulated phosphorylation of HDAC5 at Serine259/498 residues in a time- and dose-dependent manner. Ang II receptor-1, protein kinase C, and protein kinase D1 (PKD1) mediated HDAC5 phosphorylation. Furthermore, we observed that Ang II stimulated HDAC5 nuclear export, which was dependent on its PKD1-dependent phosphorylation. Consequently, both inhibiting PKD1 and HDAC5 Serine259/498 to Alanine mutant significantly attenuated Ang II–induced myocyte enhancer factor-2 (MEF2) transcriptional activity and protein synthesis in VSMCs. Conclusion These findings demonstrate for the first time that PKD1-dependent HDAC5 phosphorylation and nuclear export mediates Ang II–induced MEF2 activation and VSMC hypertrophy, and suggest that PKD1 and HDAC5 may emerge as potential targets for the treatment of pathological vascular hypertrophy. PMID:17823368
A novel angiotensin II type 1 receptor-associated protein induces cellular hypertrophy in rat vascular smooth muscle and renal proximal tubular cells.

PubMed

Guo, Deng-Fu; Tardif, Valerie; Ghelima, Karin; Chan, John S D; Ingelfinger, Julie R; Chen, XiangMei; Chenier, Isabelle

2004-05-14

Angiotensin II stimulates cellular hypertrophy in cultured vascular smooth muscle and renal proximal tubular cells. This effect is believed to be one of earliest morphological changes of heart and renal failure. However, the precise molecular mechanism involved in angiotensin II-induced hypertrophy is poorly understood. In the present study we report the isolation of a novel angiotensin II type 1 receptor-associated protein. It encodes a 531-amino acid protein. Its mRNA is detected in all human tissues examined but highly expressed in the human kidney, pancreas, heart, and human embryonic kidney cells as well as rat vascular smooth muscle and renal proximal tubular cells. Protein synthesis and relative cell size analyzed by flow cytometry studies indicate that overexpression of the novel angiotensin II type 1 receptor-associated protein induces cellular hypertrophy in cultured rat vascular smooth muscle and renal proximal tubular cells. In contrast, the hypertrophic effects was reversed in renal proximal tubular cell lines expressing the novel gene in the antisense orientation and its dominant negative mutant, which lacks the last 101 amino acids in its carboxyl-terminal tail. The hypertrophic effects are at least in part mediated via protein kinase B activation or cyclin-dependent kinase inhibitor, p27(kip1) protein expression level in vascular smooth muscle, and renal proximal tubular cells. Moreover, angiotensin II could not stimulate cellular hypertrophy in renal proximal tubular cells expressing the novel gene in the antisense orientation and its mutant. These findings may provide new molecular mechanisms to understand hypertrophic agents such as angiotensin II-induced cellular hypertrophy.
Relationship between functional electrical stimulation duty cycle and fatigue in wrist extensor muscles of patients with hemiparesis.

PubMed

Packman-Braun, R

1988-01-01

The purpose of this study was to investigate, in a sample of patients with hemiparesis secondary to cerebrovascular accident, the relationship between the ratio of stimulus on time to off time and muscle fatigue using a commercial electrical stimulation unit. An experimental model was used to test the hypothesis that the smaller the stimulus off time relative to stimulus on time, the greater will be the muscle fatigue over time. The wrist extensor muscles of 18 patients with hemiparesis were stimulated electrically, and isometric force output was recorded continuously using an adapted strain gauge-recorder apparatus. For each testing session, peak on time of the electrical stimulus was set at 5 seconds, and off time was set at 5, 15, or 25 seconds. Six randomly assigned treatment groups participated in three separate treatment sessions in a different order at 48-hour intervals. Treatment sessions were continued either until wrist extensor muscle force output decreased to 50% of its initial value or for a maximum of 30 minutes. Data analysis revealed that significant differences in muscle tension developed among all duty cycles (p less than .01). Duty-cycle ratios of 1:1, 1:3, and 1:5 were shown to be progressively less fatiguing. Within the limits of this investigation, the 1:5 duty-cycle ratio was determined to be the best suited for initial use in programs of prolonged stimulation to the wrist extensor muscles of patients with hemiparesis. The hypothesis was accepted that the smaller the stimulus off time (rest interval) with respect to the stimulus on time, the greater will be the muscle fatigue over time.
Muscle-derived stem cells isolated as non-adherent population give rise to cardiac, skeletal muscle and neural lineages.

PubMed

Arsic, Nikola; Mamaeva, Daria; Lamb, Ned J; Fernandez, Anne

2008-04-01

Stem cells with the ability to differentiate in specialized cell types can be extracted from a wide array of adult tissues including skeletal muscle. Here we have analyzed a population of cells isolated from skeletal muscle on the basis of their poor adherence on uncoated or collagen-coated dishes that show multi-lineage differentiation in vitro. When analysed under proliferative conditions, these cells express stem cell surface markers Sca-1 (65%) and Bcrp-1 (80%) but also MyoD (15%), Neuronal beta III-tubulin (25%), GFAP (30%) or Nkx2.5 (1%). Although capable of growing as non-attached spheres for months, when given an appropriate matrix, these cells adhere giving rise to skeletal muscle, neuronal and cardiac muscle cell lineages. A similar cell population could not be isolated from either bone marrow or cardiac tissue suggesting their specificity to skeletal muscle. When injected into damaged muscle, these non-adherent muscle-derived cells are retrieved expressing Pax7, in a sublaminar position characterizing satellite cells and participate in forming new myofibers. These data show that a non-adherent stem cell population can be specifically isolated and expanded from skeletal muscle and upon attachment to a matrix spontaneously differentiate into muscle, cardiac and neuronal lineages in vitro. Although competing with resident satellite cells, these cells are shown to significantly contribute to repair of injured muscle in vivo supporting that a similar muscle-derived non-adherent cell population from human muscle may be useful in treatment of neuromuscular disorders.
Collagen and Stretch Modulate Autocrine Secretion of Insulin-like Growth Factor-1 and Insulin-like Growth Factor Binding Proteins from Differentiated Skeletal Muscle Cells

NASA Technical Reports Server (NTRS)

Perrone, Carmen E.; Fenwick-Smith, Daniela; Vandenburgh, Herman H.

1995-01-01

Stretch-induced skeletal muscle growth may involve increased autocrine secretion of insulin-like growth factor-1 (IGF-1) since IGF-1 is a potent growth factor for skeletal muscle hypertrophy, and stretch elevates IGF-1 mRNA levels in vivo. In tissue cultures of differentiated avian pectoralis skeletal muscle cells, nanomolar concentrations of exogenous IGF-1 stimulated growth in mechanically stretched but not static cultures. These cultures released up to 100 pg of endogenously produced IGF-1/micro-g of protein/day, as well as three major IGF binding proteins of 31, 36, and 43 kilodaltons (kDa). IGF-1 was secreted from both myofibers and fibroblasts coexisting in the muscle cultures. Repetitive stretch/relaxation of the differentiated skeletal muscle cells stimulated the acute release of IGF-1 during the first 4 h after initiating mechanical activity, but caused no increase in the long-term secretion over 24-72 h of IGF-1, or its binding proteins. Varying the intensity and frequency of stretch had no effect on the long-term efflux of IGF-1. In contrast to stretch, embedding the differentiated muscle cells in a three-dimensional collagen (Type I) matrix resulted in a 2-5-fold increase in long-term IGF-1 efflux over 24-72 h. Collagen also caused a 2-5-fold increase in the release of the IGF binding proteins. Thus, both the extracellular matrix protein type I collagen and stretch stimulate the autocrine secretion of IGF-1, but with different time kinetics. This endogenously produced growth factor may be important for the growth response of skeletal myofibers to both types of external stimuli.
Effective fiber hypertrophy in satellite cell-depleted skeletal muscle

PubMed Central

McCarthy, John J.; Mula, Jyothi; Miyazaki, Mitsunori; Erfani, Rod; Garrison, Kelcye; Farooqui, Amreen B.; Srikuea, Ratchakrit; Lawson, Benjamin A.; Grimes, Barry; Keller, Charles; Van Zant, Gary; Campbell, Kenneth S.; Esser, Karyn A.; Dupont-Versteegden, Esther E.; Peterson, Charlotte A.

2011-01-01

An important unresolved question in skeletal muscle plasticity is whether satellite cells are necessary for muscle fiber hypertrophy. To address this issue, a novel mouse strain (Pax7-DTA) was created which enabled the conditional ablation of >90% of satellite cells in mature skeletal muscle following tamoxifen administration. To test the hypothesis that satellite cells are necessary for skeletal muscle hypertrophy, the plantaris muscle of adult Pax7-DTA mice was subjected to mechanical overload by surgical removal of the synergist muscle. Following two weeks of overload, satellite cell-depleted muscle showed the same increases in muscle mass (approximately twofold) and fiber cross-sectional area with hypertrophy as observed in the vehicle-treated group. The typical increase in myonuclei with hypertrophy was absent in satellite cell-depleted fibers, resulting in expansion of the myonuclear domain. Consistent with lack of nuclear addition to enlarged fibers, long-term BrdU labeling showed a significant reduction in the number of BrdU-positive myonuclei in satellite cell-depleted muscle compared with vehicle-treated muscle. Single fiber functional analyses showed no difference in specific force, Ca2+ sensitivity, rate of cross-bridge cycling and cooperativity between hypertrophied fibers from vehicle and tamoxifen-treated groups. Although a small component of the hypertrophic response, both fiber hyperplasia and regeneration were significantly blunted following satellite cell depletion, indicating a distinct requirement for satellite cells during these processes. These results provide convincing evidence that skeletal muscle fibers are capable of mounting a robust hypertrophic response to mechanical overload that is not dependent on satellite cells. PMID:21828094
Mechanical stimulation of skeletal muscle increases prostaglandin F2(alpha) synthesis and cyclooxygenase activity by a pertussis toxin sensitive mechanism

NASA Technical Reports Server (NTRS)

Vandenburgh, Herman H.; Shansky, Janet; Solerssi, Rosa; Chromiak, Joseph

1992-01-01

Repetitive mechanical stimulation of differentiated skeletal muscle in tissue culture increases the production of prostaglandin F(sub 2(alpha)), an anabolic stimulator of myofiber growth. Within 4 h of initiating mechanical activity, the activity of cyclooxygenase, a regulatory enzyme in prostaglandin synthesis, was increased 82% (P is less than .005), and this increase was maintained for at least 24 h. Kinetic analysis of the stretch-activated cyclooxygenase indicated a two to three-fold decrease in the enzyme's K(sub m) with no change in V(sub max). The stretch-induced increase in enzymatic activity was not inhibited by cycloheximide, was independent of cellular electrical activity (tetrodotoxin-insensitive), but was prevented by the G protein inhibitor pertussis toxin. Pertussis toxin also inhibited the stretch-induced increases in PGF(sub 2(alpha)) production, and cell growth. It is concluded that stretch of skeletal muscle increases the synthesis of the anabolic modulator PGF(sub 2(alpha)) by a G protein-dependent process which involves activation of cyclooxygenase by a posttranslational mechanism.
The effects of substance P on smooth muscle cells and on neuro-effector transmission in the guinea-pig ileum

PubMed Central

Fujisawa, Kazuaki; Ito, Yushi

1982-01-01

1 The effects of substance P (SP) on the membrane and contractile properties of the smooth muscle cell, or on neuro-effector transmission in the guinea-pig ileum were observed by means of microelectrodes, double sucrose gap and tension recording. 2 SP (10-13-10-10M) induced a phasic contraction of longitudinal muscle strips, but did not change the muscle tone of circular muscle strips, in concentrations up to 10-8M. 3 SP (10-10-10-8M) evoked three different membrane responses in longitudinal muscle cells: (i) bursts of spike discharges with no significant change in the membrane potential and input membrane resistance; (ii) bursts of spike discharges with a small but clear depolarization of the membrane and increase in the input membrane resistance; (iii) slow waves with no change in the membrane potential. 4 In the circular muscle cells, low concentrations of SP (<10-8M) did not affect the membrane potential or the spikes, but SP (10-7M) increased the spike discharges with no significant change in the membrane potential. 5 SP (10-10M) reduced the threshold depolarization required for the generation of action potentials with no change in membrane potential of the longitudinal muscle cells. 6 Pretreatment with atropine (5 × 10-6M), tetrodotoxin (TTX 10-6M) or baclofen (4.7 × 10-6M) had no effect on the excitatory actions of SP on the smooth muscle cells of longitudinal and circular muscle strips. 7 Excitatory actions of SP on the membrane potential or spike activities of longitudinal muscle cells were preserved in NaCl but not in Ca-deficient solution. 8 SP (10-10-10-9M) enhanced the amplitude of the excitatory junction potentials (e.j.ps) evoked by electrical field stimulation in longitudinal muscle cells with no change in the membrane potential and input resistance. SP (10-10-10-9M), however, did not change the amplitude of inhibitory junction potentials (i.j.ps) recorded from the circular muscle cells. 9 These results indicate that SP in relatively low
Isolation of skeletal muscle stem cells by fluorescence-activated cell sorting.

PubMed

Liu, Ling; Cheung, Tom H; Charville, Gregory W; Rando, Thomas A

2015-10-01

The prospective isolation of purified stem cell populations has dramatically altered the field of stem cell biology, and it has been a major focus of research across tissues in different organisms. Muscle stem cells (MuSCs) are now among the most intensely studied stem cell populations in mammalian systems, and the prospective isolation of these cells has allowed cellular and molecular characterizations that were not dreamed of a decade ago. In this protocol, we describe how to isolate MuSCs from limb muscles of adult mice by fluorescence-activated cell sorting (FACS). We provide a detailed description of the physical and enzymatic dissociation of mononucleated cells from limb muscles, a procedure that is essential in order to maximize cell yield. We also describe a FACS-based method that is used subsequently to obtain highly pure populations of either quiescent or activated MuSCs (VCAM(+)CD31(-)CD45(-)Sca1(-)). The isolation process takes ∼5-6 h to complete. The protocol also allows for the isolation of endothelial cells, hematopoietic cells and mesenchymal stem cells from muscle tissue.
The actin-related p41ARC subunit contributes to p21-activated kinase-1 (PAK1)-mediated glucose uptake into skeletal muscle cells.

PubMed

Tunduguru, Ragadeepthi; Zhang, Jing; Aslamy, Arianne; Salunkhe, Vishal A; Brozinick, Joseph T; Elmendorf, Jeffrey S; Thurmond, Debbie C

2017-11-17

Defects in translocation of the glucose transporter GLUT4 are associated with peripheral insulin resistance, preclinical diabetes, and progression to type 2 diabetes. GLUT4 recruitment to the plasma membrane of skeletal muscle cells requires F-actin remodeling. Insulin signaling in muscle requires p21-activated kinase-1 (PAK1), whose downstream signaling triggers actin remodeling, which promotes GLUT4 vesicle translocation and glucose uptake into skeletal muscle cells. Actin remodeling is a cyclic process, and although PAK1 is known to initiate changes to the cortical actin-binding protein cofilin to stimulate the depolymerizing arm of the cycle, how PAK1 might trigger the polymerizing arm of the cycle remains unresolved. Toward this, we investigated whether PAK1 contributes to the mechanisms involving the actin-binding and -polymerizing proteins neural Wiskott-Aldrich syndrome protein (N-WASP), cortactin, and ARP2/3 subunits. We found that the actin-polymerizing ARP2/3 subunit p41ARC is a PAK1 substrate in skeletal muscle cells. Moreover, co-immunoprecipitation experiments revealed that insulin stimulates p41ARC phosphorylation and increases its association with N-WASP coordinately with the associations of N-WASP with cortactin and actin. Importantly, all of these associations were ablated by the PAK inhibitor IPA3, suggesting that PAK1 activation lies upstream of these actin-polymerizing complexes. Using the N-WASP inhibitor wiskostatin, we further demonstrated that N-WASP is required for localized F-actin polymerization, GLUT4 vesicle translocation, and glucose uptake. These results expand the model of insulin-stimulated glucose uptake in skeletal muscle cells by implicating p41ARC as a new component of the insulin-signaling cascade and connecting PAK1 signaling to N-WASP-cortactin-mediated actin polymerization and GLUT4 vesicle translocation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
Rejuvenation of the aged muscle stem cell population restores strength to injured aged muscles

PubMed Central

Cosgrove, Benjamin D.; Gilbert, Penney M.; Porpiglia, Ermelinda; Mourkioti, Foteini; Lee, Steven P.; Corbel, Stephane Y.; Llewellyn, Michael E.; Delp, Scott L.; Blau, Helen M.

2014-01-01

The aged suffer from progressive muscle weakness and regenerative failure. We demonstrate that muscle regeneration is impaired with aging due in part to a cell-autonomous functional decline in skeletal muscle stem cells (MuSCs). Two-thirds of aged MuSCs are intrinsically defective relative to young MuSCs, with reduced capacity to repair myofibers and repopulate the stem cell reservoir in vivo following transplantation due to a higher incidence of cells that express senescence markers and that have elevated p38α/β MAPK activity. We show that these limitations cannot be overcome by transplantation into the microenvironment of young recipient muscles. In contrast, subjecting the aged MuSC population to transient inhibition of p38α/β in conjunction with culture on soft hydrogel substrates rapidly expands the residual functional aged MuSC population, rejuvenating its potential for regeneration, serial transplantation, and strengthening damaged muscles of aged mice. These findings reveal a synergy between biophysical and biochemical cues that provides a paradigm for a localized autologous muscle stem cell therapy in aged individuals. PMID:24531378
Effect of fusimotor stimulation on Ia discharge during shortening of cat soleus muscle at different speeds

PubMed Central

Appenteng, K.; Prochazka, A.; Proske, U.; Wand, P.

1982-01-01

1. In barbiturate-anaesthetized cats, the L7 and S1 dorsal and ventral roots were dissected to isolate functionally single afferents identified as primary endings of soleus muscle spindles, and motor filaments which exerted a fusimotor action on the afferents with limited action on extrafusal muscle. Up to seven filaments, with an action on a given primary ending, could be isolated and each was classified as exerting either a predominantly dynamic or static action. 2. Combined stimulation of these filaments, at rates up to 200 impulses/s could maintain afferent firing during muscle shortenings at speeds up to 200 mm/s. 3. Fusimotor stimulation could also maintain afferent firing at a target frequency of 100 impulses/s during muscle shortenings up to 200 mm/s. The timing, in relation to the onset of shortening, and the rates of fusimotor stimulation were found to be critical in achieving the target frequency. 4. Sinusoidal modulation of the frequency of fusimotor stimulation was used to study the conditions required to achieve constant afferent firing in the face of imposed sinusoidal length changes. 5. For given depths of modulation, the phase advance of fusimotor stimulation needed to produce minimum modulation of afferent firing (best compensation) increased with increasing frequency of the sinusoids. The compensation deteriorated with an increase in the frequency of the sinusoids and a change in the mean muscle lengths, although in some cases it could be restored by adjustments to the depth of modulation of fusimotor rate. This suggests that for movements of varying speeds and amplitudes, settings which are appropriate for shortening at a given velocity and mean muscle length, do not apply if either of these two variables are altered. 6. These findings demonstrate that the fusimotor system is potentially capable of eliciting constant afferent firing as envisaged in the `servo-assistance' hypothesis (Matthews, 1964, 1972; Stein, 1974). This, and the fact that
Plasma Amino Acids Stimulate Uncoupled Respiration of Muscle Subsarcolemmal Mitochondria in Lean but Not Obese Humans.

PubMed

Kras, Katon A; Hoffman, Nyssa; Roust, Lori R; Patel, Shivam H; Carroll, Chad C; Katsanos, Christos S

2017-12-01

Obesity is associated with mitochondrial dysfunction in skeletal muscle. Increasing the plasma amino acid (AA) concentrations stimulates mitochondrial adenosine triphosphate (ATP) production in lean individuals. To determine whether acute elevation in plasma AAs enhances muscle mitochondrial respiration and ATP production in subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria in obese adults. Assessment of SS and IMF mitochondrial function during saline (i.e., control) and AA infusions. Eligible participants were healthy lean (body mass index, <25 kg/m2; age, 37 ± 3 years; n = 10) and obese (body mass index >30 kg/m2; age 35 ± 3 years; n = 11) subjects. Single trial of saline infusion followed by AA infusion. SS and IMF mitochondria were isolated from muscle biopsies collected at the end of the saline and AA infusions. Mitochondrial respiration and ATP production. AA infusion increased adenosine 5'-diphosphate (ADP)-stimulated respiration and ATP production rates of SS mitochondria in the lean (P < 0.05), but not obese, subjects. Furthermore, AA infusion increased the uncoupled (i.e., non-ADP-stimulated) respiration of SS mitochondria in the lean subjects only (P < 0.05). AA infusion had no effect on any of these parameters in IMF mitochondria in either lean or obese subjects (P > 0.05). Increasing the plasma AA concentrations enhances the capacity for respiration and ATP production of muscle SS, but not IMF, mitochondria in lean individuals, in parallel with increases in uncoupled respiration. However, neither of these parameters increases in muscle SS or IMF mitochondria in obese individuals. Copyright © 2017 Endocrine Society
Sonomyography Analysis on Thickness of Skeletal Muscle During Dynamic Contraction Induced by Neuromuscular Electrical Stimulation: A Pilot Study.

PubMed

Qiu, Shuang; Feng, Jing; Xu, Jiapeng; Xu, Rui; Zhao, Xin; Zhou, Peng; Qi, Hongzhi; Zhang, Lixin; Ming, Dong

2017-01-01

Neuromuscular electrical stimulation (NMES) that stimulates skeletal muscles to induce contractions has been widely applied to restore functions of paralyzed muscles. However, the architectural changes of stimulated muscles induced by NMES are still not well understood. The present study applies sonomyography (SMG) to evaluate muscle architecture under NMES-induced and voluntary movements. The quadriceps muscles of seven healthy subjects were tested for eight cycles during an extension exercise of the knee joint with/without NMES, and SMG and the knee joint angle were recorded during the process of knee extension. A least squares support vector machine (LS-SVM) LS-SVM model was developed and trained using the data sets of six cycles collected under NMES, while the remaining data was used to test. Muscle thickness changes were extracted from ultrasound images and compared between NMES-induced and voluntary contractions, and LS-SVM was used to model a relationship between dynamical knee joint angles and SMG signals. Muscle thickness showed to be significantly correlated with joint angle in NMES-induced contractions, and a significant negative correlation was observed between Vastus intermedius (VI) thickness and rectus femoris (RF) thickness. In addition, there was a significant difference between voluntary and NMES-induced contractions . The LS-SVM model based on RF thickness and knee joint angle provided superior performance compared with the model based on VI thickness and knee joint angle or total thickness and knee joint angle. This suggests that a strong relation exists between the RF thickness and knee joint angle. These results provided direct evidence for the potential application of RF thickness in optimizing NMES system as well as measuring muscle state under NMES.
Acute insulin resistance stimulates and insulin sensitization attenuates vascular smooth muscle cell migration and proliferation.

PubMed

Cersosimo, Eugenio; Xu, Xiaojing; Upala, Sikarin; Triplitt, Curtis; Musi, Nicolas

2014-08-01

Differential activation/deactivation of insulin signaling, PI-3K and MAP-K pathways by high glucose and palmitate, with/out the insulin sensitizer pioglitazone (PIO), have been previously shown in vascular smooth muscle cells (VSMCs). To determine the biological impact of these molecular changes, we examined VSMC migration and proliferation ("M"&"P") patterns in similar conditions. VSMCs from healthy human coronary arteries were incubated in growth medium and "M"&"P" were analyzed after exposure to high glucose (25 mmol/L) ± palmitate (200 μmol/L) and ± PIO (8 μmol/L) for 5 h. "M"&"P" were assessed by: (1) polycarbonate membrane barrier with chemo-attractants and extended cell protrusions quantified by optical density (OD595 nm); (2) % change in radius area (2D Assay) using inverted microscopy images; and (3) cell viability assay expressed as cell absorbance (ABS) in media. "M" in 25 mmol/L glucose media increased by ~25% from baseline and % change in radius area rose from ~20% to ~30%. The addition of PIO was accompanied by a significant decrease in "M" from 0.25 ± 0.02 to 0.19 ± 0.02; a comparable decline from 0.25 ± 0.02 to 0.18 ± 0.02 was also seen with 25 mmol/L of glucose +200 μmol/L of palmitate. When PIO was coincubated with high glucose plus palmitate there was a 50% reduction in % change in radius. A ~10% increase in ABS, reflecting augmented "P" in media with 25 mmol/L glucose versus control was documented. The addition of PIO reduced ABS from 0.208 ± 0.03 to 0.183 ± 0.06. Both high glucose and palmitate showed ABS of ~0.140 ± 0.02, which decreased with PIO to ~0.120 ± 0.02, indicating "P" was reduced. These results confirm that high glucose and palmitate stimulate VSMCs migration and proliferation in vitro, which is attenuated by coincubation with the insulin sensitizer PIO. Although, we cannot ascertain whether these functional changes are coincident with the activation/deactivation of signal molecules, our findings are consistent with the
Acute insulin resistance stimulates and insulin sensitization attenuates vascular smooth muscle cell migration and proliferation

PubMed Central

Cersosimo, Eugenio; Xu, Xiaojing; Upala, Sikarin; Triplitt, Curtis; Musi, Nicolas

2014-01-01

Abstract Differential activation/deactivation of insulin signaling, PI‐3K and MAP‐K pathways by high glucose and palmitate, with/out the insulin sensitizer pioglitazone (PIO), have been previously shown in vascular smooth muscle cells (VSMCs). To determine the biological impact of these molecular changes, we examined VSMC migration and proliferation (“M”&”P”) patterns in similar conditions. VSMCs from healthy human coronary arteries were incubated in growth medium and “M”&”P” were analyzed after exposure to high glucose (25 mmol/L) ± palmitate (200 μmol/L) and ± PIO (8 μmol/L) for 5 h. “M”&”P” were assessed by: (1) polycarbonate membrane barrier with chemo‐attractants and extended cell protrusions quantified by optical density (OD595 nm); (2) % change in radius area (2D Assay) using inverted microscopy images; and (3) cell viability assay expressed as cell absorbance (ABS) in media. “M” in 25 mmol/L glucose media increased by ~25% from baseline and % change in radius area rose from ~20% to ~30%. The addition of PIO was accompanied by a significant decrease in “M” from 0.25 ± 0.02 to 0.19 ± 0.02; a comparable decline from 0.25 ± 0.02 to 0.18 ± 0.02 was also seen with 25 mmol/L of glucose +200 μmol/L of palmitate. When PIO was coincubated with high glucose plus palmitate there was a 50% reduction in % change in radius. A ~10% increase in ABS, reflecting augmented “P” in media with 25 mmol/L glucose versus control was documented. The addition of PIO reduced ABS from 0.208 ± 0.03 to 0.183 ± 0.06. Both high glucose and palmitate showed ABS of ~0.140 ± 0.02, which decreased with PIO to ~0.120 ± 0.02, indicating “P” was reduced. Conclusion: These results confirm that high glucose and palmitate stimulate VSMCs migration and proliferation in vitro, which is attenuated by coincubation with the insulin sensitizer PIO. Although, we cannot ascertain whether these functional changes are coincident with the activation
Autonomic Modification of Intestinal Smooth Muscle Contractility

ERIC Educational Resources Information Center

Montgomery, Laura E. A.; Tansey, Etain A.; Johnson, Chris D.; Roe, Sean M.; Quinn, Joe G.

2016-01-01

Intestinal smooth muscle contracts rhythmically in the absence of nerve and hormonal stimulation because of the activity of pacemaker cells between and within the muscle layers. This means that the autonomic nervous system modifies rather than initiates intestinal contractions. The practical described here gives students an opportunity to observe…
In vitro myotoxic effects of bupivacaine on rhabdomyosarcoma cells, immortalized and primary muscle cells.

PubMed

Metterlein, Thomas; Hoffmann, Petra; Späth, Ruth; Gruber, Michael; Graf, Bernhard M; Zink, Wolfgang

2015-01-01

Rhabdomyosarcoma is a rare malignant skeletal muscle tumor. It mainly occurs in children and young adults and has an unsatisfactory prognosis. Prior studies showed a direct myotoxic effect of bupivacaine on differentiated muscle cells in vitro and in vivo. Exact mechanisms of this myotoxicity are still not fully understood, but a myotoxic effect on malignant muscle tumor cells has not been examined so far. Thus, the aim of this study was to examine if bupivacaine has cytotoxic effects on rhabdomyosarcoma cells, immortalized muscle cells and differentiated muscle cells. Cell lines of rhabdomyosarcoma cells, immortalized muscle cells and differentiated muscle cells were established. After microscopic identification, cells were exposed to various concentrations of bupivacaine (500, 1,000, 1,750, 2,500 and 5,000 ppm) for 1 and 2 h, respectively. 24 and 28 h after incubation the cultures were stained with propidium iodid and analyzed by flow cytometry. The fraction of dead cells was calculated for each experiment and the concentration with 50% cell survival (IC50) was computed. Cell groups as well as incubation and recovery time were compared (ANOVA/Bonferroni p < 0.01). The total number of cultured cells was similar for the different local anesthetics and examined concentrations. Increasing concentrations of bupivacaine led to a decrease in survival of muscle cells. IC50 was highest for immortalized cells, followed by rhabdomyosarcoma cells and differentiated cells. Exposure time, but not recovery time, had an influence on survival. Bupivacaine has clear but different cytotoxic effects on various muscle cell types in vitro. Differentiated primary cells seem to be more vulnerable than tumor cells possibly because of more differentiated intracellular structures.
Neck muscle biomechanics and neural control.

PubMed

Fice, Jason Bradley; Siegmund, Gunter P; Blouin, Jean-Sebastien

2018-04-18

The mechanics, morphometry, and geometry of our joints, segments and muscles are fundamental biomechanical properties intrinsic to human neural control. The goal of our study was to investigate if the biomechanical actions of individual neck muscles predicts their neural control. Specifically, we compared the moment direction & variability produced by electrical stimulation of a neck muscle (biomechanics) to their preferred activation direction & variability (neural control). Subjects sat upright with their head fixed to a 6-axis load cell and their torso restrained. Indwelling wire electrodes were placed into the sternocleidomastoid (SCM), splenius capitis (SPL), and semispinalis capitis (SSC) muscles. The electrically stimulated direction was defined as the moment direction produced when a current (2-19mA) was passed through each muscle's electrodes. Preferred activation direction was defined as the vector sum of the spatial tuning curve built from RMS EMG when subjects produced isometric moments at 7.5% and 15% of their maximum voluntary contraction (MVC) in 26 3D directions. The spatial tuning curves at 15% MVC were well-defined (unimodal, p<0.05) and their preferred directions were 23, 39, & 21{degree sign} different from their electrically stimulated directions for the SCM, SPL, and SSC respectively (p<0.05). Intra-subject variability was smaller in electrically stimulated moment directions when compared to voluntary preferred directions, and intra-subject variability decreased with increased activation levels. Our findings show that the neural control of neck muscles is not based solely on optimizing individual muscle biomechanics but, as activation increases, biomechanical constraints in part dictate the activation of synergistic neck muscles.
[Effects of Electric Stimulation and Biofeedback for Pelvic Floor Muscle Exercise in Women with Vaginal Rejuvenation Women].

PubMed

Lee, Jung Bok; Choi, So Young

2015-10-01

The purpose of this study was to investigate the effects of pelvic floor muscle exercise using electric stimulation and biofeedback on maximum pressure of vaginal contraction, vaginal contraction duration and sexual function in women who have had vaginal rejuvenation. The research design was a non-equivalent control group non-synchronized design study. Participants in this study were women who had vaginal rejuvenation at C obstetrics and gynecology hospital. The 15 participants in the experimental group were given pelvic floor muscle exercise using electric stimulation and biofeedback and the 15 participants in the control group received self pelvic floor muscle exercise. For maximum pressure of vaginal contraction, the experimental group showed a statistically significant increase compared to than the control group (t=5.96, p<.001). For vaginal contraction duration, the experimental group also showed a statistically significant increase compared to the control group (t=3.23, p=.003). For women's sexual function, the experimental group showed a significant increase when compared to the control group in total sexual function scores (t=3.41, p=.002). The results indicate that pelvic floor muscle exercise with electric stimulation and biofeedback after vaginal rejuvenation is effective in strengthening vaginal contraction pressure, vaginal contraction and that it also positively functions to increase women's sexual function.

Sildenafil Stimulates the Expression of Gaseous Monoxide-Generating Enzymes in Vascular Smooth Muscle Cells via Distinct Signaling Pathways

PubMed Central

Liu, Xiao-ming; Peyton, Kelly J.; Wang, Xinhui; Durante, William

2012-01-01

Sildenafil is a cGMP-specific phosphodiesterase type 5 inhibitor that augments cGMP accumulation following the activation of soluble guanylate cyclase (sGC). In this study, we investigated whether sildenafil promotes the production of the sGC-stimulatory gases, carbon monoxide and nitric oxide, by stimulating the expression of the inducible isoforms of heme oxygenase (HO-1) and nitric oxide synthase (iNOS) in vascular smooth muscle cells (SMCs). Sildenafil increased HO-1 expression and potentiated cytokine-mediated expression of iNOS and NO synthesis by SMCs. The induction of HO-1 was unaffected by the sGC inhibitor 1H-(1,2,4)oxadiazolo[4,3-α]quinozalin-1-one (ODQ) or the (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindol91,2,3-fg:3′,2′,1′-kl)pyrrolo(3,4-i)benzodiazocine-10-carboxylic acid, methyl ester (KT 5823). However, the sildenafil-mediated increase in HO-1 promoter activity was abolished by mutating the antioxidant responsive elements in the promoter or by overexpressing a dominant-negative mutant of NF-E2-related factor-2 (Nrf2). Furthermore, the induction of HO-1 by sildenafil was accompanied by an increase in reactive oxygen species (ROS) and blocked by N-acetyl-L-cysteine and rotenone. In contrast, the enhancement of cytokine-stimulated NO synthesis by sildenafil was prevented by ODQ and the protein kinase A inhibitor (9S,10S,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo(1,2,3-fg:3′,2′,1′-kl)pyrrolo(3,4-i)(1,6)benzodiazocine-10-carboxylic acid hexyl ester (KT 5720) and duplicated by lipophilic analogues of cGMP. In conclusion, these studies demonstrate that sildenafil stimulates the expression of HO-1 and iNOS via the ROS-Nrf2 and sGC-cGMP pathway, respectively. The ability of sildenafil to block the catabolism of cGMP while stimulating the synthesis of sGC-stimulatory gaseous monoxides through the induction of HO-1 and iNOS provides a potent mechanism by which c
Repeatability and reliability of muscle relaxation properties induced by motor cortical stimulation.

PubMed

Molenaar, Joery P; Voermans, Nicol C; de Jong, Lysanne A; Stegeman, Dick F; Doorduin, Jonne; van Engelen, Baziel G

2018-03-15

Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39.1{plus minus}12.7 and 45.3{plus minus}8.7 years old, respectively) using handgrip dynamometry. All outcome measures showed greater repeatability and reliability in TMS-induced relaxation compared to voluntary relaxation. The within-subject coefficient of variability of normalized peak relaxation rate was lower in TMS-induced relaxation than in voluntary relaxation (3.0 vs 19.7% in men, and 6.1 vs 14.3% in women). The repeatability coefficient was lower (1.3 vs 6.1 s -1 in men and 2.3 vs 3.1 s -1 in women), and the intraclass correlation coefficient was higher (0.95 vs 0.53 in men and 0.78 vs 0.69 in women), for TMS-induced relaxation compared to voluntary relaxation. TMS enabled to demonstrate slowing effects of sex, muscle cooling, and muscle fatigue on relaxation properties that voluntary relaxation could not. In conclusion, repeatability and reliability of TMS-induced muscle relaxation was greater compared to voluntary muscle relaxation. TMS-induced muscle relaxation has the potential to be used in clinical practice for diagnostic purposes and therapy effect monitoring in patients with impaired muscle relaxation.
Potential role of insulin signaling on vascular smooth muscle cell migration, proliferation, and inflammation pathways.

PubMed

Cersosimo, Eugenio; Xu, Xiaojing; Musi, Nicolas

2012-02-15

To investigate the role of insulin signaling pathways in migration, proliferation, and inflammation of vascular smooth muscle cells (VSMCs), we examined the expression of active components of the phosphatidyl inositol 3 (PI-3) kinase (p-Akt) and mitogen-activated protein kinase (MAPK) (p-Erk) in primary cultures of VSMCs from human coronary arteries. VSMCs were treated in a dose-response manner with insulin (0, 1, 10, and 100 nM) for 20 min, and Akt and Erk phosphorylation were measured by Western blot analysis. In separate experiments, we evaluated the effect of 200 μM palmitate, in the presence and absence of 8 μM pioglitazone, on insulin-stimulated (100 nM for 20 min) Akt and Erk phosphorylation. The phosphorylation of Akt and Erk in VSMCs exhibited a dose dependency with a three- to fourfold increase, respectively, at the highest dose (100 nM). In the presence of palmitate, insulin-induced Akt phosphorylation was completely abolished, and there was a threefold increase in p-Erk. With addition of pioglitazone, the phosphorylation of Akt by insulin remained unchanged, whereas insulin-stimulated Erk phosphorylation was reduced by pioglitazone. These data in VSMCs indicate that high palmitate decreases insulin-stimulated Akt phosphorylation and stimulates MAPK, whereas preexposure peroxisome proliferator-activated receptor-γ agonist pioglitazone preserves Akt phosphorylation and simultaneously attenuates MAPK signaling. Our results suggest that metabolic and mitogenic insulin signals have different sensitivity, are independently regulated, and may play a role in arterial smooth muscle cells migration, proliferation, and inflammation in conditions of acute hyperinsulinemia.
Identification and functional characterization of muscle satellite cells in Drosophila

PubMed Central

Reichert, Heinrich

2017-01-01

Work on genetic model systems such as Drosophila and mouse has shown that the fundamental mechanisms of myogenesis are remarkably similar in vertebrates and invertebrates. Strikingly, however, satellite cells, the adult muscle stem cells that are essential for the regeneration of damaged muscles in vertebrates, have not been reported in invertebrates. In this study, we show that lineal descendants of muscle stem cells are present in adult muscle of Drosophila as small, unfused cells observed at the surface and in close proximity to the mature muscle fibers. Normally quiescent, following muscle fiber injury, we show that these cells express Zfh1 and engage in Notch-Delta-dependent proliferative activity and generate lineal descendant populations, which fuse with the injured muscle fiber. In view of strikingly similar morphological and functional features, we consider these novel cells to be the Drosophila equivalent of vertebrate muscle satellite cells. PMID:29072161
Stem Cells for Skeletal Muscle Tissue Engineering.

PubMed

Pantelic, Molly N; Larkin, Lisa M

2018-04-19

Volumetric muscle loss (VML) is a debilitating condition wherein muscle loss overwhelms the body's normal physiological repair mechanism. VML is particularly common among military service members who have sustained war injuries. Because of the high social and medical cost associated with VML and suboptimal current surgical treatments, there is great interest in developing better VML therapies. Skeletal muscle tissue engineering (SMTE) is a promising alternative to traditional VML surgical treatments that use autogenic tissue grafts, and rather uses isolated stem cells with myogenic potential to generate de novo skeletal muscle tissues to treat VML. Satellite cells are the native precursors to skeletal muscle tissue, and are thus the most commonly studied starting source for SMTE. However, satellite cells are difficult to isolate and purify, and it is presently unknown whether they would be a practical source in clinical SMTE applications. Alternative myogenic stem cells, including adipose-derived stem cells, bone marrow-derived mesenchymal stem cells, perivascular stem cells, umbilical cord mesenchymal stem cells, induced pluripotent stem cells, and embryonic stem cells, each have myogenic potential and have been identified as possible starting sources for SMTE, although they have yet to be studied in detail for this purpose. These alternative stem cell varieties offer unique advantages and disadvantages that are worth exploring further to advance the SMTE field toward highly functional, safe, and practical VML treatments. The following review summarizes the current state of satellite cell-based SMTE, details the properties and practical advantages of alternative myogenic stem cells, and offers guidance to tissue engineers on how alternative myogenic stem cells can be incorporated into SMTE research.
Bioenergetics mechanisms regulating muscle stem cell self-renewal commitment and function.

PubMed

Abreu, Phablo

2018-04-16

Muscle stem cells or satellite cells are crucial for muscle maintenance and repair. These cells are mitotically quiescent and uniformly express the transcription factor Pax7, intermittently entering the cell cycle to give rise to daughter myogenic precursors cells and fuse with neighboring myofibers or self-renew, replenishing the stem cell pool in adult skeletal muscle. Pivotal roles of muscle stem cells in muscle repair have been uncovered, but it still remains unclear how muscle stem cell self-renewal is molecularly regulated and how muscle stem cells maintain muscle tissue homeostasis. Defects in muscle stem cell regulation to maintain/return to quiescence and self-renew are observed in degenerative conditions such as aging and neuromuscular disease. Recent works has suggested the existence of metabolic regulation and mitochondrial alterations in muscle stem cells, influencing the self-renewal commitment and function. Here I present a brief overview of recent understanding of how metabolic reprogramming governs self-renewal commitment, which is essential for conservation of muscle satellite cell pools throughout life, as well as the implications for regenerative medicine. Copyright © 2018. Published by Elsevier Masson SAS.
Intercostal muscle twitching: An unusual manifestation of extracardiac stimulation related to right ventricular outflow tract pacing

PubMed Central

Erdogan, Okan

2007-01-01

The present case report describes a patient who underwent successful dual-chamber pacemaker implantation with active ventricular lead fixation at a high septal region in the right ventricular outflow tract. Unexpectedly, stimulation at a high output in the right ventricular outflow tract caused an unusual extracardiac stimulation, specifically, intercostal muscle twitching. PMID:17703261
Smooth Muscle-Mediated Connective Tissue Remodeling in Pulmonary Hypertension

NASA Astrophysics Data System (ADS)

Mecham, Robert P.; Whitehouse, Loren A.; Wrenn, David S.; Parks, William C.; Griffin, Gail L.; Senior, Robert M.; Crouch, Edmond C.; Stenmark, Kurt R.; Voelkel, Norbert F.

1987-07-01

Abnormal accumulation of connective tissue in blood vessels contributes to alterations in vascular physiology associated with disease states such as hypertension and atherosclerosis. Elastin synthesis was studied in blood vessels from newborn calves with severe pulmonary hypertension induced by alveolar hypoxia in order to investigate the cellular stimuli that elicit changes in pulmonary arterial connective tissue production. A two- to fourfold increase in elastin production was observed in pulmonary artery tissue and medial smooth muscle cells from hypertensive calves. This stimulation of elastin production was accompanied by a corresponding increase in elastin messenger RNA consistent with regulation at the transcriptional level. Conditioned serum harvested from cultures of pulmonary artery smooth muscle cells isolated from hypertensive animals contained one or more low molecular weight elastogenic factors that stimulated the production of elastin in both fibroblasts and smooth muscle cells and altered the chemotactic responsiveness of fibroblasts to elastin peptides. These results suggest that connective tissue changes in the pulmonary vasculature in response to pulmonary hypertension are orchestrated by the medial smooth muscle cell through the generation of specific differentiation factors that alter both the secretory phenotype and responsive properties of surrounding cells.
Low-frequency electric muscle stimulation combined with physical therapy after total hip arthroplasty for hip osteoarthritis in elderly patients: a randomized controlled trial.

PubMed

Gremeaux, Vincent; Renault, Julien; Pardon, Laurent; Deley, Gaelle; Lepers, Romuald; Casillas, Jean-Marie

2008-12-01

To assess the effects of low-frequency electric muscle stimulation associated with usual physiotherapy on functional outcome after total hip arthroplasty (THA) for hip osteoarthritis (OA) in elderly subjects. Randomized controlled trial; pre- and posttreatment measurements. Hospital rehabilitation department. Subjects (N=29) referred to the rehabilitation department after THA for hip OA. The intervention group (n=16; 78+/-8 y) received simultaneous low-frequency electric muscle stimulation of bilateral quadriceps and calf muscles (highest tolerated intensity, 1h session, 5 d/wk, for 5 weeks) associated with conventional physical therapy including resistance training. The control group (n=13; 76+/-10 y) received conventional physical therapy alone (25 sessions). Maximal isometric strength of knee extensors, FIM instrument, before and after; a six-minute walk test and a 200 m fast walk test, after; length of stay (LOS). Low-frequency electric muscle stimulation was well tolerated. It resulted in a greater improvement in strength of knee extensors on the operated side (77% vs 23%; P<.01), leading to a better balance of muscle strength between the operated and nonoperated limb. The low-frequency electric muscle stimulation group also showed a greater improvement in FIM scores, though improvements in the walk tests were similar for the 2 groups, as was LOS. Low-frequency electric muscle stimulation is a safe, well-tolerated therapy after THA for hip OA. It improves knee extensor strength, which is one of the factors leading to greater functional independence after THA.
Phloretin Inhibits Platelet-derived Growth Factor-BB-induced Rat Aortic Smooth Muscle Cell Proliferation, Migration, and Neointimal Formation After Carotid Injury.

PubMed

Wang, Dong; Wang, Qingjie; Yan, Gaoliang; Qiao, Yong; Tang, Chengchun

2015-05-01

Abnormal vascular smooth muscle cell proliferation and migration are key factors in many cardiovascular diseases. Here, we investigated the effects of phloretin on platelet-derived growth factor homodimer (PDGF-BB)-induced rat aortic smooth muscle cell (RASMC) proliferation, migration, and neointimal formation after carotid injury. Phloretin significantly inhibited the PDGF-BB-stimulated RASMC proliferation in a concentration-dependent manner (10-100 μM). Also, PDGF-BB-stimulated RASMC migration was inhibited by phloretin at 50 μM. Pretreating RASMC with phloretin dose-dependently inhibited PDGF-BB-induced Akt and p38 mitogen-activated protein kinases activation. Furthermore, phloretin increased p27 and decreased cyclin-dependent kinase 2, CDK4 expression, and p-Rb activation in PDGF-BB-stimulated RASMC in a concentration-dependent manner (10-50 μM). PDGF-BB-induced cell adhesion molecules and matrix metalloproteinase-9 expression were blocked by phloretin at 50 μM. Preincubation with phloretin dose-dependently reduced the intracellular reactive oxygen species production. In vivo study showed that phloretin (20 mg/kg) significantly reduced neointimal formation 14 days after carotid injury in rats. Thus, phloretin may have potential as a treatment against atherosclerosis and restenosis after vascular injury.
Skeletal muscle satellite cells cultured in simulated microgravity

NASA Technical Reports Server (NTRS)

Molnar, Greg; Hartzell, Charles R.; Schroedl, Nancy A.; Gonda, Steve R.

1993-01-01

Satellite cells are postnatal myoblasts responsible for providing additional nuclei to growing or regenerating muscle cells. Satellite cells retain the capacity to proliferate and differentiate in vitro and therefore provide a useful model to study postnatal muscle development. Most culture systems used to study postnatal muscle development are limited by the two-dimensional (2-D) confines of the culture dish. Limiting proliferation and differentiation of satellite cells in 2-D could potentially limit cell-cell contacts important for developing the level of organization in skeletal muscle obtained in vivo. Culturing satellite cells on microcarrier beads suspended in the High-Aspect-Ratio-Vessel (HARV) designed by NASA provides a low shear, three-dimensional (3-D) environment to study muscle development. Primary cultures established from anterior tibialis muscles of growing rats (approximately 200 gm) were used for all studies and were composed of greater than 75 % satellite cells. Different inoculation densities did not affect the proliferative potential of satellite cells in the HARV. Plating efficiency, proliferation, and glucose utilization were compared between 2-D flat culture and 3-D HARV culture. Plating efficiency (cells attached - cells plated x 100) was similar between the two culture systems. Proliferation was reduced in HARV cultures and this reduction was apparent for both satellite cells and non-satellite cells. Furthermore, reduction in proliferation within the HARV could not be attributed to reduced substrate availability since glucose levels in media from HARV and 2-D cell culture were similar. Morphologically, microcarrier beads within the HARVS were joined together by cells into three-dimensional aggregates composed of greater than 10 beads/aggregate. Aggregation of beads did not occur in the absence of cells. Myotubes were often seen on individual beads or spanning the surface of two beads. In summary, proliferation and differentiation of
Bilateral responses of upper limb muscles to transcranial magnetic stimulation in human subjects.

PubMed

Bawa, P; Hamm, J D; Dhillon, P; Gross, P A

2004-10-01

Anatomical and behavioural work on primates has shown bilateral innervation of axial and proximal limb muscles, and contralateral control of distal limb muscles. The following study examined if a clear boundary exists between the distal and proximal upper limb muscles that are controlled contralaterally or bilaterally. The right motor cortical area representing the upper limb was stimulated, while surface EMG was recorded bilaterally from various upper limb muscles during rest and phasic voluntary contractions. Peak-to-peak amplitude of motor evoked potential (MEP) was measured for each muscle on both sides. The ratio R = (ipsilateral MEP: contralateral MEP) was calculated for seven pairs of muscles. For each of the seven pairs, R was less than 1.0, implying that for each muscle and subject, the contralateral control is stronger. The boundary where R changed from almost zero to a clearly measurable magnitude depended on the subject. Ipsilateral MEPs from trapezius and pectoralis could be recorded with a small background contraction from almost all subjects; on the other hand, in deltoid and biceps brachii, ipsilateral MEPs were observed only with bimanual phasic contractions. The forearm and hand muscles, in general, did not show any ipsilateral MEPs. Major differences between subjects lay in the presence or the absence of ipsilateral MEPs in biceps brachii and deltoid, without defining a sharp boundary between proximal and distal muscles.
Sequenced response of extracellular matrix deadhesion and fibrotic regulators after muscle damage is involved in protection against future injury in human skeletal muscle

PubMed Central

Mackey, Abigail L.; Brandstetter, Simon; Schjerling, Peter; Bojsen-Moller, Jens; Qvortrup, Klaus; Pedersen, Mette M.; Doessing, Simon; Kjaer, Michael; Magnusson, S. Peter; Langberg, Henning

2011-01-01

The purpose of this study was to test the hypothesis that remodeling of skeletal muscle extracellular matrix (ECM) is involved in protecting human muscle against injury. Biopsies were obtained from medial gastrocnemius muscles after a single bout of electrical stimulation (B) or a repeated bout (RB) 30 d later, or 30 d after a single stimulation bout (RBc). A muscle biopsy was collected from the control leg for comparison with the stimulated leg. Satellite cell content, tenascin C, and muscle regeneration were assessed by immunohistochemistry; real-time PCR was used to measure mRNA levels of collagens, laminins, heat-shock proteins (HSPs), inflammation, and related growth factors. The large responses of HSPs, CCL2, and tenascin C detected 48 h after a single bout were attenuated in the RB trial, indicative of protection against injury. Satellite cell content and 12 target genes, including IGF-1, were elevated 30 d after a single bout. Among those displaying the greatest difference vs. control muscle, ECM laminin-β1 and collagen types I and III were elevated ∼6- to 9-fold (P<0.001). The findings indicate that the sequenced events of load-induced early deadhesion and later strengthening of skeletal muscle ECM play a role in protecting human muscle against future injury.—Mackey, A. L., Brandstetter, S., Schjerling, P., Bojsen-Moller, J., Qvortrup, K., Pedersen, M. M., Doessing, S. Kjaer, M., Magnusson, S. P., Langberg, H. Sequenced response of extracellular matrix deadhesion and fibrotic regulators after muscle damage is involved in protection against future injury in human skeletal muscle. PMID:21368102
Effect of Serum from Chickens Treated with Clenbuterol on Myosin Accumulation, Beta-Adrenergic Receptor Population, and Cyclic AMP Synthesis in Embryonic Chicken Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, Kristin Y.; Wuethrich, Andrew J.; Hancock, Deana L.

2002-01-01

Broiler chickens at 35 d of age were fed 1 ppm clenbuterol for 14 d. This level of dietary clenbuterol led to 5-7% increases in the weights of leg and breast muscle tissue. At the end of the 14-d period, serum was prepared from both control and clenbuterol-treated chickens, and was then employed as a component of cell culture media at a final concentration of 20% (v/v). Muscle cell cultures were prepared from both the leg and the breast muscle groups of 12-d chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 uM clenbuterol had been added, as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 d, beginning on the seventh d in culture. Neither the percent fusion nor the number of nuclei in myotubes was significantly affected by any of the treatments. The quantity of myosin heavy chains (MHCs) was not increased by serum from clenbuterol-treated chickens in either breast or leg muscle cultures; however, the MHC quantity was 50-150% higher in cultures grown in control chicken serum to which 10 and 50 nM clenbuterol had also been added. The B-adrenergic receptor (betaAR) population was 4000-7000 betaARs per cell in cultures grown in chicken serum with leg muscle cultures having approximately 25-30% more receptors than breast muscle Culture. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the betaAR Population in leg and breast muscle cultures grown in the presence of 10% horse serum was 16,000-18,000 betaARs per cell. Basal concentration of cyclic adenosine 3':5'monophosphate (cAMP) was not significantly affected by the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 uM isoproterenol, limited increases of 12-20% in cAMP Concentration above the. basal levels were observed. However, when cultures grown in the presence of horse serum were
Space travel directly induces skeletal muscle atrophy

NASA Technical Reports Server (NTRS)

Vandenburgh, H.; Chromiak, J.; Shansky, J.; Del Tatto, M.; Lemaire, J.

1999-01-01

Space travel causes rapid and pronounced skeletal muscle wasting in humans that reduces their long-term flight capabilities. To develop effective countermeasures, the basis of this atrophy needs to be better understood. Space travel may cause muscle atrophy indirectly by altering circulating levels of factors such as growth hormone, glucocorticoids, and anabolic steroids and/or by a direct effect on the muscle fibers themselves. To determine whether skeletal muscle cells are directly affected by space travel, tissue-cultured avian skeletal muscle cells were tissue engineered into bioartificial muscles and flown in perfusion bioreactors for 9 to 10 days aboard the Space Transportation System (STS, i.e., Space Shuttle). Significant muscle fiber atrophy occurred due to a decrease in protein synthesis rates without alterations in protein degradation. Return of the muscle cells to Earth stimulated protein synthesis rates of both muscle-specific and extracellular matrix proteins relative to ground controls. These results show for the first time that skeletal muscle fibers are directly responsive to space travel and should be a target for countermeasure development.
Calorie restriction enhances insulin-stimulated glucose uptake and Akt phosphorylation in both fast-twitch and slow-twitch skeletal muscle of 24-month-old rats.

PubMed

Sequea, Donel A; Sharma, Naveen; Arias, Edward B; Cartee, Gregory D

2012-12-01

Calorie restriction (CR) induces enhanced insulin-stimulated glucose uptake in fast-twitch (type II) muscle from old rats, but the effect of CR on slow-twitch (type I) muscle from old rats is unknown. The purpose of this study was to assess insulin-stimulated glucose uptake and phosphorylation of key insulin signaling proteins in isolated epitrochlearis (fast-twitch) and soleus (slow-twitch) muscles from 24-month-old ad libitum fed and CR (consuming 65% of ad libitum, intake) rats. Muscles were incubated with and without 1.2 nM insulin. CR versus ad libitum rats had greater insulin-stimulated glucose uptake and Akt phosphorylation (pAkt) on T308 and S473 for both muscles incubated with insulin. GLUT4 protein abundance and phosphorylation of the insulin receptor (Y1162/1163) and AS160 (T642) were unaltered by CR in both muscles. These results implicate enhanced pAkt as a potential mechanism for the CR-induced increase in insulin-stimulated glucose uptake by the fast-twitch epitrochlearis and slow-twitch soleus of old rats.
Role of protein kinase C alpha in endothelin-1 stimulation of cytosolic phospholipase A2 and arachidonic acid release in cultured cat iris sphincter smooth muscle cells.

PubMed

Husain, S; Abdel-Latif, A A

1998-05-20

We have investigated the role and mechanism of protein kinase C (PKC) isoforms in endothelin-1 (ET-1)-induced arachidonic acid (AA) release in cat iris sphincter smooth muscle (CISM) cells. ET-1 increased AA release in a concentration (EC50=8 nM) and time-dependent (t1/2=1.2 min) manner. Cytosolic phospholipase A2 (cPLA2), but not phospholipase C (PLC), is involved in the liberation of AA in the stimulated cells. This conclusion is supported by the findings that ET-1-induced AA release is inhibited by AACOCF3, quinacrine and manoalide, PLA2 inhibitors, but not by U-73122, a PLC inhibitor, or by RHC-80267, a diacylglycerol lipase inhibitor. A role for PKC in ET-1-induced AA release is supported by the findings that the phorbol ester, PDBu, increased AA release by 96%, that prolonged treatment of the cells with PDBu resulted in the selective down regulation of PKCalpha and the complete inhibition of ET-1-induced AA release, and that pretreatment of the cells with staurosporine or RO 31-8220, PKC inhibitors, blocked the ET-1-induced AA release. Gö-6976, a compound that inhibits PKCalpha and beta specifically, blocked ET-1-induced AA release in a concentration-dependent manner with an IC50 value of 8 nM. Thymeatoxin (0.1 microM), a specific activator of PKCalpha, beta, and gamma induced a 150% increase in AA release. Treatment of the cells with ET-1 caused significant translocation of PKCalpha, but not PKCbeta, from cytosol to the particulate fraction. These results suggest that PKCalpha plays a critical role in ET-1-induced AA release in these cells. Immunochemical analysis revealed the presence of cPLA2, p42mapk and p44mapk in the CISM cells. The data presented are consistent with a role for PKCalpha, but not for p42/p44 mitogen-activated protein kinase (MAPK), in cPLA2 activation and AA release in ET-1-stimulated CISM cells since: (i) the PKC inhibitor, RO 31-8220, inhibited ET-1-induced AA release, cPLA2 phosphorylation and cPLA2 activity, but had no inhibitory
Monitoring Autophagy in Muscle Stem Cells.

PubMed

García-Prat, Laura; Muñoz-Cánoves, Pura; Martínez-Vicente, Marta

2017-01-01

Autophagy is critical not only for the cell's adaptive response to starvation but also for cellular homeostasis, by acting as quality-control machinery for cytoplasmic components. This basal autophagic activity is particularly needed in postmitotic cells for survival maintenance. Recently, basal autophagic activity was reported in skeletal muscle stem cells (satellite cells) in their dormant quiescent state. Satellite cells are responsible for growth as well as for regeneration of muscle in response to stresses such as injury or disease. In the absence of stress, quiescence is the stem cell state of these cells throughout life, although which mechanisms maintain long-life quiescence remains largely unknown. Our recent findings showed that autophagy is necessary for quiescence maintenance in satellite cells and for retention of their regenerative functions. Importantly, damaged organelles and proteins accumulated in these cells with aging and this was connected to age-associated defective autophagy. Refueling of autophagy through genetic and pharmacological strategies restored aged satellite cell functions, and these finding have biomedical implications. In this chapter, we describe different experimental strategies to evaluate autophagic activity in satellite cells in resting muscle of mice. They should facilitate our competence to investigate stem cell functions both during tissue homeostasis as in pathological conditions.
Atractylodes macrocephala Koidz stimulates intestinal epithelial cell migration through a polyamine dependent mechanism.

PubMed

Song, Hou-Pan; Li, Ru-Liu; Zhou, Chi; Cai, Xiong; Huang, Hui-Yong

2015-01-15

decrease of cellular polyamines levels, Rho mRNAs and proteins expression, non-muscle myosin II protein formation and distribution, thereby inhibiting IEC-6 cell migration. AMK not only reversed the inhibitory effects of DFMO on the polyamines content, Rho mRNAs and proteins expression, non-muscle myosin II protein formation and distribution, but also restored cell migration to control levels. The results obtained from this study revealed that AMK significantly stimulates the migration of IEC-6 cells through a polyamine dependent mechanism, which could accelerate the healing of intestinal injury. These findings suggest the potential value of AMK in curing intestinal diseases characterized by injury and ineffective repair of the intestinal mucosa in clinical practice. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Enhancement of glucose uptake in skeletal muscle L6 cells and insulin secretion in pancreatic hamster-insulinoma-transfected cells by application of non-thermal plasma jet

NASA Astrophysics Data System (ADS)

Kumar, Naresh; Kaushik, Nagendra K.; Park, Gyungsoon; Choi, Eun H.; Uhm, Han S.

2013-11-01

Type-II diabetes Mellitus is characterized by defects in insulin action on peripheral tissues, such as skeletal muscle, adipose tissue, and liver and pancreatic beta cells. Since the skeletal muscle accounts for approximately 75% of insulin-stimulated glucose-uptake in our body, impaired insulin secretion from defected beta cell plays a major role in the afflicted glucose homoeostasis. It was shown that the intracellular reactive oxygen species and nitric oxide level was increased by non-thermal-plasma treatment in ambient air. These increased intracellular reactive species may enhance glucose uptake and insulin secretion through the activation of intracellular calcium (Ca+) and cAMP production.

CD133+ cells derived from skeletal muscles of Duchenne muscular dystrophy patients have a compromised myogenic and muscle regenerative capability.

PubMed

Meng, Jinhong; Muntoni, Francesco; Morgan, Jennifer

2018-05-12

Cell-mediated gene therapy is a possible means to treat muscular dystrophies like Duchenne muscular dystrophy. Autologous patient stem cells can be genetically-corrected and transplanted back into the patient, without causing immunorejection problems. Regenerated muscle fibres derived from these cells will express the missing dystrophin protein, thus improving muscle function. CD133+ cells derived from normal human skeletal muscle contribute to regenerated muscle fibres and form muscle stem cells after their intra-muscular transplantation into an immunodeficient mouse model. But it is not known whether CD133+ cells derived from DMD patient muscles have compromised muscle regenerative function. To test this, we compared CD133+ cells derived from DMD and normal human muscles. DMD CD133+ cells had a reduced capacity to undergo myogenic differentiation in vitro compared with CD133+ cells derived from normal muscle. In contrast to CD133+ cells derived from normal human muscle, those derived from DMD muscle formed no satellite cells and gave rise to significantly fewer muscle fibres of donor origin, after their intra-muscular transplantation into an immunodeficient, non-dystrophic, mouse muscle. DMD CD133+ cells gave rise to more clones of smaller size and more clones that were less myogenic than did CD133+ cells derived from normal muscle. The heterogeneity of the progeny of CD133+ cells, combined with the reduced proliferation and myogenicity of DMD compared to normal CD133+ cells, may explain the reduced regenerative capacity of DMD CD133+ cells. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.
Multi-muscle electrical stimulation and stand training: Effects on standing.

PubMed

Momeni, Kamyar; Ramanujam, Arvind; Garbarini, Erica L; Forrest, Gail F

2018-02-15

To examine the biomechanical and neuromuscular effects of a longitudinal multi-muscle electrical stimulation (submaximal intensities) training of the lower limbs combined with/without activity-based stand training, on the recovery of stability and function for one individual with spinal cord injury (SCI). Single-subject, longitudinal study. Neuroplasticity laboratory. A 34-year-old male, with sensory- and motor-complete SCI (C5/C6). Two consecutive interventions: 61 hours of supine, lower-limb ES (ES-alone) and 51 hours of ES combined with stand training using an overhead body-weight support system (ST + ES). Clinical measures, trunk stability, and muscle activity were assessed and compared across time points. Trunk Stability Limit (TSL) determined improvements in trunk independence. Functional clinical values increased after both interventions, with further increases post ST + ES. Post ES-alone, trunk stability was maintained at 81% body-weight (BW) loading before failure; post ST + ES, BW loading increased to 95%. TSL values decreased post ST + ES (TSL A/P =54.0 kg.cm, TSL M/L =14.5 kg.cm), compared to ES-alone (TSL A/P =8.5 kg.cm, TSL M/L =3.9 kg.cm). Trunk muscle activity decreased post ST + ES training, compared to ES-alone. Neuromuscular and postural trunk control dramatically improved following the multi-muscle ES of the lower limbs with stand training. Multi-muscle ES training paradigm of the lower limb, using traditional parameters, may contribute to the functional recovery of the trunk.
Paradoxical behavior of neuromedin U in isolated smooth muscle cells and intact tissue.

PubMed

Brighton, Paul J; Wise, Alan; Dass, Narinder B; Willars, Gary B

2008-04-01

Neuromedin U (NmU) is a neuropeptide showing high levels of structural conservation across different species. Since its discovery in 1985, NmU has been implicated in numerous physiological roles, including smooth muscle contraction, energy homeostasis, stress, intestinal ion transport, pronociception, and circadian rhythm. Two G-protein-coupled receptors have been identified for NmU and cloned from humans, rats, and mice. Recombinantly expressed NmU receptors couple to both Galpha(q/11) and Galpha(i) G-proteins, and NmU binds essentially irreversibly, preventing signaling to repetitive applications of NmU. However, it is unclear whether these properties reflect those of endogenously expressed NmU receptors or how these properties influence the functional consequences of NmU receptor signaling. Here, we have explored the signaling by rat NmU receptors expressed endogenously in cultured rat colonic smooth muscle cells and explore the functional consequence of this signaling by investigating the NmU-mediated contraction of ex vivo rat colonic smooth muscle preparations. We demonstrate that endogenous rat NmU receptors couple to both Galpha(q/11) and Galpha(i) G-proteins. Furthermore, we show complex patterns of Ca(2+) signaling, including oscillations, and provide evidence of essentially irreversible binding of NmU to smooth muscle cells. Challenge of either circular or longitudinal rat isolated colonic smooth muscle preparations with NmU resulted in robust contractions. Stimulation was direct, and paradoxically, repetitive applications of NmU mediated repetitive contractions with no evidence of desensitization, highlighting a major discrepancy in the behavior of NmU in single cells and in intact tissues. The reason for this discrepancy is presently unknown.
AKT-induced PKM2 phosphorylation signals for IGF-1-stimulated cancer cell growth

PubMed Central

Park, Young Soo; Kim, Dong Joon; Koo, Han; Jang, Se Hwan; You, Yeon-Mi; Cho, Jung Hee; Yang, Suk-Jin; Yu, Eun Sil; Jung, Yuri; Lee, Dong Chul; Kim, Jung-Ae; Park, Zee-Yong; Park, Kyung Chan; Yeom, Young Il

2016-01-01

Pyruvate kinase muscle type 2 (PKM2) exhibits post-translational modifications in response to various signals from the tumor microenvironment. Insulin-like growth factor 1 (IGF-1) is a crucial signal in the tumor microenvironment that promotes cell growth and survival in many human cancers. Herein, we report that AKT directly interacts with PKM2 and phosphorylates it at Ser-202, which is essential for the nuclear translocation of PKM2 protein under stimulation of IGF-1. In the nucleus, PKM2 binds to STAT5A and induces IGF-1-stimulated cyclin D1 expression, suggesting that PKM2 acts as an important factor inducing STAT5A activation under IGF-1 signaling. Concordantly, overexpression of STAT5A in cells deficient in PKM2 expression failed to restore IGF-induced growth, whereas reconstitution of PKM2 in PKM2 knockdown cells restored the IGF-induced growth capacity. Our findings suggest a novel role of PKM2 in promoting the growth of cancers with dysregulated IGF/phosphoinositide 3-kinase/AKT signaling. PMID:27340866
Kinetics of GLUT4 Trafficking in Rat and Human Skeletal Muscle

PubMed Central

Karlsson, Håkan K.R.; Chibalin, Alexander V.; Koistinen, Heikki A.; Yang, Jing; Koumanov, Francoise; Wallberg-Henriksson, Harriet; Zierath, Juleen R.; Holman, Geoffrey D.

2009-01-01

OBJECTIVE In skeletal muscle, insulin stimulates glucose transport activity three- to fourfold, and a large part of this stimulation is associated with a net translocation of GLUT4 from an intracellular compartment to the cell surface. We examined the extent to which insulin or the AMP-activated protein kinase activator AICAR can lead to a stimulation of the exocytosis limb of the GLUT4 translocation pathway and thereby account for the net increase in glucose transport activity. RESEARCH DESIGN AND METHODS Using a biotinylated photoaffinity label, we tagged endogenous GLUT4 and studied the kinetics of exocytosis of the tagged protein in rat and human skeletal muscle in response to insulin or AICAR. Isolated epitrochlearis muscles were obtained from male Wistar rats. Vastus lateralis skeletal muscle strips were prepared from open muscle biopsies obtained from six healthy men (age 39 ± 11 years and BMI 25.8 ± 0.8 kg/m2). RESULTS In rat epitrochlearis muscle, insulin exposure leads to a sixfold stimulation of the GLUT4 exocytosis rate (with basal and insulin-stimulated rate constants of 0.010 and 0.067 min−1, respectively). In human vastus lateralis muscle, insulin stimulates GLUT4 translocation by a similar sixfold increase in the exocytosis rate constant (with basal and insulin-stimulated rate constants of 0.011 and 0.075 min−1, respectively). In contrast, AICAR treatment does not markedly increase exocytosis in either rat or human muscle. CONCLUSIONS Insulin stimulation of the GLUT4 exocytosis rate constant is sufficient to account for most of the observed increase in glucose transport activity in rat and human muscle. PMID:19188436
Reactive oxygen species upregulate expression of muscle atrophy-associated ubiquitin ligase Cbl-b in rat L6 skeletal muscle cells.

PubMed

Uchida, Takayuki; Sakashita, Yoshihiro; Kitahata, Kanako; Yamashita, Yui; Tomida, Chisato; Kimori, Yuki; Komatsu, Akio; Hirasaka, Katsuya; Ohno, Ayako; Nakao, Reiko; Higashitani, Atsushi; Higashibata, Akira; Ishioka, Noriaki; Shimazu, Toru; Kobayashi, Takeshi; Okumura, Yuushi; Choi, Inho; Oarada, Motoko; Mills, Edward M; Teshima-Kondo, Shigetada; Takeda, Shin'ichi; Tanaka, Eiji; Tanaka, Keiji; Sokabe, Masahiro; Nikawa, Takeshi

2018-06-01

Unloading-mediated muscle atrophy is associated with increased reactive oxygen species (ROS) production. We previously demonstrated that elevated ubiquitin ligase casitas B-lineage lymphoma-b (Cbl-b) resulted in the loss of muscle volume (Nakao R, Hirasaka K, Goto J, Ishidoh K, Yamada C, Ohno A, Okumura Y, Nonaka I, Yasutomo K, Baldwin KM, Kominami E, Higashibata A, Nagano K, Tanaka K, Yasui N, Mills EM, Takeda S, Nikawa T. Mol Cell Biol 29: 4798-4811, 2009). However, the pathological role of ROS production associated with unloading-mediated muscle atrophy still remains unknown. Here, we showed that the ROS-mediated signal transduction caused by microgravity or its simulation contributes to Cbl-b expression. In L6 myotubes, the assessment of redox status revealed that oxidized glutathione was increased under microgravity conditions, and simulated microgravity caused a burst of ROS, implicating ROS as a critical upstream mediator linking to downstream atrophic signaling. ROS generation activated the ERK1/2 early-growth response protein (Egr)1/2-Cbl-b signaling pathway, an established contributing pathway to muscle volume loss. Interestingly, antioxidant treatments such as N-acetylcysteine and TEMPOL, but not catalase, blocked the clinorotation-mediated activation of ERK1/2. The increased ROS induced transcriptional activity of Egr1 and/or Egr2 to stimulate Cbl-b expression through the ERK1/2 pathway in L6 myoblasts, since treatment with Egr1/2 siRNA and an ERK1/2 inhibitor significantly suppressed clinorotation-induced Cbl-b and Egr expression, respectively. Promoter and gel mobility shift assays revealed that Cbl-b was upregulated via an Egr consensus oxidative responsive element at -110 to -60 bp of the Cbl-b promoter. Together, this indicates that under microgravity conditions, elevated ROS may be a crucial mechanotransducer in skeletal muscle cells, regulating muscle mass through Cbl-b expression activated by the ERK-Egr signaling pathway.
A Special Population of Regulatory T Cells Potentiates Muscle Repair

PubMed Central

Burzyn, Dalia; Kuswanto, Wilson; Kolodin, Dmitriy; Shadrach, Jennifer L.; Cerletti, Massimiliano; Jang, Young; Sefik, Esen; Tan, Tze Guan; Wagers, Amy J.; Benoist, Christophe; Mathis, Diane

2014-01-01

SUMMARY Long recognized to be potent suppressors of immune responses, Foxp3+CD4+ regulatory T (Treg) cells are being rediscovered as regulators of nonimmunological processes. We describe a phenotypically and functionally distinct population of Treg cells that rapidly accumulated in the acutely injured skeletal muscle of mice, just as invading myeloidlineage cells switched from a proinflammatory to a proregenerative state. A Treg population of similar phenotype accumulated in muscles of genetically dystrophic mice. Punctual depletion of Treg cells during the repair process prolonged the proinflammatory infiltrate and impaired muscle repair, while treatments that increased or decreased Treg activities diminished or enhanced (respectively) muscle damage in a dystrophy model. Muscle Treg cells expressed the growth factor Amphiregulin, which acted directly on muscle satellite cells in vitro and improved muscle repair in vivo. Thus, Treg cells and their products may provide new therapeutic opportunities for wound repair and muscular dystrophies. PMID:24315098
Cell-specific paracrine actions of IL-6 family cytokines from bone, marrow and muscle that control bone formation and resorption.

PubMed

Sims, Natalie A

2016-10-01

Bone renews itself and changes shape throughout life to account for the changing needs of the body; this requires co-ordinated activities of bone resorbing cells (osteoclasts), bone forming cells (osteoblasts) and bone's internal cellular network (osteocytes). This review focuses on paracrine signaling by the IL-6 family of cytokines between bone cells, bone marrow, and skeletal muscle in normal physiology and in pathological states where their levels may be locally or systemically elevated. These functions include the support of osteoclast formation by osteoblast lineage cells in response to interleukin 6 (IL-6), interleukin 11 (IL-11), oncostatin M (OSM) and cardiotrophin 1 (CT-1). In addition it will discuss how bone-resorbing osteoclasts promote osteoblast activity by secreting CT-1, which acts as a "coupling factor" on osteocytes, osteoblasts, and their precursors to promote bone formation. OSM, produced by osteoblast lineage cells and macrophages, stimulates bone formation via osteocytes. IL-6 family cytokines also mediate actions of other bone formation stimuli like parathyroid hormone (PTH) and mechanical loading. CT-1, OSM and LIF suppress marrow adipogenesis by shifting commitment of pluripotent precursors towards osteoblast differentiation. Ciliary neurotrophic factor (CNTF) is released as a myokine from skeletal muscle and suppresses osteoblast differentiation and bone formation on the periosteum (outer bone surface in apposition to muscle). Finally, IL-6 acts directly on marrow-derived osteoclasts to stimulate release of "osteotransmitters" that act through the cortical osteocyte network to stimulate bone formation on the periosteum. Each will be discussed as illustrations of how the extended family of IL-6 cytokines acts within the skeleton in physiology and may be altered in pathological conditions or by targeted therapies. Copyright © 2016 Elsevier Ltd. All rights reserved.
Beta-Adrenergic Receptor Expression in Muscle Cells

NASA Technical Reports Server (NTRS)

Young, Ronald B.; Bridge, K.; Vaughn, J. R.

1999-01-01

beta-adrenergic receptor (bAR) agonists presumably exert their physiological action on skeletal muscle cells through the bAR. Since the signal generated by the bAR is cyclic AMP (cAMP), experiments were initiated in primary chicken muscle cell cultures to determine if artificial elevation of intracellular cAMP by treatment with forskolin would alter the population of bAR expressed on the surface of muscle cells. Chicken skeletal muscle cells after 7 days in culture were employed for the experiments because muscle cells have attained a steady state with respect to muscle protein metabolism at this stage. Cells were treated with 0-10 uM forskolin for a total of three days. At the end of the 1, 2, and 3 day treatment intervals, the concentration of cAMP and the bAR population were measured. Receptor population was measured in intact muscle cell cultures as the difference between total binding of [H-3]CGP-12177 and non-specific binding of [H-3]CGP-12177 in the presence of 1 uM propranolol. Intracellular cAMP concentration was measured by radioimmunoassay. The concentration of cAMP in forskolin-treated cells increased up to 10-fold in a dose dependent manner. Increasing concentrations of forskolin also led to an increase in (beta)AR population, with a maximum increase of approximately 50% at 10 uM. This increase in (beta)AR population was apparent after only 1 day of treatment, and the pattern of increase was maintained for all 3 days of the treatment period. Thus, increasing the intracellular concentration of cAMP leads to up-regulation of (beta)AR population. Clenbuterol and isoproterenol gave similar effects on bAR population. The effect of forskolin on the quantity and apparent synthesis rate of the heavy chain of myosin (mhc) were also investigated. A maximum increase of 50% in the quantity of mhc was observed at 0.2 UM forskolin, but higher concentrations of forskolin reduced the quantity of mhc back to control levels.
Long-term leucine induced stimulation of muscle protein synthesis is amino acid dependent

USDA-ARS?s Scientific Manuscript database

Infusing leucine for 1 h increases skeletal muscle protein synthesis in the neonate, but this is not sustained for 2 h unless the corresponding fall in amino acids is prevented. This study aimed to determine whether a continuous leucine infusion can stimulate protein synthesis for a prolonged period...
Brain-controlled muscle stimulation for the restoration of motor function

PubMed Central

Ethier, Christian; Miller, Lee E

2014-01-01

Loss of the ability to move, as a consequence of spinal cord injury or neuromuscular disorder, has devastating consequences for the paralyzed individual, and great economic consequences for society. Functional Electrical Stimulation (FES) offers one means to restore some mobility to these individuals, improving not only their autonomy, but potentially their general health and well-being as well. FES uses electrical stimulation to cause the paralyzed muscles to contract. Existing clinical systems require the stimulation to be preprogrammed, with the patient typically using residual voluntary movement of another body part to trigger and control the patterned stimulation. The rapid development of neural interfacing in the past decade offers the promise of dramatically improved control for these patients, potentially allowing continuous control of FES through signals recorded from motor cortex, as the patient attempts to control the paralyzed body part. While application of these ‘Brain Machine Interfaces’ (BMIs) has undergone dramatic development for control of computer cursors and even robotic limbs, their use as an interface for FES has been much more limited. In this review, we consider both FES and BMI technologies and discuss the prospect for combining the two to provide important new options for paralyzed individuals. PMID:25447224
Functional Magnetic Stimulation of Inspiratory and Expiratory Muscles in Subjects With Tetraplegia.

PubMed

Zhang, Xiaoming; Plow, Ela; Ranganthan, Vinoth; Huang, Honglian; Schmitt, Melissa; Nemunaitis, Gregory; Kelly, Clay; Frost, Frederick; Lin, Vernon

2016-07-01

Respiratory complications are major causes of morbidity and mortality in persons with a spinal cord injury, partly because of respiratory muscle paralysis. Earlier investigation has demonstrated that functional magnetic stimulation (FMS) can be used as a noninvasive technology for activating expiratory muscles, thus producing useful expiratory functions (simulated cough) in subjects with spinal cord injury. To evaluate the effectiveness of FMS for conditioning inspiratory and expiratory muscles in persons with tetraplegia. A prospective before and after trial. FMS Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH. Six persons with tetraplegia. Each subject participated in a 6-week FMS protocol for conditioning the inspiratory and expiratory muscles. A magnetic stimulator was used with the center of a magnetic coil placed at the C7-T1 and T9-T10 spinous processes, respectively. Pulmonary function tests were performed before, during, and after the protocol. Respiratory variables included maximal inspiratory pressure (MIP), inspiratory reserve volume (IRV), peak inspiratory flow (PIF), maximal expiratory pressure (MEP), expiratory reserve volume (ERV), and peak expiratory flow (PEF). After 6 weeks of conditioning, the main outcome measurements (mean ± standard error) were as follows: MIP, 89.6 ± 7.3 cm H2O; IRV, 1.90 ± 0.34 L; PIF, 302.4 ± 36.3 L/min; MEP, 67.4 ± 11.1 cm H2O; ERV, 0.40 ± 0.06 L; and PEF, 372.4 ± 31.9 L/min. These values corresponded to 117%, 107%, 136%, 109%, 130%, and 124% of pre-FMS conditioning values, respectively. Significant improvements were observed in MIP (P = .022), PIF (P = .0001), and PEF (P = .0006), respectively. When FMS was discontinued for 4 weeks, these values showed decreases from their values at the end of the conditioning protocol, which suggests that continual FMS may be necessary to maintain improved respiratory functions. FMS conditioning of the inspiratory and expiratory muscles improved
The effect of SIRT1 protein knock down on PGC-1α acetylation during skeletal muscle contraction.

PubMed

Park, Dae Ryoung; Kim, Jeong Seok; Kim, Chang Keun

2014-03-01

The purpose of this study was to investigate the effect of Sirtuin 1 (SIRT1) and General control nonderepressible 5 (GCN5) knock down on peroxisome proliferator- activated receptor gamma coactivator 1-alpha (PGC-1α) deacetylation during electrical stimulated skeletal muscle contraction. Skeletal muscle primary cell were isolated from C57BL/6 mice gastrocnemius and transfected lentiviral SIRT1 and GCN5 shRNA. Knock downed muscle cell were stimulated by electrical stimulation (1Hz, 3min) and collected for PGC-1α deceatylation assays. Immunoprecipitation performed for PGC-1α deacetylation, acetyl-lysine level was measured. Our resulted showed SIRT1 knock down not influenced to PGC-1α deacetylation during electrical stimulation induced muscle contraction while GCN5 knock down decreased PGC-1α deacetylation significantly (p<0.05). This study can be concluded that GCN5 is a critical factor for muscle contraction induced PGC-1α deacetylation.
Cellular dynamics in the muscle satellite cell niche

PubMed Central

Bentzinger, C Florian; Wang, Yu Xin; Dumont, Nicolas A; Rudnicki, Michael A

2013-01-01

Satellite cells, the quintessential skeletal muscle stem cells, reside in a specialized local environment whose anatomy changes dynamically during tissue regeneration. The plasticity of this niche is attributable to regulation by the stem cells themselves and to a multitude of functionally diverse cell types. In particular, immune cells, fibrogenic cells, vessel-associated cells and committed and differentiated cells of the myogenic lineage have emerged as important constituents of the satellite cell niche. Here, we discuss the cellular dynamics during muscle regeneration and how disease can lead to perturbation of these mechanisms. To define the role of cellular components in the muscle stem cell niche is imperative for the development of cell-based therapies, as well as to better understand the pathobiology of degenerative conditions of the skeletal musculature. PMID:24232182
Application of cell co-culture system to study fat and muscle cells.

PubMed

Pandurangan, Muthuraman; Hwang, Inho

2014-09-01

Animal cell culture is a highly complex process, in which cells are grown under specific conditions. The growth and development of these cells is a highly unnatural process in vitro condition. Cells are removed from animal tissues and artificially cultured in various culture vessels. Vitamins, minerals, and serum growth factors are supplied to maintain cell viability. Obtaining result homogeneity of in vitro and in vivo experiments is rare, because their structure and function are different. Living tissues have highly ordered complex architecture and are three-dimensional (3D) in structure. The interaction between adjacent cell types is quite distinct from the in vitro cell culture, which is usually two-dimensional (2D). Co-culture systems are studied to analyze the interactions between the two different cell types. The muscle and fat co-culture system is useful in addressing several questions related to muscle modeling, muscle degeneration, apoptosis, and muscle regeneration. Co-culture of C2C12 and 3T3-L1 cells could be a useful diagnostic tool to understand the muscle and fat formation in animals. Even though, co-culture systems have certain limitations, they provide a more realistic 3D view and information than the individual cell culture system. It is suggested that co-culture systems are useful in evaluating the intercellular communication and composition of two different cell types.
Effects of transportation during the hot season, breed and electrical stimulation on histochemical and meat quality characteristics of goat longissimus muscle.

PubMed

Kadim, Isam T; Mahgoub, Osman; Al-Marzooqi, Waleed; Khalaf, Samera; Al-Sinawi, Shadia S H; Al-Amri, Issa

2010-06-01

The effects of transportation and electrical stimulation (90 V) on physiological, histochemical and meat quality characteristics of two breeds of Omani goats were assessed. Twenty 1-year-old male goats from each breed (Batina and Dhofari) were divided into two groups: 3 h transported during the hot season (42 degrees C day time temperature) and non-transported. Animals were blood-sampled before loading and prior to slaughter. Electrical stimulation was applied 20 min postmortem to 50% randomly selected carcasses of both breeds. Temperature and pH decline of the Longissimus was monitored. Ultimate pH, shear force, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and colour were measured from samples of Longissimus dorsi muscles. Electrical stimulation and transportation had a significant effect on most biochemical and meat quality characteristics of Longissimus dorsi. The transported goats had higher plasma cortisol (P < 0.01), adrenaline, nor-adrenaline and dopamine concentrations (P < 0.05) than non-transported goats. Electrical stimulation resulted in a significantly (P < 0.05) more rapid muscle pH fall during the first 12 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) longer sarcomeres, lower shear force value, a lighter colour (higher L* value), higher expressed juice and myofibrillar fragmentation index than those from non-stimulated ones. Meat from transported goats had significantly higher pH, expressed juice and shear force, but contained significantly lower sarcomere length and L* values than non-transported goats. The proportion of the myosin ATPase staining did not change as a function of stimulation, transportation or breed. These results indicated that subjecting goats to transportation for 3 h under high ambient temperatures can generate major physiological and muscle metabolism responses. Electrical stimulation improved quality characteristics of meat from both groups
Skeletal muscle PLIN3 and PLIN5 are serine phosphorylated at rest and following lipolysis during adrenergic or contractile stimulation

PubMed Central

MacPherson, Rebecca E K; Vandenboom, Rene; Roy, Brian D; Peters, Sandra J

2013-01-01

In adipose tissue, access of adipose triglyceride and hormone-sensitive lipases (ATGL and HSL) to the lipid droplet depends on PLIN1 phosphorylation, however, PLIN1 is not expressed in skeletal muscle and the phosphorylation of the expressed PLINs has yet to be investigated. Further, direct interactions between skeletal muscle PLINs and HSL are unknown. We investigated the isolated and combined effects of epinephrine and contraction on PLIN-to-lipase interactions as well as phosphorylation. Isolated rat solei were assigned to one of four 30 min in vitro conditions (25°C): (1) rest; (2) intermittent tetanic stimulation (60 Hz for 150 msec; train rate 20/min); (3) 5 nmol/L epinephrine; (4) intermittent tetanic stimulation and 5 nmol/L epinephrine. Immunoprecipitation of serine phosphorylated proteins followed by Western blotting for PLIN2, PLIN3, PLIN5, revealed that only PLIN2 is not phosphorylated under any of the experimental conditions. This is the first study to show that in whole rat skeletal muscle PLIN3 and PLIN5 are serine phosphorylated. The degree of serine phosphorylation remained unchanged following adrenergic and/or contractile stimulation. Oil red O staining of muscle sections for lipid content shows a significant decrease following each condition, confirming lipolysis occurred (P < 0.05). PLIN2, 3, and 5 all interact with HSL and ATGL, but these interactions were unchanged following treatments. Our results show that in skeletal muscle, PLIN2 is not serine phosphorylated at rest or with lipolytic stimulation and that while PLIN3, PLIN5 are serine phosphorylated at rest, the degree of phosphorylation does not change with lipolytic stimulation. PMID:24303154
Trichinella spiralis: nurse cell formation with emphasis on analogy to muscle cell repair

PubMed Central

Wu, Zhiliang; Sofronic-Milosavljevic, Lj; Nagano, Isao; Takahashi, Yuzo

2008-01-01

Trichinella infection results in formation of a capsule in infected muscles. The capsule is a residence of the parasite which is composed of the nurse cell and fibrous wall. The process of nurse cell formation is complex and includes infected muscle cell response (de-differentiation, cell cycle re-entry and arrest) and satellite cell responses (activation, proliferation and differentiation). Some events that occur during the nurse cell formation are analogous to those occurring during muscle cell regeneration/repair. This article reviews capsule formation with emphasis on this analogy. PMID:18710582
Electrical stimulation of the lumbrical muscles in an incomplete quadriplegic patient: case report.

PubMed

Carroll, S G; Bird, S F; Brown, D J

1992-03-01

The increasing number of incomplete cervical spinal cord injuries means that more attention needs to be focused on the rehabilitation of the incomplete quadriplegic hand. A case study, describing the application of electrical stimulation for strengthening the paretic lumbrical muscles, is presented. A 2 week strengthening program resulted in a 33% increase in the force produced by the lumbrical muscles. No loss of strength had occurred 4 weeks after cessation of the treatment. The magnitude and speed of this result should be of interest to those clinicians who seek to maximise patient independence in minimal time.
Apoptosis in capillary endothelial cells in ageing skeletal muscle

PubMed Central

Wang, Huijuan; Listrat, Anne; Meunier, Bruno; Gueugneau, Marine; Coudy-Gandilhon, Cécile; Combaret, Lydie; Taillandier, Daniel; Polge, Cécile; Attaix, Didier; Lethias, Claire; Lee, Kijoon; Goh, Kheng Lim; Béchet, Daniel

2014-01-01

The age-related loss of skeletal muscle mass and function (sarcopenia) is a consistent hallmark of ageing. Apoptosis plays an important role in muscle atrophy, and the intent of this study was to specify whether apoptosis is restricted to myofibre nuclei (myonuclei) or occurs in satellite cells or stromal cells of extracellular matrix (ECM). Sarcopenia in mouse gastrocnemius muscle was characterized by myofibre atrophy, oxidative type grouping, delocalization of myonuclei and ECM fibrosis. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) indicated a sharp rise in apoptosis during ageing. TUNEL coupled with immunostaining for dystrophin, paired box protein-7 (Pax7) or laminin-2α, respectively, was used to identify apoptosis in myonuclei, satellite cells and stromal cells. In adult muscle, apoptosis was not detected in myofibres, but was restricted to stromal cells. Moreover, the age-related rise in apoptotic nuclei was essentially due to stromal cells. Myofibre-associated apoptosis nevertheless occurred in old muscle, but represented < 20% of the total muscle apoptosis. Specifically, apoptosis in old muscle affected a small proportion (0.8%) of the myonuclei, but a large part (46%) of the Pax7+ satellite cells. TUNEL coupled with CD31 immunostaining further attributed stromal apoptosis to capillary endothelial cells. Age-dependent rise in apoptotic capillary endothelial cells was concomitant with altered levels of key angiogenic regulators, perlecan and a perlecan domain V (endorepellin) proteolytic product. Collectively, our results indicate that sarcopenia is associated with apoptosis of satellite cells and impairment of capillary functions, which is likely to contribute to the decline in muscle mass and functionality during ageing. PMID:24245531

Skeletal muscle cells express ICAM-1 after muscle overload and ICAM-1 contributes to the ensuing hypertrophic response.

PubMed

Dearth, Christopher L; Goh, Qingnian; Marino, Joseph S; Cicinelli, Peter A; Torres-Palsa, Maria J; Pierre, Philippe; Worth, Randall G; Pizza, Francis X

2013-01-01

We previously reported that leukocyte specific β2 integrins contribute to hypertrophy after muscle overload in mice. Because intercellular adhesion molecule-1 (ICAM-1) is an important ligand for β2 integrins, we examined ICAM-1 expression by murine skeletal muscle cells after muscle overload and its contribution to the ensuing hypertrophic response. Myofibers in control muscles of wild type mice and cultures of skeletal muscle cells (primary and C2C12) did not express ICAM-1. Overload of wild type plantaris muscles caused myofibers and satellite cells/myoblasts to express ICAM-1. Increased expression of ICAM-1 after muscle overload occurred via a β2 integrin independent mechanism as indicated by similar gene and protein expression of ICAM-1 between wild type and β2 integrin deficient (CD18-/-) mice. ICAM-1 contributed to muscle hypertrophy as demonstrated by greater (p<0.05) overload-induced elevations in muscle protein synthesis, mass, total protein, and myofiber size in wild type compared to ICAM-1-/- mice. Furthermore, expression of ICAM-1 altered (p<0.05) the temporal pattern of Pax7 expression, a marker of satellite cells/myoblasts, and regenerating myofiber formation in overloaded muscles. In conclusion, ICAM-1 expression by myofibers and satellite cells/myoblasts after muscle overload could serve as a mechanism by which ICAM-1 promotes hypertrophy by providing a means for cell-to-cell communication with β2 integrin expressing myeloid cells.
Skeletal Muscle Cells Express ICAM-1 after Muscle Overload and ICAM-1 Contributes to the Ensuing Hypertrophic Response

PubMed Central

Dearth, Christopher L.; Goh, Qingnian; Marino, Joseph S.; Cicinelli, Peter A.; Torres-Palsa, Maria J.; Pierre, Philippe; Worth, Randall G.; Pizza, Francis X.

2013-01-01

We previously reported that leukocyte specific β2 integrins contribute to hypertrophy after muscle overload in mice. Because intercellular adhesion molecule-1 (ICAM-1) is an important ligand for β2 integrins, we examined ICAM-1 expression by murine skeletal muscle cells after muscle overload and its contribution to the ensuing hypertrophic response. Myofibers in control muscles of wild type mice and cultures of skeletal muscle cells (primary and C2C12) did not express ICAM-1. Overload of wild type plantaris muscles caused myofibers and satellite cells/myoblasts to express ICAM-1. Increased expression of ICAM-1 after muscle overload occurred via a β2 integrin independent mechanism as indicated by similar gene and protein expression of ICAM-1 between wild type and β2 integrin deficient (CD18-/-) mice. ICAM-1 contributed to muscle hypertrophy as demonstrated by greater (p<0.05) overload-induced elevations in muscle protein synthesis, mass, total protein, and myofiber size in wild type compared to ICAM-1-/- mice. Furthermore, expression of ICAM-1 altered (p<0.05) the temporal pattern of Pax7 expression, a marker of satellite cells/myoblasts, and regenerating myofiber formation in overloaded muscles. In conclusion, ICAM-1 expression by myofibers and satellite cells/myoblasts after muscle overload could serve as a mechanism by which ICAM-1 promotes hypertrophy by providing a means for cell-to-cell communication with β2 integrin expressing myeloid cells. PMID:23505517
Analysis of muscle activation in each body segment in response to the stimulation intensity of whole-body vibration.

PubMed

Lee, Dae-Yeon

2017-02-01

[Purpose] The purpose of this study was to investigate the effects of a whole-body vibration exercise, as well as to discuss the scientific basis to establish optimal intensity by analyzing differences between muscle activations in each body part, according to the stimulation intensity of the whole-body vibration. [Subjects and Methods ] The study subjects included 10 healthy men in their 20s without orthopedic disease. Representative muscles from the subjects' primary body segments were selected while the subjects were in upright positions on exercise machines; electromyography electrodes were attached to the selected muscles. Following that, the muscle activities of each part were measured at different intensities. No vibration, 50/80 in volume, and 10/25/40 Hz were mixed and applied when the subjects were on the whole-vibration exercise machines in upright positions. After that, electromyographic signals were collected and analyzed with the root mean square of muscular activation. [Results] As a result of the analysis, it was found that the muscle activation effects had statistically meaningful differences according to changes in exercise intensity in all 8 muscles. When the no-vibration status was standardized and analyzed as 1, the muscle effect became lower at higher frequencies, but became higher at larger volumes. [Conclusion] In conclusion, it was shown that the whole-body vibration stimulation promoted muscle activation across the entire body part, and the exercise effects in each muscle varied depending on the exercise intensities.
Effects of dexamethasone treatment on insulin-stimulated rates of glycolysis and glycogen synthesis in isolated incubated skeletal muscles of the rat.

PubMed Central

Leighton, B; Challiss, R A; Lozeman, F J; Newsholme, E A

1987-01-01

1. Rats were treated with dexamethasone for 4 days before measurement of the rates of lactate formation [which is an index of hexose transport; see Challiss, Lozeman, Leighton & Newsholme (1986) Biochem. J. 233, 377-381] and glycogen synthesis in response to various concentrations of insulin in isolated incubated soleus and extensor digitorum longus muscle preparations. 2. The concentration of insulin required to stimulate these processes half-maximally in soleus and extensor digitorum longus muscles isolated from control rats was about 100 muunits/ml. 3. Dexamethasone increases the concentration of insulin required to stimulate glycolysis half-maximally in soleus and extensor digitorum longus preparations to 250 and 300 muunits/ml respectively. The respective insulin concentrations necessary to stimulate glycogen synthesis half-maximally were about 430 and 370 muunits/ml for soleus and extensor digitorum longus muscle preparations isolated from steroid-treated rats. 5. Dexamethasone treatment did not change the amount of insulin bound to soleus muscle. PMID:3318810
Isolation, characterization, and molecular regulation of muscle stem cells

PubMed Central

Fukada, So-ichiro; Ma, Yuran; Ohtani, Takuji; Watanabe, Yoko; Murakami, Satoshi; Yamaguchi, Masahiko

2013-01-01

Skeletal muscle has great regenerative capacity which is dependent on muscle stem cells, also known as satellite cells. A loss of satellite cells and/or their function impairs skeletal muscle regeneration and leads to a loss of skeletal muscle power; therefore, the molecular mechanisms for maintaining satellite cells in a quiescent and undifferentiated state are of great interest in skeletal muscle biology. Many studies have demonstrated proteins expressed by satellite cells, including Pax7, M-cadherin, Cxcr4, syndecan3/4, and c-met. To further characterize satellite cells, we established a method to directly isolate satellite cells using a monoclonal antibody, SM/C-2.6. Using SM/C-2.6 and microarrays, we measured the genes expressed in quiescent satellite cells and demonstrated that Hesr3 may complement Hesr1 in generating quiescent satellite cells. Although Hesr1- or Hesr3-single knockout mice show a normal skeletal muscle phenotype, including satellite cells, Hesr1/Hesr3-double knockout mice show a gradual decrease in the number of satellite cells and increase in regenerative defects dependent on satellite cell numbers. We also observed that a mouse's genetic background affects the regenerative capacity of its skeletal muscle and have established a line of DBA/2-background mdx mice that has a much more severe phenotype than the frequently used C57BL/10-mdx mice. The phenotype of DBA/2-mdx mice also seems to depend on the function of satellite cells. In this review, we summarize the methodology of direct isolation, characterization, and molecular regulation of satellite cells based on our results. The relationship between the regenerative capacity of satellite cells and progression of muscular disorders is also summarized. In the last part, we discuss application of the accumulating scientific information on satellite cells to treatment of patients with muscular disorders. PMID:24273513
Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication

PubMed Central

Mackey, Abigail L.; Rasmussen, Lotte K.; Kadi, Fawzi; Schjerling, Peter; Helmark, Ida C.; Ponsot, Elodie; Aagaard, Per; Durigan, João Luiz Q.; Kjaer, Michael

2016-01-01

With this study we investigated the role of nonsteroidal anti-inflammatory drugs (NSAIDs) in human skeletal muscle regeneration. Young men ingested NSAID [1200 mg/d ibuprofen (IBU)] or placebo (PLA) daily for 2 wk before and 4 wk after an electrical stimulation–induced injury to the leg extensor muscles of one leg. Muscle biopsies were collected from the vastus lateralis muscles before and after stimulation (2.5 h and 2, 7, and 30 d) and were assessed for satellite cells and regeneration by immunohistochemistry and real-time RT-PCR, and we also measured telomere length. After injury, and compared with PLA, IBU was found to augment the proportion of ActiveNotch1+ satellite cells at 2 d [IBU, 29 ± 3% vs. PLA, 19 ± 2% (means ± sem)], satellite cell content at 7 d [IBU, 0.16 ± 0.01 vs. PLA, 0.12 ± 0.01 (Pax7+ cells/fiber)], and to expedite muscle repair at 30 d. The PLA group displayed a greater proportion of embryonic myosin+ fibers and a residual ∼2-fold increase in mRNA levels of matrix proteins (all P < 0.05). Endomysial collagen was also elevated with PLA at 30 d. Minimum telomere length shortening was not observed. In conclusion, ingestion of NSAID has a potentiating effect on Notch activation of satellite cells and muscle remodeling during large-scale regeneration of injured human skeletal muscle.—Mackey, A. L., Rasmussen, L. K., Kadi, F., Schjerling, P., Helmark, I. C., Ponsot, E., Aagaard, P., Durigan, J. L. Q., Kjaer, M. Activation of satellite cells and the regeneration of human skeletal muscle are expedited by ingestion of nonsteroidal anti-inflammatory medication. PMID:26936358
Whole body heat stress attenuates the pressure response to muscle metaboreceptor stimulation in humans.

PubMed

Cui, Jian; Blaha, Cheryl; Sinoway, Lawrence I

2016-11-01

The effects of whole body heat stress on sympathetic and cardiovascular responses to stimulation of muscle metaboreceptors and mechanoreceptors remains unclear. We examined the muscle sympathetic nerve activity (MSNA), blood pressure, and heart rate in 14 young healthy subjects during fatiguing isometric handgrip exercise, postexercise circulatory occlusion (PECO), and passive muscle stretch during PECO. The protocol was performed under normothermic and whole body heat stress (increase internal temperature ~0.6°C via a heating suit) conditions. Heat stress increased the resting MSNA and heart rate. Heat stress did not alter the mean blood pressure (MAP), heart rate, and MSNA responses (i.e., changes) to fatiguing exercise. During PECO, whole body heat stress accentuated the heart rate response [change (Δ) of 5.8 ± 1.5 to Δ10.0 ± 2.1 beats/min, P = 0.03], did not alter the MSNA response (Δ16.4 ± 2.8 to Δ17.3 ± 3.8 bursts/min, P = 0.74), and lowered the MAP response (Δ20 ± 2 to Δ12 ± 1 mmHg, P < 0.001). Under normothermic conditions, passive stretch during PECO evoked significant increases in MAP and MSNA (both P < 0.001). Of note, heat stress prevented the MAP and MSNA responses to stretch during PECO (both P > 0.05). These data suggest that whole body heat stress attenuates the pressor response due to metaboreceptor stimulation, and the sympathetic nerve response due to mechanoreceptor stimulation. Copyright © 2016 the American Physiological Society.
Inducing myoblast re-entry into the cell cycle: a potential mechanism for laser-enhanced skeletal muscle regeneration

NASA Astrophysics Data System (ADS)

Liu, T.; Fang, Y.; Zhang, C. P.; Chen, P.; Wang, C. Z.; Kang, H. X.; Shen, B. J.; Liang, J.; Fu, X. B.

2014-09-01

This study investigated the effect of low-level laser irradiation (LLLI) on the cell cycle and proliferative activity of cultured myoblasts, and sought to elucidate the possible cellular mechanism by which LLLI promotes the regeneration of skeletal muscle in vivo. Primary myoblasts isolated from rat hindlegs were irradiated with helium-neon laser light at different energy densities. Distributions of cell-cycle subpopulations and the expression of cell-cycle regulatory proteins in myoblasts were assessed using flow cytometric analysis and western blot assay. It was found that laser irradiation stimulated cell-cycle entry; induced the expression of cyclin A and cyclin D; and increased cell proliferation index and bromodeoxyuridine incorporation as compared to the unirradiated control cells, indicating LLLI augmented the number of proliferative myoblasts in the S phase and G2/M phase of the cell cycle. These results suggest that LLLI at certain fluxes and wavelengths could activate quiescent myoblasts, leading to cell division and facilitating new myofiber formation. This could contribute to the improvement of skeletal muscle regeneration following trauma and myopathic diseases.
Injectable biomimetic liquid crystalline scaffolds enhance muscle stem cell transplantation

PubMed Central

Sleep, Eduard; McClendon, Mark T.; Preslar, Adam T.; Chen, Charlotte H.; Sangji, M. Hussain; Pérez, Charles M. Rubert; Haynes, Russell D.; Meade, Thomas J.; Blau, Helen M.; Stupp, Samuel I.

2017-01-01

Muscle stem cells are a potent cell population dedicated to efficacious skeletal muscle regeneration, but their therapeutic utility is currently limited by mode of delivery. We developed a cell delivery strategy based on a supramolecular liquid crystal formed by peptide amphiphiles (PAs) that encapsulates cells and growth factors within a muscle-like unidirectionally ordered environment of nanofibers. The stiffness of the PA scaffolds, dependent on amino acid sequence, was found to determine the macroscopic degree of cell alignment templated by the nanofibers in vitro. Furthermore, these PA scaffolds support myogenic progenitor cell survival and proliferation and they can be optimized to induce cell differentiation and maturation. We engineered an in vivo delivery system to assemble scaffolds by injection of a PA solution that enabled coalignment of scaffold nanofibers with endogenous myofibers. These scaffolds locally retained growth factors, displayed degradation rates matching the time course of muscle tissue regeneration, and markedly enhanced the engraftment of muscle stem cells in injured and noninjured muscles in mice. PMID:28874575
Branched Chain Amino Acid Oxidation in Cultured Rat Skeletal Muscle Cells

PubMed Central

Pardridge, William M.; Casanello-Ertl, Delia; Duducgian-Vartavarian, Luiza

1980-01-01

Leucine metabolism in skeletal muscle is linked to protein turnover. Since clofibrate is known both to cause myopathy and to decrease muscle protein content, the present investigations were designed to examine the effects of acute clofibrate treatment on leucine oxidation. Rat skeletal muscle cells in tissue culture were used in these studies because cultivated skeletal muscle cells, like muscle in vivo, have been shown to actively utilize branched chain amino acids and to produce alanine. The conversion of [1-14C]leucine to 14CO2 or to the [1-14C]keto-acid of leucine (α-keto-isocaproate) was linear for at least 2 h of incubation; the production of 14CO2 from [1-14C]leucine was saturable with a Km = 6.3 mM and a maximum oxidation rate (Vmax) = 31 nmol/mg protein per 120 min. Clofibric acid selectively inhibited the oxidation of [1-14C]leucine (Ki = 0.85 mM) and [U-14C]isoleucine, but had no effect on the oxidation of [U-14C]glutamate, -alanine, -lactate, or -palmitate. The inhibition of [1-14C]leucine oxidation by clofibrate was also observed in the rat quarter-diaphragm preparation. Clofibrate primarily inhibited the production of 14CO2 and had relatively little effect on the production of [1-14C]keto-acid of leucine. A physiological concentration—3.0 g/100 ml—of albumin, which actively binds clofibric acid, inhibited but did not abolish the effects of a 2-mM concentration of clofibric acid on leucine oxidation. Clofibrate treatment stimulated the net consumption of pyruvate, and inhibited the net production of alanine. The drug also increased the cytosolic NADH/NAD+ ratio as reflected by an increase in the lactate/pyruvate ratio, in association with a decrease in cell aspartate levels. The changes in pyruvate metabolism and cell redox state induced by the drug were delayed compared with the nearly immediate inhibition of leucine oxidation. These studies suggest that clofibric acid, in concentrations that approximate high therapeutic levels of the drug
Muscle stem cell dysfunction impairs muscle regeneration in a mouse model of Down syndrome.

PubMed

Pawlikowski, Bradley; Betta, Nicole Dalla; Elston, Tiffany; Williams, Darian A; Olwin, Bradley B

2018-03-09

Down syndrome, caused by trisomy 21, is characterized by a variety of medical conditions including intellectual impairments, cardiovascular defects, blood cell disorders and pre-mature aging phenotypes. Several somatic stem cell populations are dysfunctional in Down syndrome and their deficiencies may contribute to multiple Down syndrome phenotypes. Down syndrome is associated with muscle weakness but skeletal muscle stem cells or satellite cells in Down syndrome have not been investigated. We find that a failure in satellite cell expansion impairs muscle regeneration in the Ts65Dn mouse model of Down syndrome. Ts65Dn satellite cells accumulate DNA damage and over express Usp16, a histone de-ubiquitinating enzyme that regulates the DNA damage response. Impairment of satellite cell function, which further declines as Ts65Dn mice age, underscores stem cell deficiencies as an important contributor to Down syndrome pathologies.
Nuclear fusion-independent smooth muscle differentiation of human adipose-derived stem cells induced by a smooth muscle environment.

PubMed

Zhang, Rong; Jack, Gregory S; Rao, Nagesh; Zuk, Patricia; Ignarro, Louis J; Wu, Benjamin; Rodríguez, Larissa V

2012-03-01

Human adipose-derived stem cells hASC have been isolated and were shown to have multilineage differentiation capacity. Although both plasticity and cell fusion have been suggested as mechanisms for cell differentiation in vivo, the effect of the local in vivo environment on the differentiation of adipose-derived stem cells has not been evaluated. We previously reported the in vitro capacity of smooth muscle differentiation of these cells. In this study, we evaluate the effect of an in vivo smooth muscle environment in the differentiation of hASC. We studied this by two experimental designs: (a) in vivo evaluation of smooth muscle differentiation of hASC injected into a smooth muscle environment and (b) in vitro evaluation of smooth muscle differentiation capacity of hASC exposed to bladder smooth muscle cells. Our results indicate a time-dependent differentiation of hASC into mature smooth muscle cells when these cells are injected into the smooth musculature of the urinary bladder. Similar findings were seen when the cells were cocultured in vitro with primary bladder smooth muscle cells. Chromosomal analysis demonstrated that microenvironment cues rather than nuclear fusion are responsible for this differentiation. We conclude that cell plasticity is present in hASCs, and their differentiation is accomplished in the absence of nuclear fusion. Copyright © 2011 AlphaMed Press.
Xin, an actin binding protein, is expressed within muscle satellite cells and newly regenerated skeletal muscle fibers.

PubMed

Hawke, Thomas J; Atkinson, Daniel J; Kanatous, Shane B; Van der Ven, Peter F M; Goetsch, Sean C; Garry, Daniel J

2007-11-01

Xin is a muscle-specific actin binding protein of which its role and regulation within skeletal muscle is not well understood. Here we demonstrate that Xin mRNA is robustly upregulated (>16-fold) within 12 h of skeletal muscle injury and is localized to the muscle satellite cell population. RT-PCR confirmed the expression pattern of Xin during regeneration, as well as within primary muscle myoblast cultures, but not other known stem cell populations. Immunohistochemical staining of single myofibers demonstrate Xin expression colocalized with the satellite cell marker Syndecan-4 further supporting the mRNA expression of Xin in satellite cells. In situ hybridization of regenerating muscle 5-7 days postinjury illustrates Xin expression within newly regenerated myofibers. Promoter-reporter assays demonstrate that known myogenic transcription factors [myocyte enhancer factor-2 (MEF2), myogenic differentiation-1 (MyoD), and myogenic factor-5 (Myf-5)] transactivate Xin promoter constructs supporting the muscle-specific expression of Xin. To determine the role of Xin within muscle precursor cells, proliferation, migration, and differentiation analysis using Xin, short hairpin RNA (shRNA) were undertaken in C2C12 myoblasts. Reducing endogenous Xin expression resulted in a 26% increase (P < 0.05) in cell proliferation and a 20% increase (P < 0.05) in myoblast migratory capacity. Skeletal muscle myosin heavy chain protein levels were increased (P < 0.05) with Xin shRNA administration; however, this was not accompanied by changes in myoglobin protein (another marker of differentiation) nor overt morphological differences relative to differentiating control cells. Taken together, the present findings support the hypothesis that Xin is expressed within muscle satellite cells during skeletal muscle regeneration and is involved in the regulation of myoblast function.
IGF1 stimulates greater muscle hypertrophy in the absence of myostatin in male mice

USDA-ARS?s Scientific Manuscript database

Insulin-like growth factors (IGFs) and myostatin have opposing roles in regulating the growth and size of skeletal muscle, with IGF1 stimulating, and myostatin inhibiting, growth. However, it remains unclear whether these proteins have mutually dependent, or independent, roles. To clarify this issue...
Effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with knee osteoarthritis.

PubMed

Park, Seong Hoon; Hwangbo, Gak

2015-03-01

[Purpose] The aim of this study was to investigate the effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with osteoarthritis of the knee. [Subjects] Thirty women over 65 years of age diagnosed with knee osteoarthritis participated in the present study. The subjects were randomly assigned to a control group (n=10), a progressive resistance training group (n=10), or a Russian electrical stimulation group (n=10). [Methods] Each group was treated 3 times weekly for 8 weeks, and each session lasted 45 minutes. Muscle strength was assessed by measuring the peak torque of the quadriceps femoris muscle. Outcome measurements were performed at baseline and at the fourth and eighth weeks of the treatment period. [Results] All groups showed significant intragroup differences in the quadriceps femoris muscle peak torque after the treatment intervention. There were significant intergroup differences between the Russian electrical stimulation group and the other groups. [Conclusion] The results of this study suggest that combined application of progressive resistance training and Russian electrical stimulation can be effective in strengthening the quadriceps femoris muscle in elderly women with knee osteoarthritis.
Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on the decline and recovery of muscle force.

PubMed

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2017-05-02

Neuromuscular electrical stimulation (NMES) is commonly used to activate skeletal muscles and reverse muscle atrophy in clinical populations. Clinical recommendations for NMES suggest the use of short pulse widths (100-200 μs) and low-to-moderate pulse frequencies (30-50 Hz). However, this type of NMES causes rapid muscle fatigue due to the (non-physiological) high stimulation intensities and non-orderly recruitment of motor units. The use of both wide pulse widths (1000 μs) and tendon vibration might optimize motor unit activation through spinal reflex pathways and thus delay the onset of muscle fatigue, increasing muscle force and mass. Thus, the objective of this study was to examine the acute effects of patellar tendon vibration superimposed onto wide-pulse width (1000 μs) knee extensor electrical stimulation (NMES, 30 Hz) on peak muscle force, total impulse before "muscle fatigue", and the post-exercise recovery of muscle function. Tendon vibration (Vib), NMES (STIM) or NMES superimposed onto vibration (STIM + Vib) were applied in separate sessions to 16 healthy adults. Total torque-time integral (TTI), maximal voluntary contraction torque (MVIC) and indirect measures of muscle damage were tested before, immediately after, 1 h and 48 h after each stimulus. TTI increased (145.0 ± 127.7%) in STIM only for "positive responders" to the tendon vibration (8/16 subjects), but decreased in "negative responders" (-43.5 ± 25.7%). MVIC (-8.7%) and rectus femoris electromyography (RF EMG) (-16.7%) decreased after STIM (group effect) for at least 1 h, but not after STIM + Vib. No changes were detected in indirect markers of muscle damage in any condition. Tendon vibration superimposed onto wide-pulse width NMES increased TTI only in 8 of 16 subjects, but reduced voluntary force loss (fatigue) ubiquitously. Negative responders to tendon vibration may derive greater benefit from wide-pulse width NMES alone.
Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans.

PubMed

Everman, Sarah; Meyer, Christian; Tran, Lee; Hoffman, Nyssa; Carroll, Chad C; Dedmon, William L; Katsanos, Christos S

2016-10-01

Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change (P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased (P < 0.01) whole body phenylalanine rate of appearance (μmol·kg -1 ·min -1 ), indicating suppression of muscle proteolysis, in both the control (1.02 ± 0.04 vs 0.76 ± 0.04) and the BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments (P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA. Copyright © 2016 the American Physiological Society.
Insulin does not stimulate muscle protein synthesis during increased plasma branched-chain amino acids alone but still decreases whole body proteolysis in humans

PubMed Central

Everman, Sarah; Meyer, Christian; Tran, Lee; Hoffman, Nyssa; Carroll, Chad C.; Dedmon, William L.

2016-01-01

Insulin stimulates muscle protein synthesis when the levels of total amino acids, or at least the essential amino acids, are at or above their postabsorptive concentrations. Among the essential amino acids, branched-chain amino acids (BCAA) have the primary role in stimulating muscle protein synthesis and are commonly sought alone to stimulate muscle protein synthesis in humans. Fourteen healthy young subjects were studied before and after insulin infusion to examine whether insulin stimulates muscle protein synthesis in relation to the availability of BCAA alone. One half of the subjects were studied in the presence of postabsorptive BCAA concentrations (control) and the other half in the presence of increased plasma BCAA (BCAA). Compared with that prior to the initiation of the insulin infusion, fractional synthesis rate of muscle protein (%/h) did not change (P > 0.05) during insulin in either the control (0.04 ± 0.01 vs 0.05 ± 0.01) or the BCAA (0.05 ± 0.02 vs. 0.05 ± 0.01) experiments. Insulin decreased (P < 0.01) whole body phenylalanine rate of appearance (μmol·kg−1·min−1), indicating suppression of muscle proteolysis, in both the control (1.02 ± 0.04 vs 0.76 ± 0.04) and the BCAA (0.89 ± 0.07 vs 0.61 ± 0.03) experiments, but the change was not different between the two experiments (P > 0.05). In conclusion, insulin does not stimulate muscle protein synthesis in the presence of increased circulating levels of plasma BCAA alone. Insulin's suppressive effect on proteolysis is observed independently of the levels of circulating plasma BCAA. PMID:27530230
Skeletal Muscle Satellite Cell Activation Following Cutaneous Burn in Rats

DTIC Science & Technology

2013-12-01

satellite cell activation and survival during oxidative stress. J Muscle Res Cell Motil 2011;32(2):99–109. [33] Rathbone CR, Booth FW, Lees SJ. Sirt1 ...Skeletal muscle satellite cell activation following cutaneous burn in rats Xiaowu Wu*, Thomas J. Walters, Christopher R. Rathbone Extremity Trauma...f o Article history: Accepted 15 October 2012 Keywords: Muscle precursor cell Thermal injury Atrophy Skeletal muscle Activation a b s t r a c t
Kir2.1 regulates rat smooth muscle cell proliferation, migration, and post-injury carotid neointimal formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiao, Yong; Tang, Chengchun, E-mail: tangchengchun@medmail.com.cn; Wang, Qingjie

Phenotype switching of vascular smooth muscle cells (VSMC) from the contractile type to the synthetic type is a hallmark of vascular disorders such as atherosclerosis and restenosis after angioplasty. Inward rectifier K{sup +} channel 2.1 (Kir2.1) has been identified in VSMC. However, whether it plays a functional role in regulating cellular transformation remains obscure. In this study, we evaluated the role of Kir2.1 on VSMC proliferation, migration, phenotype switching, and post-injury carotid neointimal formation. Kir2.1 knockdown significantly suppressed platelet-derived growth factor BB-stimulated rat vascular smooth muscle cells (rat-VSMC) proliferation and migration. Deficiency in Kir2.1 contributed to the restoration of smoothmore » muscle α-actin, smooth muscle 22α, and calponin and to a reduction in osteopontin expression in rat-VSMC. Moreover, the in vivo study showed that rat-VSMC switched to proliferative phenotypes and that knockdown of Kir2.1 significantly inhibited neointimal formation after rat carotid injury. Kir2.1 may be a potential therapeutic target in the treatment of cardiovascular diseases, such as atherosclerosis and restenosis following percutaneous coronary intervention.« less

Transcriptome analysis of cattle muscle identifies potential markers for skeletal muscle growth rate and major cell types.

PubMed

Guo, Bing; Greenwood, Paul L; Cafe, Linda M; Zhou, Guanghong; Zhang, Wangang; Dalrymple, Brian P

2015-03-13

This study aimed to identify markers for muscle growth rate and the different cellular contributors to cattle muscle and to link the muscle growth rate markers to specific cell types. The expression of two groups of genes in the longissimus muscle (LM) of 48 Brahman steers of similar age, significantly enriched for "cell cycle" and "ECM (extracellular matrix) organization" Gene Ontology (GO) terms was correlated with average daily gain/kg liveweight (ADG/kg) of the animals. However, expression of the same genes was only partly related to growth rate across a time course of postnatal LM development in two cattle genotypes, Piedmontese x Hereford (high muscling) and Wagyu x Hereford (high marbling). The deposition of intramuscular fat (IMF) altered the relationship between the expression of these genes and growth rate. K-means clustering across the development time course with a large set of genes (5,596) with similar expression profiles to the ECM genes was undertaken. The locations in the clusters of published markers of different cell types in muscle were identified and used to link clusters of genes to the cell type most likely to be expressing them. Overall correspondence between published cell type expression of markers and predicted major cell types of expression in cattle LM was high. However, some exceptions were identified: expression of SOX8 previously attributed to muscle satellite cells was correlated with angiogenesis. Analysis of the clusters and cell types suggested that the "cell cycle" and "ECM" signals were from the fibro/adipogenic lineage. Significant contributions to these signals from the muscle satellite cells, angiogenic cells and adipocytes themselves were not as strongly supported. Based on the clusters and cell type markers, sets of five genes predicted to be representative of fibro/adipogenic precursors (FAPs) and endothelial cells, and/or ECM remodelling and angiogenesis were identified. Gene sets and gene markers for the analysis of
Neuromuscular Electrical Stimulation for Treatment of Muscle Impairment: Critical Review and Recommendations for Clinical Practice

PubMed Central

Houghton, Pamela; Anthony, Joseph; Rennie, Sandy; Shay, Barbara L.; Hoens, Alison M.

2017-01-01

Purpose: In response to requests from physiotherapists for guidance on optimal stimulation of muscle using neuromuscular electrical stimulation (NMES), a review, synthesis, and extraction of key data from the literature was undertaken by six Canadian physical therapy (PT) educators, clinicians, and researchers in the field of electrophysical agents. The objective was to identify commonly treated conditions for which there was a substantial body of literature from which to draw conclusions regarding the effectiveness of NMES. Included studies had to apply NMES with visible and tetanic muscle contractions. Method: Four electronic databases (CINAHL, Embase, PUBMED, and SCOPUS) were searched for relevant literature published between database inceptions until May 2015. Additional articles were identified from bibliographies of the systematic reviews and from personal collections. Results: The extracted data were synthesized using a consensus process among the authors to provide recommendations for optimal stimulation parameters and application techniques to address muscle impairments associated with the following conditions: stroke (upper or lower extremity; both acute and chronic), anterior cruciate ligament reconstruction, patellofemoral pain syndrome, knee osteoarthritis, and total knee arthroplasty as well as critical illness and advanced disease states. Summaries of key details from each study incorporated into the review were also developed. The final sections of the article outline the recommended terminology for describing practice using electrical currents and provide tips for safe and effective clinical practice using NMES. Conclusion: This article provides physiotherapists with a resource to enable evidence-informed, effective use of NMES for PT practice. PMID:29162949
Role of protein kinase C alpha and mitogen-activated protein kinases in endothelin-1-stimulation of cytosolic phospholipase A2 in iris sphincter smooth muscle.

PubMed

Abdel-Latif, A A; Husain, S; Yousufzai, S Y

2000-11-01

We have investigated the roles of protein kinase C (PKC) and mitogen-activated protein kinases (MAPK) in the phosphorylation and activation of cytosolic phospholipase A2 (cPLA2) in endothelin-1- (ET-1) stimulated cat iris sphincter smooth muscle (CISM) cells. We found that in these cells both PKC and p38 MAP kinases play a critical role in ET-1-induced cPLA, phosphorylation and arachidonic acid (AA) release. Our findings indicate that stimulation of the endothelin-A- (ET(A)) receptor leads to: (1) activation of Gq protein which stimulates phospholipase C to hydrolyze the polyphosphoinositide PIP, into diacylglycerol (DAG) and inositol trisphosphate (IP3), the DAG may then activate PKC to phosphorylate and activate cPLA2; and (2) activation of Gi protein, which, through a series of kinases, leads to the stimulation of p38 MAPK and subsequently to phosphorylation and activation of cPLA2. The ability of the activated ET(A)-receptor, which is coupled to both Gq and Gi proteins, to recruit and activate this complex signal transduction mechanism remains to be clarified.
Effects of the belt electrode skeletal muscle electrical stimulation system on lower extremity skeletal muscle activity: Evaluation using positron emission tomography.

PubMed

Numata, Hitoaki; Nakase, Junsuke; Inaki, Anri; Mochizuki, Takafumi; Oshima, Takeshi; Takata, Yasushi; Kinuya, Seigo; Tsuchiya, Hiroyuki

2016-01-01

Lower-extremity muscle weakness in athletes after lower limb trauma or surgery can hinder their return to sports, and the associated muscle atrophy may lead to deterioration in performance after returning to sports. Recently, belt electrode skeletal muscle electrical stimulation (B-SES) which can contract all the lower limb skeletal muscles simultaneously was developed. However, no study has evaluated skeletal muscle activity with B-SES. Since only superficial muscles as well as a limited number of muscles can be investigated using electromyography, we investigated whether positron emission tomography (PET) can evaluate the activity of all the skeletal muscles in the body simultaneously. The purpose of this study was to evaluate the effectiveness of the B-SES system using PET. Twelve healthy males (mean age, 24.3 years) were divided into two groups. The subjects in the control group remained in a sitting position for 10 min, and [(18)F] fluorodeoxyglucose (FDG) was intravenously injected. In the exercise group, subjects exercised using the B-SES system for 20 min daily for three consecutive days as a pre-test exercise. On the measurement day, they exercised for 10 min, received an injection of FDG, and exercised for another 10 min. PET-computed tomography images were obtained in each group 60 min after the FDG injection. Regions of interest were drawn in each lower-extremity muscle. We compared each skeletal muscle metabolism using the standardized uptake value. In the exercise group, FDG accumulation in the gluteus maximus, gluteus medius, gluteus minimus, quadriceps femoris, sartorius, and hamstrings was significantly higher than the muscles in the control (P < 0.05). Exercise with B-SES increased the skeletal muscle activity of the gluteal muscles as well as the most lower-extremity muscles simultaneously. Copyright © 2015 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Role of magnolol in the proliferation of vascular smooth muscle cells.

PubMed

Wu, L; Zou, H; Xia, W; Dong, Q; Wang, L

2015-05-01

Proliferation of vascular smooth muscle cells (VSMCs) contributes to the development of vascular remodeling. Recently, magnolol has been reported to have a potential role in regulating tumor necrosis factor α-induced proliferation of VSMCs. However, the role of magnolol in platelet-derived growth factor (PDGF)-induced proliferation of VSMCs remains unknown. Our purpose was to elucidate the effect of magnolol on the proliferation of VSMCs induced by PDGF-BB and to investigate the underlying molecular mechanisms. Our data demonstrated that magnolol inhibited rat VSMC proliferation and DNA synthesis stimulated by 20 ng/ml PDGF-BB without causing cell cytotoxicity. Flow cytometric analysis showed that magnolol inhibited S-phase entry of VSMCs. We also demonstrated that magnolol caused this effect by inhibiting the mRNA and protein expression of cyclin D1, cyclin E, and cyclin-dependent kinases 2 and 4 in PDGF-BB-stimulated VSMCs. Further analysis showed that the inhibitory effect of magnolol on the proliferation of VSMCs was associated with the inhibition of the PDGF-BB-stimulated production of intracellular reactive oxygen species (ROS) and Ras, MEK, and ERK1/2 activation. These results demonstrate that magnolol can block the proliferation of VSMCs through inhibition of intracellular ROS production and Ras-MEK-ERK1/2 pathways. Magnolol, therefore, has a potential application in preventing atherosclerosis and restenosis.
Electrical Stimulation of Artificial Heart Muscle: A Look Into the Electrophysiologic and Genetic Implications.

PubMed

Mohamed, Mohamed A; Islas, Jose F; Schwartz, Robert J; Birla, Ravi K

Development of tissue-engineered hearts for treatment of myocardial infarction or biologic pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. To further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously. In this study, we examined the effect of an intermittent biphasic square wave on our artificial heart muscle (AHM) composed of neonatal rat cardiac cells and fibrin gel. Twitch forces, spontaneous contraction rates, biopotentials, gene expression profiles, and histologic observations were examined for the ES protocol over a 12 day culture period. We demonstrate improved consistency between samples for twitch force and contraction rate, and higher normalized twitch force amplitudes for electrically stimulated AHMs. Improvements in electrophysiology within the AHM were noted by higher conduction velocities and lower latency in electrical response for electrically stimulated AHMs. Genes expressing key electrophysiologic and structural markers peaked at days 6 and 8 of culture, only a few days after the initiation of ES. These results may be used for optimization strategies to establish protocols for producing AHMs capable of replacing damaged heart tissue in either a contractile or electrophysiologic capacity. Optimized AHMs can lead to alternative treatments to heart failure and alleviate the limited donor supply crisis.
Electrical Stimulation of Artificial Heart Muscle: a look into the electrophysiological and genetic implications

PubMed Central

Mohamed, Mohamed A; Islas, Jose F; Schwartz, Robert J; Birla, Ravi K

2016-01-01

Development of tissue-engineered hearts for treatment of myocardial infarction or biological pacemakers has been hindered by the production of mostly arrhythmic or in-synergistic constructs. Electrical stimulation (ES) of these constructs has been shown to produce tissues with greater twitch force and better adrenergic response. In order to further our understanding of the mechanisms underlying the effect of ES, we fabricated a bioreactor capable of delivering continuous or intermittent waveforms of various types to multiple constructs simultaneously. In this study, we examined the effect of an intermittent biphasic square wave on our artificial heart muscle (AHM) composed of neonatal rat cardiac cells and fibrin gel. Twitch forces, spontaneous contraction rates, biopotentials, gene expression profiles, and histological observations were examined for the ES protocol over a 12 day culture period. We demonstrate improved consistency between samples for twitch force and contraction rate, and higher normalized twitch force amplitudes for electrically stimulated AHM. Improvements in electrophysiology within the AHM was noted by higher conduction velocities and lower latency in electrical response for electrically stimulated AHM. Genes expressing key electrophysiological and structural markers peaked at days 6 and 8 of culture, only a few days after the initiation of ES. These results may be used for optimization strategies to establish protocols for producing AHM capable of replacing damaged heart tissue in either a contractile or electrophysiological capacity. Optimized AHM can lead to alternative treatments to heart failure and alleviate the limited donor supply crisis. PMID:28459744
Alternate rhythmic vibratory stimulation of trunk muscles affects walking cadence and velocity in Parkinson's disease.

PubMed

De Nunzio, Alessandro M; Grasso, Margherita; Nardone, Antonio; Godi, Marco; Schieppati, Marco

2010-02-01

During the administration of timed bilateral alternate vibration to homonymous leg or trunk muscles during quiet upright stance, Parkinsonian (PD) patients undergo cyclic antero-posterior and medio-lateral transfers of the centre of foot pressure. This event might be potentially exploited for improving gait in these patients. Here, we tested this hypothesis by applying alternate muscle vibration during walking in PD. Fifteen patients and 15 healthy subjects walked on an instrumented walkway under four conditions: no vibration (no-Vib), and vibration of tibialis anterior (TA-Vib), soleus (Sol-Vib) and erector spinae (ES-Vib) muscles of both sides. Trains of vibration (internal frequency 100 Hz) were delivered to right and left side at alternating frequency of 10% above preferred step cadence. During vibration, stride length, cadence and velocity increased in both patients and healthy subjects, significantly so for ES-Vib. Stance and swing time tended to decrease. Width of support base increased with Sol-Vib or TA-Vib, but was unaffected by ES-Vib. Alternate ES vibration enhances gait velocity in PD. The stronger effect of ES over leg muscle vibration might depend on the relevance of the proprioceptive inflow from the trunk muscles and on the absence of adverse effects on the support base width. Trunk control is defective in PD. The effect of timed vibratory stimulation on gait suggests the potential use of trunk proprioceptive stimulation for tuning the central pattern generators for locomotion in PD. Copyright (c) 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Single Cell Gene Expression Profiling of Skeletal Muscle-Derived Cells.

PubMed

Gatto, Sole; Puri, Pier Lorenzo; Malecova, Barbora

2017-01-01

Single cell gene expression profiling is a fundamental tool for studying the heterogeneity of a cell population by addressing the phenotypic and functional characteristics of each cell. Technological advances that have coupled microfluidic technologies with high-throughput quantitative RT-PCR analyses have enabled detailed analyses of single cells in various biological contexts. In this chapter, we describe the procedure for isolating the skeletal muscle interstitial cells termed Fibro-Adipogenic Progenitors (FAPs ) and their gene expression profiling at the single cell level. Moreover, we accompany our bench protocol with bioinformatics analysis designed to process raw data as well as to visualize single cell gene expression data. Single cell gene expression profiling is therefore a useful tool in the investigation of FAPs heterogeneity and their contribution to muscle homeostasis.
Isolation of Primary Human Skeletal Muscle Cells

PubMed Central

Spinazzola, Janelle M.; Gussoni, Emanuela

2017-01-01

Primary myoblast culture is a valuable tool in research of muscle disease, pathophysiology, and pharmacology. This protocol describes techniques for dissociation of cells from human skeletal muscle biopsies and enrichment for a highly myogenic population by fluorescence-activated cell sorting (FACS). We also describe methods for assessing myogenicity and population expansion for subsequent in vitro study. PMID:29152538
[gammadelta T cells stimulated by zoledronate kill osteosarcoma cells].

PubMed

Jiang, Hui; Xu, Qiang; Yang, Chao; Cao, Zhen-Guo; Li, Zhao-Xu; Ye, Zhao-Ming

2010-12-01

To investigate the cytotoxicity of human γδT cells from PBMCs stimulated by zoledronate against osteosarcoma cell line HOS in vitro and in vivo and evaluate the relavent pathways. The peripheral blood mononuclear cells (PBMCs)of healthy donors were stimulated by single dose zoledronate and cultured in the present of IL-2 for two weeks, analysising the percentage of γδT cells on a FACSCalibur cytometer.Study the cytotoxicity of γδT cells against the osteosarcoma line HOS using LDH release assay kit. Pre-treatment of γδT cells with anti-human γδTCR antibody, anti-human NKG2D antibody and concanamycin A to bolck the relavent pathways for evaluating the mechenisms of its cytotoxicity. In vivo, BALB/c mice were inoculated subcutaneously osteosarcoma cell HOS for developing hypodermal tumors. And they were randomized into two groups: unteated group, γδT cell therapy group. Tumor volume and weight of the two groups were compared. After two weeks of culture, γδT cells from zoledronate-stimulated PBMCs could reach (95±3)%. When the E:T as 6:1, 12:1, 25:1, 50:1, the percentage of osteosarcoma cell HOS killed by γδT cells was 26.8%, 31.5%, 37.8%, 40.9%, respectively.When anti-huma γδTCR antibody, anti-human NKG2D antibody and concanamycin A blocked the relavent pathways, the percentage was 32.3%, 4.7%, 16.7% ( E:T as 25:1), respectively. In vivo, the tumor inhibition rate of the group of γδT cell therapy was 42.78%. γδT cells derived from PBMCs stimulated by zoledronate can acquired pure γδT cells. And they show strong cytoxicity against osteosarcoma cell line HOS in vitro and in vivo.
Optimal arrangement of magnetic coils for functional magnetic stimulation of the inspiratory muscles in dogs.

PubMed

Lin, Vernon Weh-Hau; Zhu, Ercheng; Sasse, Scott A; Sassoon, Catherine; Hsiao, Ian N

2005-12-01

In an attempt to maximize inspiratory pressure and volume, the optimal position of a single or of dual magnetic coils during functional magnetic stimulation (FMS) of the inspiratory muscles was evaluated in twenty-three dogs. Unilateral phrenic magnetic stimulation (UPMS) or bilateral phrenic magnetic stimulation (BPMS), posterior cervical magnetic stimulation (PCMS), anterior cervical magnetic stimulation (ACMS) as well as a combination of PCMS and ACMS were performed. Trans-diaphragmatic pressure (Pdi), flow, and lung volume changes with an open airway were measured. Transdiaphragmatic pressure was also measured with an occluded airway. Changes in inspiratory parameters during FMS were compared with 1) electrical stimulation of surgically exposed bilateral phrenic nerves (BPES) and 2) ventral root electrical stimulation at C5-C7 (VRES C5-C7). Relative to the Pdi generated by BPES of 36.3 +/- 4.5 cm H2O (Mean +/- SEM), occluded Pdi(s) produced by UPMS, BPMS, PCMS, ACMS, and a combined PCMS + ACMS were 51.7%, 61.5%, 22.4%, 100.3%, and 104.5% of the maximal Pdi, respectively. Pdi(s) produced by UPMS, BPMS, PCMS, ACMS, and combined ACMS + PCMS were 38.0%, 45.2%, 16.5%, 73.8%, and 76.8%, respectively, of the Pdi induced by VRES (C5-C7) (48.0 +/- 3.9 cm H2O). The maximal Pdi(s) generated during ACMS and combined PCMS + ACMS were higher than the maximal Pdi(s) generated during UPMS, BPMS, or PCMS (p < 0.05). ACMS alone induced 129.8% of the inspiratory flow (73.0 +/- 9.4 L/ min) and 77.5% of the volume (626 +/- 556 ml) induced by BPES. ACMS and combined PCMS + ACMS produce a greater inspiratory pressure than UPMS, BPMS or PCMS. ACMS can be used to generate sufficient inspiratory pressure, flow, and volume for activation of the inspiratory muscles.
JunB transcription factor maintains skeletal muscle mass and promotes hypertrophy

PubMed Central

Raffaello, Anna; Milan, Giulia; Masiero, Eva; Carnio, Silvia; Lee, Donghoon

2010-01-01

The size of skeletal muscle cells is precisely regulated by intracellular signaling networks that determine the balance between overall rates of protein synthesis and degradation. Myofiber growth and protein synthesis are stimulated by the IGF-1/Akt/mammalian target of rapamycin (mTOR) pathway. In this study, we show that the transcription factor JunB is also a major determinant of whether adult muscles grow or atrophy. We found that in atrophying myotubes, JunB is excluded from the nucleus and that decreasing JunB expression by RNA interference in adult muscles causes atrophy. Furthermore, JunB overexpression induces hypertrophy without affecting satellite cell proliferation and stimulated protein synthesis independently of the Akt/mTOR pathway. When JunB is transfected into denervated muscles, fiber atrophy is prevented. JunB blocks FoxO3 binding to atrogin-1 and MuRF-1 promoters and thus reduces protein breakdown. Therefore, JunB is important not only in dividing populations but also in adult muscle, where it is required for the maintenance of muscle size and can induce rapid hypertrophy and block atrophy. PMID:20921137
Testosterone Combined with Electrical Stimulation and Standing: Effect on Muscle and Bone

DTIC Science & Technology

2015-10-01

JJPVAMC). During year 1 of the study, the Study Team (Drs. Forrest, Bauman, and Harkema) established a new partnership with a pharmaceutical company...AbbVie) to supply Drug and Placebo for all potential study participants. Each of the study sites submitted to the pharmaceutical company all requested...stimulation, dynamic standing protocol, muscle volume, MRI , bone mineral density, DXA, QCT scans, blood markers, urine markers, 60 sessions of training
The pH heterogeneity in human calf muscle during neuromuscular electrical stimulation.

PubMed

Stutzig, Norman; Rzanny, Reinhard; Moll, Kevin; Gussew, Alexander; Reichenbach, Jürgen R; Siebert, Tobias

2017-06-01

The aim of the study was to examine pH heterogeneity during fatigue induced by neuromuscular electrical stimulation (NMES) using phosphorus magnetic resonance spectroscopy ( 31 P-MRS). It is hypothesized that three pH components would occur in the 31 P-MRS during fatigue, representing three fiber types. The medial gastrocnemius of eight subjects was stimulated within a 3-Tesla whole body MRI scanner. The maximal force during stimulation (F stim ) was examined by a pressure sensor. Phosphocreatine (PCr), adenosintriphosphate, inorganic phosphate (Pi), and the corresponding pH were estimated by a nonvolume-selective 31 P-MRS using a small loop coil at rest and during fatigue. During fatigue, F stim and PCr decreased to 27% and 33% of their initial levels, respectively. In all cases, the Pi peak increased when NMES was started and split into three different peaks. Based on the single Pi peaks during fatigue, an alkaline (6.76 ± 0.08), a medium (6.40 ± 0.06), and an acidic (6.09 ± 0.05) pH component were observed compared to the pH (7.02 ± 0.02) at rest. It is suggested that NMES is able to induce pH heterogeneity in the medial gastrocnemius, and that the single Pi peaks represent the different muscle fiber types of the skeletal muscle. Magn Reson Med 77:2097-2106, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.
The effects of electromyography-triggered electrical stimulation on shoulder subluxation, muscle activation, pain, and function in persons with stroke: A pilot study.

PubMed

Jeon, Somyung; Kim, Young; Jung, Kyoungsim; Chung, Yijung

2017-01-01

The purpose of this study was to examine the effects of task-oriented electromyography-triggered stimulation for shoulder subluxation, muscle activation, pain and upper extremity function in hemiparetic stroke patients. Twenty participants with subacute hemiparetic stroke were recruited for this study and were randomly divided into two groups: experimental group (n = 10) and control group (n = 10). Subjects in the experimental group participated in task-oriented electromyography triggered stimulation for 30 minutes, five times a week for four weeks, whereas the control group received cyclic functional electrical stimulation for 30 minutes, five times a week for four weeks. Subjects in both groups received conventional physical therapy for four weeks (30 min/day, five times/week). Data collected included the degree of shoulder subluxation which had been confirmed by X-ray, muscle activation of the supraspinatus and posterior deltoid muscles by electromyography, pain by the Visual Analogue Scale (VAS), and hand function by the Fugl-Meyer Assessment (FMA) before and after the four week exercise period. The results showed significant improvement in shoulder subluxation, muscle activation, and VAS results in the experimental group, compared with the control group(p < 0.05). FMA scores showed no significant differences between the two groups. In conclusion, task-oriented electromyography-triggered stimulation improved shoulder subluxation, muscle activation, pain and upper extremity function. These results suggest that task-oriented electromyography-triggered stimulation is effective and beneficial for individuals with subacute stroke, and that further studies should be conducted on multivarious anatomical regions.
Inhibition of xanthine oxidase reduces oxidative stress and improves skeletal muscle function in response to electrically stimulated isometric contractions in aged mice

PubMed Central

Ryan, Michael J.; Jackson, Janna R.; Hao, Yanlei; Leonard, Stephen S.; Alway, Stephen E.

2012-01-01

Oxidative stress is a putative factor responsible for reducing function and increasing apoptotic signaling in skeletal muscle with aging. This study examined the contribution and functional significance of the xanthine oxidase enzyme as a potential source of oxidant production in aged skeletal muscle during repetitive in situ electrically stimulated isometric contractions. Xanthine oxidase activity was inhibited in young adult and aged mice via a subcutaneously placed time release (2.5 mg/day) allopurinol pellet, 7 days prior to the start of in situ electrically stimulated isometric contractions. Gastrocnemius muscles were electrically activated with 20 maximal contractions for three consecutive days. Xanthine oxidase activity was 65% greater in the gastrocnemius muscle of aged mice compared to young mice. Xanthine oxidase activity also increased after in situ electrically stimulated isometric contractions in muscles from both young (33%) and aged (28%) mice, relative to contralateral non-contracted muscles. Allopurinol attenuated the exercise-induced increase in oxidative stress, but it did not affect the elevated basal levels of oxidative stress that was associated with aging. In addition, inhibition of xanthine oxidase activity decreased caspase 3 activity, but it had no effect on other markers of mitochondrial associated apoptosis. Our results show that compared to control conditions, suppression of xanthine oxidase activity by allopurinol reduced xanthine oxidase activity, H2O2 levels, lipid peroxidation and caspase-3 activity, prevented the in situ electrically stimulated isometric contraction-induced loss of glutathione, prevented the increase of catalase and copper-zinc superoxide dismutase activities, and increased maximal isometric force in the plantar flexor muscles of aged mice after repetitive electrically evoked contractions. PMID:21530649
The Impact of Aerobic Exercise on the Muscle Stem Cell Response.

PubMed

Joanisse, Sophie; Snijders, Tim; Nederveen, Joshua P; Parise, Gianni

2018-04-16

Satellite cells are indispensable for skeletal muscle repair and regeneration and are associated with muscle growth in humans. Aerobic exercise training results in improved skeletal muscle health also translating to an increase in satellite cell pool activation. We postulate that aerobic exercise improves satellite cell function in skeletal muscle.
Stem cells, angiogenesis and muscle healing: a potential role in massage therapies?

PubMed

Best, Thomas M; Gharaibeh, Burhan; Huard, Johnny

2013-11-01

Skeletal muscle injuries are among the most common and frequently disabling injuries sustained by athletes. Repair of injured skeletal muscle is an area that continues to present a challenge for sports medicine clinicians and researchers due, in part, to complete muscle recovery being compromised by development of fibrosis leading to loss of function and susceptibility to re-injury. Injured skeletal muscle goes through a series of coordinated and interrelated phases of healing including degeneration, inflammation, regeneration and fibrosis. Muscle regeneration initiated shortly after injury can be limited by fibrosis which affects the degree of recovery and predisposes the muscle to reinjury. It has been demonstrated in animal studies that antifibrotic agents that inactivate transforming growth factor (TGF)-β1 have been effective at decreasing scar tissue formation. Several studies have also shown that vascular endothelial growth factor (VEGF) can increase the efficiency of skeletal muscle repair by increasing angiogenesis and, at the same time, reducing the accumulation of fibrosis. We have isolated and thoroughly characterised a population of skeletal muscle-derived stem cells (MDSCs) that enhance repair of damaged skeletal muscle fibres by directly differentiating into myofibres and secreting paracrine factors that promote tissue repair. Indeed, we have found that MDSCs transplanted into skeletal and cardiac muscles have been successful at repair probably because of their ability to secrete VEGF that works in a paracrine fashion. The application of these techniques to the study of sport-related muscle injuries awaits investigation. Other useful strategies to enhance skeletal muscle repair through increased vascularisation may include gene therapy, exercise, neuromuscular electrical stimulation and, potentially, massage therapy. Based on recent studies showing an accelerated recovery of muscle function from intense eccentric exercise through massage
Stem cells, angiogenesis and muscle healing: a potential role in massage therapies?

PubMed

Best, Thomas M; Gharaibeh, Burhan; Huard, Johnny

2013-06-01

Skeletal muscle injuries are among the most common and frequently disabling injuries sustained by athletes. Repair of injured skeletal muscle is an area that continues to present a challenge for sports medicine clinicians and researchers due, in part, to complete muscle recovery being compromised by development of fibrosis leading to loss of function and susceptibility to re-injury. Injured skeletal muscle goes through a series of coordinated and interrelated phases of healing including degeneration, inflammation, regeneration and fibrosis. Muscle regeneration initiated shortly after injury can be limited by fibrosis which affects the degree of recovery and predisposes the muscle to reinjury. It has been demonstrated in animal studies that antifibrotic agents that inactivate transforming growth factor (TGF)-β1 have been effective at decreasing scar tissue formation. Several studies have also shown that vascular endothelial growth factor (VEGF) can increase the efficiency of skeletal muscle repair by increasing angiogenesis and, at the same time, reducing the accumulation of fibrosis. We have isolated and thoroughly characterised a population of skeletal muscle-derived stem cells (MDSCs) that enhance repair of damaged skeletal muscle fibres by directly differentiating into myofibres and secreting paracrine factors that promote tissue repair. Indeed, we have found that MDSCs transplanted into skeletal and cardiac muscles have been successful at repair probably because of their ability to secrete VEGF that works in a paracrine fashion. The application of these techniques to the study of sport-related muscle injuries awaits investigation. Other useful strategies to enhance skeletal muscle repair through increased vascularisation may include gene therapy, exercise, neuromuscular electrical stimulation and, potentially, massage therapy. Based on recent studies showing an accelerated recovery of muscle function from intense eccentric exercise through massage

The angiotensin II receptor type 1b is the primary sensor of intraluminal pressure in cerebral artery smooth muscle cells.

PubMed

Pires, Paulo W; Ko, Eun-A; Pritchard, Harry A T; Rudokas, Michael; Yamasaki, Evan; Earley, Scott

2017-07-15

The angiotensin II receptor type 1b (AT 1 R b ) is the primary sensor of intraluminal pressure in cerebral arteries. Pressure or membrane-stretch induced stimulation of AT 1 R b activates the TRPM4 channel and results in inward transient cation currents that depolarize smooth muscle cells, leading to vasoconstriction. Activation of either AT 1 R a or AT 1 R b with angiotensin II stimulates TRPM4 currents in cerebral artery myocytes and vasoconstriction of cerebral arteries. The expression of AT 1 R b mRNA is ∼30-fold higher than AT 1 R a in whole cerebral arteries and ∼45-fold higher in isolated cerebral artery smooth muscle cells. Higher levels of expression are likely to account for the obligatory role of AT 1 R b for pressure-induced vasoconstriction . ABSTRACT: Myogenic vasoconstriction, which reflects the intrinsic ability of smooth muscle cells to contract in response to increases in intraluminal pressure, is critically important for the autoregulation of blood flow. In smooth muscle cells from cerebral arteries, increasing intraluminal pressure engages a signalling cascade that stimulates cation influx through transient receptor potential (TRP) melastatin 4 (TRPM4) channels to cause membrane depolarization and vasoconstriction. Substantial evidence indicates that the angiotensin II receptor type 1 (AT 1 R) is inherently mechanosensitive and initiates this signalling pathway. Rodents express two types of AT 1 R - AT 1 R a and AT 1 R b - and conflicting studies provide support for either isoform as the primary sensor of intraluminal pressure in peripheral arteries. We hypothesized that mechanical activation of AT 1 R a increases TRPM4 currents to induce myogenic constriction of cerebral arteries. However, we found that development of myogenic tone was greater in arteries from AT 1 R a knockout animals compared with controls. In patch-clamp experiments using native cerebral arterial myocytes, membrane stretch-induced cation currents were blocked by the TRPM
Evoked Electromyographically Controlled Electrical Stimulation

PubMed Central

Hayashibe, Mitsuhiro

2016-01-01

Time-variant muscle responses under electrical stimulation (ES) are often problematic for all the applications of neuroprosthetic muscle control. This situation limits the range of ES usage in relevant areas, mainly due to muscle fatigue and also to changes in stimulation electrode contact conditions, especially in transcutaneous ES. Surface electrodes are still the most widely used in noninvasive applications. Electrical field variations caused by changes in the stimulation contact condition markedly affect the resulting total muscle activation levels. Fatigue phenomena under functional electrical stimulation (FES) are also well known source of time-varying characteristics coming from muscle response under ES. Therefore, it is essential to monitor the actual muscle state and assess the expected muscle response by ES so as to improve the current ES system in favor of adaptive muscle-response-aware FES control. To deal with this issue, we have been studying a novel control technique using evoked electromyography (eEMG) signals to compensate for these muscle time-variances under ES for stable neuroprosthetic muscle control. In this perspective article, I overview the background of this topic and highlight important points to be aware of when using ES to induce the desired muscle activation regardless of the time-variance. I also demonstrate how to deal with the common critical problem of ES to move toward robust neuroprosthetic muscle control with the Evoked Electromyographically Controlled Electrical Stimulation paradigm. PMID:27471448
Sphingosine-1-phosphate induces pro-remodelling response in airway smooth muscle cells

PubMed Central

Fuerst, E; Foster, H R; Ward, J P T; Corrigan, C J; Cousins, D J; Woszczek, G

2014-01-01

Background Increased proliferation of airway smooth muscle (ASM) cells leading to hyperplasia and increased ASM mass is one of the most characteristic features of airway remodelling in asthma. A bioactive lipid, sphingosine-1-phosphate (S1P), has been suggested to affect airway remodelling by stimulation of human ASM cell proliferation. Objective To investigate the effect of S1P on signalling and regulation of gene expression in ASM cells from healthy and asthmatic individuals. Methods Airway smooth muscle cells grown from bronchial biopsies of healthy and asthmatic individuals were exposed to S1P. Gene expression was analysed using microarray, real-time PCR and Western blotting. Receptor signalling and function were determined by mRNA knockdown and intracellular calcium mobilization experiments. Results S1P potently regulated the expression of more than 80 genes in human ASM cells, including several genes known to be involved in the regulation of cell proliferation and airway remodelling (HBEGF, TGFB3, TXNIP, PLAUR, SERPINE1, RGS4). S1P acting through S1P2 and S1P3 receptors activated intracellular calcium mobilization and extracellular signal-regulated and Rho-associated kinases to regulate gene expression. S1P-induced responses were not inhibited by corticosteroids and did not differ significantly between ASM cells from healthy and asthmatic individuals. Conclusion S1P induces a steroid-resistant, pro-remodelling pathway in ASM cells. Targeting S1P or its receptors could be a novel treatment strategy for inhibiting airway remodelling in asthma. PMID:25041788
[Repetitive peripheral muscle stimulation vs. pelvic floor muscle training : Comparison of two approaches to incontinence treatment].

PubMed

Schrank, Sabine; Adlbrecht, Laura; Mayer, Hanna

2017-04-27

Although there are various measures for the prevention, treatment, and management of urinary incontinence (UI), absorbing aids (and only scant continence-promoting measures) are primarily used in nursing homes in Austria. Repetitive peripheral muscle stimulation (RPMS) is already used as a common method for the treatment and prevention of incontinence in the outpatient setting and is an effective alternative compared to the usual incontinence treatments. However, there are no empirical data as yet on the effect of RPMS in nursing home residents. The primary objective of this study was to evaluate and compare two forms of UI treatment: RPMS and pelvic floor muscle exercises. To this end, a non-equivalent control group design was used. For the purposes of data collection, standardized instruments were used at three points of measurement. The sample consisted of 112 people from 22 institutions. The severity of UI showed a trend, albeit non-significant, toward improvement in both groups. However, a greater increase in quality of life and subjective satisfaction with treatment was observed in the RPMS group compared with the pelvic floor group. Pelvic floor muscle exercises carried out in a consistent and well-guided manner show similar effects compared with technology-assisted therapies. While pelvic floor muscle exercises are feasible in only a small proportion of nursing home residents, RPMS training could be a useful adjunct to conservative incontinence treatment and is also suitable for cognitively impaired individuals. As such, a larger number of elderly individuals could gain access to an appropriate and effective incontinence therapy.
Anti-atherogenic effect of trivalent chromium-loaded CPMV nanoparticles in human aortic smooth muscle cells under hyperglycemic conditions in vitro

NASA Astrophysics Data System (ADS)

Ganguly, Rituparna; Wen, Amy M.; Myer, Ashley B.; Czech, Tori; Sahu, Soumyadip; Steinmetz, Nicole F.; Raman, Priya

2016-03-01

Atherosclerosis, a major macrovascular complication associated with diabetes, poses a tremendous burden on national health care expenditure. Despite extensive efforts, cost-effective remedies are unknown. Therapies for atherosclerosis are challenged by a lack of targeted drug delivery approaches. Toward this goal, we turn to a biology-derived drug delivery system utilizing nanoparticles formed by the plant virus, Cowpea mosaic virus (CPMV). The aim herein is to investigate the anti-atherogenic potential of the beneficial mineral nutrient, trivalent chromium, loaded CPMV nanoparticles in human aortic smooth muscle cells (HASMC) under hyperglycemic conditions. A non-covalent loading protocol is established yielding CrCl3-loaded CPMV (CPMV-Cr) carrying 2000 drug molecules per particle. Using immunofluorescence microscopy, we show that CPMV-Cr is readily taken up by HASMC in vitro. In glucose (25 mM)-stimulated cells, 100 nM CPMV-Cr inhibits HASMC proliferation concomitant to attenuated proliferating cell nuclear antigen (PCNA, proliferation marker) expression. This is accompanied by attenuation in high glucose-induced phospho-p38 and pAkt expression. Moreover, CPMV-Cr inhibits the expression of pro-inflammatory cytokines, transforming growth factor-β (TGF-β) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), in glucose-stimulated HASMCs. Finally glucose-stimulated lipid uptake is remarkably abrogated by CPMV-Cr, revealed by Oil Red O staining. Together, these data provide key cellular evidence for an atheroprotective effect of CPMV-Cr in vascular smooth muscle cells (VSMC) under hyperglycemic conditions that may promote novel therapeutic ventures for diabetic atherosclerosis.
Anti-atherogenic effect of trivalent chromium-loaded CPMV nanoparticles in human aortic smooth muscle cells under hyperglycemic conditions in vitro.

PubMed

Ganguly, Rituparna; Wen, Amy M; Myer, Ashley B; Czech, Tori; Sahu, Soumyadip; Steinmetz, Nicole F; Raman, Priya

2016-03-28

Atherosclerosis, a major macrovascular complication associated with diabetes, poses a tremendous burden on national health care expenditure. Despite extensive efforts, cost-effective remedies are unknown. Therapies for atherosclerosis are challenged by a lack of targeted drug delivery approaches. Toward this goal, we turn to a biology-derived drug delivery system utilizing nanoparticles formed by the plant virus, Cowpea mosaic virus (CPMV). The aim herein is to investigate the anti-atherogenic potential of the beneficial mineral nutrient, trivalent chromium, loaded CPMV nanoparticles in human aortic smooth muscle cells (HASMC) under hyperglycemic conditions. A non-covalent loading protocol is established yielding CrCl3-loaded CPMV (CPMV-Cr) carrying 2000 drug molecules per particle. Using immunofluorescence microscopy, we show that CPMV-Cr is readily taken up by HASMC in vitro. In glucose (25 mM)-stimulated cells, 100 nM CPMV-Cr inhibits HASMC proliferation concomitant to attenuated proliferating cell nuclear antigen (PCNA, proliferation marker) expression. This is accompanied by attenuation in high glucose-induced phospho-p38 and pAkt expression. Moreover, CPMV-Cr inhibits the expression of pro-inflammatory cytokines, transforming growth factor-β (TGF-β) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), in glucose-stimulated HASMCs. Finally glucose-stimulated lipid uptake is remarkably abrogated by CPMV-Cr, revealed by Oil Red O staining. Together, these data provide key cellular evidence for an atheroprotective effect of CPMV-Cr in vascular smooth muscle cells (VSMC) under hyperglycemic conditions that may promote novel therapeutic ventures for diabetic atherosclerosis.
Development of a nitric oxide-releasing analogue of the muscle relaxant guaifenesin for skeletal muscle satellite cell myogenesis.

PubMed

Wang, Guqi; Burczynski, Frank J; Hasinoff, Brian B; Zhang, Kaidong; Lu, Qilong; Anderson, Judy E

2009-01-01

Nitric oxide (NO) mediates activation of satellite precursor cells to enter the cell cycle. This provides new precursor cells for skeletal muscle growth and muscle repair from injury or disease. Targeting a new drug that specifically delivers NO to muscle has the potential to promote normal function and treat neuromuscular disease, and would also help to avoid side effects of NO from other treatment modalities. In this research, we examined the effectiveness of the NO donor, iosorbide dinitrate (ISDN), and a muscle relaxant, methocarbamol, in promoting satellite cell activation assayed by muscle cell DNA synthesis in normal adult mice. The work led to the development of guaifenesin dinitrate (GDN) as a new NO donor for delivering nitric oxide to muscle. The results revealed that there was a strong increase in muscle satellite cell activation and proliferation, demonstrated by a significant 38% rise in DNA synthesis after a single transdermal treatment with the new compound for 24 h. Western blot and immunohistochemistry analyses showed that the markers of satellite cell myogenesis, expression of myf5, myogenin, and follistatin, were increased after 24 h oral administration of the compound in adult mice. This research extends our understanding of the outcomes of NO-based treatments aimed at promoting muscle regeneration in normal tissue. The potential use of such treatment for conditions such as muscle atrophy in disuse and aging, and for the promotion of muscle tissue repair as required after injury or in neuromuscular diseases such as muscular dystrophy, is highlighted.
Efficient Generation of iPS Cells from Skeletal Muscle Stem Cells

PubMed Central

Tan, Kah Yong; Eminli, Sarah; Hettmer, Simone; Hochedlinger, Konrad; Wagers, Amy J.

2011-01-01

Reprogramming of somatic cells into inducible pluripotent stem cells generally occurs at low efficiency, although what limits reprogramming of particular cell types is poorly understood. Recent data suggest that the differentiation status of the cell targeted for reprogramming may influence its susceptibility to reprogramming as well as the differentiation potential of the induced pluripotent stem (iPS) cells that are derived from it. To assess directly the influence of lineage commitment on iPS cell derivation and differentiation, we evaluated reprogramming in adult stem cell and mature cell populations residing in skeletal muscle. Our data using clonal assays and a second-generation inducible reprogramming system indicate that stem cells found in mouse muscle, including resident satellite cells and mesenchymal progenitors, reprogram with significantly greater efficiency than their more differentiated daughters (myoblasts and fibroblasts). However, in contrast to previous reports, we find no evidence of biased differentiation potential among iPS cells derived from myogenically committed cells. These data support the notion that adult stem cells reprogram more efficiently than terminally differentiated cells, and argue against the suggestion that “epigenetic memory” significantly influences the differentiation potential of iPS cells derived from distinct somatic cell lineages in skeletal muscle. PMID:22028872
Association of Calf Muscle Pump Stimulation With Sleep Quality in Adults.

PubMed

Baniak, Lynn M; Pierce, Carolyn S; McLeod, Kenneth J; Chasens, Eileen R

2016-12-01

Prevention of lower extremity fluid pooling (LEFP) is associated with improved sleep quality. Physical activity and compression stockings are non-invasive methods used to manage LEFP, but both are associated with low adherence. Calf muscle pump (CMP) stimulation is an alternative and more convenient approach. Convenience sampling was used to recruit 11 participants between ages 45 and 65 with poor sleep quality. A within-person single-group pre-test-post-test design was used to evaluate changes in sleep quality, daytime sleepiness, and functional outcomes sensitive to impaired sleep as measured by the Pittsburgh Sleep Quality Index (PSQI), Functional Outcomes of Sleep Questionnaire, and Epworth Sleepiness Scale after 4 weeks of CMP stimulation. Statistical analysis included effect size (ES) calculations. After daily use of CMP stimulation, participants demonstrated improvement in overall sleep quality (ES = -.97) and a large reduction in daily disturbance from poor sleep (ES = -1.25). Moderate improvements were observed in daytime sleepiness (ES = -.53) and functional outcomes sensitive to sleepiness (ES = .49). Although causality could not be determined with this study design, these results support further research to determine whether CMP stimulation can improve sleep quality. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.
The Use Of Laser Irradiation To Stimulate Adipose Derived Stem Cell Proliferation And Differentiation For Use In Autologous Grafts

NASA Astrophysics Data System (ADS)

Abrahamse, Heidi

2009-09-01

Stem cells are characterized by the qualities of self-renewal, long term viability, and the ability to differentiate into various cell types. Historically, stem cells have been isolated from the inner cell mass of blastocysts and harvesting these cells resulted in the death of the embryo leading to religious, political and ethical issues. The identification and subsequent isolation of adult stem cells from bone marrow stroma have been welcomed as an alternate source for stem cells. The clinical use of Mesenchymal Stem Cells (MSCs) presented problems such as limited cell number, pain and morbidity upon isolation. Adipose tissue is derived from the mesenchyme, is easily isolated, a reliable source of stem cells and able to differentiate into different cell types including smooth muscle. Over the past few years, the identification and characterization of stem cells has led the potential use of these cells as a promising alternative to cell replacement therapy. Smooth muscle is a major component of human tissues and is essential for the normal functioning of many different organs. Low intensity laser irradiation has been shown to increase viability, protein expression and migration of stem cells in vitro, and to stimulate proliferation of various types of stem cells. In addition, the use of laser irradiation to stimulate differentiation in the absence of growth factors has also been demonstrated in normal human neural progenitor cells (NHNPCs) in vitro where NHNPCs are not only capable of being sustained by light in the absence of growth factors, but that they are also able to differentiate normally as assessed by neurite formation. Our work has focused on the ability of laser irradiation to proliferate adipose derived stem cells (ADSCs), maintain ADSC character and increase the rate and maintenance of differentiation of ADSCs into smooth muscle and skin fibroblast cells. Current studies are also investigating the effect of different irradiation wavelengths and
Functional electrical stimulation exercise increases GLUT-1 and GLUT-4 in paralyzed skeletal muscle.

PubMed

Chilibeck, P D; Bell, G; Jeon, J; Weiss, C B; Murdoch, G; MacLean, I; Ryan, E; Burnham, R

1999-11-01

The study purpose was to determine the effect of functional electrical stimulation (FES)-leg cycle ergometer training (30 minutes on 3 d/wk for 8 weeks) on the GLUT-1 and GLUT-4 content of paralyzed skeletal muscle. Biopsy samples of vastus lateralis muscle were obtained pre- and post-training from five individuals with motor-complete spinal cord injury ([SCI] four men and one woman aged 31 to 50 years, 3 to 25 years postinjury involving C5-T8). Western blot analysis indicated that GLUT-1 increased by 52% and GLUT-4 increased by 72% with training (P < .05). This coincided with an increase in the muscle oxidative capacity as indicated by a 56% increase in citrate synthase (CS) activity (P < .05) and an improvement in the insulin sensitivity index as determined from oral glucose tolerance tests (P < .05). It is concluded that FES endurance training is effective to increase glucose transporter protein levels in paralyzed skeletal muscle of individuals with SCI.
Histone deacetylase 8 regulates cortactin deacetylation and contraction in smooth muscle tissues

PubMed Central

Li, Jia; Chen, Shu; Cleary, Rachel A.; Wang, Ruping; Gannon, Olivia J.; Seto, Edward

2014-01-01

Histone deacetylases (HDACs) are a family of enzymes that mediate nucleosomal histone deacetylation and gene expression. Some members of the HDAC family have also been implicated in nonhistone protein deacetylation, which modulates cell-cycle control, differentiation, and cell migration. However, the role of HDACs in smooth muscle contraction is largely unknown. Here, HDAC8 was localized both in the cytoplasm and the nucleus of mouse and human smooth muscle cells. Knockdown of HDAC8 by lentivirus-encoding HDAC8 shRNA inhibited force development in response to acetylcholine. Treatment of smooth muscle tissues with HDAC8 inhibitor XXIV (OSU-HDAC-44) induced relaxation of precontracted smooth muscle tissues. In addition, cortactin is an actin-regulatory protein that undergoes deacetylation during migration of NIH 3T3 cells. In this study, acetylcholine stimulation induced cortactin deacetylation in mouse and human smooth muscle tissues, as evidenced by immunoblot analysis using antibody against acetylated lysine. Knockdown of HDAC8 by RNAi or treatment with the inhibitor attenuated cortactin deacetylation and actin polymerization without affecting myosin activation. Furthermore, expression of a charge-neutralizing cortactin mutant inhibited contraction and actin dynamics during contractile activation. These results suggest a novel mechanism for the regulation of smooth muscle contraction. In response to contractile stimulation, HDAC8 may mediate cortactin deacetylation, which subsequently promotes actin filament polymerization and smooth muscle contraction. PMID:24920679
Human Satellite Cell Transplantation and Regeneration from Diverse Skeletal Muscles

PubMed Central

Xu, Xiaoti; Wilschut, Karlijn J.; Kouklis, Gayle; Tian, Hua; Hesse, Robert; Garland, Catharine; Sbitany, Hani; Hansen, Scott; Seth, Rahul; Knott, P. Daniel; Hoffman, William Y.; Pomerantz, Jason H.

2015-01-01

Summary Identification of human satellite cells that fulfill muscle stem cell criteria is an unmet need in regenerative medicine. This hurdle limits understanding how closely muscle stem cell properties are conserved among mice and humans and hampers translational efforts in muscle regeneration. Here, we report that PAX7 satellite cells exist at a consistent frequency of 2–4 cells/mm of fiber in muscles of the human trunk, limbs, and head. Xenotransplantation into mice of 50–70 fiber-associated, or 1,000–5,000 FACS-enriched CD56+/CD29+ human satellite cells led to stable engraftment and formation of human-derived myofibers. Human cells with characteristic PAX7, CD56, and CD29 expression patterns populated the satellite cell niche beneath the basal lamina on the periphery of regenerated fibers. After additional injury, transplanted satellite cells robustly regenerated to form hundreds of human-derived fibers. Together, these findings conclusively delineate a source of bona-fide endogenous human muscle stem cells that will aid development of clinical applications. PMID:26352798
Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montes, Daniela K.; Brenet, Marianne; Muñoz, Vanessa C.

Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. Themore » AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration.« less
Reconstruction of Multiple Facial Nerve Branches Using Skeletal Muscle-Derived Multipotent Stem Cell Sheet-Pellet Transplantation.

PubMed

Saito, Kosuke; Tamaki, Tetsuro; Hirata, Maki; Hashimoto, Hiroyuki; Nakazato, Kenei; Nakajima, Nobuyuki; Kazuno, Akihito; Sakai, Akihiro; Iida, Masahiro; Okami, Kenji

2015-01-01

Head and neck cancer is often diagnosed at advanced stages, and surgical resection with wide margins is generally indicated, despite this treatment being associated with poor postoperative quality of life (QOL). We have previously reported on the therapeutic effects of skeletal muscle-derived multipotent stem cells (Sk-MSCs), which exert reconstitution capacity for muscle-nerve-blood vessel units. Recently, we further developed a 3D patch-transplantation system using Sk-MSC sheet-pellets. The aim of this study is the application of the 3D Sk-MSC transplantation system to the reconstitution of facial complex nerve-vascular networks after severe damage. Mouse experiments were performed for histological analysis and rats were used for functional examinations. The Sk-MSC sheet-pellets were prepared from GFP-Tg mice and SD rats, and were transplanted into the facial resection model (ST). Culture medium was transplanted as a control (NT). In the mouse experiment, facial-nerve-palsy (FNP) scoring was performed weekly during the recovery period, and immunohistochemistry was used for the evaluation of histological recovery after 8 weeks. In rats, contractility of facial muscles was measured via electrical stimulation of facial nerves root, as the marker of total functional recovery at 8 weeks after transplantation. The ST-group showed significantly higher FNP (about three fold) scores when compared to the NT-group after 2-8 weeks. Similarly, significant functional recovery of whisker movement muscles was confirmed in the ST-group at 8 weeks after transplantation. In addition, engrafted GFP+ cells formed complex branches of nerve-vascular networks, with differentiation into Schwann cells and perineurial/endoneurial cells, as well as vascular endothelial and smooth muscle cells. Thus, Sk-MSC sheet-pellet transplantation is potentially useful for functional reconstitution therapy of large defects in facial nerve-vascular networks.
Reconstruction of Multiple Facial Nerve Branches Using Skeletal Muscle-Derived Multipotent Stem Cell Sheet-Pellet Transplantation

PubMed Central

Saito, Kosuke; Tamaki, Tetsuro; Hirata, Maki; Hashimoto, Hiroyuki; Nakazato, Kenei; Nakajima, Nobuyuki; Kazuno, Akihito; Sakai, Akihiro; Iida, Masahiro; Okami, Kenji

2015-01-01

Head and neck cancer is often diagnosed at advanced stages, and surgical resection with wide margins is generally indicated, despite this treatment being associated with poor postoperative quality of life (QOL). We have previously reported on the therapeutic effects of skeletal muscle-derived multipotent stem cells (Sk-MSCs), which exert reconstitution capacity for muscle-nerve-blood vessel units. Recently, we further developed a 3D patch-transplantation system using Sk-MSC sheet-pellets. The aim of this study is the application of the 3D Sk-MSC transplantation system to the reconstitution of facial complex nerve-vascular networks after severe damage. Mouse experiments were performed for histological analysis and rats were used for functional examinations. The Sk-MSC sheet-pellets were prepared from GFP-Tg mice and SD rats, and were transplanted into the facial resection model (ST). Culture medium was transplanted as a control (NT). In the mouse experiment, facial-nerve-palsy (FNP) scoring was performed weekly during the recovery period, and immunohistochemistry was used for the evaluation of histological recovery after 8 weeks. In rats, contractility of facial muscles was measured via electrical stimulation of facial nerves root, as the marker of total functional recovery at 8 weeks after transplantation. The ST-group showed significantly higher FNP (about three fold) scores when compared to the NT-group after 2–8 weeks. Similarly, significant functional recovery of whisker movement muscles was confirmed in the ST-group at 8 weeks after transplantation. In addition, engrafted GFP+ cells formed complex branches of nerve-vascular networks, with differentiation into Schwann cells and perineurial/endoneurial cells, as well as vascular endothelial and smooth muscle cells. Thus, Sk-MSC sheet-pellet transplantation is potentially useful for functional reconstitution therapy of large defects in facial nerve-vascular networks. PMID:26372044
Matrix metalloproteinase inhibition negatively affects muscle stem cell behavior

PubMed Central

Bellayr, Ian; Holden, Kyle; Mu, Xiaodong; Pan, Haiying; Li, Yong

2013-01-01

Skeletal muscle is a large and complex system that is crucial for structural support, movement and function. When injured, the repair of skeletal muscle undergoes three phases: inflammation and degeneration, regeneration and fibrosis formation in severe injuries. During fibrosis formation, muscle healing is impaired because of the accumulation of excess collagen. A group of zinc-dependent endopeptidases that have been found to aid in the repair of skeletal muscle are matrix metalloproteinases (MMPs). MMPs are able to assist in tissue remodeling through the regulation of extracellular matrix (ECM) components, as well as contributing to cell migration, proliferation, differentiation and angiogenesis. In the present study, the effect of GM6001, a broad-spectrum MMP inhibitor, on muscle-derived stem cells (MDSCs) is investigated. We find that MMP inhibition negatively impacts skeletal muscle healing by impairing MDSCs in migratory and multiple differentiation abilities. These results indicate that MMP signaling plays an essential role in the wound healing of muscle tissue because their inhibition is detrimental to stem cells residing in skeletal muscle. PMID:23329998
Role of insulin-like growth factor-I in the regulation of skeletal muscle adaptation to increased loading

NASA Technical Reports Server (NTRS)

Adams, G. R.

1998-01-01

Adaptations in muscle mass stimulated by changes in muscle loading state entail alternations in the synthesis and degradation of myofiber proteins and the modulation of myonuclear number such that the ratio between the number of myonuclei and the size of the myofibers remains relatively constant. As depicted schematically in Figure 2.6, the literature regarding the role of IGF-in mediating muscle adaptation to alterations in loading state suggests the following conclusions: During periods of increased loading, myofibers upregulate the expression and secretion of IGF-I. Acting as an autocrine and/or paracrine growth factor, IGF-I stimulates myofiber anabolic processes. Acting as a paracrine growth factor, IGF-I also stimulates adjacent satellite cells to enter the cell cycle and proliferate. Continued myofiber production of IGF-I stimulates some satellite cells to differentiate and then fuse with myofibers, thus providing additional myonuclei in order to maintain or reestablish the myonucleus to myofiber size ratios of the enlarged myofibers.
Requirement of myomaker-mediated stem cell fusion for skeletal muscle hypertrophy.

PubMed

Goh, Qingnian; Millay, Douglas P

2017-02-10

Fusion of skeletal muscle stem/progenitor cells is required for proper development and regeneration, however the significance of this process during adult muscle hypertrophy has not been explored. In response to muscle overload after synergist ablation in mice, we show that myomaker, a muscle specific membrane protein essential for myoblast fusion, is activated mainly in muscle progenitors and not myofibers. We rendered muscle progenitors fusion-incompetent through genetic deletion of myomaker in muscle stem cells and observed a complete reduction of overload-induced hypertrophy. This blunted hypertrophic response was associated with a reduction in Akt and p70s6k signaling and protein synthesis, suggesting a link between myonuclear accretion and activation of pro-hypertrophic pathways. Furthermore, fusion-incompetent muscle exhibited increased fibrosis after muscle overload, indicating a protective role for normal stem cell activity in reducing myofiber strain associated with hypertrophy. These findings reveal an essential contribution of myomaker-mediated stem cell fusion during physiological adult muscle hypertrophy.
Role of G protein-coupled estrogen receptor-1, matrix metalloproteinases 2 and 9, and heparin binding epidermal growth factor-like growth factor in estradiol-17β-stimulated bovine satellite cell proliferation.

PubMed

Kamanga-Sollo, E; Thornton, K J; White, M E; Dayton, W R

2014-10-01

In feedlot steers, estradiol-17β (E2) and combined E2 and trenbolone acetate (a testosterone analog) implants enhance rate and efficiency of muscle growth; and, consequently, these compounds are widely used as growth promoters. Although the positive effects of E2 on rate and efficiency of bovine muscle growth are well established, the mechanisms involved in these effects are not well understood. Combined E2 and trenbolone acetate implants result in significantly increased muscle satellite cell number in feedlot steers. Additionally, E2 treatment stimulates proliferation of cultured bovine satellite cells (BSC). Studies in nonmuscle cells have shown that binding of E2 to G protein-coupled estrogen receptor (GPER)-1 results in activation of matrix metalloproteinases 2 and 9 (MMP2/9) resulting in proteolytic release of heparin binding epidermal growth factor-like growth factor (hbEGF) from the cell surface. Released hbEGF binds to and activates the epidermal growth factor receptor resulting in increased proliferation. To assess if GPER-1, MMP2/9, and/or hbEGF are involved in the mechanism of E2-stimulated BSC proliferation, we have examined the effects of G36 (a specific inhibitor of GPER-1), CRM197 (a specific inhibitor of hbEGF), and MMP-2/MMP-9 Inhibitor II (an inhibitor of MMP2/9 activity) on E2-stimulated BSC proliferation. Inhibition of GPER-1, MMP2/9, or hbEGF suppresses E2-stimulated BSC proliferation (P < 0.001) suggesting that all these are required in order for E2 to stimulate BSC proliferation. These results strongly suggest that E2 may stimulate BSC proliferation by binding to GPER-1 resulting in MMP2/9-catalyzed release of cell membrane-bound hbEGF and subsequent activation of epidermal growth factor receptor by binding of released hbEGF. Copyright © 2014 Elsevier Inc. All rights reserved.

Molecular and Cellular Mechanisms of Muscle Aging and Sarcopenia and Effects of Electrical Stimulation in Seniors.

PubMed

Barber, Laura; Scicchitano, Bianca Maria; Musaro, Antonio

2015-08-24

The prolongation of skeletal muscle strength in aging and neuromuscular disease has been the objective of numerous studies employing a variety of approaches. It is generally accepted that cumulative failure to repair damage related to an overall decrease in anabolic processes is a primary cause of functional impairment in muscle. The functional performance of skeletal muscle tissues declines during post- natal life and it is compromised in different diseases, due to an alteration in muscle fiber composition and an overall decrease in muscle integrity as fibrotic invasions replace functional contractile tissue. Characteristics of skeletal muscle aging and diseases include a conspicuous reduction in myofiber plasticity (due to the progressive loss of muscle mass and in particular of the most powerful fast fibers), alteration in muscle-specific transcriptional mechanisms, and muscle atrophy. An early decrease in protein synthetic rates is followed by a later increase in protein degradation, to affect biochemical, physiological, and morphological parameters of muscle fibers during the aging process. Alterations in regenerative pathways also compromise the functionality of muscle tissues. In this review we will give an overview of the work on molecular and cellular mechanisms of aging and sarcopenia and the effects of electrical stimulation in seniors..
Design of a muscle cell-specific expression vector utilising human vascular smooth muscle alpha-actin regulatory elements.

PubMed

Keogh, M C; Chen, D; Schmitt, J F; Dennehy, U; Kakkar, V V; Lemoine, N R

1999-04-01

The facility to direct tissue-specific expression of therapeutic gene constructs is desirable for many gene therapy applications. We describe the creation of a muscle-selective expression vector which supports transcription in vascular smooth muscle, cardiac muscle and skeletal muscle, while it is essentially silent in other cell types such as endothelial cells, hepatocytes and fibroblasts. Specific transcriptional regulatory elements have been identified in the human vascular smooth muscle cell (VSMC) alpha-actin gene, and used to create an expression vector which directs the expression of genes in cis to muscle cells. The vector contains an enhancer element we have identified in the 5' flanking region of the human VSMC alpha-actin gene involved in mediating VSMC expression. Heterologous pairing experiments have shown that the enhancer does not interact with the basal transcription complex recruited at the minimal SV40 early promoter. Such a vector has direct application in the modulation of VSMC proliferation associated with intimal hyperplasia/restenosis.
Skeletal muscle stem cells from animals I. Basic cell biology

USDA-ARS?s Scientific Manuscript database

Skeletal muscle stem cells from food-producing animals have been of interest to agricultural life scientists seeking to develop a better understanding of the molecular regulation of lean tissue (skeletal muscle protein hypertrophy) and intramuscular fat (marbling) development. Enhanced understanding...
Two years of Functional Electrical Stimulation by large surface electrodes for denervated muscles improve skin epidermis in SCI

PubMed Central

Albertin, Giovanna; Kern, Helmut; Hofer, Christian; Guidolin, Diego; Porzionato, Andrea; Rambaldo, Anna; Caro, Raffaele De; Piccione, Francesco; Marcante, Andrea; Zampieri, Sandra

2018-01-01

Our previous studies have shown that severely atrophic Quadriceps muscles of spinal cord injury (SCI) patients suffering with complete conus and cauda equina lesions, and thus with permanent denervation-induced atrophy and degeneration of muscle fibers, were almost completely rescued to normal size after two years of home-based Functional Electrical Stimulation (h-bFES). Since we used large surface electrodes to stimulate the thigh muscles, we wanted to know if the skin was affected by long-term treatment. Here we report preliminary data of morphometry of skin biopsies harvested from legs of 3 SCI patients before and after two years of h-bFES to determine the total area of epidermis in transverse skin sections. By this approach we support our recently published results obtained randomly measuring skin thickness in the same biopsies after H-E stain. The skin biopsies data of three subjects, taken together, present indeed a statistically significant 30% increase in the area of the epidermis after two years of h-bFES. In conclusion, we confirm a long term positive modulation of electrostimulated epidermis, that correlates with the impressive improvements of the FES-induced muscle strength and bulk, and of the size of the muscle fibers after 2-years of h-bFES. PMID:29686823
Effect of Serum from Chickens Treated with Clenbuterol on Myosin Accumulation, Beta-Adrenergic Receptor Population, and Cyclic AM Synthesis in Embryonic Chicken Skeletal Muscle Cell Cultures

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Wuethrich, A. J.; Hancock, D. L.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Broiler chickens at 35 days of age were fed 1 ppm clenbuterol for 14 days. This level of dietary clenbuterol led to 5-7% increases in weights of leg and breast muscle tissue. At the end of the 14-day period, serum was prepared from both control and clenbuterol-treated chickens and was then employed as a component of cell culture media at a final concentration of 20% (v/v). Muscle cell cultures were prepared from both the leg and breast muscle groups of twelve-day chick embryos. Treatment groups included control chicken serum to which 10 nM, 50 nM, and 1 micron clenbuterol had been added, as well as cells grown in media containing 10% horse serum. Cultures were subjected to each treatment for 3 days beginning on the seventh day in culture. Neither the percent fusion nor the number of nuclei in myotubes were significantly affected by any of the treatments. The quantity of MHC was not increased by serum from clenbuterol-treated chickens in either breast and leg muscle cultures; however, MHC quantity was 50- 100% higher in cultures grown in control chicken serum to which 10 nM and 50 nM clenbuterol had also been added. The Beta-AR population was 4,000-7,000 Beta-AR per cell in cultures grown in chicken serum, with leg muscle cultures having approximately 25-30% more receptors than breast muscle cultures. Receptor population was not significantly affected by the presence of clenbuterol or by the presence of serum from clenbuterol-treated chickens. In contrast, the Beta-AR population in leg and breast muscle cultures grown in the presence of 10% horse serum was 18,000-20,000 Beta-AR per cell. Basal concentration of cAMP was not significantly affected by any of the treatments. When cultures grown in chicken serum were stimulated for 10 min with 1 micron isoproterenol, limited increases of 12-20% in cAMP concentration above basal levels were observed. However, when cultures grown in the presence of horse serum were stimulated with 1 micron isoproterenol, increases of 600
The combined influence of stretch, mobility and electrical stimulation in the prevention of muscle fiber atrophy caused hypokinesia and hypodynamia

NASA Technical Reports Server (NTRS)

Goldspink, G.; Goldspink, D.; Loughna, P.

1984-01-01

The morphological and biochemical changes which occur in the hind limb muscles of the rat in response to hypokinesia and hypodynamia were investigated. Hind limb cast fixation and suspension techniques were employed to study the musclar atrophy after five days of hypokinesia and hypodynamia induced by suspension, appreciable muscular atrophy was apparent, particularly in the anti-gravity muscles. The effect of passive stretching and electrical stimulation on muscle atrophy was studied. Changes in muscle protein mass were assessed with spectrophotometric and radioactive techniques. Passive stretch is shown to counteract muscle disuse atrophy. The change in the numbers of specific muscle fibers in atrophied muscles is discussed.
Protein Availability and Satellite Cell Dynamics in Skeletal Muscle.

PubMed

Shamim, Baubak; Hawley, John A; Camera, Donny M

2018-06-01

Human skeletal muscle satellite cells are activated in response to both resistance and endurance exercise. It was initially proposed that satellite cell proliferation and differentiation were only required to support resistance exercise-induced hypertrophy. However, satellite cells may also play a role in muscle fibre remodelling after endurance-based exercise and extracellular matrix regulation. Given the importance of dietary protein, particularly branched chain amino acids, in supporting myofibrillar and mitochondrial adaptations to both resistance and endurance-based training, a greater understanding of how protein intake impacts satellite cell activity would provide further insight into the mechanisms governing skeletal muscle remodelling with exercise. While many studies have investigated the capacity for protein ingestion to increase post-exercise rates of muscle protein synthesis, few investigations have examined the role for protein ingestion to modulate satellite cell activity. Here we review the molecular mechanisms controlling the activation of satellite cells in response to mechanical stress and protein intake in both in vitro and in vivo models. We provide a mechanistic framework that describes how protein ingestion may enhance satellite activity and promote exercise adaptations in human skeletal muscle.
Application of electrical stimulation for functional tissue engineering in vitro and in vivo

NASA Technical Reports Server (NTRS)

Park, Hyoungshin (Inventor); Freed, Lisa (Inventor); Vunjak-Novakovic, Gordana (Inventor); Langer, Robert (Inventor); Radisic, Milica (Inventor)

2013-01-01

The present invention provides new methods for the in vitro preparation of bioartificial tissue equivalents and their enhanced integration after implantation in vivo. These methods include submitting a tissue construct to a biomimetic electrical stimulation during cultivation in vitro to improve its structural and functional properties, and/or in vivo, after implantation of the construct, to enhance its integration with host tissue and increase cell survival and functionality. The inventive methods are particularly useful for the production of bioartificial equivalents and/or the repair and replacement of native tissues that contain electrically excitable cells and are subject to electrical stimulation in vivo, such as, for example, cardiac muscle tissue, striated skeletal muscle tissue, smooth muscle tissue, bone, vasculature, and nerve tissue.
Enhanced Cultivation Of Stimulated Murine B Cells

NASA Technical Reports Server (NTRS)

Sammons, David W.

1994-01-01

Method of in vitro cultivation of large numbers of stimulated murine B lymphocytes. Cells electrofused with other cells to produce hybridomas and monoclonal antibodies. Offers several advantages: polyclonally stimulated B-cell blasts cultivated for as long as 14 days, hybridomas created throughout culture period, yield of hybridomas increases during cultivation, and possible to expand polyclonally in vitro number of B cells specific for antigenic determinants first recognized in vivo.
Regulation of natriuretic peptide receptor A and B expression by transforming growth factor-beta 1 in cultured aortic smooth muscle cells.

PubMed

Fujio, N; Gossard, F; Bayard, F; Tremblay, J

1994-06-01

Two types of natriuretic peptide receptors (NPR-A and NPR-B) are membrane guanylate cyclases whose relative expression varies in different tissues. Because natriuretic peptides have been shown to inhibit aortic smooth muscle proliferation, we investigated the regulation of NPR-A and NPR-B in these cells under different proliferative conditions. NPR subtype mRNA levels were measured by our newly developed quantitative reverse transcription-polymerase chain reaction assay using mutated NPR-A and NPR-B cRNA as internal standards. The functional impact of their expression was determined by atrial natriuretic peptide (ANP)- and C-type natriuretic peptide (CNP)-induced stimulation of cyclic GMP production. In the intact aorta, NPR-B mRNA levels were found to be 10-fold higher than those of NPR-A. This dominance was further amplified (1000-fold) in long-term cultures (10 to 15 passages) of aortic smooth muscle cells (ASMC). Higher cyclic GMP production with CNP than with ANP was observed in cultured ASMC from Wistar-Kyoto (WKY) rats. Similar stimulation by the two agonists was noted in spontaneously hypertensive rat (SHR) cells, paralleled by a 10-fold increase in NPR-A mRNA levels and ANP stimulation of cyclic GMP in hypertensive cells. The present study also evaluated NPR-A and NPR-B mRNA control by transforming growth factor-beta 1 (TGF-beta 1), an important regulator of cell proliferation that is overexpressed in SHR ASMC. TGF-beta 1 decreased both NPR-A and NPR-B mRNA levels with a predominant effect in SHR cells at high cell density.(ABSTRACT TRUNCATED AT 250 WORDS)
Development and epithelial organisation of muscle cells in the sea anemone Nematostella vectensis.

PubMed

Jahnel, Stefan M; Walzl, Manfred; Technau, Ulrich

2014-01-01

Nematostella vectensis, a member of the cnidarian class Anthozoa, has been established as a promising model system in developmental biology, but while information about the genetic regulation of embryonic development is rapidly increasing, little is known about the cellular organization of the various cell types in the adult. Here, we studied the anatomy and development of the muscular system of N. vectensis to obtain further insights into the evolution of muscle cells. The muscular system of N. vectensis is comprised of five distinct muscle groups, which are differentiated into a tentacle and a body column system. Both systems house longitudinal as well as circular portions. With the exception of the ectodermal tentacle longitudinal muscle, all muscle groups are of endodermal origin. The shape and epithelial organization of muscle cells vary considerably between different muscle groups. Ring muscle cells are formed as epitheliomuscular cells in which the myofilaments are housed in the basal part of the cell, while the apical part is connected to neighboring cells by apical cell-cell junctions. In the longitudinal muscles of the column, the muscular part at the basal side is connected to the apical part by a long and narrow cytoplasmic bridge. The organization of these cells, however, remains epitheliomuscular. A third type of muscle cell is represented in the longitudinal muscle of the tentacle. Using transgenic animals we show that the apical cell-cell junctions are lost during differentiation, resulting in a detachment of the muscle cells to a basiepithelial position. These muscle cells are still located within the epithelium and outside of the basal matrix, therefore constituting basiepithelial myocytes. We demonstrate that all muscle cells, including the longitudinal basiepithelial muscle cells of the tentacle, initially differentiate from regular epithelial cells before they alter their epithelial organisation. A wide range of different muscle cell
Transient stimulation expands superior antitumor T cells for adoptive therapy.

PubMed

Kagoya, Yuki; Nakatsugawa, Munehide; Ochi, Toshiki; Cen, Yuchen; Guo, Tingxi; Anczurowski, Mark; Saso, Kayoko; Butler, Marcus O; Hirano, Naoto

2017-01-26

Adoptive cell therapy is a potentially curative therapeutic approach for patients with cancer. In this treatment modality, antitumor T cells are exponentially expanded in vitro prior to infusion. Importantly, the results of recent clinical trials suggest that the quality of expanded T cells critically affects their therapeutic efficacy. Although anti-CD3 mAb-based stimulation is widely used to expand T cells in vitro, a protocol to generate T cell grafts for optimal adoptive therapy has yet to be established. In this study, we investigated the differences between T cell stimulation mediated by anti-CD3/CD28 mAb-coated beads and cell-based artificial antigen-presenting cells (aAPCs) expressing CD3/CD28 counter-receptors. We found that transient stimulation with cell-based aAPCs, but not prolonged stimulation with beads, resulted in the superior expansion of CD8 + T cells. Transiently stimulated CD8 + T cells maintained a stem cell-like memory phenotype and were capable of secreting multiple cytokines significantly more efficiently than chronically stimulated T cells. Importantly, the chimeric antigen receptor-engineered antitumor CD8 + T cells expanded via transient stimulation demonstrated superior persistence and antitumor responses in adoptive immunotherapy mouse models. These results suggest that restrained stimulation is critical for generating T cell grafts for optimal adoptive immunotherapy for cancer.
Matching native electrical stimulation by graded chemical stimulation in isolated mouse adrenal chromaffin cells.

PubMed

Fulop, Tiberiu; Smith, Corey

2007-11-30

Adrenal chromaffin cells release multiple transmitters in response to sympathetic stimulation. Modest cell firing, matching sympathetic tone, releases small freely soluble catecholamines. Elevated electrical firing rates matching input under sympathetic stress results in release of catecholamines as well as semi-soluble vaso- and neuro-active peptides packaged within the dense core of the secretory granule. This activity-dependent differential transmitter release has been shown to rely on a mechanistic shift in the mode of exocytosis through the regulated dilation of the secretory fusion pore between granule and cell surface membranes. However, biochemical description of the mechanism regulating fusion pore dilation remains elusive. In the experimental setting, electrical stimulation designed to mimic sympathetic input, is achieved through single-cell voltage-clamp. While precise, this approach is incompatible with biochemical and proteomic analysis, both of which require large sample sizes. We address this limitation in the current study. We describe a bulk chemical stimulation paradigm calibrated to match defined electrical activity. We utilize calcium and single-cell amperometric measurements to match extracellular potassium concentrations to physiological electrical stimulation under sympathetic tone as well as acute stress conditions. This approach provides larger samples of uniformly stimulated cells for determining molecular players in activity-dependent differential transmitter release from adrenal chromaffin cells.
The Response of Prostate Smooth Muscle Cells to Testosterone Is Determined by the Subcellular Distribution of the Androgen Receptor.

PubMed

Peinetti, Nahuel; Scalerandi, María Victoria; Cuello Rubio, Mariana Micaela; Leimgruber, Carolina; Nicola, Juan Pablo; Torres, Alicia Ines; Quintar, Amado Alfredo; Maldonado, Cristina Alicia

2018-02-01

Androgen signaling in prostate smooth muscle cells (pSMCs) is critical for the maintenance of prostate homeostasis, the alterations of which are a central aspect in the development of pathological conditions. Testosterone can act through the classic androgen receptor (AR) in the cytoplasm, eliciting genomic signaling, or through different types of receptors located at the plasma membrane for nongenomic signaling. We aimed to find evidence of nongenomic testosterone-signaling mechanisms in pSMCs and their participation in cell proliferation, differentiation, and the modulation of the response to lipopolysaccharide. We demonstrated that pSMCs can respond to testosterone by a rapid activation of ERK1/2 and Akt. Furthermore, a pool of ARs localized at the cell surface of pSMCs is responsible for a nongenomic testosterone-induced increase in cell proliferation. Through membrane receptor stimulation, testosterone favors a muscle phenotype, indicated by an increase in smooth muscle markers. We also showed that the anti-inflammatory effects of testosterone, capable of attenuating lipopolysaccharide-induced proinflammatory actions, are promoted only by receptors located inside the cell. We postulate that testosterone might perform prohomeostatic effects through intracellular-initiated mechanisms by modulating cell proliferation and inflammation, whereas some pathological, hyperproliferative actions would be induced by membrane-initiated nongenomic signaling in pSMCs. Copyright © 2018 Endocrine Society.
Effect of tendon vibration during wide-pulse neuromuscular electrical stimulation (NMES) on muscle force production in people with spinal cord injury (SCI).

PubMed

Bochkezanian, Vanesa; Newton, Robert U; Trajano, Gabriel S; Vieira, Amilton; Pulverenti, Timothy S; Blazevich, Anthony J

2018-02-13

Neuromuscular electrical stimulation (NMES) is commonly used in skeletal muscles in people with spinal cord injury (SCI) with the aim of increasing muscle recruitment and thus muscle force production. NMES has been conventionally used in clinical practice as functional electrical stimulation (FES), using low levels of evoked force that cannot optimally stimulate muscular strength and mass improvements, and thus trigger musculoskeletal changes in paralysed muscles. The use of high intensity intermittent NMES training using wide-pulse width and moderate-intensity as a strength training tool could be a promising method to increase muscle force production in people with SCI. However, this type of protocol has not been clinically adopted because it may generate rapid muscle fatigue and thus prevent the performance of repeated high-intensity muscular contractions in paralysed muscles. Moreover, superimposing patellar tendon vibration onto the wide-pulse width NMES has been shown to elicit further increases in impulse or, at least, reduce the rate of fatigue in repeated contractions in able-bodied populations, but there is a lack of evidence to support this argument in people with SCI. Nine people with SCI received two NMES protocols with and without superimposing patellar tendon vibration on different days (i.e. STIM and STIM+vib), which consisted of repeated 30 Hz trains of 58 wide-pulse width (1000 μs) symmetric biphasic pulses (0.033-s inter-pulse interval; 2 s stimulation train; 2-s inter-train interval) being delivered to the dominant quadriceps femoris. Starting torque was 20% of maximal doublet-twitch torque and stimulations continued until torque declined to 50% of the starting torque. Total knee extensor impulse was calculated as the primary outcome variable. Total knee extensor impulse increased in four subjects when patellar tendon vibration was imposed (59.2 ± 15.8%) but decreased in five subjects (- 31.3 ± 25.7%). However, there were no
Transient stimulation expands superior antitumor T cells for adoptive therapy

PubMed Central

Kagoya, Yuki; Nakatsugawa, Munehide; Ochi, Toshiki; Guo, Tingxi; Anczurowski, Mark; Saso, Kayoko; Butler, Marcus O.

2017-01-01

Adoptive cell therapy is a potentially curative therapeutic approach for patients with cancer. In this treatment modality, antitumor T cells are exponentially expanded in vitro prior to infusion. Importantly, the results of recent clinical trials suggest that the quality of expanded T cells critically affects their therapeutic efficacy. Although anti-CD3 mAb-based stimulation is widely used to expand T cells in vitro, a protocol to generate T cell grafts for optimal adoptive therapy has yet to be established. In this study, we investigated the differences between T cell stimulation mediated by anti–CD3/CD28 mAb–coated beads and cell-based artificial antigen-presenting cells (aAPCs) expressing CD3/CD28 counter-receptors. We found that transient stimulation with cell-based aAPCs, but not prolonged stimulation with beads, resulted in the superior expansion of CD8+ T cells. Transiently stimulated CD8+ T cells maintained a stem cell–like memory phenotype and were capable of secreting multiple cytokines significantly more efficiently than chronically stimulated T cells. Importantly, the chimeric antigen receptor–engineered antitumor CD8+ T cells expanded via transient stimulation demonstrated superior persistence and antitumor responses in adoptive immunotherapy mouse models. These results suggest that restrained stimulation is critical for generating T cell grafts for optimal adoptive immunotherapy for cancer. PMID:28138559
Requirement of myomaker-mediated stem cell fusion for skeletal muscle hypertrophy

PubMed Central

Goh, Qingnian; Millay, Douglas P

2017-01-01

Fusion of skeletal muscle stem/progenitor cells is required for proper development and regeneration, however the significance of this process during adult muscle hypertrophy has not been explored. In response to muscle overload after synergist ablation in mice, we show that myomaker, a muscle specific membrane protein essential for myoblast fusion, is activated mainly in muscle progenitors and not myofibers. We rendered muscle progenitors fusion-incompetent through genetic deletion of myomaker in muscle stem cells and observed a complete reduction of overload-induced hypertrophy. This blunted hypertrophic response was associated with a reduction in Akt and p70s6k signaling and protein synthesis, suggesting a link between myonuclear accretion and activation of pro-hypertrophic pathways. Furthermore, fusion-incompetent muscle exhibited increased fibrosis after muscle overload, indicating a protective role for normal stem cell activity in reducing myofiber strain associated with hypertrophy. These findings reveal an essential contribution of myomaker-mediated stem cell fusion during physiological adult muscle hypertrophy. DOI: http://dx.doi.org/10.7554/eLife.20007.001 PMID:28186492
Mucosally transplanted mesenchymal stem cells stimulate intestinal healing by promoting angiogenesis.

PubMed

Manieri, Nicholas A; Mack, Madison R; Himmelrich, Molly D; Worthley, Daniel L; Hanson, Elaine M; Eckmann, Lars; Wang, Timothy C; Stappenbeck, Thaddeus S

2015-09-01

Mesenchymal stem cell (MSC) therapy is an emerging field of regenerative medicine; however, it is often unclear how these cells mediate repair. Here, we investigated the use of MSCs in the treatment of intestinal disease and modeled abnormal repair by creating focal wounds in the colonic mucosa of prostaglandin-deficient mice. These wounds developed into ulcers that infiltrated the outer intestinal wall. We determined that penetrating ulcer formation in this model resulted from increased hypoxia and smooth muscle wall necrosis. Prostaglandin I₂ (PGI₂) stimulated VEGF-dependent angiogenesis to prevent penetrating ulcers. Treatment of mucosally injured WT mice with a VEGFR inhibitor resulted in the development of penetrating ulcers, further demonstrating that VEGF is critical for mucosal repair. We next used this model to address the role of transplanted colonic MSCs (cMSCs) in intestinal repair. Compared with intravenously injected cMSCs, mucosally injected cMSCs more effectively prevented the development of penetrating ulcers, as they were more efficiently recruited to colonic wounds. Importantly, mucosally injected cMSCs stimulated angiogenesis in a VEGF-dependent manner. Together, our results reveal that penetrating ulcer formation results from a reduction of local angiogenesis and targeted injection of MSCs can optimize transplantation therapy. Moreover, local MSC injection has potential for treating diseases with features of abnormal angiogenesis and repair.
Monitoring respiratory muscles.

PubMed

Nava, S

1998-12-01

The respiratory system consists of two main parts, the lung and the ventilatory pump. The latter consists of the bony structure of the thorax, the central respiratory controllers, the inspiratory and expiratory muscles, and the nerves innervating these muscles. Respiratory muscle fatigue occurs when respiratory muscle endurance is exceeded. Muscle fatigue is defined as a condition in which there is a reduction in the capacity for developing force and/or velocity of a muscle, resulting from muscle activity, and which is reversible by rest. The respiratory muscles are somewhat difficult to assess and the techniques employed are still relatively primitive. The most important methods of respiratory muscles function assessment are: 1) the vital capacity manoeuvre, which depends on maximum inspiratory and expiratory effort by the muscles and may be a useful indicator of respiratory muscle function; 2) radiological screening has been proposed for the detection of diaphragm paralysis. This may be helpful if the paralysis is unilateral, but bilateral paralysis is difficult to detect; and 3) respiratory muscles strength may be assessed with either voluntary or nonvoluntary manoeuvres. The function of the inspiratory muscles is assessed with 3 voluntary dependent manoeuvres. They are the so called Müller manoeuvre (or maximal inspiratory pressure), the sniff test and the combined test. All these three manoeuvres generate a pressure that is a reflection of complex interactions between several muscle groups since the efforts produce different mechanisms of activity of inspiratory and expiratory muscles. Two techniques are presently employed to assess diaphragm function, not being dependent on the patient's motivation: electrical phrenic nerve stimulation and cervical magnetic stimulation. Since it is less painful, magnetic cervical stimulation overcomes some of the difficulties encountered during electrical stimulation. With these two techniques recordings of diaphragmatic
Myogenic Growth Factor Present in Skeletal Muscle is Purified by Heparin-Affinity Chromatography

NASA Astrophysics Data System (ADS)

Kardami, Elissavet; Spector, Dennis; Strohman, Richard C.

1985-12-01

A myogenic growth factor has been purified from a skeletal muscle, the anterior latissimus dorsi, of adult chickens. In the range of 1-10 ng, this factor stimulates DNA synthesis as well as protein and muscle-specific myosin accumulation in myogenic cell cultures. Purification is achieved through binding of the factor to heparin. The factor is distinct from transferrin and works synergistically with transferrin in stimulating myogenesis in vitro.

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