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Sample records for guinea-pig cardiac myocytes

  1. Toward an integrative computational model of the Guinea pig cardiac myocyte.

    PubMed

    Gauthier, Laura Doyle; Greenstein, Joseph L; Winslow, Raimond L

    2012-01-01

    The local control theory of excitation-contraction (EC) coupling asserts that regulation of calcium (Ca(2+)) release occurs at the nanodomain level, where openings of single L-type Ca(2+) channels (LCCs) trigger openings of small clusters of ryanodine receptors (RyRs) co-localized within the dyad. A consequence of local control is that the whole-cell Ca(2+) transient is a smooth continuous function of influx of Ca(2+) through LCCs. While this so-called graded release property has been known for some time, its functional importance to the integrated behavior of the cardiac ventricular myocyte has not been fully appreciated. We previously formulated a biophysically based model, in which LCCs and RyRs interact via a coarse-grained representation of the dyadic space. The model captures key features of local control using a low-dimensional system of ordinary differential equations. Voltage-dependent gain and graded Ca(2+) release are emergent properties of this model by virtue of the fact that model formulation is closely based on the sub-cellular basis of local control. In this current work, we have incorporated this graded release model into a prior model of guinea pig ventricular myocyte electrophysiology, metabolism, and isometric force production. The resulting integrative model predicts the experimentally observed causal relationship between action potential (AP) shape and timing of Ca(2+) and force transients, a relationship that is not explained by models lacking the graded release property. Model results suggest that even relatively subtle changes in AP morphology that may result, for example, from remodeling of membrane transporter expression in disease or spatial variation in cell properties, may have major impact on the temporal waveform of Ca(2+) transients, thus influencing tissue level electromechanical function. PMID:22783206

  2. Toward an Integrative Computational Model of the Guinea Pig Cardiac Myocyte

    PubMed Central

    Gauthier, Laura Doyle; Greenstein, Joseph L.; Winslow, Raimond L.

    2012-01-01

    The local control theory of excitation-contraction (EC) coupling asserts that regulation of calcium (Ca2+) release occurs at the nanodomain level, where openings of single L-type Ca2+ channels (LCCs) trigger openings of small clusters of ryanodine receptors (RyRs) co-localized within the dyad. A consequence of local control is that the whole-cell Ca2+ transient is a smooth continuous function of influx of Ca2+ through LCCs. While this so-called graded release property has been known for some time, its functional importance to the integrated behavior of the cardiac ventricular myocyte has not been fully appreciated. We previously formulated a biophysically based model, in which LCCs and RyRs interact via a coarse-grained representation of the dyadic space. The model captures key features of local control using a low-dimensional system of ordinary differential equations. Voltage-dependent gain and graded Ca2+ release are emergent properties of this model by virtue of the fact that model formulation is closely based on the sub-cellular basis of local control. In this current work, we have incorporated this graded release model into a prior model of guinea pig ventricular myocyte electrophysiology, metabolism, and isometric force production. The resulting integrative model predicts the experimentally observed causal relationship between action potential (AP) shape and timing of Ca2+ and force transients, a relationship that is not explained by models lacking the graded release property. Model results suggest that even relatively subtle changes in AP morphology that may result, for example, from remodeling of membrane transporter expression in disease or spatial variation in cell properties, may have major impact on the temporal waveform of Ca2+ transients, thus influencing tissue level electromechanical function. PMID:22783206

  3. Two Types of Calcium Channels in Guinea Pig Ventricular Myocytes

    NASA Astrophysics Data System (ADS)

    Mitra, Raman; Morad, Martin

    1986-07-01

    In cardiac muscle, Ca2+ plays a key role in regulation of numerous processes, including generation of the action potential and development of tension. The entry of Ca2+ into the cell is regulated primarily by voltage-gated channels in the membrane. Until recently, it was felt that only one type of Ca2+ channel existed in cardiac ventricular muscle. Experiments reported here suggest that in isolated guinea pig ventricular myocytes, there are two distinct types of Ca2+ channels with markedly different activation thresholds, inactivation kinetics, and sensitivities to inorganic and organic Ca2+ channel blockers. The channels were also distinguished based on their response to increased frequency of clamping such that the current through the low-threshold channel decreased while that through the high-threshold channel increased. In a few cells, the current through both channels was enhanced by isoproterenol, a β -adrenergic agonist, but only the high-threshold channel was enhanced by the Ca2+-channel agonist Bay K 8644. Thus, isolated guinea pig ventricular myocytes appear to have two types of Ca2+ channels distinguished by various criteria.

  4. The relationship between contraction and intracellular sodium in rat and guinea-pig ventricular myocytes.

    PubMed Central

    Harrison, S M; McCall, E; Boyett, M R

    1992-01-01

    1. The contraction, measured optically, and the intracellular Na+ activity (aNai), measured with the Na(+)-sensitive fluorescent dye SBFI, have been recorded simultaneously in rat and guinea-pig ventricular myocytes. 2. In rat and guinea-pig ventricular myocytes at rest, aNai was 7.8 +/- 0.3 mM (n = 4) and 5.1 +/- 0.3 mM (n = 16), respectively. 3. When both rat and guinea-pig ventricular myocytes were stimulated at 1 Hz after a rest there was usually a gradual increase in twitch shortening (referred to as a 'staircase') over several minutes accompanied by an increase in aNai over a similar time course. Twitch shortening increased by 21 +/- 3% (n = 6) and 20 +/- 4% (n = 16) (of steady-state twitch shortening during 1 Hz stimulation) per millimolar rise in aNai in rat and guinea-pig ventricular myocytes, respectively. 4. When rat and guinea-pig ventricular myocytes were exposed to strophanthidin to block the Na(+)-K+ pump, there were increases in twitch shortening and aNai over similar time courses. Twitch shortening increased by 24 +/- 4% (n = 5) and 20 +/- 3% (n = 10) (of control twitch shortening) per millimolar rise in aNai in rat and guinea-pig ventricular myocytes respectively. 5. The inotropic effect of cardiac glycosides, such as strophanthidin, is widely regarded to be principally the result of the rise in aNai. The similarity of the relation between twitch shortening and aNai during the staircase and on application of strophanthidin suggests that the progressive increase in the strength of contraction during the staircase was also linked to the rise in aNai. 6. In guinea-pig, but not rat, ventricular myocytes there was hysteresis in the relation between twitch shortening and aNai on application and wash-off of strophanthidin. This indicates that strophanthidin has another inotropic action in guinea-pig ventricular myocytes. 7. A computer model of excitation-contraction coupling has been developed to simulate the staircase and the action of cardiac glycoside

  5. Inhibitory effect of 2,3-butanedione monoxime (BDM) on Na+/Ca2+ exchange current in guinea-pig cardiac ventricular myocytes

    PubMed Central

    Watanabe, Yasuhide; Iwamoto, Takahiro; Matsuoka, Isao; Ohkubo, Satoko; Ono, Tomoyuki; Watano, Tomokazu; Shigekawa, Munekazu; Kimura, Junko

    2001-01-01

    The effect of 2,3-butanedione monoxime (BDM), a ‘chemical phosphatase', on Na+/Ca2+ exchange current (INCX) was investigated using the whole-cell voltage-clamp technique in single guinea-pig cardiac ventricular myocytes and in CCL39 fibroblast cells expressing canine NCX1. INCX was identified as a current sensitive to KB-R7943, a relatively selective NCX inhibitor, at 140 mM Na+ and 2 mM Ca2+ in the external solution and 20 mM Na+ and 433 nM free Ca2+ in the pipette solution. In guinea-pig ventricular cells, BDM inhibited INCX in a concentration-dependent manner. The IC50 value was 2.4 mM with a Hill coefficients of 1. The average time for 50% inhibition by 10 mM BDM was 124±31 s (n=5). The effect of BDM was not affected by 1 μM okadaic acid in the pipette solution, indicating that the inhibition was not via activation of okadaic acid-sensitive protein phosphatases. Intracellular trypsin treatment via the pipette solution significantly suppressed the inhibitory effect of BDM, implicating an intracellular site of action of BDM. PAM (pralidoxime), another oxime compound, also inhibited INCX in a manner similar to BDM. Isoprenaline at 50 μM and phorbol 12-myristate 13-acetate (PMA) at 8 μM did not reverse the inhibition of INCX by BDM. BDM inhibited INCX in CCL39 cells expressing NCX1 and in its mutant in which its three major phosphorylatable serine residues were replaced with alanines. We conclude that BDM inhibits INCX but the mechanism of inhibition is not by dephosphorylation of the Na+/Ca2+ exchanger as a ‘chemical phosphatase'. PMID:11250883

  6. Cell swelling has differential effects on the rapid and slow components of delayed rectifier potassium current in guinea pig cardiac myocytes

    PubMed Central

    1995-01-01

    Cell swelling has been shown to cause activation of a variety of cardiac sarcolemmal ionic conductances including potassium channels. The aim of this study was to investigate the effect of swelling on the two subtypes of delayed rectifier potassium current (IKr and IKs) in single guinea pig myocytes using the whole-cell configuration of the patch clamp technique. When the holding potential was set at -40 mV and stepped to +40 mV for 1 s under isoosmotic conditions (300 mOsm) a delayed rectifier current (IK) was activated (0.86 +/- 0.05 nA; n = 43). Switching to a hypoosmotic solution (200 mOsm) caused a rapid increase in IK to a mean value of 1.43 +/- 0.10 nA (p < 0.05; n = 43). The effect of swelling on the two subtypes of IK was studied by analysis of deactivating tail currents using an envelope of tails protocol (stepping from -40 to +40 mV for 18 different pulse durations between 50 ms and 2.9 s; n = 16). Swelling caused a decrease in current amplitude measured at the end of the pulse (and IKtail) at short durations (< or = 150 ms) however, when the pulse duration was > 1 s swelling caused a significant increase in current. Using a pulse protocol to measure IKr with minimal contamination by IKs (voltage step from -40 to -10 mV for 250 ms) a 50-100 pA current was elicited which could be completely blocked by dofetilide (0.2 microM; n = 3). Introduction of hypoosmotic solution caused a significant decrease in IKr and when dofetilide (0.2 or 1.0 microM) was introduced the current remaining was decreased further (p < 0.05; n = 5), but was not completely blocked, thus suggesting that swelling had decreased the ability of dofetilide to block IKr. Similar results were obtained over a range of dofetilide concentrations and with a second IKr blocker, La3+. In Ca(2+)-free external solutions, pulsing to -10 mV for 500 ms to measure IKr in the absence of IKs, and to +60 mV for 5 s (with 0.2 microM dofetilide) to evoke only IKs, it was clear that swelling significantly

  7. Slow recovery of excitability and the Wenckebach phenomenon in the single guinea pig ventricular myocyte.

    PubMed

    Delmar, M; Michaels, D C; Jalife, J

    1989-09-01

    The cellular mechanisms of Wenckebach periodicity were investigated in single, enzymatically dissociated guinea pig ventricular myocytes, as well as in computer reconstructions of transmembrane potential of the ventricular cell. When depolarizing current pulses of the appropriate magnitude were delivered repetitively to a well-polarized myocyte, rate-dependent activation failure was observed. Such behavior accurately mimicked the Wenckebach phenomenon in cardiac activation and was the consequence of variations in cell excitability during the diastolic phase of the cardiac cycle. The recovery of cell excitability during diastole was studied through the application of single test pulses of fixed amplitude and duration at variable delays with respect to a basic train of normal action potentials. The results show that recovery of excitability is a slow process that can greatly outlast action potential duration (i.e., postrepolarization refractoriness). Two distinct types of subthreshold responses were recorded when activation failure occurred: one was tetrodotoxin- and cobalt-insensitive (type 1) and the other was sensitive to sodium-channel blockade (type 2). Type 1 responses, which were commonly associated with the typical structure of the Wenckebach phenomenon (Mobitz type 1 block), were found to be the result of the nonlinear conductance properties of the inward rectifier current, IK1. Type 2 sodium-channel-mediated responses were associated with the so-called "millisecond Wenckebach." These responses may be implicated in the mechanism of Mobitz type 2 rate-dependent block. Single-cell voltage-clamp experiments suggest that variations in excitability during diastole are a consequence of the slow deactivation kinetics of the delayed rectifier, IK. Computer simulations of the ventricular cell response to depolarizing current pulses reproduced very closely all the response patterns obtained in the experimental preparation. It is concluded that postrepolarization

  8. Urocortin2 prolongs action potential duration and modulates potassium currents in guinea pig myocytes and HEK293 cells.

    PubMed

    Yang, Li-Zhen; Zhu, Yi-Chun

    2015-07-01

    We previously reported that activation of corticotropin releasing factor receptor type 2 by urocortin2 up-regulates both L-type Ca(2+) channels and intracellular Ca(2+) concentration in ventricular myocytes and plays an important role in cardiac contractility and arrhythmogenesis. This study goal was to further test the hypothesis that urocortin2 may modulate action potentials as well as rapidly and slowly activating delayed rectifier potassium currents. With whole cell patch-clamp techniques, action potentials and slowly activating delayed rectifier potassium currents were recorded in isolated guinea pig ventricular myocytes, respectively. And rapidly activating delayed rectifier potassium currents were tested in hERG-HEK293 cells. Urocortin2 produced a time- and concentration-dependent prolongation of action potential duration. The EC50 values of action potential duration and action potential duration at 90% of repolarization were 14.73 and 24.3nM respectively. The prolongation of action potential duration of urocortin2 was almost completely or partly abolished by H-89 (protein kinase A inhibitor) or KB-R7943 (Na(+)/Ca(2+) exchange inhibitor) pretreatment respectively. And urocortin2 caused reduction of rapidly activating delayed rectifier potassium currents in hERG-HEK293 cells. In addition, urocortin2 slowed the rate of slowly activating delayed rectifier potassium channel activation, and rightward shifted the threshold of slowly activating delayed rectifier potassium currents to more positive potentials. Urocortin2 prolonged action potential duration via activation of protein kinase A and Na(+)/ Ca(2+) exchange in isolated guinea pig ventricular myocytes in a time- and concentration- dependent manner. In hERG-HEK293 cells, urocortin2 reduced rapidly activating delayed rectifier potassium current density which may contribute to action potential duration prolongation.

  9. Localization and quantitation of cardiac annexins II, V, and VI in hypertensive guinea pigs.

    PubMed

    Trouvé, P; Legot, S; Bélikova, I; Marotte, F; Bénévolensky, D; Russo-Marie, F; Samuel, J L; Charlemagne, D

    1999-04-01

    Annexins are characterized by Ca2+-dependent binding to phospholipids. Annexin II mainly participates in cell-cell adhesion and signal transduction, whereas annexins V and VI also seem to regulate intracellular calcium cycling. Their abundance and localization were determined in left ventricle (LV) and right ventricle (RV) from hypertensive guinea pigs, during the transition from compensatory hypertrophy to heart failure. Immunoblot analysis of annexins II, V, and VI revealed an increased accumulation (2.6-, 1.45-, and 2.3-fold, respectively) in LV from hypertensive guinea pigs and no modification in RV. Immunofluorescent labeling of annexins II, V, and VI; of Na+-K+-ATPase; and of sarcomeric alpha-actinin showed that in control LV and RV, 1) annexin II is present in nonmuscle cells; 2) annexins V and VI are mainly observed in the sarcolemma and intercalated disks of myocytes; 3) annexins II, V, and VI strongly label endothelial cells and adventitia of coronary arteries; and 4) annexin VI is present in the media. At the onset of heart failure, the most striking changes are the increased protein accumulation in LV and the very strong labeling of annexins II, V, and VI in interstitial tissue, suggesting a role in fibrosis development and cardiac remodeling. PMID:10199838

  10. Functional diversity of electrogenic Na+–HCO3− cotransport in ventricular myocytes from rat, rabbit and guinea pig

    PubMed Central

    Yamamoto, Taku; Swietach, Pawel; Rossini, Alessandra; Loh, Shih-Hurng; Vaughan-Jones, Richard D; Spitzer, Kenneth W

    2005-01-01

    The Na+–HCO3− cotransporter (NBC) is an important sarcolemmal acid extruder in cardiac muscle. The characteristics of NBC expressed functionally in heart are controversial, with reports suggesting electroneutral (NBCn; 1HCO3− : 1Na+; coupling coefficient n = 1) or electrogenic forms of the transporter (NBCe; equivalent to 2HCO3− : 1Na+; n = 2). We have used voltage-clamp and epifluorescence techniques to compare NBC activity in isolated ventricular myocytes from rabbit, rat and guinea pig. Depolarization (by voltage clamp or hyperkalaemia) reversibly increased steady-state pHi while hyperpolarization decreased it, effects seen only in CO2/HCO3−-buffered solutions, and blocked by S0859 (cardiac NBC inhibitor). Species differences in amplitude of these pHi changes were rat > guinea pig ≈ rabbit. Tonic depolarization (−140 mV to −0 mV) accelerated NBC-mediated pHi recovery from an intracellular acid load. At 0 mV, NBC-mediated outward current at resting pHi was +0.52 ± 0.05 pA pF−1 (rat, n = 5), +0.26 ± 0.05 pA pF−1 (guinea pig, n = 5) and +0.10 ± 0.03 pA pF−1 (rabbit, n = 9), with reversal potentials near −100 mV, consistent with n = 2. The above results indicate a functionally active voltage-sensitive NBCe in these species. Voltage-clamp hyperpolarization negative to the reversal potential for NBCe failed, however, to terminate or reverse NBC-mediated pHi-recovery from an acid load although it was slowed significantly, suggesting electroneutral NBC may also be operational. NBC-mediated pHi recovery was associated with a rise of [Na+]i at a rate ∼25% of that mediated via NHE, and consistent with an apparent NBC stoichiometry between n = 1 and n = 2. In conclusion, NBCe in the ventricular myocyte displays considerable functional variation among the three species tested (greatest in rat, least in rabbit) and may coexist with some NBCn activity. PMID:15550467

  11. A plant histaminase modulates cardiac anaphylactic response in guinea pig.

    PubMed

    Masini, Emanuela; Vannacci, Alfredo; Marzocca, Cosimo; Mannaioni, Pier Francesco; Befani, Olivia; Federico, Rodolfo; Toma, Alessandro; Mondovì, Bruno

    2002-08-30

    The effect of a copper amine oxidase (histaminase) purified from the pea seedling as free or immobilized enzyme on the response to specific antigen was studied in isolated hearts from actively sensitized guinea pigs. In vitro challenge with the specific antigen of hearts from actively sensitized animals evokes a positive inotropic and chronotropic effect, a coronary constriction, followed by dilation and an increase in the amount of histamine and nitrites, the oxidation product of nitric oxide, in the perfusates. In the presence of both forms of histaminases, the positive inotropic and chronotropic responses as well as the coronary constriction and the release of histamine were fully blocked. The amount of nitrites, appearing in the perfusates when anaphylaxis is elicited in the presence of both forms of histaminases, is significantly increased, as well as nitric oxide synthase activity and cyclic GMP content in cardiac tissue, while cardiac calcium overload was significantly prevented. These observations demonstrate that the decrease in the anaphylactic release of histamine and the subsequent abatement of the cardiac response to antigen can be accounted for by the inactivation by histaminase of the released histamine and by a stimulation of endogenous nitric oxide production. PMID:12200124

  12. Protective effects of isorhynchophylline on cardiac arrhythmias in rats and guinea pigs.

    PubMed

    Gan, Runtao; Dong, Guo; Yu, Jiangbo; Wang, Xu; Fu, Songbin; Yang, Shusen

    2011-09-01

    As one important constituent extracted from a traditional Chinese medicine, Uncaria Rhynchophylla Miq Jacks, isorhynchophylline has been used to treat hypertension, epilepsy, headache, and other illnesses. Whether isorhynchophylline protects hearts against cardiac arrhythmias is still incompletely investigated. This study was therefore aimed to examine the preventive effects of isorhynchophylline on heart arrhythmias in guinea pigs and rats and then explore their electrophysiological mechanisms. In vivo, ouabain and calcium chloride were used to establish experimental arrhythmic models in guinea pigs and rats. In vitro, the whole-cell patch-lamp technique was used to study the effect of isorhynchophylline on action potential duration and calcium channels in acutely isolated guinea pig and rat cardiomyocytes. The dose of ouabain required to induce cardiac arrhythmias was much larger in guinea pigs administered with isorhynchophylline. Additionally, the onset time of cardiac arrhythmias induced by calcium chloride was prolonged, and the duration was shortened in rats pretreated with isorhynchophylline. The further study showed that isorhynchophylline could significantly decrease action potential duration and inhibit calcium currents in isolated guinea pig and rat cardiomyocytes in a dose-dependent manner. In summary, isorhynchophylline played a remarkably preventive role in cardiac arrhythmias through the inhibition of calcium currents in rats and guinea pigs.

  13. High-fat diet-dependent modulation of the delayed rectifier K(+) current in adult guinea pig atrial myocytes.

    PubMed

    Aromolaran, Ademuyiwa S; Colecraft, Henry M; Boutjdir, Mohamed

    2016-06-01

    Obesity is associated with hyperlipidemia, electrical remodeling of the heart, and increased risk of supraventricular arrhythmias in both male and female patients. The delayed rectifier K(+) current (IK), is an important regulator of atrial repolarization. There is a paucity of studies on the functional role of IK in response to obesity. Here, we assessed the obesity-mediated functional modulation of IK in low-fat diet (LFD), and high-fat diet (HFD) fed adult guinea pigs. Guinea pigs were randomly divided into control and obese groups fed, ad libitum, with a LFD (10 kcal% fat) or a HFD (45 kcal% fat) respectively. Action potential duration (APD), and IK were studied in atrial myocytes and IKr and IKs in HEK293 cells using whole-cell patch clamp electrophysiology. HFD guinea pigs displayed a significant increase in body weight, total cholesterol and total triglycerides within 50 days. Atrial APD at 30% (APD30) and 90% (APD90) repolarization were shorter, while atrial IK density was significantly increased in HFD guinea pigs. Exposure to palmitic acid (PA) increased heterologously expressed IKr and IKs densities, while oleic acid (OA), severely reduced IKr and had no effect on IKs. The data are first to show that in obese guinea pigs abbreviated APD is due to increased IK density likely through elevations of PA. Our findings may have crucial implications for targeted treatment options for obesity-related arrhythmias.

  14. [Study of Magnolia grandiflora extracts in guinea pigs cardiac muscle].

    PubMed

    del Valle Mondragón, Leonardo; Tenorio López, Fermín Alejandro; Torres Narváez, Juan Carlos; Zarco Olvera, Gabriela; Pastelín Hernández, Gustavo

    2004-01-01

    Several extracts from diverse Magnolia grandiflora varieties were pharmacological evaluated in the cardiac muscle. From March to July, flowers and leaves from Magnolia grandiflora, native from the National Institute of Cardiology "Ignacio Chávez", from north, west, and orient zones from Mexico City, and from Puebla, Colima and Chiapas states were collected. They were separately processed and the extracts were obtained by maceration with ethanol-water (1:3 v/v) at 4 degrees C during two weeks. Qualitative analysis was accomplished with thin-layer, column and high-performance liquid chromatographies (HPLC). Functional and molecular analysis was made by specific chemical reactivity and by protonic magnetic resonance (RMN 1H). Pharmacological evaluation was completed in isolated and perfused male guinea pigs hearts. Extracts, fractions, and compounds were administrated by serial bolus in a gradual dose-response curves study in which left intraventricular pressure and coronary perfusion pressure were recorded, evaluating by such the positive inotropic and vasodilator effects of Magnolia grandiflora extracts. Vulgarenol and 2-p-hydroxyphenyl-2-hydroxy-ethylamine were isolated and identified, and the obtained results suggest that its positive inotropic and vasodilator effects are owed to these substances, being complemented by magnograndiolide and tyramine.

  15. Intramembrane charge movement in guinea-pig and rat ventricular myocytes.

    PubMed Central

    Hadley, R W; Lederer, W J

    1989-01-01

    1. Non-linear capacitative current (charge movement) was studied in isolated guinea-pig and rat ventricular myocytes. Linear capacitance was subtracted using standard procedures. Most of the experiments were done with guinea-pig myocytes, while rat myocytes were used for comparison. 2. When a myocyte was held at -100 mV, depolarizing clamp steps produced a rapid outward current transient, which was followed by an inward current transient upon repolarization. This current was identified as the movement of charged particles in the cell membrane, rather than ionic movement across the membrane, for the following reasons: (1) the current saturated at membrane potentials positive to +20 mV; (2) the current was capacitative in nature, having no reversal potential; (3) in general, the charge moved during depolarization (Qon) approximated the charge moved during repolarization (Qoff). 3. Qoff was significantly less than Qon for a depolarization from -100 mV to 0 mV. However, the Qoff/Qon ratio approached unity if the cell was instead repolarized to -140 mV. This was interpreted as being due to the immobilization of a fraction of the charge during the depolarization, which recovered rapidly enough to be measured at -140 mV, but recovered too slowly at -100 mV. 4. Charge movement in these cells had a sigmoidal dependence on the membrane potential, which could be empirically described by the two-state Boltzmann equation Q = Qmax/(1 + exp[-(V-V*)/kappa]), where Q is the charge movement at potential V, Qmax is the maximum charge, V* is the membrane potential at Q = Qmax/2, and kappa is a slope factor. Qmax was 11.7 nC/microF, V* was -18 mV and kappa was 16 mV in guinea-pig myocytes held at -100 mV, while the values in rat myocytes were 10.9 nC/microF, -32 mV and 13 mV. 5. The charge movement could be partially immobilized by a prior depolarization. This effect developed over a broad voltage range, from -120 to +20 mV. The fraction of charge that could be immobilized by a 10 s

  16. Stimulatory action of protein kinase Cɛ isoform on the slow component of delayed rectifier K+ current in guinea-pig atrial myocytes

    PubMed Central

    Toda, H; Ding, W-G; Yasuda, Y; Toyoda, F; Ito, M; Matsuura, H; Horie, M

    2007-01-01

    Background and purpose: Protein kinase C (PKC) comprises at least twelve isoforms and has an isoform-specific action on cardiac electrical activity. The slow component of delayed rectifier K+ current (I Ks) is one of the major repolarizing currents in the hearts of many species and is also potentiated by PKC activation. Little is known, however, about PKC isoform(s) functionally involved in the potentiation of I Ks in native cardiac myocytes. Experimental approach: I Ks was recorded from guinea-pig atrial myocytes, using the whole-cell configuration of patch-clamp method. Key results: Bath application of phenylephrine enhanced I Ks concentration-dependently with EC50 of 5.4 μM and the maximal response (97.1±11.9% increase, n=16) was obtained at 30 μM. Prazosin (1 μM) almost totally abolished the potentiation of I Ks by phenylephrine, supporting the involvement of α1-adrenoceptors. The stimulatory action of phenylephrine was significantly, if not entirely, inhibited by the general PKC inhibitor bisindolylmaleimide I but was little affected by Gö-6976, Gö-6983 and rottlerin. Furthermore, this stimulatory effect was significantly reduced by dialyzing atrial myocytes with PKCɛ-selective inhibitory peptide ɛV1-2 but was not significantly affected by conventional PKC isoform-selective inhibitory peptide βC2-4. Phorbol 12-myristate 13-acetate (PMA) at 100 nM substantially increased I Ks by 64.2±1.3% (n=6), which was also significantly attenuated by an internal dialysis with ɛV1-2 but not with βC2-4. Conclusions and implications: The present study provides experimental evidence to suggest that, in native guinea-pig cardiac myocytes, activation of PKC contributes to α1-adrenoceptor-mediated potentiation of I Ks and that ɛ is the isoform predominantly involved in this PKC action. PMID:17339832

  17. Effects of trimebutine maleate on delayed rectifier K+ currents in guinea-pig ventricular myocytes.

    PubMed

    Morisawa, T; Hasegawa, J; Tanabe, K; Watanabe, A; Kitano, M; Kishimoto, Y

    2000-04-01

    The effects of trimebutine maleate, a drug commonly used to regulate motility in the gastrointestinal tract, on the delayed rectifier K+ current (I(K)) were evaluated in guinea-pig ventricular myocytes to determine whether the drug has a proarrhythmic effect through blockade of I(K). Trimebutine decreased I(K) in a concentration-dependent manner. To investigate the effects of trimebutine on two components of I(K) (I(Kr) and I(Ks); rapidly activated and slowly activated components, respectively), we performed the envelope-of-tails test. Trimebutine-sensitive I(K) was determined by digital subtraction of I(K) during exposure to trimebutine from control I(K) for each duration of the test pulse over the range 50 ms-2 s. The ratio of deltaI(K,tail)/deltaI(K) plotted against pulse duration for trimebutine-sensitive I(K) gradually decreased to a steady-state value as the duration of the test pulse was lengthened. This finding suggested a weak inhibitory effect of trimebutine on both I(Kr) and I(Ks). The effects of trimebutine on the inward rectifier K+ current (I(K1)) responsible for the resting potential and final repolarization phase of the action potential were investigated by applying voltage clamp ramps over a broad range of potentials. No significant effects were observed at 10 or 100 microM. We next investigated the effects of the drug on the L-type Ca2+ current (I(Ca)). Significant inhibition of I(Ca) was observed at trimebutine concentrations greater than 10 microM. These results suggested that trimebutine maleate has weak inhibitory effects on I(Kr), I(Ks) and I(Ca) at concentrations much higher than those in clinical use. PMID:10813550

  18. Modulation of the muscarinic K+ channel by P2-purinoceptors in guinea-pig atrial myocytes.

    PubMed Central

    Matsuura, H; Ehara, T

    1996-01-01

    1. Activation of muscarinic K+ (KACh) channels by P2-purinergic agonists, such as ATP, decreases monotonically in the continued presence of agonist. We investigated the mechanisms underlying this process of decline in guinea-pig atrial myocytes using the patch-clamp technique. 2. External ATP reversibly depressed the acetylcholine (ACh, 5.5-11 microM)-induced KACh current in a concentration-dependent manner with a half-maximal inhibitory concentration (IC50) of 5.4 microM. 3. External ATP irreversibly reduced guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S)-induced KACh current both in control and pertussis toxin (PTX)-pretreated cells, suggesting (i) that the ATP-induced inhibition of KACh current occurred at some step(s) downstream from the activation of the PTX-sensitive G protein, GK, and (ii) that a PTX-insensitive G protein was involved in the signal transduction pathway. 4. The potency order of ATP analogues in reducing KACh current was ATP > or = 2-methylthio-ATP > or = alpha, beta-methylene-ATP, indicating involvement of a P2Y-type purinoceptor. 5. In the cell-attached patch recording, ATP (100 microM) applied to the bath solution reduced the activity of the KACh channels activated by ACh in the pipette, in two out of eight experiments, suggesting the possible involvement of cytosolic second messengers in the inhibition of KACh channels. 6. The ATP-induced reduction of KACh current was not affected by a protein kinase C inhibitor, 1-(5-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride (H-7), suggesting that this response was not mediated by the activation of protein kinase C. 7. These results demonstrate that, in addition to the membrane-delimited activation through GK, external ATP causes an inhibition of the KACh channel probably by activating a PTX-insensitive G protein and cytosolic second messenger(s), which may underlie the monotonic decrease of the ATP-activated KACh current. PMID:8961182

  19. Transport of cyanide into guinea pig cardiac mitochondria.

    PubMed

    Wisler, J A; Dulaney, M D; Pellicore, L S; Lenz, D E

    1991-05-01

    The transport of cyanide (CN) into cells has been presumed to be by passive diffusion. Recently, there have been reports that CN, in the form of an anion, may enter the cell by active or facilitated transport. To characterize the mechanism(s) and kinetics of CN movement across the cell membrane, we measured the rate of 14CN (Na salt) uptake into guinea-pig mitochondria. Initial velocities of CN movement into mitochondria were determined at time points ranging from 10-100 msec and at CN concentrations ranging from 1 microM-10 mM using a rapid filtration device. A Hofstee plot of the data suggests that an active or facilitated transport predominates at lower CN concentrations (less than 10 microM), whereas passive diffusion of CN predominates at higher CN concentrations. The kinetic constants for the active phase transport were Jmax = 0.9 pmol/ms and Kt = 14 microM. These results suggest that a large portion of CN movement across the cell membrane is due to an active or facilitated transport phenomenon.

  20. Effects of photoreleased cADP-ribose on calcium transients and calcium sparks in myocytes isolated from guinea-pig and rat ventricle.

    PubMed Central

    Cui, Y; Galione, A; Terrar, D A

    1999-01-01

    Actions of photoreleased cADP-ribose (cADPR), a novel regulator of calcium-induced calcium release (CICR) from ryanodine-sensitive stores, were investigated in cardiac myocytes. Photoreleased cADPR caused an increase in the magnitude of whole-cell calcium transients studied in mammalian cardiac ventricular myocytes (both guinea-pig and rat) using confocal microscopy). Approx. 15 s was required following photorelease of cADPR for the development of its maximal effect. Photoreleased cADPR also increased the frequency of calcium 'sparks', which are thought to be elementary events which make up the whole-cell calcium transient, and were studied in rat myocytes, but had little or no effect on spark characteristics (amplitude, rise time, decay time and distance to half amplitude). The potentiating effects of photoreleased cADPR on both whole-cell transients and the frequency of calcium sparks were prevented by cytosolic application of the antagonist 8-amino-cADPR (5 microM). These experiments, therefore, provide the first evidence in any cell type for an effect of cADPR on calcium sparks, and are the first to show the actions of photoreleased cADPR on whole-cell calcium transients in mammalian cells. The observations are consistent with the effects of cADPR in enhancing the calcium sensitivity of CICR from the sarcoplasmic reticulum in cardiac ventricular myocytes, leading to an increase in the probability of occurrence of calcium sparks and to an increase in whole-cell calcium transients. The slow time-course for development of the full effect on whole-cell calcium transients might be taken to indicate that the influence of cADPR on CICR may involve complex molecular interactions rather than a simple direct action of cADPR on the ryanodine-receptor channels. PMID:10455010

  1. Integrated Omic Analysis of a Guinea Pig Model of Heart Failure and Sudden Cardiac Death.

    PubMed

    Foster, D Brian; Liu, Ting; Kammers, Kai; O'Meally, Robert; Yang, Ni; Papanicolaou, Kyriakos N; Talbot, C Conover; Cole, Robert N; O'Rourke, Brian

    2016-09-01

    Here, we examine key regulatory pathways underlying the transition from compensated hypertrophy (HYP) to decompensated heart failure (HF) and sudden cardiac death (SCD) in a guinea pig pressure-overload model by integrated multiome analysis. Relative protein abundances from sham-operated HYP and HF hearts were assessed by iTRAQ LC-MS/MS. Metabolites were quantified by LC-MS/MS or GC-MS. Transcriptome profiles were obtained using mRNA microarrays. The guinea pig HF proteome exhibited classic biosignatures of cardiac HYP, left ventricular dysfunction, fibrosis, inflammation, and extravasation. Fatty acid metabolism, mitochondrial transcription/translation factors, antioxidant enzymes, and other mitochondrial procsses, were downregulated in HF but not HYP. Proteins upregulated in HF implicate extracellular matrix remodeling, cytoskeletal remodeling, and acute phase inflammation markers. Among metabolites, acylcarnitines were downregulated in HYP and fatty acids accumulated in HF. The correlation of transcript and protein changes in HF was weak (R(2) = 0.23), suggesting post-transcriptional gene regulation in HF. Proteome/metabolome integration indicated metabolic bottlenecks in fatty acyl-CoA processing by carnitine palmitoyl transferase (CPT1B) as well as TCA cycle inhibition. On the basis of these findings, we present a model of cardiac decompensation involving impaired nuclear integration of Ca(2+) and cyclic nucleotide signals that are coupled to mitochondrial metabolic and antioxidant defects through the CREB/PGC1α transcriptional axis.

  2. Integrated Omic Analysis of a Guinea Pig Model of Heart Failure and Sudden Cardiac Death.

    PubMed

    Foster, D Brian; Liu, Ting; Kammers, Kai; O'Meally, Robert; Yang, Ni; Papanicolaou, Kyriakos N; Talbot, C Conover; Cole, Robert N; O'Rourke, Brian

    2016-09-01

    Here, we examine key regulatory pathways underlying the transition from compensated hypertrophy (HYP) to decompensated heart failure (HF) and sudden cardiac death (SCD) in a guinea pig pressure-overload model by integrated multiome analysis. Relative protein abundances from sham-operated HYP and HF hearts were assessed by iTRAQ LC-MS/MS. Metabolites were quantified by LC-MS/MS or GC-MS. Transcriptome profiles were obtained using mRNA microarrays. The guinea pig HF proteome exhibited classic biosignatures of cardiac HYP, left ventricular dysfunction, fibrosis, inflammation, and extravasation. Fatty acid metabolism, mitochondrial transcription/translation factors, antioxidant enzymes, and other mitochondrial procsses, were downregulated in HF but not HYP. Proteins upregulated in HF implicate extracellular matrix remodeling, cytoskeletal remodeling, and acute phase inflammation markers. Among metabolites, acylcarnitines were downregulated in HYP and fatty acids accumulated in HF. The correlation of transcript and protein changes in HF was weak (R(2) = 0.23), suggesting post-transcriptional gene regulation in HF. Proteome/metabolome integration indicated metabolic bottlenecks in fatty acyl-CoA processing by carnitine palmitoyl transferase (CPT1B) as well as TCA cycle inhibition. On the basis of these findings, we present a model of cardiac decompensation involving impaired nuclear integration of Ca(2+) and cyclic nucleotide signals that are coupled to mitochondrial metabolic and antioxidant defects through the CREB/PGC1α transcriptional axis. PMID:27399916

  3. The effects of compensated cardiac hypertrophy on dihydropyridine and ryanodine receptors in rat, ferret and guinea-pig hearts.

    PubMed

    Rannou, F; Sainte-Beuve, C; Oliviero, P; Do, E; Trouvé, P; Charlemagne, D

    1995-05-01

    The number of dihydropyridine and ryanodine receptors (DHP-R and RyR) has been measured in control and hypertrophied ventricles from rats, guinea pigs and ferrets to determine whether these two channels contribute to the alterations in excitation-contraction coupling (ECC), and in Ca2+ transient during compensated cardiac hypertrophy. We found that ventricular hypertrophy did not change the density of DHP-R. Mild hypertrophy did not alter the density of RyR in the rat but decreased it in the guinea-pig and in the ferret (30% and 36%, respectively). Severe hypertrophy decreased the density of RyR by 20% in the rat and by 34% in the guinea-pig. Therefore, the decrease is greater in ferret and guinea-pig hearts than in rat heart. We conclude that the sarcoplasmic reticulum (SR) Ca2+ release channels but not the L-type Ca2+ channels could contribute to the slowing of intracellular Ca2+ movements and to the reduced velocity of shortening of the hypertrophied hearts. We suggest that, in the guinea pig and ferret hearts which express only the beta myosin heavy chain (MHC) isoform, the reduced velocity of shortening during hypertrophy is related to the decrease in RyR density, whereas in the rat, it is regulated primarily via a shift in the MHC isoform, except in severe hypertrophy in which the moderate decrease in RyR would also be involved. PMID:7473781

  4. Angiotensin receptors alter myocardial infarction-induced remodeling of the guinea pig cardiac plexus.

    PubMed

    Hardwick, Jean C; Ryan, Shannon E; Powers, Emily N; Southerland, E Marie; Ardell, Jeffrey L

    2015-07-15

    Neurohumoral remodeling is fundamental to the evolution of heart disease. This study examined the effects of chronic treatment with an ACE inhibitor (captopril, 3 mg·kg(-1)·day(-1)), AT1 receptor antagonist (losartan, 3 mg·kg(-1)·day(-1)), or AT2 receptor agonist (CGP42112A, 0.14 mg·kg(-1)·day(-1)) on remodeling of the guinea pig intrinsic cardiac plexus following chronic myocardial infarction (MI). MI was surgically induced and animals recovered for 6 or 7 wk, with or without drug treatment. Intracellular voltage recordings from whole mounts of the cardiac plexus were used to monitor changes in neuronal responses to norepinephrine (NE), muscarinic agonists (bethanechol), or ANG II. MI produced an increase in neuronal excitability with NE and a loss of sensitivity to ANG II. MI animals treated with captopril exhibited increased neuronal excitability with NE application, while MI animals treated with CGP42112A did not. Losartan treatment of MI animals did not alter excitability with NE compared with untreated MIs, but these animals did show an enhanced synaptic efficacy. This effect on synaptic function was likely due to presynaptic AT1 receptors, since ANG II was able to reduce output to nerve fiber stimulation in control animals, and this effect was prevented by inclusion of losartan in the bath solution. Analysis of AT receptor expression by Western blot showed a decrease in both AT1 and AT2 receptors with MI that was reversed by all three drug treatments. These data indicate that neuronal remodeling of the guinea pig cardiac plexus following MI is mediated, in part, by activation of both AT1 and AT2 receptors.

  5. Alteration of the L-type calcium current in guinea-pig single ventricular myocytes by heptaminol hydrochloride.

    PubMed Central

    Peineau, N.; Mongo, K. G.; Le Guennec, J. Y.; Garnier, D.; Argibay, J. A.

    1992-01-01

    1. The effects of heptaminol on calcium current amplitude and characteristics were studied in single ventricular myocytes of guinea-pig by use of the whole cell configuration of the patch clamp technique. 2. A concentration-dependent decrease in ICa amplitude was observed. At heptaminol concentration as low as 10(-6) M, this effect was observed in only two cells (n = 6). At 10(-5) M the reduction of ICa was of 30 +/- 15% (n = 11). 3. The current recovery from inactivation at -40 mV holding potential (HP) seemed less sensitive to perfusion with heptaminol (greater than 10(-6) M). However, at -80 mV HP the overshoot of the recovery curve was decreased by heptaminol. 4. Both at -40 mV and -80 mV HP, heptaminol (10(-5) M) significantly increased the steady state inactivation of ICa. 5. As previously proposed by others to explain the effects of membrane active substances, the effects of heptaminol may result from alterations in cell membrane properties and possibly from an increase in intracellular free calcium ion concentration. PMID:1422567

  6. The effect of oxygen free radicals on calcium current and dihydropyridine binding sites in guinea-pig ventricular myocytes.

    PubMed Central

    Guerra, L.; Cerbai, E.; Gessi, S.; Borea, P. A.; Mugelli, A.

    1996-01-01

    1. We used electrophysiological and binding techniques to determine the effects of oxygen free radicals (OFRs) generated by dihydroxyfumaric acid (DHF, 5 mM) on calcium current and dihydropyridine binding sites in guinea-pig isolated ventricular myocytes. 2. Binding of [3H]-PN200-110 to isolated ventricular myocytes revealed one population of binding sites with a KD of 0.11 +/- 0.01 nM and Bmax of 139.1 +/- 6.9 fmol mg-1 protein (n = 24). After 15 min of exposure to DHF, the density, but not the affinity of [3H]-PN200-110 binding sites was significantly (P < 0.01) reduced to 35% of the control value (Bmax = 49.4 +/- 3.7 fmol mg-1 protein, KD = 0.11 +/- 0.01 nM, n = 15). In the presence of superoxide dismutase (SOD) and catalase (CAT) the reduction in [3H]-PN200-110 binding sites was almost completely prevented (Bmax = 120.5 +/- 7.4 in control, n = 4 and 98.8 +/- 7.4 fmol mg-1 protein in DHF plus SOD and CAT, n = 4). KD values were not modified (0.08 +/- 0.01 in control and 0.09 +/- 0.01 nM in DHF plus SOD and CAT). 3. The time-course of the reduction of [3H]-PN200-110 binding sites by OFRs was paralleled by the decrease in L-type calcium current (Ica,L) measured in patch-clamped guinea-pig ventricular myocytes either in the absence or in the presence of EGTA in the patch pipette. In the former conditions OFRs induced the appearance of calcium-dependent alterations, i.e. the transient inward current, within 10 min. After 30 min of incubation with DHF, [3H]-PN200-110 binding sites were reduced to 25% of the control value. 4. In myocytes incubated with the antilipoperoxidant agent, butylated hydroxytoluene (BHT, 50 microM), the decrease in [3H]-PN200-110 binding sites caused by DHF was partially prevented (Bmax values after 30 min exposure to DHF were 55.5 +/- 1.9 and 23.7 +/- 5.9 fmol mg-1 protein in the presence and in the absence of BHT respectively, P < 0.05). BHT did not affect the decrease in [3H]-PN200-110 binding sites during the first 15 min of exposure to

  7. Voltage dependence of sodium-calcium exchange current in guinea-pig atrial myocytes determined by means of an inhibitor.

    PubMed Central

    Lipp, P; Pott, L

    1988-01-01

    1. Spontaneous transient inward currents (Iti) caused by cyclic release of Ca2+ ions from the sarcoplasmic reticulum were studied in cultured atrial myocytes from hearts of adult guinea-pigs. K+ channel currents were blocked by replacing K+ on both sides of the membrane by Cs+; the L-type Ca2+ current was inhibited by D600. 2. The voltage dependence of peak Iti and the background current displayed distinct outward-going rectification. The I-V curves for both currents approach each other at strongly positive membrane potentials but do not intersect. 3. 3'-4'Dichlorobenzamil (DCB) causes a concentration-dependent inhibition of peak Iti and a shift of the holding current (at -60 to -40 mV) in the inward direction. Inhibition of Iti is half-maximal at a concentration of 30 microM. 4. DCB reduces the outward-rectifying component of both peak Iti and the background current. The I-V curves of the control and DCB-inhibited currents intersect at ca. +10 mV (peak Iti) and negative to -75 mV (background current), suggesting the reversal potential of the DCB-inhibited current to be shifted by ca. 85 mV in the positive direction if Cai2+ rises following Ca2+ release. 5. The voltage dependence of the DCB-inhibited currents is highly compatible with the concept of Na+-Ca2+ exchange being the charge-carrying mechanism of the outward-rectifying background current. Ca2+ release from the SR alters the I-V curve of this current according to the shift of the thermodynamic driving force. PMID:2855345

  8. The cardiac effects of a novel A1-adenosine receptor agonist in guinea pig isolated heart.

    PubMed

    Belardinelli, L; Lu, J; Dennis, D; Martens, J; Shryock, J C

    1994-12-01

    Adenosine increases atrioventricular (AV) nodal conduction time and is used for termination of AV nodal re-entrant tachycardias, but it is rapidly metabolized. The purposes of the present study were to characterize the cardiac actions and effects of an orally active and stable adenosine analog, N6-cyclohexyl-2-O-methyladenosine (SDZ WAG-994) and to evaluate its potential as an antiarrhythmic agent. Guinea pig hearts were isolated and perfused with oxygenated Krebs-Henseleit solution. SDZ WAG-994 slowed the atrial rate and prolonged the AV nodal conduction time of spontaneously beating hearts in a concentration-dependent manner. The EC50 values for the negative chronotropic and dromotropic effects of SDZ WAG-994 were 0.69 +/- 0.04 and 1.49 +/- 0.54 microM, respectively. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (0.2 microM) significantly antagonized SDZ WAG-994-induced stimulus-to-His bundle (S-H) interval prolongation. The negative dromotropic effect of SDZ WAG-994 showed very strong frequency dependence. In hearts paced at an atrial cycle length of 300 msec (200 beats/min), the EC50 value of SDZ WAG-994 to prolong the S-H interval was 3.7-fold lower (0.40 +/- 0.02 microM) than in unpaced hearts, and at atrial pacing cycle lengths of 500 and 250 msec, 0.3 microM SDZ WAG-994 prolonged the S-H interval by 8 and 26 msec, respectively. SDZ WAG-994 also decreased coronary perfusion pressure (EC50 = 1.50 +/- 0.80 microM); this effect of SDZ WAG-994 was attenuated by adenosine deaminase and by 8-cyclopentyltheophylline (2 microM). Radioligand binding assays revealed that SDZ WAG-994 had a 280-fold greater affinity for A1- than for A2a receptors of the guinea pig brain. The marked frequency dependence of the negative dromotropic effect of SDZ WAG-994 suggests that this A1 agonist may be highly effective in the termination of AV nodal re-entrant tachycardias. PMID:7996449

  9. Inactivation of the cardiac Na+ channels in guinea-pig ventricular cells through the open state.

    PubMed

    Mitsuiye, T; Noma, A

    1995-06-15

    1. The inactivation kinetics of the Na+ current were investigated using the improved oil-gap voltage clamp method in single ventricular cells of guinea-pig hearts. 2. Activation of the Na+ current was observed on depolarization more positive than -50 mV from a holding potential of -100 mV, and inactivation was complete during these depolarizations. The time course of current decay was fitted by a double exponential at potentials between -40 and -15 mV, and virtually by a single exponential at more positive potentials. The decay time courses examined either by the double-pulse protocol or the single-pulse protocol were similar. 3. The double-pulse protocol clearly revealed a sigmoidal onset of inactivation on depolarization. The initial delay of inactivation decreased with more positive potentials. The time course of double-pulse inactivation was reconstructed by integrating the Na+ current recorded by a continuous depolarization. 4. These findings are consistent with the hypothesis that the cardiac Na+ channel inactivates exclusively through the open state.

  10. Clobutinol delays ventricular repolarization in the guinea pig heart: comparison with cardiac effects of HERG K+ channel inhibitor E-4031.

    PubMed

    Takahara, Akira; Sasaki, Rieko; Nakamura, Mariko; Sendo, Akiko; Sakurai, Yukiko; Namekata, Iyuki; Tanaka, Hikaru

    2009-12-01

    Clobutinol has been clinically reported to induce long QT syndrome. To clarify its cardiac electrophysiological properties, we compared effects of clobutinol on the isolated myocardium and anesthetized guinea pig heart with those of a hERG K channel blocker, E-4031. In isolated guinea pig ventricular tissues, clobutinol (3 microM) as well as E-4031 (10-100 nM) prolonged the action potential duration without affecting maximum upstroke velocity, but no further prolongation was observed after application of 30 microM clobutinol. In anesthetized closed-chest guinea pigs, clobutinol (1 and 10 mg/kg, intravenously) and E-4031 (0.01 and 1 mg/kg, intravenously) prolonged the QT interval and duration of the monophasic action potential (MAP) in a dose-dependent manner and at the same time increased the beat-to-beat variability of the MAP duration and reversed use-dependent prolongation of the MAP duration and triangulation of the MAP configuration. These results suggest that clobutinol delayed the ventricular repolarization and increased the proarrhythmic parameters linked to the hERG K channel inhibitor-induced torsade de pointes arrhythmias.

  11. Clobutinol delays ventricular repolarization in the guinea pig heart: comparison with cardiac effects of HERG K+ channel inhibitor E-4031.

    PubMed

    Takahara, Akira; Sasaki, Rieko; Nakamura, Mariko; Sendo, Akiko; Sakurai, Yukiko; Namekata, Iyuki; Tanaka, Hikaru

    2009-12-01

    Clobutinol has been clinically reported to induce long QT syndrome. To clarify its cardiac electrophysiological properties, we compared effects of clobutinol on the isolated myocardium and anesthetized guinea pig heart with those of a hERG K channel blocker, E-4031. In isolated guinea pig ventricular tissues, clobutinol (3 microM) as well as E-4031 (10-100 nM) prolonged the action potential duration without affecting maximum upstroke velocity, but no further prolongation was observed after application of 30 microM clobutinol. In anesthetized closed-chest guinea pigs, clobutinol (1 and 10 mg/kg, intravenously) and E-4031 (0.01 and 1 mg/kg, intravenously) prolonged the QT interval and duration of the monophasic action potential (MAP) in a dose-dependent manner and at the same time increased the beat-to-beat variability of the MAP duration and reversed use-dependent prolongation of the MAP duration and triangulation of the MAP configuration. These results suggest that clobutinol delayed the ventricular repolarization and increased the proarrhythmic parameters linked to the hERG K channel inhibitor-induced torsade de pointes arrhythmias. PMID:19770670

  12. The role of the anaesthetised guinea-pig in the preclinical cardiac safety evaluation of drug candidate compounds

    SciTech Connect

    Marks, Louise; Borland, Samantha; Philp, Karen; Ewart, Lorna; Lainée, Pierre; Skinner, Matthew; Kirk, Sarah; Valentin, Jean-Pierre

    2012-09-01

    Despite rigorous preclinical and clinical safety evaluation, adverse cardiac effects remain a leading cause of drug attrition and post-approval drug withdrawal. A number of cardiovascular screens exist within preclinical development. These screens do not, however, provide a thorough cardiac liability profile and, in many cases, are not preventing the progression of high risk compounds. We evaluated the suitability of the anaesthetised guinea-pig for the assessment of drug-induced changes in cardiovascular parameters. Sodium pentobarbitone anaesthetised male guinea-pigs received three 15 minute intravenous infusions of ascending doses of amoxicillin, atenolol, clonidine, dobutamine, dofetilide, flecainide, isoprenaline, levosimendan, milrinone, moxifloxacin, nifedipine, paracetamol, verapamil or vehicle, followed by a 30 minute washout. Dose levels were targeted to cover clinical exposure and above, with plasma samples obtained to evaluate effect/exposure relationships. Arterial blood pressure, heart rate, contractility function (left ventricular dP/dt{sub max} and QA interval) and lead II electrocardiogram were recorded throughout. In general, the expected reference compound induced effects on haemodynamic, contractility and electrocardiographic parameters were detected confirming that all three endpoints can be measured accurately and simultaneously in one small animal. Plasma exposures obtained were within, or close to the expected clinical range of therapeutic plasma levels. Concentration–effect curves were produced which allowed a more complete understanding of the margins for effects at different plasma exposures. This single in vivo screen provides a significant amount of information pertaining to the cardiovascular risk of drug candidates, ultimately strengthening strategies addressing cardiovascular-mediated compound attrition and drug withdrawal. -- Highlights: ► Evaluation of the anaesthetised guinea-pig to determine cardiac liability.

  13. The antagonistic effect of K+o and dihydro-ouabain on the Na+ pump current of single rat and guinea-pig cardiac cells.

    PubMed Central

    Hermans, A N; Glitsch, H G; Verdonck, F

    1995-01-01

    1. The antagonistic effect of extracellular potassium ions (K+o) and dihydro-ouabain (DHO) on the Na(+)-K+ pump current (Ip) was studied in isolated ventricular cells. 2. The myocytes were isolated from rats and guinea-pigs, two species with different sensitivity towards cardiac glycosides. Ip measurements were performed at 32-34 degrees C by means of whole-cell recording. The membrane potential was held at -20 mV throughout. 3. The DHO concentration ([DHO]) required for half-maximal Ip inhibition (apparent KD value, KD') amounted to 2.4 x 10(-3) and 1.4 x 10(-5) M for rat and guinea-pig myocytes, respectively, at 5.4 mM K+o. 4. The data suggest one-to-one binding of DHO to the Na(+)-K+ pump and a smaller association rate constant, as well as a larger dissociation rate constant, for binding of DHO in the rat cells. 5. Ip activation by K+o was nearly identical in myocytes of both species and was measured to be half-maximal at approximately 1 mM K+o. Half-maximal Ip activation by K+o remained essentially unchanged, but Ip decreased in media containing [DHO] near the respective KD' at 5.4 mM K+o. 6. The concentration-response curve of Ip inhibition by DHO was shifted to higher [DHO] at higher [K+]o. KD' increased correspondingly. The slope of the curve was unaffected. 7. Ip and KD' displayed a similar dependence on [K+]o. 8. KD' was larger in Na(+)-free than in Na(+)-containing media under conditions in which the activation of Ip by K+o was nearly the same. 9. It is concluded that the antagonism between K+o and DHO, with regard to the activation of Ip, is non-competitive. A possible mechanism of the antagonism is discussed. The mechanism implies binding of K+o and DHO to different conformational states of the Na(+)-K+ pump which are temporarily exposed to the external face of the sarcolemma in the pump cycle. The DHO-bound states do not participate in the generation of Ip. PMID:7623280

  14. [Na] and [K] dependence of the Na/K pump current-voltage relationship in guinea pig ventricular myocytes

    PubMed Central

    1989-01-01

    Na/K pump current was determined between -140 and +60 mV as steady- state, strophanthidin-sensitive, whole-cell current in guinea pig ventricular myocytes, voltage-clamped and internally dialyzed via wide- tipped pipettes. Solutions were designed to minimize all other components of membrane current. A device for exchanging the solution inside the pipette permitted investigation of Na/K pump current-voltage (I-V) relationships at several levels of pipette [Na] [( Na]pip) in a single cell; the effects of changes in external [Na] [( Na]o) or external [K] [( K]o) were also studied. At 50 mM [Na]pip, 5.4 mM [K]o, and approximately 150 mM [Na]o, Na/K pump current was steeply voltage dependent at negative potentials but was approximately constant at positive potentials. Under those conditions, reduction of [Na]o enhanced pump current at negative potentials but had little effect at positive potentials: at zero [Na]o, pump current was only weakly voltage dependent. At 5.4 mM [K]o and approximately 150 mM [Na]o, reduction of [Na]pip from 50 mM scaled down the sigmoid pump I-V relationship and shifted it slightly to the right (toward more positive potentials). Pump current at 0 mV was activated by [Na]pip according to the Hill equation with best-fit K0.5 approximately equal to 11 mM and Hill coefficient nH approximately equal to 1.4. At zero [Na]o, reduction of [Na]pip seemed to simply scale down the relatively flat pump I-V relationship: Hill fit parameters for pump activation by [Na]pip at 0 mV were K0.5 approximately equal to 10 mM, nH approximately equal to 1.4. At 50 mM [Na]pip and high [Na]o, reduction of [K]o from 5.4 mM scaled down the sigmoid I-V relationship and shifted it slightly to the right: at 0 mV, K0.5 approximately equal to 1.5 mM and nH approximately equal to 1.0. At zero [Na]o, lowering [K]o simply scaled down the flat pump I-V relationships yielding, at 0 mV, K0.5 approximately equal to 0.2 mM, nH approximately equal to 1.1. The voltage

  15. Cardiac actions of phencyclidine in isolated guinea pig and rat heart: possible involvement of slow channels

    SciTech Connect

    Temma, K.; Akera, T.; Ng, Y.C.

    1985-03-01

    The mechanisms responsible for the positive inotropic effect of phencyclidine were studied in isolated preparations of guinea pig and rat heart. In electrically paced left atrial muscle preparations, phencyclidine increased the force of contraction; rat heart muscle preparations were more sensitive than guinea pig heart muscle preparations. The positive inotropic effect of phencyclidine was not significantly reduced by a combination of phentolamine and nadolol; however, the effect was competitively blocked by verapamil in the presence of phentolamine and nadolol. Inhibition of the outward K+ current by tetraethylammonium chloride also produced a positive inotropic effect; however, the effect of tetraethylammonium was reduced by phentolamine and nadolol, and was almost insensitive to verapamil. The inotropic effect of phencyclidine was associated with a marked prolongation of the action potential duration and a decrease in maximal upstroke velocity of the action potential, with no change in the resting membrane potential. The specific (/sup 3/H)phencyclidine binding observed with membrane preparations from guinea pig ventricular muscle was saturable with a single class of high-affinity binding site. This binding was inhibited by verapamil, diltiazem, or nitrendipine, but not by ryanodine or tetrodotoxin. These results suggest that the positive inotropic effect of phencyclidine results from enhanced Ca/sup 2 +/ influx via slow channels, either by stimulation of the channels or secondary to inhibition of outward K/sup +/ currents.

  16. Gene Transfer into Cardiac Myocytes

    PubMed Central

    Lang, Sarah E.; Westfall, Margaret V.

    2016-01-01

    Traditional methods for DNA transfection are often inefficient and toxic for terminally differentiated cells, such as cardiac myocytes. Vector-based gene transfer is an efficient approach for introducing exogenous cDNA into these types of primary cell cultures. In this chapter, separate protocols for adult rat cardiac myocyte isolation and gene transfer with recombinant adenovirus are provided and are routinely utilized for studying the effects of sarcomeric proteins on myofilament function. PMID:25836585

  17. Inhibition of muscarinic K+ current in guinea-pig atrial myocytes by PD 81,723, an allosteric enhancer of adenosine binding to A1 receptors

    PubMed Central

    Brandts, B; Bünemann, M; Hluchy, J; Sabin, G V; Pott, L

    1997-01-01

    PD 81,723 has been shown to enhance binding of adenosine to A1 receptors by stabilizing G protein-receptor coupling (‘allosteric enhancement'). Evidence has been provided that in the perfused hearts and isolated atria PD 81,723 causes a sensitization to adenosine via this mechanism. We have studied the effect of PD 81,723 in guinea-pig isolated atrial myocytes by use of whole-cell measurement of the muscarinic K+ current (IK(ACh)) activated by different Gi-coupled receptors (A1, M2, sphingolipid). PD 81,273 caused inhibition of IK(ACh) (IC50≃5 μM) activated by either of the three receptors. Receptor-independent IK(ACh) in cells loaded with GTP-γ-S and background IK(ACh), which contributes to the resting conductance of atrial myocytes, were equally sensitive to PD 81,723. At no combination of concentrations of adenosine and PD 81,723 could an enhancing effect be detected. The compound was active from the outside only. Loading of the cells with PD 81,723 (50 μM) via the patch pipette did not affect either IK(ACh) or its sensitivity to adenosine. We suggest that PD 81,723 acts as an inhibitor of inward rectifying K+ channels; this is supported by the finding that ventricular IK1, which shares a large degree of homology with the proteins (GIRK1/GIRK4) forming IK(ACh) but is not G protein-gated, was also blocked by this compound. It is concluded that the functional effects of PD 81,723 described in the literature are not mediated by the A1 adenosine receptor-Gi-IK(ACh) pathway. PMID:9249260

  18. Remodeling of intrinsic cardiac neurons: effects of β-adrenergic receptor blockade in guinea pig models of chronic heart disease.

    PubMed

    Hardwick, Jean C; Southerland, E Marie; Girasole, Allison E; Ryan, Shannon E; Negrotto, Sara; Ardell, Jeffrey L

    2012-11-01

    Chronic heart disease induces remodeling of cardiac tissue and associated neuronal components. Treatment of chronic heart disease often involves pharmacological blockade of adrenergic receptors. This study examined the specific changes in neuronal sensitivity of guinea pig intrinsic cardiac neurons to autonomic modulators in animals with chronic cardiac disease, in the presence or absence of adrenergic blockage. Myocardial infarction (MI) was produced by ligature of the coronary artery and associated vein on the dorsal surface of the heart. Pressure overload (PO) was induced by a banding of the descending dorsal aorta (∼20% constriction). Animals were allowed to recover for 2 wk and then implanted with an osmotic pump (Alzet) containing either timolol (2 mg·kg(-1)·day(-1)) or vehicle, for a total of 6-7 wk of drug treatment. At termination, intracellular recordings from individual neurons in whole mounts of the cardiac plexus were used to assess changes in physiological responses. Timolol treatment did not inhibit the increased sensitivity to norepinephrine seen in both MI and PO animals, but it did inhibit the stimulatory effects of angiotensin II on the norepinephrine-induced increases in neuronal excitability. Timolol treatment also inhibited the increase in synaptically evoked action potentials observed in PO animals with stimulation of fiber tract bundles. These results demonstrate that β-adrenergic blockade can inhibit specific aspects of remodeling within the intrinsic cardiac plexus. In addition, this effect was preferentially observed with active cardiac disease states, indicating that the β-receptors were more influential on remodeling during dynamic disease progression.

  19. Cardiac and pulmonary anaphylaxis in guinea pigs and rabbits induced by glycoprotein isolated from tobacco leaves and cigarette smoke condensate

    SciTech Connect

    Levi, R.; Zavecz, J.H.; Burke, J.A.; Becker, C.G.

    1982-03-01

    Cigarette smoking is a major risk factor for heart attack. The pathologic mechanisms responsible for this association are obscure. It has been reported that approximately one-third of human volunteers, smokers and nonsmokers, exhibit immediate cutaneous hypersensitivity to a glycoprotein antigen (TGP) purified from cured tobacco leaves and present in cigarette smoke. It is also known that the heart is a primary target organ for anaphylactic reaction in many animals, including primates. In experiments described herein anaphylaxis was induced in the isolated hearts and lungs of rabbits and guinea pigs previously sensitized by immunization with TGP and challenged with TGP isolated from either tobacco leaf or cigarette smoke condensate. Cardiac anaphylaxis was characterized by sinus tachycardia, decreased contractility, decreased coronary perfusion accompanied by hypoxic electrocardiographic changes, and a variety of rhythm disturbances, including idioventricular tachyarrhythmias. These observations suggest that allergic reactions to tobacco constituents may initiate cardiac arrhythmia and sudden death in some smokers and may, in part, underly the association between cigarette smoking and heart attack.

  20. /sup 3/H-ouabain binding and sodium-pump activity measured in myocytes isolated from guinea-pig heart

    SciTech Connect

    Stemmer, P.

    1986-01-01

    Because of the toxicity of millimolar ouabain, non-specific /sup 3/H-ouabain binding was assessed by monitoring the dissociation of the bound drug. Analysis of specific /sup 3/H-ouabain binding to myocytes yielded non-linear Scatchard plots. Nonlinearity appears to result from reduced /sup 3/H-ouabain binding due to low intracellular Na/sup 2/ concentration. Addition of 2 ..mu..M monensin, A Na/sup +/ ionophore, significantly increased /sup 3/H-ouabain binding. Incubation in Ca/sup 2 +/-free solution (0.25 mM EGTA) stimulated /sup 3/H-ouabain binding to a greater degree than monensin and caused Scatchard plots to have two distinct linear components. Monensin had no significant effects when /sup 3/H-ouabain binding occurred in Ca/sup 2 +/-free solution. Effects of Ca/sup 2 +/-free incubation to increase /sup 3/H-ouabain binding suggest that Ca/sup 2 +/ has a direct effect on /sup 3/H-ouabain binding. Alternatively, Ca/sup 2 +/-free incubation may increase Na/sup +/ permeability of the sarcolemma. Isoproterenol, phenylephrine, TPA (phorbol 12-myristate 13-acetate), La/sup 3 +/, and the Ca/sup 2 +/-ionophore A23187 failed to cause significant changes in /sup 3/H-ouabain binding when myocytes were incubated in a solution containing 0.5 or 2.5 ..mu..M /sup 3/H-ouabain, 0.1 mM Ca/sup 2 +/ and 1 mM K/sup +/.

  1. Isosteviol Sensitizes sarcKATP Channels towards Pinacidil and Potentiates Mitochondrial Uncoupling of Diazoxide in Guinea Pig Ventricular Myocytes

    PubMed Central

    Fan, Zhuo; Wen, Ting; Chen, Yaoxu; Huang, Lijie; Lin, Wei; Yin, Chunxia; Tan, Wen

    2016-01-01

    KATP channel is an important mediator or factor in physiological and pathological metabolic pathway. Activation of KATP channel has been identified to be a critical step in the cardioprotective mechanism against IR injury. On the other hand, desensitization of the channel to its opener or the metabolic ligand ATP in pathological conditions, like cardiac hypertrophy, would decrease the adaption of myocardium to metabolic stress and is a disadvantage for drug therapy. Isosteviol, obtained by acid hydrolysis of stevioside, has been demonstrated to play a cardioprotective role against diseases of cardiovascular system, like anti-IR injury, antihypertension, antihyperglycemia, and so forth. The present study investigated the effect of isosteviol (STV) on sarcKATP channel current induced by pinacidil and mitochondrial flavoprotein oxidation induced by diazoxide. Our results showed that preincubating cells with STV not only increased the current amplitude and activating rate of sarcKATP channels induced by pinacidil but also potentiated diazoxide-elicited oxidation of flavoprotein in mitochondria. PMID:26949448

  2. Rapid component I(Kr) of cardiac delayed rectifier potassium currents in guinea-pig is inhibited by alpha(1)-adrenoreceptor activation via protein kinase A and protein kinase C-dependent pathways.

    PubMed

    Wang, Sen; Xu, Dong-Jie; Cai, Jing-Bo; Huang, Yuan-Zhu; Zou, Jian-Gang; Cao, Ke-Jiang

    2009-04-17

    Ventricular tachyarrhythmias are often precipitated by physical or emotional stress, indicating a link between increased adrenergic stimulation and cardiac ion channel activity. Human ether-a-go-go related gene (hERG) potassium channels conduct the rapid component of delayed rectifier potassium current, I(kr), a crucial component for action potential repolarization. To evaluate the correlation between increased alpha(1)-adrenergic activity and the rapid component of cardiac I(kr), whole-cell patch-clamp recording was performed in isolated guinea-pig ventricular myocytes. Stimulation of alpha(1)-adrenoceptors using phenylephrine (0.1 nM-100 microM) reduced I(kr) current in a dose-dependent manner at 37 degrees C. Phenylephrine (0.1 microM) reduced I(kr) current to 66.83+/-3.16%. Chelerythrine (1 microM), a specific inhibitor of protein kinase C (PKC) completely inhibited the changes in I(kr) trigged by 0.1 microM phenylephrine. KT5720 (2.5 microM), a specific inhibitor of protein kinase A (PKA) partially inhibited the current decrease induced by 0.1 microM phenylephrine. Both chelerythrine and KT5720 drastically reduced the phenylephrine-induced effects, indicating possible involvement of PKC and PKA in the alpha(1)-adrenergic inhibition of I(kr). Our data suggest a link between I(kr) and the alpha(1)-adrenoceptor, involving activation of PKC and PKA in arrhythmogenesis.

  3. Myocardial KChIP2 Expression in Guinea Pig Resolves an Expanded Electrophysiologic Role.

    PubMed

    Nassal, Drew M; Wan, Xiaoping; Liu, Haiyan; Deschênes, Isabelle

    2016-01-01

    Cardiac ion channels and their respective accessory subunits are critical in maintaining proper electrical activity of the heart. Studies have indicated that the K+ channel interacting protein 2 (KChIP2), originally identified as an auxiliary subunit for the channel Kv4, a component of the transient outward K+ channel (Ito), is a Ca2+ binding protein whose regulatory function does not appear restricted to Kv4 modulation. Indeed, the guinea pig myocardium does not express Kv4, yet we show that it still maintains expression of KChIP2, suggesting roles for KChIP2 beyond this canonical auxiliary interaction with Kv4 to modulate Ito. In this study, we capitalize on the guinea pig as a system for investigating how KChIP2 influences the cardiac action potential, independent of effects otherwise attributed to Ito, given the endogenous absence of the current in this species. By performing whole cell patch clamp recordings on isolated adult guinea pig myocytes, we observe that knock down of KChIP2 significantly prolongs the cardiac action potential. This prolongation was not attributed to compromised repolarizing currents, as IKr and IKs were unchanged, but was the result of enhanced L-type Ca2+ current due to an increase in Cav1.2 protein. In addition, cells with reduced KChIP2 also displayed lowered INa from reduced Nav1.5 protein. Historically, rodent models have been used to investigate the role of KChIP2, where dramatic changes to the primary repolarizing current Ito may mask more subtle effects of KChIP2. Evaluation in the guinea pig where Ito is absent, has unveiled additional functions for KChIP2 beyond its canonical regulation of Ito, which defines KChIP2 as a master regulator of cardiac repolarization and depolarization.

  4. Calcium binding to cardiac myocytes protected from proteolytic enzyme activity.

    PubMed

    Bailey, L E; Fawzi, A B

    1985-04-17

    Excitation-contraction coupling in cardiac muscle is dependent on extracellular calcium and calcium bound to the surface of the myocardial cell. In this study, we examined the physical characteristics of calcium binding to adult guinea pig ventricular myocytes disaggregated mechanically in oxygenated tissue culture medium containing a proteinase inhibitor (aprotinin), and separated from cellular debris by Cytodex beads. Cells prepared in this manner excluded Trypan blue and showed no evidence of spontaneous contraction or contracture. Scatchard plots of calcium binding determined by continuous flow equilibrium dialysis revealed a high-affinity, low-capacity pool, Ka = 65 X 10(3) M-1 and Bt = 1.3 nmol X mg-1 and a low-affinity, high-capacity pool, Ka = 141 M-1 and Bt = 138 nmol X mg-1. The low-affinity pool was not detectable after lanthanum, trypsin or collagenase treatment or in cells prepared without aprotinin in the isolation medium. Both neuraminidase and phospholipase C reduced Bt of the low-affinity pool by one half, but only neuraminidase affected the affinity constant of this pool. Ka was increased to 516.7 M-1, similar to the apparent affinity constant for calcium binding estimated from dP/dtmax measured at several extracellular calcium concentrations (470 M-1). The results suggest that calcium bound to sarcolemmal phospholipids represents the superficial calcium involved in excitation-contraction coupling in the heart.

  5. Modeling the isolated cardiac myocyte.

    PubMed

    Puglisi, Jose L; Wang, Fei; Bers, Donald M

    2004-01-01

    Computer modeling of cardiac myocytes has flourished in recent years. Models have evolved from mathematical descriptions of ionic channels alone to more sophisticated formulations that include calcium transport mechanisms, ATP production and metabolic pathways. The increased complexity is fueled by the new data available in the field. The continuous production of experimental data has led to the evolution of increasingly refined descriptions of the phenomena by modelers. Integrating the numerous systems involved in cardiac myocyte homeostasis makes the use of computer models necessary due to the unreliability of intuitive approaches. However the complexity of the model should not imply a cumbersome operation of the program. As with any tool, computer models have to be easy to operate or their strength will be diminished and potential users will not benefit fully from them. The contribution of the computer modeler to their respective biological fields will be more successful and enduring if modelers devote sufficient time to implement their equations into a model with user-friendly characteristics. PMID:15142742

  6. Redox signaling in cardiac myocytes

    PubMed Central

    Santos, Celio X.C.; Anilkumar, Narayana; Zhang, Min; Brewer, Alison C.; Shah, Ajay M.

    2011-01-01

    The heart has complex mechanisms that facilitate the maintenance of an oxygen supply–demand balance necessary for its contractile function in response to physiological fluctuations in workload as well as in response to chronic stresses such as hypoxia, ischemia, and overload. Redox-sensitive signaling pathways are centrally involved in many of these homeostatic and stress-response mechanisms. Here, we review the main redox-regulated pathways that are involved in cardiac myocyte excitation–contraction coupling, differentiation, hypertrophy, and stress responses. We discuss specific sources of endogenously generated reactive oxygen species (e.g., mitochondria and NADPH oxidases of the Nox family), the particular pathways and processes that they affect, the role of modulators such as thioredoxin, and the specific molecular mechanisms that are involved—where this knowledge is available. A better understanding of this complex regulatory system may allow the development of more specific therapeutic strategies for heart diseases. PMID:21236334

  7. Chloride current in mammalian cardiac myocytes. Novel mechanism for autonomic regulation of action potential duration and resting membrane potential

    PubMed Central

    1990-01-01

    The properties of the autonomically regulated chloride current (ICl) were studied in isolated guinea pig ventricular myocytes. This current was elicited upon exposure to isoproterenol (ISO) and reversed upon concurrent exposure to acetylcholine (ACh). ICl was time independent and exhibited outward rectification. The responses to ISO and ACh could be blocked by propranolol and atropine, respectively, and ICl was also elicited by forskolin, 8-bromoadenosine 3',5'-cyclic monophosphate, and 3-isobutyl-l-methylxanthine, indicating that the current is regulated through a cAMP-dependent pathway. The reversal potential of the ISO- induced current followed the predicted chloride equilibrium potential, consistent with it being carried predominantly by Cl-. Activation of ICl produced changes in the resting membrane potential and action potential duration, which were Cl- gradient dependent. These results indicate that under physiological conditions ICl may play an important role in regulating action potential duration and resting membrane potential in mammalian cardiac myocytes. PMID:2165130

  8. Electrical consequences of cardiac myocyte: fibroblast coupling.

    PubMed

    McArthur, Lisa; Chilton, Lisa; Smith, Godfrey L; Nicklin, Stuart A

    2015-06-01

    Gap junctions are channels which allow electrical signals to propagate through the heart from the sinoatrial node and through the atria, conduction system and onwards to the ventricles, and hence are essential for co-ordinated cardiac contraction. Twelve connexin (Cx) proteins make up one gap junction channel, of which there are three main subtypes in the heart; Cx40, Cx43 and Cx45. In the cardiac myocyte, gap junctions are present mainly at the intercalated discs between neighbouring myocytes, and assist in rapid electrical conduction throughout the ventricular myocardium. Fibroblasts provide the structural skeleton of the myocardium and fibroblast numbers significantly increase in heart disease. Fibroblasts also express connexins and this may facilitate heterocellular electrical coupling between myocytes and fibroblasts in the setting of cardiac disease. Interestingly, cardiac fibroblasts have been demonstrated to increase Cx43 expression in experimental models of myocardial infarction and functional gap junctions between myocytes and fibroblasts have been reported. Therefore, in the setting of heart disease enhanced cardiac myocyte: fibroblast coupling may influence the electrical activity of the myocyte and contribute to arrhythmias.

  9. Integrative modeling of the cardiac ventricular myocyte

    PubMed Central

    Winslow, Raimond L.; Cortassa, Sonia; O'Rourke, Brian; Hashambhoy, Yasmin L.; Rice, John Jeremy; Greenstein, Joseph L.

    2011-01-01

    Cardiac electrophysiology is a discipline with a rich 50-year history of experimental research coupled with integrative modeling which has enabled us to achieve a quantitative understanding of the relationships between molecular function and the integrated behavior of the cardiac myocyte in health and disease. In this paper, we review the development of integrative computational models of the cardiac myocyte. We begin with a historical overview of key cardiac cell models that helped shape the field. We then narrow our focus to models of the cardiac ventricular myocyte and describe these models in the context of their subcellular functional systems including dynamic models of voltage-gated ion channels, mitochondrial energy production, ATP-dependent and electrogenic membrane transporters, intracellular Ca dynamics, mechanical contraction, and regulatory signal transduction pathways. We describe key advances and limitations of the models as well as point to new directions for future modeling research. PMID:20865780

  10. Engineering design of a cardiac myocyte

    NASA Astrophysics Data System (ADS)

    Adams, W. J.; Pong, T.; Geisse, N. A.; Sheehy, S. P.; Diop-Frimpong, B.; Parker, K. K.

    2007-04-01

    We describe a design algorithm to build a cardiac myocyte with specific spatial dimensions and physiological function. Using a computational model of a cardiac muscle cell, we modeled calcium (Ca2+) wave dynamics in a cardiac myocyte with controlled spatial dimensions. The modeled myocyte was replicated in vitro when primary neonate rat ventricular myocytes were cultured on micropatterned substrates. The myocytes remodel to conform to the two dimensional boundary conditions and assume the shape of the printed extracellular matrix island. Mechanical perturbation of the myocyte with an atomic force microscope results in calcium-induced calcium release from intracellular stores and the propagation of a Ca2+ wave, as indicated by high speed video microscopy using fluorescent indicators of intracellular Ca2+. Analysis and comparison of the measured wavefront dynamics with those simulated in the computer model reveal that the engineered myocyte behaves as predicted by the model. These results are important because they represent the use of computer modeling, computer-aided design, and physiological experiments to design and validate the performance of engineered cells. The ability to successfully engineer biological cells and tissues for assays or therapeutic implants will require design algorithms and tools for quality and regulatory assurance.

  11. Cardiac Ca(2+) channel-blocking effects of the cyproheptadine derivative AH-1058 in isolated guinea pig cardiomyocytes.

    PubMed

    Dohmoto, Hideki; Takahara, Akira; Uneyama, Hisayuki; Yoshimoto, Ryota

    2003-02-01

    The Ca(2+) channel-blocking efficacy of the cyproheptadine derivative AH-1058 (4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-1-[(E)-3-(3-methoxy-2-nitro)phenyl-2-propenyl]piperidine hydrochloride) was quantitatively assessed using isolated guinea pig cardiomyocytes. AH-1058 (0.001 - 10 microM) and its mother compound cyproheptadine (1 - 100 microM) reduced the Ca(2+) currents elicited from the holding potential of -80 or -40 mV. The IC(50) values for cyproheptadine at holding potentials of -80 and -40 mV were 42.44 and 7.75 microM, respectively, whereas those for AH-1058 were 4.91 and 0.32 microM, respectively, whose potency was equivalent to those of the typical Ca(2+) channel blocker verapamil. These results suggest that the introduction of the cinnamil structure to cyproheptadine can generate a potent L-type Ca(2+) channel-blocking compound as potent as verapamil.

  12. Functional cross-talk between the α1- and β1-adrenergic receptors modulates the rapidly activating delayed rectifier potassium current in guinea pig ventricular myocytes.

    PubMed

    Xu, Di; Wang, Sen; Wu, Ting-Ting; Wang, Xiao-Yan; Qian, Jin; Guo, Yan

    2014-08-15

    The rapidly activating delayed rectifier potassium current (IKr) plays a critical role in cardiac repolarization. Although IKr is known to be regulated by both α1- and β1-adrenergic receptors (ARs), the cross-talk and feedback mechanisms that dictate its response to α1- and β1-AR activation are not known. In the present study, IKr was recorded using the whole-cell patch-clamp technique. IKr amplitude was measured before and after the sequential application of selective adrenergic agonists targeting α1- and β1-ARs. Stimulation of either receptor alone (α1-ARs using 1 μM phenylephrine (PE) or β1-ARs using 10 μM xamoterol (Xamo)) reduced IKr by 0.22 ± 0.03 and 0.28 ± 0.01, respectively. The voltage-dependent activation curve of IKr shifted in the negative direction. The half-maximal activation voltage (V0.5) was altered by -6.35 ± 1.53 and -1.95 ± 2.22 mV, respectively, with no major change in the slope factor (k). When myocytes were pretreated with Xamo, PE-induced reduction in IKr was markedly blunted and the corresponding change in V0.5 was significantly altered. Similarly, when cells were pretreated with PE, Xamo-induced reduction of IKr was significantly attenuated. The present results demonstrate that functional cross-talk between α1- and β1-AR signaling regulates IKr. Such non-linear regulation may form a protective mechanism under excessive adrenergic stimulation.

  13. Kinetic modulation of guinea-pig cardiac L-type calcium channels by fendiline and reversal of the effects of Bay K 8644.

    PubMed

    Schreibmayer, W; Tripathi, O; Tritthart, H A

    1992-05-01

    1. The modulation of L-type calcium channel current (ICa) by fendiline, a diphenylalkylamine type of calcium channel blocker was investigated on guinea-pig ventricular myocytes by use of the whole-cell patch-clamp technique. 2. Fendiline-induced block of ICa is accompanied by modulation of the channel kinetics in a complex manner. The time course of ICa inactivation is significantly faster and the channel availability (f infinity) curve is shifted considerably to more negative potentials by fendiline. These findings can be interpreted qualitatively in terms of a modulated receptor. 3. When the 1,4-dihydropyridine agonist (4R, 4S)-Bay K 8644 was added in presence of 30 microM fendiline a further reduction of ICa instead of the expected stimulatory effect was observed. 4. A similar 'paradoxical' inhibition of ICa was produced by the pure agonist enantiomer (4S)-Bay K 8644. Thus this novel effect of Bay K 8644 cannot be attributed to changes in affinity of the 1,4-dihydropyridine receptor site for (4R)-Bay K 8644 during fendiline action. 5. The IC50 for fendiline was reduced to 3.0 +/- 0.1 microM (control value: 17.0 +/- 2.4 microM) and the Hill slope in its presence was increased to 1.90 +/- 0.1 (control value: 1.39 +/- 0.23) by 1 microM (4R, 4S)-Bay K 8644. 6. (4R,4S)-Bay K 8644 caused the expected stimulation of ICa in the presence of verapamil, diltiazem and nifedipine, overcoming the inhibitory effect of these calcium channel blockers. 7. The 'paradoxical' inhibitory effect of the agonist Bay K 8644 can be explained in terms of an allosteric interaction between fendiline and the dihydropyridine agonist.

  14. Accentuated antagonism by angiotensin II on guinea-pig cardiac L-type Ca-currents enhanced by beta-adrenergic stimulation.

    PubMed

    Ai, T; Horie, M; Obayashi, K; Sasayama, S

    1998-07-01

    To examine mechanism(s) underlying the accentuated antagonism by angiotensin II (A-II) on twitch tension, we recorded L-type Ca2+ currents (ICa,L) using conventional patch-clamp techniques in single, guinea-pig, ventricular myocytes. ICa,L was recorded by a step-pulse protocol after eliminating K+ conductances (internal Cs+ plus tetraethylammonium chloride and K+-free extracellular solution). A-II (100 nM) did not affect basal ICa,L, but inhibited ICa,L that had been enhanced (approximately 200% of control) by (ISO, isoproterenol 100 nM). The inhibitory action of A-II was concentration dependent (concentration eliciting 50% inhibition 88+/-9 pM, n=41) and the ISO-enhanced component of ICa,L was completely blocked by A-II at concentrations above 10 nM. CV-11974 (500 nM), an A-II type-1 receptor (AT1) antagonist, prevented the inhibitory action of A-II. Pre-incubation with pertussis toxin (PTX) abolished the inhibitory effect of A-II. A-II also inhibited the ICa, L enhanced by histamine (500 nM) and forskolin (1 microM), but failed to affect ICa,L enhanced by intracellular cyclic adenosine monophosphate (1 mM). The inhibitory action of A-II may therefore involve AT1 receptors/PTX-sensitive, guanine nucleotide-binding (G) proteins (Gi)/adenylate cyclase and partially explains the A-II-dependent accentuated antagonism of inotropy.

  15. Role of ion channels in sepsis-induced atrial tachyarrhythmias in guinea pigs

    PubMed Central

    Aoki, Yuta; Hatakeyama, Noboru; Yamamoto, Seiji; Kinoshita, Hiroyuki; Matsuda, Naoyuki; Hattori, Yuichi; Yamazaki, Mitsuaki

    2012-01-01

    BACKGROUND AND PURPOSE Supraventricular tachyarrhythmias, including atrial fibrillation, are occasionally observed in patients suffering from sepsis. Modulation of cardiac ion channel function and expression by sepsis may have a role in the genesis of tachyarrhythmias. EXPERIMENTAL APPROACH Sepsis was induced by LPS (i.p.; 300 µg·kg−1) in guinea pigs. Membrane potentials and ionic currents were measured in atrial myocytes isolated from guinea pigs 10 h after LPS, using whole cell patch-clamp methods. KEY RESULTS In atrial cells from LPS-treated animals, action potential duration (APD) was significantly shortened. It was associated with a reduced L-type Ca2+ current and an increased delayed rectifier K+ current. These electrophysiological changes were eliminated when NG-nitro-l-arginine methyl ester (l-NAME) or S-ethylisothiourea was given together with LPS. In atrial tissues from LPS-treated animals, Ca2+ channel subunits (Cav1.2 and Cav1.3) decreased and delayed rectifier K+ channel subunits (Kv11.1 and Kv7.1) increased. However, L-NAME treatment did not substantially reverse such changes in atrial expression in LPS-treated animals, with the exception that Kv11.1 subunits returned to control levels. After LPS injection, inducible NOS in atrial tissues was up-regulated, and atrial NO production clearly increased. CONCLUSIONS AND IMPLICATIONS In atrial myocytes from guinea pigs with sepsis, APD was significantly shortened. This may reflect nitration of the ion channels which would alter channel functions, rather than changes in atrial expression of the channels. Shortening of APD could serve as one of the mechanisms underlying atrial tachyarrhythmia in sepsis. PMID:22050008

  16. Tertiapin-Q removes a large and rapidly acting component of vagal slowing of the guinea-pig cardiac pacemaker.

    PubMed

    Bolter, Chris P; Turner, Michael J

    2009-10-01

    The participation of acetylcholine-activated potassium current (I(K,ACh)) and hyperpolarization-activated pacemaker current (I(f)) in vagal bradycardia were examined using vagally-innervated preparations of guinea-pig atria. Preparations were maintained in Krebs-Henseleit solution (36 degrees C). Before treatment, trains of vagal stimuli (10 s at 2, 5 and 10 Hz) produced graded bradycardias displaying rapid onset and offset. Tertiapin-Q (300 nM), which blocks I(K,ACh), had no effect on baseline atrial rate. In tertiapin-Q, vagal bradycardia displayed a gradual onset and offset, with a peak response ~50% of that recorded in control conditions. Cumulative addition of 1 mM ZD7288 (blocker of I(f)) caused atrial rate to fall by ~60%, but had no further effect on the amplitude of the vagal bradycardia, while response onset and offset became slightly faster. From these observations, we argue that (i) vagal bradycardia was attributable primarily to activation of I(K,ACh), (ii) vagal modulation of I(f) had a minor influence on the rate of onset and offset of bradycardia, and (iii) removal of the influence of I(K,ACh) unmasked a slow response, of undetermined origin, to vagal stimulation. In a separate set of experiments we compared the effects of 1 mM Ba(2+) and 300 nM tertiapin-Q on vagal bradycardia. Ba(2+) reduced baseline atrial rate and the response to vagal stimulation. Subsequent cumulative addition of tertiapin-Q had no additional effect on baseline atrial rate, but caused further reduction in the amplitude of vagal bradycardia, suggesting that 1 mM Ba(2+) did not achieve a complete block of I(K,ACh) in this preparation. PMID:19481505

  17. Tumor Necrosis Factor Alpha Inhibits L-Type Ca2+ Channels in Sensitized Guinea Pig Airway Smooth Muscle through ERK 1/2 Pathway

    PubMed Central

    Reyes-García, Jorge; Flores-Soto, Edgar; Solís-Chagoyán, Héctor; Sommer, Bettina; Díaz-Hernández, Verónica; García-Hernández, Luz María

    2016-01-01

    Tumor necrosis factor alpha (TNF-α) is a potent proinflammatory cytokine that plays a significant role in the pathogenesis of asthma by inducing hyperresponsiveness and airway remodeling. TNF-α diminishes the L-type voltage dependent Ca2+ channel (L-VDCC) current in cardiac myocytes, an observation that seems paradoxical. In guinea pig sensitized tracheas KCl responses were lower than in control tissues. Serum from sensitized animals (Ser-S) induced the same phenomenon. In tracheal myocytes from nonsensitized (NS) and sensitized (S) guinea pigs, an L-VDCC current (ICa) was observed and diminished by Ser-S. The same decrease was detected in NS myocytes incubated with TNF-α, pointing out that this cytokine might be present in Ser-S. We observed that a small-molecule inhibitor of TNF-α (SMI-TNF) and a TNF-α receptor 1 (TNFR1) antagonist (WP9QY) reversed ICa decrease induced by Ser-S in NS myocytes, confirming the former hypothesis. U0126 (a blocker of ERK 1/2 kinase) also reverted the decrease in ICa. Neither cycloheximide (a protein synthesis inhibitor) nor actinomycin D (a transcription inhibitor) showed any effect on the TNF-α-induced ICa reduction. We found that CaV1.2 and CaV1.3 mRNA and proteins were expressed in tracheal myocytes and that sensitization did not modify them. In cardiac myocytes, ERK 1/2 phosphorylates two sites of the L-VDCC, augmenting or decreasing ICa; we postulate that, in guinea pig tracheal smooth muscle, TNF-α diminishes ICa probably by phosphorylating the L-VDCC site that reduces its activity through the ERK1/2 MAP kinase pathway. PMID:27445440

  18. Tumor Necrosis Factor Alpha Inhibits L-Type Ca(2+) Channels in Sensitized Guinea Pig Airway Smooth Muscle through ERK 1/2 Pathway.

    PubMed

    Reyes-García, Jorge; Flores-Soto, Edgar; Solís-Chagoyán, Héctor; Sommer, Bettina; Díaz-Hernández, Verónica; García-Hernández, Luz María; Montaño, Luis M

    2016-01-01

    Tumor necrosis factor alpha (TNF-α) is a potent proinflammatory cytokine that plays a significant role in the pathogenesis of asthma by inducing hyperresponsiveness and airway remodeling. TNF-α diminishes the L-type voltage dependent Ca(2+) channel (L-VDCC) current in cardiac myocytes, an observation that seems paradoxical. In guinea pig sensitized tracheas KCl responses were lower than in control tissues. Serum from sensitized animals (Ser-S) induced the same phenomenon. In tracheal myocytes from nonsensitized (NS) and sensitized (S) guinea pigs, an L-VDCC current (ICa) was observed and diminished by Ser-S. The same decrease was detected in NS myocytes incubated with TNF-α, pointing out that this cytokine might be present in Ser-S. We observed that a small-molecule inhibitor of TNF-α (SMI-TNF) and a TNF-α receptor 1 (TNFR1) antagonist (WP9QY) reversed ICa decrease induced by Ser-S in NS myocytes, confirming the former hypothesis. U0126 (a blocker of ERK 1/2 kinase) also reverted the decrease in ICa. Neither cycloheximide (a protein synthesis inhibitor) nor actinomycin D (a transcription inhibitor) showed any effect on the TNF-α-induced ICa reduction. We found that CaV1.2 and CaV1.3 mRNA and proteins were expressed in tracheal myocytes and that sensitization did not modify them. In cardiac myocytes, ERK 1/2 phosphorylates two sites of the L-VDCC, augmenting or decreasing ICa; we postulate that, in guinea pig tracheal smooth muscle, TNF-α diminishes ICa probably by phosphorylating the L-VDCC site that reduces its activity through the ERK1/2 MAP kinase pathway.

  19. Tumor Necrosis Factor Alpha Inhibits L-Type Ca(2+) Channels in Sensitized Guinea Pig Airway Smooth Muscle through ERK 1/2 Pathway.

    PubMed

    Reyes-García, Jorge; Flores-Soto, Edgar; Solís-Chagoyán, Héctor; Sommer, Bettina; Díaz-Hernández, Verónica; García-Hernández, Luz María; Montaño, Luis M

    2016-01-01

    Tumor necrosis factor alpha (TNF-α) is a potent proinflammatory cytokine that plays a significant role in the pathogenesis of asthma by inducing hyperresponsiveness and airway remodeling. TNF-α diminishes the L-type voltage dependent Ca(2+) channel (L-VDCC) current in cardiac myocytes, an observation that seems paradoxical. In guinea pig sensitized tracheas KCl responses were lower than in control tissues. Serum from sensitized animals (Ser-S) induced the same phenomenon. In tracheal myocytes from nonsensitized (NS) and sensitized (S) guinea pigs, an L-VDCC current (ICa) was observed and diminished by Ser-S. The same decrease was detected in NS myocytes incubated with TNF-α, pointing out that this cytokine might be present in Ser-S. We observed that a small-molecule inhibitor of TNF-α (SMI-TNF) and a TNF-α receptor 1 (TNFR1) antagonist (WP9QY) reversed ICa decrease induced by Ser-S in NS myocytes, confirming the former hypothesis. U0126 (a blocker of ERK 1/2 kinase) also reverted the decrease in ICa. Neither cycloheximide (a protein synthesis inhibitor) nor actinomycin D (a transcription inhibitor) showed any effect on the TNF-α-induced ICa reduction. We found that CaV1.2 and CaV1.3 mRNA and proteins were expressed in tracheal myocytes and that sensitization did not modify them. In cardiac myocytes, ERK 1/2 phosphorylates two sites of the L-VDCC, augmenting or decreasing ICa; we postulate that, in guinea pig tracheal smooth muscle, TNF-α diminishes ICa probably by phosphorylating the L-VDCC site that reduces its activity through the ERK1/2 MAP kinase pathway. PMID:27445440

  20. Guinea pig models of asthma.

    PubMed

    McGovern, Alice E; Mazzone, Stuart B

    2014-01-01

    Described in this unit are methods for establishing guinea pig models of asthma. Sufficient detail is provided to enable investigators to study bronchoconstriction, cough, airway hyperresponsiveness, inflammation, and remodeling. PMID:25446291

  1. Contributions of cardiac "funny" (f) channels and sarcoplasmic reticulum Ca2+ in regulating beating rate of mouse and guinea pig sinoatrial node.

    PubMed

    Nazarov, Islom B; Schofield, Christopher J; Terrar, Derek A

    2015-12-01

    The aim of this study was to investigate the effects on spontaneous beating rate of mouse atrial preparations following selective block of cardiac "funny" (f) channels, I(f), and/or suppression of sarcoplasmic reticulum (SR) function in the absence and presence of β-adrenoceptor stimulation. ZD7288 [to block I(f)] caused a substantial reduction (222 ± 13 bpm) in beating rate from 431 ± 14 to 209 ± 14 bpm, ryanodine alone (to block SR Ca(2+) release) reduced beating rate by 105 ± 11 bpm, with subsequent addition of ZD7288 further reducing rate by 57 ± 9 bpm. Cyclopiazonic acid (CPA) alone (to inhibit Ca(2+) reuptake by the SR) reduced beating rate by 148 ± 13 bpm with subsequent addition of ZD7288 further reducing rate by 79 ± 12 bpm. In additional experiments measuring Ca(2+) transients in the SA node region using Rhod-2, effects of ivabradine and ZD7288 on rate were again substantially reduced after CPA. Effects of CPA alone on rate developed much more slowly than effects on Ca(2+) transient amplitude. ZD7288, ivabradine, and CPA reduced the slope and maximum response of the log(concentration)-response curves for effects of isoprenaline on beating rate. Very little response to isoprenaline remained after treatment with CPA followed by ZD7288. Similar changes in isoprenaline log(concentration)-response curves were seen in guinea pig preparations. These observations are consistent with a role for Ca(2+) released from the SR in regulating I(f) and therefore beating rate of SA node preparations; there appear to be additional contributions of SR-derived Ca(2+) to effects of β-adrenoceptor stimulation on beating rate that are independent of I(f). PMID:26660545

  2. Experimental aerosolized guinea pig-adapted Zaire ebolavirus (variant: Mayinga) causes lethal pneumonia in guinea pigs.

    PubMed

    Twenhafel, N A; Shaia, C I; Bunton, T E; Shamblin, J D; Wollen, S E; Pitt, L M; Sizemore, D R; Ogg, M M; Johnston, S C

    2015-01-01

    Eight guinea pigs were aerosolized with guinea pig-adapted Zaire ebolavirus (variant: Mayinga) and developed lethal interstitial pneumonia that was distinct from lesions described in guinea pigs challenged subcutaneously, nonhuman primates challenged by the aerosol route, and natural infection in humans. Guinea pigs succumbed with significant pathologic changes primarily restricted to the lungs. Intracytoplasmic inclusion bodies were observed in many alveolar macrophages. Perivasculitis was noted within the lungs. These changes are unlike those of documented subcutaneously challenged guinea pigs and aerosolized filoviral infections in nonhuman primates and human cases. Similar to findings in subcutaneously challenged guinea pigs, there were only mild lesions in the liver and spleen. To our knowledge, this is the first report of aerosol challenge of guinea pigs with guinea pig-adapted Zaire ebolavirus (variant: Mayinga). Before choosing this model for use in aerosolized ebolavirus studies, scientists and pathologists should be aware that aerosolized guinea pig-adapted Zaire ebolavirus (variant: Mayinga) causes lethal pneumonia in guinea pigs.

  3. Guinea-pig reaginic antibody

    PubMed Central

    Margni, R. A.; Hajos, Silvia E.

    1973-01-01

    The physicochemical and biological properties of purified guinea-pig reaginic antibody were studied. It is a labile protein different to γ1. Its antibody activity is completely destroyed by heating at 56° for 6 hours and by treatment with mercaptoethanol. The capacity to give PCA is decreased by repeated freezing and thawing. It is a bivalent antibody, haemagglutinating, does not fix complement and is capable of sensitizing guinea-pig skin for PCA reaction after a latent period of a week but not after 3 hours. Reaginic antibody appears on day 7–8 after the first inoculation and the higher levels (PCA reaction) are obtained at the eleventh to thirteenth days. After the fifteenth to seventeenth days the PCA is negative. The reaginic antibody does not pass the placenta. Higher levels of reaginic antibody were obtained when the guinea-pigs were inoculated with the antigen in saline with simultaneous inoculation, intraperitoneally, of killed Bordetella pertussis, phase I. PMID:4354828

  4. Guinea-pig reaginic antibody

    PubMed Central

    Margni, R. A.; Hajos, Silvia E.

    1973-01-01

    The methods for isolation and purification of a guinea-pig serum protein with homocytotropic antibody activity and characteristics of IgE are described. By precipitation in the equivalence zone or immunoadsorption and chromatography on DEAE-cellulose, we isolated an homocytotropic antibody, that was not able to give a precipitin line when it was reacted directly with the antigen. It was capable of sensitizing guinea-pig skin for PCA after a latent period of 24–48 hours but not after 3 hours; it was sensitive to treatment with mercaptoethanol. It had antigenic determinants present in the other guinea-pig immunoglobulins and particular antigenic determinants. All these properties make us believe that this protein belongs to an immunoglobulin different from γ1 and similar to the reaginic antibody (IgE) described in other species. ImagesFIG. 3FIG. 4FIG. 5 PMID:4126261

  5. Coccidiosis in guinea-pigs.

    PubMed

    Ellis, P A; Wright, A E

    1961-07-01

    The attention of laboratory workers is drawn to the possibility of coccidiosis as a cause of death in guinea-pigs. The purchase of a number of guinea-pigs infected with this protozoon was followed by 12 deaths when these animals were injected with material for diagnostic purposes. No deaths occurred in the laboratory stock herd, as these were kept separate from the newcomers and were not infected. The life history of the parasite is described, together with the post-mortem findings in our series of animals.

  6. Mechanically induced orientation of adult rat cardiac myocytes in vitro

    NASA Technical Reports Server (NTRS)

    Samuel, J.-L.; Vandenburgh, H. H.

    1990-01-01

    The present study describes the spatial orientation of a population of freshly isolated adult rat cardiac myocytes using a computerized mechanical cell stimulator device for tissue cultured cells. A continuous unidirectional stretch of the substratum at 60 to 400 microns/min for 120 to 30 min, respectively, during the cell attachment period in a serum-free medium was found to induce a significant threefold increase in the number of rod-shaped myocytes oriented parallel to the direction of movement. The myocytes orient less well with unidirectional substratum stretching after their adhesion to the substratum. Adult myocytes plated onto a substratum undergoing continuous 10-percent stretch-relaxation cycling show no significant change in the myocyte orientation or cytoskeletal organization. In addition to the type of mechanical activity, orientation of rod-shaped myocytes is dependent on the speed of the substratum, the final stretch amplitude, and the timing between initiation of substratum stretching and adhesion of myocytes to the substratum.

  7. Guinea Pigs: Versatile Animals for the Classroom

    ERIC Educational Resources Information Center

    Barman, Charles R.

    1977-01-01

    Guinea pigs are presented as versatile classroom animals. Suggestions for animal behavior and genetics studies are given. Also included is information concerning sex determination and the breeding of guinea pigs, and hints on keeping these animals in the classroom. References and illustrations complete the article. (MA)

  8. Isolation and characterization of Guinea pig properidin.

    PubMed

    Nicholson, A; Austen, K F

    1977-01-01

    Guinea pig properdin was purified to homogeneity by employing as an assay during isolation its capacity to augment the hemolytic activity of a heterologous human C3b-dependent C3 convertase, C3B. The purified protein elicited a monospecific antibody response in a rabbit. The antiserum, by immunodiffusion, gave a reaction of identity between a protein in whole guinea pig serum and the immunogen. A solid phase immunoadsorbent prepared with the antiserum removed properdin function from the purified protein. The purified guinea pig protein exhibited the classical properdin function of reconstituting a human RP for zymosan-induced C3 inactivation. The guinea pig properdin also agglutinated red cell intermediates bearing either guinea pig or human C3b and retarded the decay of homologous C3 convertase, C3B. These activities are the same as those observed for purified human properdin and validate the amplification function of properdin on terminal component activation in a second species.

  9. Endocrine tumours in the guinea pig.

    PubMed

    Künzel, Frank; Mayer, Jörg

    2015-12-01

    Functional endocrine tumours have long been thought to be rare in guinea pigs, although conditions such as hyperthyroidism and hyperadrenocorticism have been documented with increasing frequency so the prevalence of hormonal disorders may have been underestimated. Both the clinical signs and diagnosis of hyperthyroidism in guinea pigs appear to be very similar to those described in feline hyperthyroidism, and methimazole has been proven to be a practical therapy option. Hyperadrenocorticism has been confirmed in several guinea pigs with an adrenocorticotropic hormone stimulation test using saliva as a non-invasive sample matrix; trilostane has been successfully used to treat a guinea pig with hyperadrenocorticism. Insulinomas have only rarely been documented in guinea pigs and one animal was effectively treated with diazoxide. PMID:26542368

  10. Endocrine tumours in the guinea pig.

    PubMed

    Künzel, Frank; Mayer, Jörg

    2015-12-01

    Functional endocrine tumours have long been thought to be rare in guinea pigs, although conditions such as hyperthyroidism and hyperadrenocorticism have been documented with increasing frequency so the prevalence of hormonal disorders may have been underestimated. Both the clinical signs and diagnosis of hyperthyroidism in guinea pigs appear to be very similar to those described in feline hyperthyroidism, and methimazole has been proven to be a practical therapy option. Hyperadrenocorticism has been confirmed in several guinea pigs with an adrenocorticotropic hormone stimulation test using saliva as a non-invasive sample matrix; trilostane has been successfully used to treat a guinea pig with hyperadrenocorticism. Insulinomas have only rarely been documented in guinea pigs and one animal was effectively treated with diazoxide.

  11. Guinea Pig Ciliary Muscle Development

    PubMed Central

    Pucker, Andrew D.; Carpenter, Ashley R.; McHugh, Kirk M.; Mutti, Donald O.

    2014-01-01

    Purpose The purpose of this study was to develop a method for quantifying guinea pig ciliary muscle volume (CMV) and to determine its relationship to age and ocular biometric measurements. Methods Six albino guinea pigs eyes were collected at each of five ages (n=30 eyes). Retinoscopy and photography were used to document refractive error, eye size, and eye shape. Serial sections through the excised eyes were made and then labeled with an α-smooth muscle actin antibody. The CM was then visualized with an Olympus BX51 microscope, reconstructed with Stereo Investigator (MBF Bioscience) and analyzed using Neurolucida Explorer (MBF Bioscience). Full (using all sections) and partial (using a subset of sections) reconstruction methods were used to determine CMV. Results There was no significant difference between the full and partial volume determination methods (P = 0.86). The mean CMV of the 1, 10, 20, 30, and 90-day old eyes was 0.40 ± 0.16 mm3, 0.48 ± 0.13 mm3, 0.67 ± 0.15 mm3, 0.86 ± 0.35 mm3, and 1.09 ± 0.63 mm3, respectively. CMV was significantly correlated with log age (P = 0.001), ocular length (P = 0.003), limbal circumference (P = 0.01), and equatorial diameter (P = 0.003). It was not correlated with refractive error (P = 0.73) or eye shape (P = 0.60). Multivariate regression determined that biometric variables were not significantly associated with CMV after adjustment for age. Conclusions Three-dimensional reconstruction was an effective means of determining CMV. These data provide evidence that CM growth occurs with age in tandem with eye size in normal albino guinea pigs. Additional work is needed to determine the relationship between CMV and abnormal ocular growth. PMID:24901488

  12. Vagus nerve stimulation mitigates intrinsic cardiac neuronal and adverse myocyte remodeling postmyocardial infarction

    PubMed Central

    Beaumont, Eric; Southerland, Elizabeth M.; Hardwick, Jean C.; Wright, Gary L.; Ryan, Shannon; Li, Ying; KenKnight, Bruce H.; Armour, J. Andrew

    2015-01-01

    This paper aims to determine whether chronic vagus nerve stimulation (VNS) mitigates myocardial infarction (MI)-induced remodeling of the intrinsic cardiac nervous system (ICNS), along with the cardiac tissue it regulates. Guinea pigs underwent VNS implantation on the right cervical vagus. Two weeks later, MI was produced by ligating the ventral descending coronary artery. VNS stimulation started 7 days post-MI (20 Hz, 0.9 ± 0.2 mA, 14 s on, 48 s off; VNS-MI, n = 7) and was compared with time-matched MI animals with sham VNS (MI n = 7) vs. untreated controls (n = 8). Echocardiograms were performed before and at 90 days post-MI. At termination, IC neuronal intracellular voltage recordings were obtained from whole-mount neuronal plexuses. MI increased left ventricular end systolic volume (LVESV) 30% (P = 0.027) and reduced LV ejection fraction (LVEF) 6.5% (P < 0.001) at 90 days post-MI compared with baseline. In the VNS-MI group, LVESV and LVEF did not differ from baseline. IC neurons showed depolarization of resting membrane potentials and increased input resistance in MI compared with VNS-MI and sham controls (P < 0.05). Neuronal excitability and sensitivity to norepinephrine increased in MI and VNS-MI groups compared with controls (P < 0.05). Synaptic efficacy, as determined by evoked responses to stimulating input axons, was reduced in VNS-MI compared with MI or controls (P < 0.05). VNS induced changes in myocytes, consistent with enhanced glycogenolysis, and blunted the MI-induced increase in the proapoptotic Bcl-2-associated X protein (P < 0.05). VNS mitigates MI-induced remodeling of the ICNS, correspondingly preserving ventricular function via both neural and cardiomyocyte-dependent actions. PMID:26276818

  13. Vaccination with Trypanosoma rangeli induces resistance of guinea pigs to virulent Trypanosoma cruzi.

    PubMed

    Basso, B; Moretti, E; Fretes, R

    2014-01-15

    Chagas' disease, endemic in Latin America, is spread in natural environments through animal reservoirs, including marsupials, mice and guinea pigs. Farms breeding guinea pigs for food are located in some Latin-American countries with consequent risk of digestive infection. The aim of this work was to study the effect of vaccination with Trypanosoma rangeli in guinea pigs challenged with Trypanosoma cruzi. Animals were vaccinated with fixated epimastigotes of T. rangeli, emulsified with saponin. Controls received only PBS. Before being challenged with T. cruzi, parasitemia, survival rates and histological studies were performed. The vaccinated guinea pigs revealed significantly lower parasitemia than controls (p<0.0001-0.01) and a discrete lymphomonocytic infiltrate in cardiac and skeletal muscles was present. In the chronic phase, the histological view was normal. In contrast, control group revealed amastigote nests and typical histopathological alterations compatible with chagasic myocarditis, endocarditis and pericarditis. These results, together with previous works in our laboratory, show that T. rangeli induces immunoprotection in three species of animals: mice, guinea pigs and dogs. The development of vaccines for use in animals, like domestic dogs and guinea pigs in captivity, opens up new opportunities for preventive tools, and could reduce the risk of infection with T. cruzi in the community.

  14. 9 CFR 113.38 - Guinea pig safety test.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Guinea pig safety test. 113.38 Section... Standard Procedures § 113.38 Guinea pig safety test. The guinea pig safety test provided in this section... be injected either intramuscularly or subcutaneously into each of two guinea pigs and the...

  15. 9 CFR 113.38 - Guinea pig safety test.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Guinea pig safety test. 113.38 Section... Standard Procedures § 113.38 Guinea pig safety test. The guinea pig safety test provided in this section... be injected either intramuscularly or subcutaneously into each of two guinea pigs and the...

  16. 9 CFR 113.38 - Guinea pig safety test.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Guinea pig safety test. 113.38 Section... Standard Procedures § 113.38 Guinea pig safety test. The guinea pig safety test provided in this section... be injected either intramuscularly or subcutaneously into each of two guinea pigs and the...

  17. Rat cardiac myocyte adenosine transport and metabolism

    SciTech Connect

    Ford, D.A.; Rovetto, M.J.

    1987-01-01

    Based on the importance of myocardial adenosine and adenine nucleotide metabolism, the adenosine salvage pathway in ventricular myocytes was studied. Accurate estimates of transport rates, separate from metabolic fllux, were determined. Adenosine influx was constant between 3 and 60 s. Adenosine metabolism maintained intracellular adenosine concentrations < 10% of the extracellular adenosine concentrations and thus unidirectional influx could be measured. Myocytes transported adenosine via saturable and nonsaturable processes. A minimum estimate of the V/sub max/ of myocytic adenosine kinase indicated the saturable component of adenosine influx was independent of adenosine kinase activity. Saturable transport was inhibited by nitrobenzylthioinosine and verapamil. Extracellular adenosine taken up myocytes was rapidly phosphorylated to adenine taken up by myocytes was rapidly phosphorylated to adenine nucleotides. Not all extracellular adenosine, though, was phosphorylated on entering myocytes, since free, as opposed to protein-bound, intracellular adenosine was detected after digitonin extraction of cells in the presence of 1 mM ethylene-diaminetetraacetic acid.

  18. Measuring mitochondrial function in intact cardiac myocytes

    PubMed Central

    Dedkova, Elena N.; Blatter, Lothar A.

    2011-01-01

    Mitochondria are involved in cellular functions that go beyond the traditional role of these organelles as the power plants of the cell. Mitochondria have been implicated in several human diseases, including cardiac dysfunction, and play a role in the aging process. Many aspects of our knowledge of mitochondria stem from studies performed on the isolated organelle. Their relative inaccessibility imposes experimental difficulties to study mitochondria in their natural environment – the cytosol of intact cells – and has hampered a comprehensive understanding of the plethora of mitochondrial functions. Here we review currently available methods to study mitochondrial function in intact cardiomyocytes. These methods primarily use different flavors of fluorescent dyes and genetically encoded fluorescent proteins in conjunction with high-resolution imaging techniques. We review methods to study mitochondrial morphology, mitochondrial membrane potential, Ca2+ and Na+ signaling, mitochondrial pH regulation, redox state and ROS production, NO signaling, oxygen consumption, ATP generation and the activity of the mitochondrial permeability transition pore. Where appropriate we complement this review on intact myocytes with seminal studies that were performed on isolated mitochondria, permeabilized cells, and in whole hearts. PMID:21964191

  19. Effect of azelastine on cardiac repolarization of guinea-pig cardiomyocytes, hERG K⁺ channel, and human L-type and T-type Ca²⁺ channel.

    PubMed

    Park, Mi-Hyeong; Lee, Seung Ho; Chu, Dae Hyun; Won, Kwang Hee; Choi, Bok Hee; Choe, Han; Jo, Su-Hyun

    2013-09-20

    Azelastine is a second generation histamine H₁-receptor antagonist used as an anti-asthmatic and anti-allergic drug that can induce QT prolongation and torsades de pointes. We investigated the acute effects of azelastine on human ether-a-go-go-related gene (hERG) channels, action potential duration (APD), and L-type (I(Ca,L)) and T-type Ca²⁺ current (I(Ca,T)) to determine the electrophysiological basis for its proarrhythmic potential. Azelastine increased the APD at 90% of repolarization concentration dependently, with an IC₅₀ of 1.08 nM in guinea-pig ventricular myocytes. We examined the effects of azelastine on the hERG channels expressed in Xenopus oocytes and HEK293 cells using two-microelectrode voltage-clamp and patch-clamp techniques. Azelastine induced a concentration-dependent decrease of the hERG current amplitude at the end of the voltage steps and tail currents. The IC₅₀ for the azelastine-induced block of the hERG currents expressed in HEK293 cells was 11.43 nM, while the drug inhibited I(Ca,L) and I(Ca,T) with IC₅₀ values of 7.60 and 26.21 μM, respectively. The S6 domain mutations, Y652A partially attenuated and F656A abolished hERG current block. These results suggest that azelastine is a potent blocker of hERG channels rather than I(Ca,L) or I(Ca,T), providing molecular mechanisms for the arrhythmogenic side effects during the clinical administration of azelastine. PMID:24005046

  20. Malignant transformation of guinea pig cells after exposure to ultraviolet-irradiated guinea pig cytomegalovirus

    SciTech Connect

    Isom, H.C.; Mummaw, J.; Kreider, J.W.

    1983-04-30

    Guinea pig cells were malignantly transformed in vitro by ultraviolet (uv)-irradiated guinea pig cytomegalovirus (GPCMV). When guinea pig hepatocyte monolayers were infected with uv-irradiated GPCMV, three continuous epithelioid cell lines which grew in soft agarose were established. Two independently derived GPCMV-transformed liver cells and a cell line derived from a soft agarose clone of one of these lines induced invasive tumors when inoculated subcutaneously or intraperitoneally into nude mice. The tumors were sarcomas possibly derived from hepatic stroma or sinusoid. Transformed cell lines were also established after infection of guinea pig hepatocyte monolayers with human cytomegalovirus (HCMV) or simian virus 40 (SV40). These cell lines also formed colonies in soft agarose and induced sarcomas in nude mice. It is concluded that (i) GPCMV can malignantly transform guinea pig cells; (ii) cloning of GPCMV-transformed cells in soft agarose produced cells that induced tumors with a shorter latency period but with no alteration in growth rate or final tumor size; and (iii) the tumors produced by GPCMV-and HCMV-transformed guinea pig cells were more similar to each other in growth rate than to those induced by SV40-transformed guinea pig cells.

  1. Biology of the cardiac myocyte in heart disease

    PubMed Central

    Peter, Angela K.; Bjerke, Maureen A.; Leinwand, Leslie A.

    2016-01-01

    Cardiac hypertrophy is a major risk factor for heart failure, and it has been shown that this increase in size occurs at the level of the cardiac myocyte. Cardiac myocyte model systems have been developed to study this process. Here we focus on cell culture tools, including primary cells, immortalized cell lines, human stem cells, and their morphological and molecular responses to pathological stimuli. For each cell type, we discuss commonly used methods for inducing hypertrophy, markers of pathological hypertrophy, advantages for each model, and disadvantages to using a particular cell type over other in vitro model systems. Where applicable, we discuss how each system is used to model human disease and how these models may be applicable to current drug therapeutic strategies. Finally, we discuss the increasing use of biomaterials to mimic healthy and diseased hearts and how these matrices can contribute to in vitro model systems of cardiac cell biology. PMID:27418636

  2. Nuclear Morphology and Deformation in Engineered Cardiac Myocytes and Tissues

    PubMed Central

    Bray, Mark-Anthony; Adams, William J.; Geisse, Nicholas A.; Feinberg, Adam W.; Sheehy, Sean P.; Parker, Kevin Kit

    2010-01-01

    Cardiac tissue engineering requires finely-tuned manipulation of the extracellular matrix (ECM) microenvironment to optimize internal myocardial organization. The myocyte nucleus is mechanically connected to the cell membrane via cytoskeletal elements, making it a target for the cellular response to perturbation of the ECM. However, the role of ECM spatial configuration and myocyte shape on nuclear location and morphology is unknown. In this study, printed ECM proteins were used to configure the geometry of cultured neonatal rat ventricular myocytes. Engineered one- and two-dimensional tissue constructs and single-myocyte islands were assayed using live fluorescence imaging to examine nuclear position, morphology and motion as a function of the imposed ECM geometry during diastolic relaxation and systolic contraction. Image analysis showed that anisotropic tissue constructs cultured on microfabricated ECM lines possessed a high degree of nuclear alignment similar to that found in vivo; nuclei in isotropic tissues were polymorphic in shape with an apparently random orientation. Nuclear eccentricity was also increased for the anisotropic tissues, suggesting that intracellular forces deform the nucleus as the cell is spatially confined. During systole, nuclei experienced increasing spatial confinement in magnitude and direction of displacement as tissue anisotropy increased, yielding anisotropic deformation. Thus, the nature of nuclear displacement and deformation during systole appears to rely on a combination of the passive myofibril spatial organization and the active stress fields induced by contraction. Such findings have implications in understanding the genomic consequences and functional response of cardiac myocytes to their ECM surroundings under conditions of disease. PMID:20382423

  3. Neutrophil adherence to isolated adult cardiac myocytes. Induction by cardiac lymph collected during ischemia and reperfusion.

    PubMed Central

    Youker, K; Smith, C W; Anderson, D C; Miller, D; Michael, L H; Rossen, R D; Entman, M L

    1992-01-01

    Canine neutrophils can be induced to adhere in vitro to isolated adult cardiac myocytes by stimulation of the neutrophils with chemotactic factors such as zymosan-activated serum (ZAS) only if the myocytes have been previously exposed to cytokines such as interleukin 1 (IL-1) or tumor necrosis factor-alpha. These cytokines induce synthesis and surface expression of intercellular adhesion molecule-1 (ICAM-1) on the myocyte, and neutrophil adhesion is almost entirely CD18 and ICAM-1 dependent. The present study examines cardiac-specific lymph collected from awake dogs during 1-h coronary occlusion and 3 d of reperfusion for its ability to induce both ICAM-1 expression in cardiac myocytes, and neutrophil-myocyte adherence. Reperfusion lymph induced ICAM-1 expression in isolated myocytes, and myocyte adherence to ZAS-stimulated neutrophils that was completely inhibited by anti-CD18 and anti-ICAM-1 monoclonal antibodies. This activity peaked at 90 min of reperfusion and persisted for up to 72 h. Preischemic lymph was not stimulatory. IL-1 appeared not to be a stimulating factor in lymph in that dilutions of lymph were found to inhibit the stimulatory effects of recombinant IL-1 beta. However, investigation of interleukin 6 (IL-6) revealed that recombinant IL-6 stimulated myocyte adhesiveness for ZAS-stimulated neutrophils (ED50 = 0.002 U/ml) and expression of ICAM-1 by isolated myocytes. IL-6 neutralizing antibody markedly reduced the ability of reperfusion lymph to stimulate adhesion and ICAM-1 expression, and estimates of levels of IL-6 in reperfusion lymph ranged from 0.035 to 0.14 U/ml. These results indicate that cytokines capable of promoting neutrophil-myocyte adhesion occur in extracellular fluid during reperfusion of ischemic myocardium, and that one of these cytokines is IL-6. Neutrophil-myocyte adhesion may be of pathogenic significance because it may enhance the cytotoxic activity of the neutrophil. Images PMID:1346618

  4. Cytoskeletal prestress regulates nuclear shape and stiffness in cardiac myocytes

    PubMed Central

    Lee, Hyungsuk; Adams, William J; Alford, Patrick W; McCain, Megan L; Feinberg, Adam W; Sheeny, Sean P; Goss, Josue A

    2015-01-01

    Mechanical stresses on the myocyte nucleus have been associated with several diseases and potentially transduce mechanical stimuli into cellular responses. Although a number of physical links between the nuclear envelope and cytoplasmic filaments have been identified, previous studies have focused on the mechanical properties of individual components of the nucleus, such as the nuclear envelope and lamin network. The mechanical interaction between the cytoskeleton and chromatin on nuclear deformability remains elusive. Here, we investigated how cytoskeletal and chromatin structures influence nuclear mechanics in cardiac myocytes. Rapid decondensation of chromatin and rupture of the nuclear membrane caused a sudden expansion of DNA, a consequence of prestress exerted on the nucleus. To characterize the prestress exerted on the nucleus, we measured the shape and the stiffness of isolated nuclei and nuclei in living myocytes during disruption of cytoskeletal, myofibrillar, and chromatin structure. We found that the nucleus in myocytes is subject to both tensional and compressional prestress and its deformability is determined by a balance of those opposing forces. By developing a computational model of the prestressed nucleus, we showed that cytoskeletal and chromatin prestresses create vulnerability in the nuclear envelope. Our studies suggest the cytoskeletal–nuclear–chromatin interconnectivity may play an important role in mechanics of myocyte contraction and in the development of laminopathies by lamin mutations. PMID:25908635

  5. 5'-Adenosine monophosphate and adenosine metabolism, and adenosine responses in mouse, rat and guinea pig heart.

    PubMed

    Headrick, J P; Peart, J; Hack, B; Garnham, B; Matherne, G P

    2001-11-01

    We examined myocardial 5'-adenosine monophosphate (5'-AMP) catabolism, adenosine salvage and adenosine responses in perfused guinea pig, rat and mouse heart. MVO(2) increased from 71+/-8 microl O(2)/min per g in guinea pig to 138+/-17 and 221+/-15 microl O(2)/min per g in rat and mouse. VO(2)/beat was 0.42+/-0.03, 0.50+/-0.03 and 0.55+/-0.04 microl O(2)/g in guinea pig, rat and mouse, respectively. Resting and peak coronary flows were highest in mouse vs. rat and guinea pig, and peak ventricular pressures and Ca(2+) sensitivity declined as heart mass increased. Net myocardial 5'-AMP dephosphorylation increased significantly as mass declined (3.8+/-0.5, 9.0+/-1.4 and 11.0+/-1.6 nmol/min per g in guinea pig, rat and mouse, respectively). Despite increased 5'-AMP catabolism, coronary venous [adenosine] was similar in guinea pig, rat and mouse (45+/-8, 69+/-10 and 57+/-14 nM, respectively). Comparable venous [adenosine] was achieved by increased salvage vs. deamination: 64%, 41% and 39% of adenosine formed was rephosphorylated while 23%, 46%, and 50% was deaminated in mouse, rat and guinea pig, respectively. Moreover, only 35-45% of inosine and its catabolites derive from 5'-AMP (vs. IMP) dephosphorylation in all species. Although post-ischemic purine loss was low in mouse (due to these adaptations), functional tolerance to ischemia decreased with heart mass. Cardiovascular sensitivity to adenosine also differed between species, with A(1) receptor sensitivity being greatest in mouse while A(2) sensitivity was greatest in guinea pig. In summary: (i) cardiac 5'-AMP dephosphorylation, VO(2), contractility and Ca(2+) sensitivity all increase as heart mass falls; (ii) adaptations in adenosine salvage vs. deamination limit purine loss and yield similar adenosine levels across species; (iii) ischemic tolerance declines with heart mass; and (iv) cardiovascular sensitivity to adenosine varies, with increasing A(2) sensitivity relative to A(1) sensitivity in larger hearts.

  6. Transmission in the guinea pig model.

    PubMed

    Lowen, Anice C; Bouvier, Nicole M; Steel, John

    2014-01-01

    The ability of an influenza virus to transmit efficiently from human-to-human is a major factor in determining the epidemiological impact of that strain. The use of a relevant animal model to identify viral determinants of transmission, as well as host and environmental factors affecting transmission efficiency, is therefore critical for public health. The characterization of newly emerging influenza viruses in terms of their potential to transmit in a mammalian host is furthermore an important part of pandemic risk assessment. For these reasons, a guinea pig model of influenza virus transmission was developed in 2006. The guinea pig provides an important alternative to preexisting models for influenza. Most influenza viruses do not readily transmit among mice. Ferrets, while highly relevant, are expensive and can be difficult to obtain in high numbers. Moreover, it is generally accepted that efforts to accurately model human disease are strengthened by the use of multiple animal species. Herein, we provide an overview of influenza virus infectivity, growth, and transmission in the guinea pig and highlight knowledge gained on the topic of influenza virus transmission using the guinea pig model.

  7. Chlamydial pneumonitis induced in newborn guinea pigs.

    PubMed Central

    Rank, R G; Hough, A J; Jacobs, R F; Cohen, C; Barron, A L

    1985-01-01

    One- to three-day-old guinea pigs were inoculated intranasally with the chlamydial agent of guinea pig inclusion conjunctivitis. Physical signs of infection included a marked increase in respiration rate on days 5 to 10 of infection and radiographic evidence of pneumonia on day 6. When animals were killed at various times after infection and lung tissue was examined by histopathology, evidence of pneumonia was found beginning on day 4 and lasting as long as day 12, with maximal pathological changes on days 6 to 8. The pneumonia was generally unilateral and consisted of an acute inflammatory component in the bronchioles with granulocytes in both the lumen and the wall of the bronchioles and an interstitial and intra-alveolar mononuclear infiltrate in the parenchyma of the lung. Chlamydial antigen was detected in the bronchial epithelial cells by immunoperoxidase staining, and the guinea pig inclusion conjunctivitis organism was isolated from lung tissue on days 6 to 9. No other significant bacteria were isolated from lung tissue or seen on gram stains of lung sections. Both immunoglobulin M and immunoglobulin G serum antibodies to the guinea pig inclusion conjunctivitis agent were detected as early as day 8 and reached peak levels on day 12. The infection was apparently self-limiting. This model presents the opportunity to investigate pathophysiological and immunological aspects of chlamydial respiratory infections in a neonatal animal. Images PMID:3980080

  8. Hypoxic-induced stress protein expression in rat cardiac myocytes

    SciTech Connect

    Howard, G.; Geoghegan, T.E.

    1986-05-01

    Mammalian stress proteins can be induced in cells and tissues exposed to a variety of conditions including hyperthermia and diminished O/sub 2/ supply. The authors have previously shown that the expression of three stress proteins (71, 85, and 95 kDa) was induced in cardiac tissue from mice exposed to hypoxic conditions. The expression of mRNAs coding for the 85 and 95 kDa proteins increase with time of exposure to hypoxia, while the mRNA coding for the 71 kDa protein is transiently induced. The authors extended these studies to investigate the expression of stress proteins in isolated rat cardiac myocytes. Freshly prepared myocytes were exposed to control, hypoxic, anoxic, or heat-shock environments for up to 16 h. The proteins were then labeled for 6 hours with (/sup 35/S)methionine. Analysis of the solubilized proteins by SDS-PAGE and autoradiography showed that there was a 6-fold increase in synthesis of the 85 kDa protein upon exposure to hypoxia but not heat-shock conditions. The 71 kDa protein was present at high levels in both control and treated myocyte protein preparations, and presumably had been induced during the isolation procedure. Total RNA isolated from intact rat heart and isolated myocytes was compared by cell-free translation analysis and showed induction of RNAs coding for several stress proteins in the myocyte preparation. The induced proteins at 85 and 95 kDa have molecular weights similar to reported cell stress and/or glucose-regulated proteins.

  9. Characterization of the sodium channel blocking properties of the major metabolites of cocaine in single cardiac myocytes.

    PubMed

    Crumb, W J; Clarkson, C W

    1992-06-01

    Clinical reports indicate that almost 30% of cocaine overdose-related deaths occur 2 to 5 hr after administration, when an appreciable amount of cocaine can be expected to have been converted to metabolites. We investigated the effects of the three major metabolites of cocaine: benzoylecgonine, ecgonine methyl ester and norcocaine on sodium channels in isolated guinea pig myocytes using the whole cell variant of the patch clamp technique at 16 +/- 0.5 degrees C. Benzoylecgonine and ecgonine methyl ester did not produce a significant block of sodium current at a concentration of 100 microM. In contrast, 30 microM norcocaine was found to reduce sodium current in a use-dependent manner qualitatively similar to cocaine. The time course of sodium current block development and recovery were characterized. With 30 microM norcocaine, two phases of block development were defined: a rapid phase (tau = 11.9 +/- 11.6 msec) and a slow phase (tau = 2.2 +/- 0.5 sec). Recovery from drug-induced block at -140 mV was approximately twice as fast for norcocaine (tau = 4.6 +/- 1.7 sec, n = 7) compared to cocaine (tau = 8.4 +/- 0.9 sec, n = 6). Norcocaine was found to have a higher affinity for inactivated cardiac sodium channels (Kdi = 5.7 +/- 0.9 microM) than cocaine (Kdi = 7.8 +/- 1.2 microM) (P less than .01); however, norcocaine produced less use-dependent block due to its faster unbinding kinetics. These data indicate that although norcocaine and cocaine are potent sodium channel blockers, benzoylecgonine and ecgonine methyl ester are ineffective blockers at clinically relevant concentrations (i.e., less than or equal to 100 microM).

  10. The cochleogram of the guinea pig.

    PubMed

    Linss, Volker; Linss, Werner; Emmerich, Edeltraut; Richter, Frank

    2007-04-01

    The cochleogram is an important tool to relate properties of the cochlea (e.g. hair cell loss, damaged hair cells) to their position in the cochlear turns, to calculate the average hair cell density, and to measure the length of the whole cochlea. In this work different methods of plotting cochleograms are compared. We suggest that a sector-wise division of the cochlea for counting a cochleogram has advantages over line diagrams that provide a higher spatial resolution but might lead to misinterpretations of the degree of missing hair cells. The scanning electron microscopic analysis of 171 guinea pig cochleas revealed a mean basilar membrane length of 16.4 +/- 1.4 mm (mean +/- standard deviation) with sector lengths of 6.9, 4.2, 3.2, and 1.9 mm, thus adding relevant information to the morphology of the guinea pig cochlea. PMID:17082943

  11. Integrins and Integrin-Associated Proteins in the Cardiac Myocyte

    PubMed Central

    Ross, Robert S.

    2014-01-01

    Integrins are heterodimeric, transmembrane receptors that are expressed in all cells, including those in the heart. They participate in multiple critical cellular processes including adhesion, extracellular matrix organization, signaling, survival, and proliferation. Particularly relevant for a contracting muscle cell, integrins are mechanotransducers, translating mechanical to biochemical information. While it is likely that cardiovascular clinicians and scientists have highest recognition of integrins in the cardiovascular system from drugs used to inhibit platelet aggregation, the focus of this article will be on the role of integrins specifically in the cardiac myocyte. Following a general introduction to integrin biology, the manuscript will discuss important work on integrin signaling, mechanotransduction, and lessons learned about integrin function from a range of model organisms. Then we will detail work on integrin-related proteins in the myocyte, how integrins may interact with ion channels and mediate viral uptake into cells, and also play a role in stem cell biology. Finally, we will discuss directions for future study. PMID:24481847

  12. Methoxatin (PQQ) in guinea-pig neutrophils.

    PubMed

    Bishop, A; Paz, M A; Gallop, P M; Karnovsky, M L

    1994-10-01

    PQQ, also called methoxatin, has been isolated from guinea-pig neutrophils. The organic cations diphenyleneiodonium (DPI) and diphenyliodonium (BPI) and the aromatic o-diamine 4,5-dimethylphenylenediamine (DIMPDA) sequester synthetic PQQ and inhibit its redox-cycling activity in a model system. Standards were made of adducts of tritiated PQQ with unlabeled DIMPDA and of unlabeled PQQ with tritiated DPI or DIMPDA. PQQ adducts were isolated from guinea-pig neutrophils with each of the tritiated inhibitors. They were separated and defined by high-performance liquid chromatography (HPLC). Tiron, a disodium benzene disulphonic acid, broke the DPI-PQQ adduct isolated from neutrophils and released free PQQ. Both DPI and DIMPDA, as well as BPI, blocked O2.- release by stimulated neutrophils. The blockade exerted by these inhibitors was released by the addition of PQQ to the cell suspensions. The data demonstrate the presence of PQQ in guinea-pig neutrophils and suggest that it has a possible role, direct or indirect, in the O2.(-)-producing respiratory burst.

  13. pH regulation in adult cardiac myocytes

    SciTech Connect

    Wallert, M.A.

    1989-01-01

    The purpose of this study is to examine the pH{sub i} regulatory mechanisms of adult ventricular myocytes, the cells that perform the pumping work of the heart. The cell system for this study was the ventricular myocyte, isolated by enzymatic dissociation from adult rate heart. In agreement with the findings on other cardiac model cells, I demonstrated the existence of a Cl{sup {minus}}/HCO{sub 3}{sup {minus}} exchanger and a Na{sup +}/H{sup +} exchanger in ventricular myocytes. The existence of the anion exchanger was demonstrated in {sup 36}Cl{sup {minus}} flux experiments and as stilbene disulfonate-inhibitable and Cl{sup {minus}} gradient-dependent intracellular pH shifts in the presence of bicarbonate. The fluorescein derivative BCECF served as a fluorescent probe of intracellular pH in the these experiments. The existence of the Na{sup +}/H{sup +} exchanger was demonstrated in pH{sub i} experiments using BCECF. Further experiments characterized the kinetics of the Na{sup +}/H{sup +} exchanger and its regulation. The steady-state pH{sub i} of ventricular myocytes was 7.16 {+-} 0.11 at pH{sub 0} = 7.4. Several agonists caused a rise in steady-state pH{sub i}: the protein kinase stimulator phorbol myristate acetate (PMA), the {alpha}{sub 1}-adrenergic agonist 6-fluoro-norepinephrine (6F-NE) and the {beta}-agonist UK14304, and ATP.

  14. The Guinea Pigs of a Problem-Based Learning Curriculum

    ERIC Educational Resources Information Center

    Reddy, Sarasvathie; McKenna, Sioux

    2016-01-01

    Participants in a study on learning the clinical aspects of medicine in a problem-based learning (PBL) curriculum repeatedly referred to themselves as "Guinea pigs" at the mercy of a curriculum experiment. This article interrogates and problematises the "Guinea pig" identity ascribed to and assumed by the first cohort of…

  15. Heterogeneous infectiousness in guinea pigs experimentally infected with Trypanosoma cruzi.

    PubMed

    Castillo-Neyra, Ricardo; Borrini Mayorí, Katty; Salazar Sánchez, Renzo; Ancca Suarez, Jenny; Xie, Sherrie; Náquira Velarde, Cesar; Levy, Michael Z

    2016-02-01

    Guinea pigs are important reservoirs of Trypanosoma cruzi, the causative parasite of Chagas disease, and in the Southern Cone of South America, transmission is mediated mainly by the vector Triatoma infestans. Interestingly, colonies of Triatoma infestans captured from guinea pig corrals sporadically have infection prevalence rates above 80%. Such high values are not consistent with the relatively short 7-8 week parasitemic period that has been reported for guinea pigs in the literature. We experimentally measured the infectious periods of a group of T. cruzi-infected guinea pigs by performing xenodiagnosis and direct microscopy each week for one year. Another group of infected guinea pigs received only direct microscopy to control for the effect that inoculation by triatomine saliva may have on parasitemia in the host. We observed infectious periods longer than those previously reported in a number of guinea pigs from both the xenodiagnosis and control groups. While some guinea pigs were infectious for a short time, other "super-shedders" were parasitemic up to 22 weeks after infection, and/or positive by xenodiagnosis for a year after infection. This heterogeneity in infectiousness has strong implications for T. cruzi transmission dynamics and control, as super-shedder guinea pigs may play a disproportionate role in pathogen spread. PMID:26432777

  16. Heterogeneous infectiousness in guinea pigs experimentally infected with Trypanosoma cruzi.

    PubMed

    Castillo-Neyra, Ricardo; Borrini Mayorí, Katty; Salazar Sánchez, Renzo; Ancca Suarez, Jenny; Xie, Sherrie; Náquira Velarde, Cesar; Levy, Michael Z

    2016-02-01

    Guinea pigs are important reservoirs of Trypanosoma cruzi, the causative parasite of Chagas disease, and in the Southern Cone of South America, transmission is mediated mainly by the vector Triatoma infestans. Interestingly, colonies of Triatoma infestans captured from guinea pig corrals sporadically have infection prevalence rates above 80%. Such high values are not consistent with the relatively short 7-8 week parasitemic period that has been reported for guinea pigs in the literature. We experimentally measured the infectious periods of a group of T. cruzi-infected guinea pigs by performing xenodiagnosis and direct microscopy each week for one year. Another group of infected guinea pigs received only direct microscopy to control for the effect that inoculation by triatomine saliva may have on parasitemia in the host. We observed infectious periods longer than those previously reported in a number of guinea pigs from both the xenodiagnosis and control groups. While some guinea pigs were infectious for a short time, other "super-shedders" were parasitemic up to 22 weeks after infection, and/or positive by xenodiagnosis for a year after infection. This heterogeneity in infectiousness has strong implications for T. cruzi transmission dynamics and control, as super-shedder guinea pigs may play a disproportionate role in pathogen spread.

  17. A 2-D guinea pig lung proteome map

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guinea pigs represent an important model for a number of infectious and non-infectious pulmonary diseases. The guinea pig genome has recently been sequenced to full coverage, opening up new research avenues using genomics, transcriptomics and proteomics techniques in this species. In order to furth...

  18. Microfluidic partitioning of the extracellular space around single cardiac myocytes.

    PubMed

    Klauke, Norbert; Smith, Godfrey L; Cooper, Jonathan M

    2007-02-01

    This paper describes the partitioning of the extracellular space around an electrically activated single cardiac myocyte, constrained within a microfluidic device. Central to this new method is the production of a hydrophobic gap-structure, which divides the extracellular space into two distinct microfluidic pools. The content of these pools was controlled using a pair of concentric automated pipets (subsequently called "dual superfusion pipet"), each providing the ability to dispense (i.e., the source, inner pipet) and aspirate (the sink, outer pipet) a buffer solution (perfusate) into each of the two pools. For rapid solution switching around the cell, additional dual superfusion pipets were inserted into the microchannel for defined time periods using a piezostepper, enabling us to add a test solution, such as a drug. Three distinct areas of the cell were manipulated, namely, the microfluidic environment, the cellular membrane, and the intracellular space. Planar integrated microelectrodes enabled the electrical stimulation of the cardiomyocyte and the recording of the evoked action potential. The device was mounted on an inverted microscope to allow simultaneous sarcomere length and epifluorescence measurements during evoked electrical activity, including, for example, the response of the stimulated end of the cardiac myocyte in comparison with the untreated cell end.

  19. Changes in gene expression with iron loading and chelation in cardiac myocytes and non-myocytic fibroblasts.

    PubMed

    Parkes, J G; Liu, Y; Sirna, J B; Templeton, D M

    2000-02-01

    Iron overload is associated with long-term cardiac iron accumulation and tissue changes such as fibrosis. To determine short-term iron-dependent changes in expression of genes associated with iron homeostasis and fibrosis we measured mRNA on Northern blots prepared from cultured rat neonatal cardiomyocytes and non-myocytes (fibroblasts) as a function of iron loading and chelation. Transferrin receptor mRNA was reduced in myocytes exposed to various concentrations of iron for 3 days and this decline was associated with a 63% decline in iron-response element (IRE) binding of iron regulatory protein-1, indicating that myocytes utilize IRE-dependent mechanisms to modulate gene expression. In myocytes iron caused a dose-dependent decline in mRNAs coding for transforming growth factor- beta(1)(TGF- beta(1)), biglycan, and collagen type I while plasminogen activator inhibitor-1 mRNA was unaffected by iron loading and decorin mRNA doubled. Total TGF- beta bioactivity was also decreased by iron loading. Thus, the effects of iron loading on genes related to cardiac fibrosis are gene-specific. Addition of deferoxamine for 1 day did not have any significant effect on any of these genes. Parallel changes in gene expression were exhibited by non-myocytes (fibroblasts), where chelation also decreased TGF- beta(1)mRNA and activity, and mRNA for collagen type I and biglycan, and collagen synthesis. In addition to these changes in transcripts associated with matrix formation the mRNA of the metabolic enzyme glyceraldehyde-3-phosphate dehydrogenase was unaffected by iron loading but doubled in both cell types upon treatment with deferoxamine. These findings suggest that in both cardiac myocytes and non-myocyte fibroblasts gene expression is coupled to intracellular iron pools by gene-specific and IRE-dependent and idependent mechanisms. This linkage may influence matrix deposition, a significant component of cardiac injury.

  20. ANAPHYLAXIS IN CHOPPED GUINEA PIG LUNG

    PubMed Central

    Austen, K. F.; Brocklehurst, W. E.

    1961-01-01

    The quantitative release of histamine by specific antigen from perfused, chopped, sensitized guinea pig lung has been used to study the effect of peptidase substrates and inhibitors on the anaphylactic reaction. The anaphylactic release of histamine is prevented by chymotrypsin substrates and inhibitors but not by trypsin, carboxypeptidase, or leucine aminopeptidase substrates or the soybean trypsin inhibitor. The chymotrypsin substrates and inhibitors appear to be acting on an antigen-antibody-activated step because these substances fail to inhibit if the tissue is washed free of them prior to antigen addition, and because there is complete desensitization of the tissue without histamine release when the antigen is added in the presence of these inhibitors. The inhibitors work equally well in tissue from passively sensitized animals or in tissue from animals actively sensitized with either ovalbumin or bovine gamma globulin. These observations suggest that activation of a chymotrypsin-like enzyme is a necessary condition for the anaphylactic release of histamine in guinea pig lung. Diisopropylfluophosphate is inhibitory when present at the time of antigen addition but not when the tissue is washed free of unfixed diisopropylfluophosphate prior to adding antigen. This indicates that diisopropylfluophosphate must be acting exclusively on an enzyme which exists in lung tissue in a precursor form resistant to diisopropylfluophosphate until activated by the antigen-antibody interaction. Thiol alkylating or oxidizing agents also prevent the anaphylactic release of histamine, but in contrast to the situation with diisopropylfluophosphate and the other chymotrypsin inhibitors, the phase of the anaphylactic reaction inhibited by N-ethylmaleimide is available prior to the antigen-antibody interaction. The similarities and differences between immune hemolysis and anaphylaxis in chopped guinea pig lung are considered in detail. PMID:13685194

  1. Mitochondria-Targeted Antioxidant Prevents Cardiac Dysfunction Induced by Tafazzin Gene Knockdown in Cardiac Myocytes

    PubMed Central

    He, Quan; Harris, Nicole; Ren, Jun; Han, Xianlin

    2014-01-01

    Tafazzin, a mitochondrial acyltransferase, plays an important role in cardiolipin side chain remodeling. Previous studies have shown that dysfunction of tafazzin reduces cardiolipin content, impairs mitochondrial function, and causes dilated cardiomyopathy in Barth syndrome. Reactive oxygen species (ROS) have been implicated in the development of cardiomyopathy and are also the obligated byproducts of mitochondria. We hypothesized that tafazzin knockdown increases ROS production from mitochondria, and a mitochondria-targeted antioxidant prevents tafazzin knockdown induced mitochondrial and cardiac dysfunction. We employed cardiac myocytes transduced with an adenovirus containing tafazzin shRNA as a model to investigate the effects of the mitochondrial antioxidant, mito-Tempo. Knocking down tafazzin decreased steady state levels of cardiolipin and increased mitochondrial ROS. Treatment of cardiac myocytes with mito-Tempo normalized tafazzin knockdown enhanced mitochondrial ROS production and cellular ATP decline. Mito-Tempo also significantly abrogated tafazzin knockdown induced cardiac hypertrophy, contractile dysfunction, and cell death. We conclude that mitochondria-targeted antioxidant prevents cardiac dysfunction induced by tafazzin gene knockdown in cardiac myocytes and suggest mito-Tempo as a potential therapeutic for Barth syndrome and other dilated cardiomyopathies resulting from mitochondrial oxidative stress. PMID:25247053

  2. Two functionally different Na/K pumps in cardiac ventricular myocytes

    PubMed Central

    1995-01-01

    The whole-cell patch-clamp technique was used to voltage clamp acutely isolated myocytes at -60 mV and study effects of ionic environment on Na/K pump activity. In quiescent guinea pig myocytes, normal intracellular Na+ is approximately 6 mM, which gives a total pump current of 0.25 +/- 0.09 pA/pF, and an inward background sodium current of 0.75 +/- 0.26 pA/pF. The average capacitance of a cell is 189 +/- 61 pF. Our main conclusion is the total Na/K pump current comprises currents from two different types of pumps, whose functional responses to the extracellular environment are different. Pump current was reversibly blocked with two affinities by extracellular dihydro-ouabain (DHO). We determined dissociation constants of 72 microM for low affinity (type-1) pumps and 0.75 microM for high affinity (type-h) pumps. These dissociation constants did not detectably change with two intracellular Na+ concentrations, one saturating and one near half- saturating, and with two extracellular K+ concentrations of 4.6 and 1.0 mM. Ion effects on type-h pumps were therefore measured using 5 microM DHO and on total pump current using 1 mM DHO. Extracellular K+ half- maximally activated the type-h pumps at 0.4 mM and the type-1 at 3.7 mM. Extracellular H+ blocked the type-1 pumps with half-maximal blockade at a pH of 7.71 whereas the type-h pumps were insensitive to extracellular pH. Both types of pumps responded similarly to changes in intracellular-Na+, with 9.6 mM causing half-maximal activation. Neither changes in intracellular pH between 6.0 and 7.2, nor concentrations of intracellular K+ of 140 mM or below, had any effect on either type of pump. The lack of any effect of intracellular K+ suggests the dissociation constants are in the molar range so this step in the pump cycle is not rate limiting under normal physiological conditions. Changes in intracellular-Na+ did not affect the half-maximal activation by extracellular K+, and vice versa. We found DHO-blockade of Na/K pump

  3. Functional consequences of caspase activation in cardiac myocytes

    NASA Astrophysics Data System (ADS)

    Communal, Catherine; Sumandea, Marius; de Tombe, Pieter; Narula, Jagat; Solaro, R. John; Hajjar, Roger J.

    2002-04-01

    Cardiomyocyte apoptosis is present in many cardiac disease states, including heart failure and ischemic heart disease. Apoptosis is associated with the activation of caspases that mediate the cleavage of vital and structural proteins. However, the functional contribution of apoptosis to these conditions is not known. Furthermore, in cardiac myocytes, apoptosis may not be complete, allowing the cells to persist for a prolonged period within the myocardium. Therefore, we examined whether caspase-3 cleaved cardiac myofibrillar proteins and, if so, whether it affects contractile function. The effects of caspase-3 were studied in vitro on individual components of the cardiac myofilament including -actin, -actinin, myosin heavy chain, myosin light chain 1/2, tropomyosin, cardiac troponins (T, I, C), and the trimeric troponin complex. Exposure of the myofibrillar protein (listed above) to caspase-3 for 4 h resulted in the cleavage of -actin and -actinin, but not myosin heavy chain, myosin light chain 1/2, and tropomyosin, into three fragments (30, 20, and 15 kDa) and one major fragment (45 kDa), respectively. When cTnT, cTnI, and cTnC were incubated individually with caspase-3, there was no detectable cleavage. However, when the recombinant troponin complex was exposed to caspase-3, cTnT was cleaved, resulting in fragments of 25 kDa. Furthermore, rat cardiac myofilaments exposed to caspase-3 exhibited similar patterns of myofibrillar protein cleavage. Treatment with the caspase inhibitor DEVD-CHO or z-VAD-fmk abolished the cleavage. Myofilaments, isolated from adult rat ventricular myocytes after induction of apoptotic pathway by using -adrenergic stimulation, displayed a similar pattern of actin and TnT cleavage. Exposure of skinned fiber to caspase-3 decreased maximal Ca2+-activated force and myofibrillar ATPase activity. Our results indicate that caspase-3 cleaved myofibrillar proteins, resulting in an impaired force/Ca2+ relationship and myofibrillar ATPase activity

  4. Agrin regulation of alpha3 sodium-potassium ATPase activity modulates cardiac myocyte contraction.

    PubMed

    Hilgenberg, Lutz G W; Pham, Bryan; Ortega, Maria; Walid, Saif; Kemmerly, Thomas; O'Dowd, Diane K; Smith, Martin A

    2009-06-19

    Drugs that inhibit Na,K-ATPases, such as digoxin and ouabain, alter cardiac myocyte contractility. We recently demonstrated that agrin, a protein first identified at the vertebrate neuromuscular junction, binds to and regulates the activity of alpha3 subunit-containing isoforms of the Na,K-ATPase in the mammalian brain. Both agrin and the alpha3 Na,K-ATPase are expressed in heart, but their potential for interaction and effect on cardiac myocyte function was unknown. Here we show that agrin binds to the alpha3 subunit of the Na,K-ATPase in cardiac myocyte membranes, inducing tyrosine phosphorylation and inhibiting activity of the pump. Agrin also triggers a rapid increase in cytoplasmic Na(+) in cardiac myocytes, suggesting a role in cardiac myocyte function. Consistent with this hypothesis, spontaneous contraction frequencies of cultured cardiac myocytes prepared from mice in which agrin expression is blocked by mutation of the Agrn gene are significantly higher than in the wild type. The Agrn mutant phenotype is rescued by acute treatment with recombinant agrin. Furthermore, exposure of wild type myocytes to an agrin antagonist phenocopies the Agrn mutation. These data demonstrate that the basal frequency of myocyte contraction depends on endogenous agrin-alpha3 Na,K-ATPase interaction and suggest that agrin modulation of the alpha3 Na,K-ATPase is important in regulating heart function.

  5. ErbB4 localization to cardiac myocyte nuclei, and its role in myocyte DNA damage response

    SciTech Connect

    Icli, Basak; Bharti, Ajit; Pentassuglia, Laura; Peng, Xuyang; Sawyer, Douglas B.

    2012-02-03

    Highlights: Black-Right-Pointing-Pointer ErbB4 localizes to cardiac myocyte nuclei as a full-length receptor. Black-Right-Pointing-Pointer Cardiac myocytes express predominantly JM-a/CYT-1 ErbB4. Black-Right-Pointing-Pointer Myocyte p53 activation in response to doxorubicin requires ErbB4 activity. -- Abstract: The intracellular domain of ErbB4 receptor tyrosine kinase is known to translocate to the nucleus of cells where it can regulate p53 transcriptional activity. The purpose of this study was to examine whether ErbB4 can localize to the nucleus of adult rat ventricular myocytes (ARVM), and regulate p53 in these cells. We demonstrate that ErbB4 does locate to the nucleus of cardiac myocytes as a full-length protein, although nuclear location occurs as a full-length protein that does not require Protein Kinase C or {gamma}-secretase activity. Consistent with this we found that only the non-cleavable JM-b isoform of ErbB4 is expressed in ARVM. Doxorubicin was used to examine ErbB4 role in regulation of a DNA damage response in ARVM. Doxorubicin induced p53 and p21 was suppressed by treatment with AG1478, an EGFR and ErbB4 kinase inhibitor, or suppression of ErbB4 expression with small interfering RNA. Thus ErbB4 localizes to the nucleus as a full-length protein, and plays a role in the DNA damage response induced by doxorubicin in cardiac myocytes.

  6. Biosynthesis of plasmenylcholine in guinea pig heart

    SciTech Connect

    Wientzek, M.; Choy, P.C.

    1986-05-01

    In some mammalian hearts, up to 40% of the choline phosphoglyceride (CPG) exists as plasmenylcholine (1-alkenyl-2-acyl-glycero-3-phosphocholine). Although the majority of diacylphosphatidylcholine (PC) in mammalian hearts is synthesized from choline via the CDP-choline pathway, the formation of plasmenylcholine from choline was not known. In this study, they investigated the biosynthesis of plasmenyl-choline in the isolated guinea pig heart by perfusion with (/sup 3/H)choline. Labelled choline containing metabolites and labelled plasmenylcholine were isolated and determined at different perfusion time points. Significant amounts of labelling were found only in choline, phosphocholine, CDP-choline, plasmenyl-choline and PC. In addition, a precursor-product relationship was observed between the labelling of CDP-choline and plasmenylcholine. Such a relationship was not observed between choline and plasmenylcholine. Hence, they postulate that the incorporation of choline into plasmenylcholine is via the CDP-choline pathway and not via base exchange. The ability to condense 1-alkenyl-2-acyl-glycerol with CDP-choline was also demonstrated in vitro with guinea pig heart microsomes.

  7. Ouabain uptake by endocytosis in isolated guinea pig atria

    SciTech Connect

    Nunez-Duran, H.; Riboni, L.; Ubaldo, E.; Kabela, E.; Barcenas-Ruiz, L. Instituto Nacional de Cardiologia, Mexico DF )

    1988-10-01

    Mammalian cells specifically internalize some molecular species through receptor-mediated endocytosis (RME). The authors have used four different experimental protocols to investigate whether ouabain enters cardiac cells of guinea pig atrium through this pathway. First, by electron microscope morphometry the authors found that ouabain increased endocytic vesicles in atrial cells. Second, by scintillation counting they found that ({sup 3}H)ouabain uptake by the tissue is decreased by three treatments that decrease RME, i.e., NH{sub 4}Cl, trifluoperazine, and 16 mM (K{sup +}){sub 0}. Third, by radioautography at the electron microscope level, they checked that in preceding experiments ({sup 3}H)ouabain was washed out of plasma membrane after 60-min rinse and interiorized into the cardiac cells. Fourth, isometric tension recordings showed that the positive inotropic effect of ouabain was diminished in the presence of inhibitors, whereas that of a hydrophobic analogue, ouabagenin, was not affected. These results suggest that ouabain enters cardiac cells through RME and also that an intracellular site may, at least in part, be responsible for its inotropic effect.

  8. The min K channel underlies the cardiac potassium current IKs and mediates species-specific responses to protein kinase C.

    PubMed Central

    Varnum, M D; Busch, A E; Bond, C T; Maylie, J; Adelman, J P

    1993-01-01

    A clone encoding the guinea pig (gp) min K potassium channel was isolated and expressed in Xenopus oocytes. The currents, gpIsK, exhibit many of the electrophysiological and pharmacological properties characteristic of gpIKs, the slow component of the delayed rectifier potassium conductance in guinea pig cardiac myocytes. Depolarizing commands evoke outward potassium currents that activate slowly, with time constants on the order of seconds. The currents are blocked by the class III antiarrhythmic compound clofilium but not by the sotalol derivative E4031 or low concentrations of lanthanum. Like IKs in guinea pig myocytes, gpIsK is modulated by stimulation of protein kinase A and protein kinase C (PKC). In contrast to rat and mouse IsK, which are decreased upon stimulation of PKC, myocyte IK and gpIsK in oocytes are increased after PKC stimulation. Substitution of an asparagine residue at position 102 by serine (N102S), the residue found in the analogous position of the mouse and rat min K proteins, results in decreased gpIsK in response to PKC stimulation. These results support the hypothesis that the min K protein underlies the slow component of the delayed rectifier potassium current in ventricular myocytes and account for the species-specific responses to stimulation of PKC. Images Fig. 1 PMID:8265583

  9. Experimental poisoning of guinea pig (Cavia porcellus) with Indigofera suffruticosa.

    PubMed

    Salvador, I S; Medeiros, R M T; Pessoa, C R M; Oliveira, D M; Duarte, A L A; Fighera, R A; Riet-Correa, F

    2011-05-01

    Indigofera suffruticosa causes hemolytic anemia and hemoglobinuria in cattle. The plant was administered to six groups of two guinea pigs each, at the daily dose of 10 g/kg body weight, for periods of 2, 4, 6, 8, 10 and 15 days. The guinea pigs progressively developed reduced hematocrits and hemoglobin concentrations, and finally presented anemia, without hemoglobinuria. Urine passed by guinea pigs that had ingested the plant for more than 24 h acquired a turquoise blue pigmentation 8-10 h after urination. It is suggested that the anemia is caused by the aniline contained in I. suffruticosa.

  10. Experimental poisoning of guinea pig (Cavia porcellus) with Indigofera suffruticosa.

    PubMed

    Salvador, I S; Medeiros, R M T; Pessoa, C R M; Oliveira, D M; Duarte, A L A; Fighera, R A; Riet-Correa, F

    2011-05-01

    Indigofera suffruticosa causes hemolytic anemia and hemoglobinuria in cattle. The plant was administered to six groups of two guinea pigs each, at the daily dose of 10 g/kg body weight, for periods of 2, 4, 6, 8, 10 and 15 days. The guinea pigs progressively developed reduced hematocrits and hemoglobin concentrations, and finally presented anemia, without hemoglobinuria. Urine passed by guinea pigs that had ingested the plant for more than 24 h acquired a turquoise blue pigmentation 8-10 h after urination. It is suggested that the anemia is caused by the aniline contained in I. suffruticosa. PMID:21396390

  11. Radiation-induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-01-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  12. Radiation-induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1992-11-01

    The effect of x rays on brain weight of guinea pig pups at birth was studied for 21-day old embroys exposed in utero to doses of 75 and 100 mGy. When compared to controls and when corrected for body weight, gestation time, litter size, sex, and examiner differences the brains of irradiated pups weighed approximately 46 mg less than those of controls (p<0.001) for the 75-mGy group and about 55 mg less for the 100-mGy group. Brains of females weighed 51 mg less than those of males of the same body weight. Dam weight and caging conditions had no observed effect on brain weight.

  13. 9 CFR 113.38 - Guinea pig safety test.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... observed for 7 days. (b) If unfavorable reactions attributable to the product occur in either of the guinea pigs during the observation period, the serial or subserial is unsatisfactory. If unfavorable...

  14. Verrucotoxin inhibits KATP channels in cardiac myocytes through a muscarinic M3 receptor-PKC pathway.

    PubMed

    Wang, Jian-Wu; Yazawa, Kazuto; Hao, Li-Ying; Onoue, Yoshio; Kameyama, Masaki

    2007-06-01

    Verrucotoxin is the major component of venom from the stonefish (Synanceia verrucosa). Stings from the dorsal spines of the stonefish produce intensive pain, convulsions, hypotension, paralysis, respiratory weakness and collapse of the cardiovascular system, occasionally leading to death. It has been reported that verrucotoxin might modulate ATP-sensitive K+ (KATP) current in frog atrial fibers. However, the mechanism by which verrucotoxin acts on KATP current remains unclear. In this study, we examined whether verrucotoxin inhibited KATP current in guinea pig ventricular myocytes, using the patch clamp method. Verrucotoxin suppressed KATP current induced by pinacidil (KATP channel opener) in a concentration-dependent manner, with a half maximum concentration of 16.3 microg/ml. The effect of verrucotoxin on KATP current was suppressed by atropine (1 microM), a muscarinic receptor antagonist, or by 4-diphenylacetoxy-N-methylpiperidine (100 nM), a muscarinic M3 receptor antagonist. Furthermore, the effect of verrucotoxin on KATP current was attenuated by the protein kinase C (PKC) inhibitor chelerythrine (10 microM) and calphostin C (10 microM), yet not by the cAMP-dependent protein kinase (PKA) inhibitor H-89 (0.5 microM). These results suggest that verrucotoxin inhibits KATP current through the muscarinic M3 receptor-PKC pathway. These findings enhance our understanding of the toxic effects of verrucotoxin from the stonefish. PMID:17362922

  15. Protective effect of eicosapentaenoic acid on ouabain toxicity in neonatal rat cardiac myocytes

    SciTech Connect

    Hallaq, H.; Leaf, A. ); Sellmayer, A. ); Smith, T.W. )

    1990-10-01

    Isolated neonatal cardiac myocytes have been utilized as a model for the study of cardiac arrhythmogenic factors. The myocytes respond to the toxic effects of a potent cardiac glycoside, ouabain at 0.1 mM, by an increase in their spontaneous beating rate and a reduction in amplitude of contractions resulting within minutes in a lethal state of contracture. Incubating the isolated myocytes for 3{endash}5 days in culture medium enriched with 5 {mu}M arachidonic acid had no effect on the development of lethal contracture after subsequent exposure to 0.1 mM ouabain. By contrast, incubating the myocytes for 3{endash}5 days with 5 {mu}M eicosapentaenoic acid completely prevented the toxic effects of ouabain at 0.1 mM. No differences in bumetanide-inhibitable {sup 86}Rb flux were observed between the three preparations. However, measurements with fura-2 of cytosolic free calcium levels indicated that control and arachidonic acid-enriched myocytes developed toxic cytosolic calcium concentrations of 845 {plus minus} 29 and 757 {plus minus} 64 nM, respectively, on exposure to 0.1 mM ouabain, whereas in eicosapentaenoic acid-enriched myocytes, physiologic calcium levels were preserved. Incubating the myocytes with eicosapentaenoic acid for 3{endash}5 days resulted in a small reduction of arachidonic acid and a small but significant increase of eicosapentaenoic acid in membrane phospolipids of the myocytes.

  16. Absence of pork-like insulin in guinea pig tissues.

    PubMed Central

    Eng, J; Yalow, R S

    1982-01-01

    By using a technique for concentrating insulin 100-fold from tissue extracts with 75-95% recoveries, we earlier failed to detect pork-like insulin in guinea pig tissues and thus were unable to confirm reports from the National Institutes of Health that these tissues contain a pork-like insulin at concentrations averaging 1 ng/g. This difference could have been due to differences in strains of guinea pigs studied or in the species specificities of the antisera used for radioimmunoassay. In the current study, tissue extracts from both NIH and Hartley guinea pigs were assayed with three antisera routinely used in our laboratory and one antiserum that had been used in the National Institutes of Health laboratory. We observed that pork-like insulin in tissues from both strains of guinea pigs as determined with the four antisera is less than 0.02 ng/g. We therefore conclude that is is unlikely that nonpancreatic guinea pig tissues contain or synthesize a peptide resembling pork or other non-guinea pig mammalian insulin. PMID:7045868

  17. A new assay system for guinea pig interferon biological activity.

    PubMed

    Yamamoto, Toshiko; Jeevan, Amminikutty; Ohishi, Kazue; Nojima, Yasuhiro; Umemori, Kiyoko; Yamamoto, Saburo; McMurray, David N

    2002-07-01

    We have developed an assay system for guinea pig interferon (IFN) based on reduction of viral cytopathic effect (CPE) in various cell lines. CPE inhibition was detected optimally in the guinea pig fibroblast cell line 104C1 infected with encephalomyocarditis virus (EMCV). The amount of biologically active guinea pig IFN was quantified by estimating viable cell numbers colorimetrically by means of a tetrazolium compound, 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt (WST-1) and 1-methoxy-5-methylphenazinium methylsulfate (PMS). WST-1 color developed until stopped by the addition of sulfuric acid. This had no effect on the colorimetric assay, and the color was stable for at least 24 h. The acid also inactivated the EMCV and, thus, eliminated the viral hazard. Inhibition of CPE activity was highly correlated with the concentration of culture supernatants from BCG-vaccinated guinea pig splenocytes stimulated in vitro with tuberculin or an immunostimulatory oligoDNA. This assay detected guinea pig IFN and human IFN-alpha, but not IFN-gamma from human, mouse, rat, pig, or dog. This assay system has proved useful for the titration of guinea pig IFN, being easy to perform, free from viral hazard, relatively species specific, highly reproducible, and inexpensive.

  18. Dependence of Na-K pump current on internal Na+ in mammalian cardiac myocytes.

    PubMed

    Mogul, D J; Singer, D H; Ten Eick, R E

    1990-08-01

    Na-K pump current (Ipump) is a function of the intracellular Na+ concentration [( Na+]i). We examined the quantitative relationship between Ipump and [Na+]i in isolated guinea pig ventricular myocytes under steady-state conditions. [Na+]i was controlled and "clamped" at several selected concentrations using wide-tipped pipette microelectrodes, and membrane current was measured using the whole cell patch voltage-clamp technique. Ipump generated at a holding potential of -40 mV was determined by measuring the change in steady-state holding current before and during exposure to dihydroouabain (1 mM); Ipump was measured at 11 levels of [Na+]i ranging from 0 to 80 mM (n = 63) with only one measurement per cell and normalized to cell capacitance to account for differences between myocytes in sarcolemmal surface area. Ipump exhibited a nonlinear dependence on [Na+]i; a Hill analysis of the relationship yielded a half-maximal [Na+]i for pump stimulation of 43.2 mM and a Hill coefficient of 1.53. An alternative analysis of the experimental data was performed assuming that occupation of three internal binding sites by Na+ is required for enzyme turnover. Regression analysis gave the best fit when only two different binding affinities (KD) are postulated. The values are KD1 = 1 mM, KD2 = KD3 = 29 mM. From the analysis using the latter model, the level of [Na+]i at which Ipump saturated closely approximated the theoretical saturation level calculated from published estimates of pump turnover rate and density. The maximal sensitivity of the Na-K pump to changes in [Na+]i occurs when internal [Na+] is within the range for the normal resting physiological level. PMID:2167023

  19. MicroRNA-214 protects cardiac myocytes against H2O2-induced injury.

    PubMed

    Lv, Guangwei; Shao, Suxia; Dong, Hua; Bian, Xiaohua; Yang, Xingwei; Dong, Shimin

    2014-01-01

    Reactive oxygen species (ROS)-induced cardiac myocyte injury resulting from changes in the expression levels of multiple genes plays a critical role in the pathogenesis of numerous heart diseases. The purpose of this study was to determine the potential roles of microRNA-214 (miR-214) in hydrogen peroxide (H2O2)-mediated gene regulation in cardiac myocytes. In this study, we used quantitative real-time RT-PCR (qRT-PCR) to demonstrate that miR-214 was upregulated in cardiac myocytes after treatment with H2O2. We transfected cells with pre-miR-214 to upregulate miR-214 expression and transfected cells with a miR-214 inhibitor (anti-miR-214) to downregulate miR-214 expression. H2O2-induced cardiac cell apoptosis was detected by flow cytometry. The level of apoptosis was increased by the miR-214 inhibitor and decreased by pre-miR-214. Therefore, we believe that miR-214 plays a positive role in H2O2-induced cardiac cell apoptosis. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is constitutively active and is considered to be the primary downregulator of the pro-oncogenic PI3K/Akt pathway. Western blot analysis revealed that the expression of the PTEN protein in cardiac myocytes decreased after H2O2 induction. Anti-miR-214 increased PTEN protein expression level, in contrast, pre-miR-214 decreased the PTEN protein expression level in cultured cardiac myocytes. These results indicate that PTEN is regulated by miR-214 and serves as an important target of miR-214 in cardiac myocytes. In conclusion, miR-214 is sensitive to H2O2 stimulation, and miR-214 protects cardiac myocytes against H2O2-induced injury via one of its targets, PTEN.

  20. VAMP-1, VAMP-2, and syntaxin-4 regulate ANP release from cardiac myocytes.

    PubMed

    Ferlito, Marcella; Fulton, William B; Zauher, Mohamed A; Marbán, Eduardo; Steenbergen, Charles; Lowenstein, Charles J

    2010-11-01

    ANP is a peptide released by cardiac myocytes that regulates blood pressure and natriuresis. However, the molecular mechanisms controlling ANP release from cardiac myocytes are not defined. We now identify three components of the exocytic machinery that regulate ANP release from atrial myocytes. We found that cardiac myocytes express N-ethylmaleimide sensitive factor (NSF), soluble NSF attachment protein (α-SNAP), and SNAP receptors (SNAREs). Additionally we found that specific SNARE molecules, VAMP-1 and VAMP-2, both co-sediment and co-localize with ANP. Also, one SNARE molecule, syntaxin-4, partially co-sediments and partially co-localizes with ANP. Furthermore, these three SNAREs, syntaxin-4 and VAMP-1 and VAMP-2, form a SNARE complex inside cardiac myocytes. Finally, knockdown of VAMP-1, VAMP-2, or syntaxin-4 blocks regulated release of ANP. In contrast, silencing of VAMP-3 did not have an effect on ANP release. Our data suggest that three specific SNAREs regulate cardiac myocyte exocytosis of ANP. Pathways that modify the exocytic machinery may influence natriuresis and blood pressure.

  1. VAMP-1, VAMP-2 and Syntaxin-4 Regulate ANP Release from Cardiac Myocytes

    PubMed Central

    Ferlito, Marcella; Fulton, William B.; Zauher, A. M.; Marbán, Eduardo; Steenbergen, Charles; Lowenstein, Charles J.

    2010-01-01

    ANP is a peptide released by cardiac myocytes that regulates blood pressure and natriuresis. However, the molecular mechanisms controlling ANP release from cardiac myocytes are not defined. We now identify three components of the exocytic machinery that regulate ANP release from atrial myocytes. We found that cardiac myocytes express N-ethylmaleimide sensitive factor (NSF), soluble NSF attachment protein (α-SNAP), and SNAP receptors (SNAREs). Additionally we found that specific SNARE molecules, VAMP1 and VAMP-2, both co-sediment and co-localize with ANP. Also, one SNARE molecule, syntaxin-4, partially co-sediments and partially co-localizes with ANP. Furthermore, these three SNAREs, sytntaxin-4 and VAMP-1 and VAMP-2 form a SNARE complex inside cardiac myocytes. Finally, knockdown of VAMP1, VAMP-2 or syntaxin-4 blocks regulated release of ANP. In contrast, silencing of VAMP-3 did not have an effect on ANP release. Our data suggest that three specific SNAREs regulate cardiac myocyte exocytosis of ANP. Pathways that modify the exocytic machinery may influence natriuresis and blood pressure. PMID:20801128

  2. Electrophysiological Determination of Submembrane Na(+) Concentration in Cardiac Myocytes.

    PubMed

    Hegyi, Bence; Bányász, Tamás; Shannon, Thomas R; Chen-Izu, Ye; Izu, Leighton T

    2016-09-20

    In the heart, Na(+) is a key modulator of the action potential, Ca(2+) homeostasis, energetics, and contractility. Because Na(+) currents and cotransport fluxes depend on the Na(+) concentration in the submembrane region, it is necessary to accurately estimate the submembrane Na(+) concentration ([Na(+)]sm). Current methods using Na(+)-sensitive fluorescent indicators or Na(+) -sensitive electrodes cannot measure [Na(+)]sm. However, electrophysiology methods are ideal for measuring [Na(+)]sm. In this article, we develop patch-clamp protocols and experimental conditions to determine the upper bound of [Na(+)]sm at the peak of action potential and its lower bound at the resting state. During the cardiac cycle, the value of [Na(+)]sm is constrained within these bounds. We conducted experiments in rabbit ventricular myocytes at body temperature and found that 1) at a low pacing frequency of 0.5 Hz, the upper and lower bounds converge at 9 mM, constraining the [Na(+)]sm value to ∼9 mM; 2) at 2 Hz pacing frequency, [Na(+)]sm is bounded between 9 mM at resting state and 11.5 mM; and 3) the cells can maintain [Na(+)]sm to the above values, despite changes in the pipette Na(+) concentration, showing autoregulation of Na(+) in beating cardiomyocytes. PMID:27653489

  3. Regulation of L-type calcium channel by phospholemman in cardiac myocytes.

    PubMed

    Zhang, Xue-Qian; Wang, JuFang; Song, Jianliang; Rabinowitz, Joseph; Chen, Xiongwen; Houser, Steven R; Peterson, Blaise Z; Tucker, Amy L; Feldman, Arthur M; Cheung, Joseph Y

    2015-07-01

    We evaluated whether phospholemman (PLM) regulates L-type Ca(2+) current (ICa) in mouse ventricular myocytes. Expression of α1-subunit of L-type Ca(2+) channels between wild-type (WT) and PLM knockout (KO) hearts was similar. Compared to WT myocytes, peak ICa (at -10 mV) from KO myocytes was ~41% larger, the inactivation time constant (τ(inact)) of ICa was ~39% longer, but deactivation time constant (τ(deact)) was similar. In the presence of isoproterenol (1 μM), peak ICa was ~48% larger and τ(inact) was ~144% higher in KO myocytes. With Ba(2+) as the permeant ion, PLM enhanced voltage-dependent inactivation but had no effect on τ(deact). To dissect the molecular determinants by which PLM regulated ICa, we expressed PLM mutants by adenovirus-mediated gene transfer in cultured KO myocytes. After 24h in culture, KO myocytes expressing green fluorescent protein (GFP) had significantly larger peak ICa and longer τ(inact) than KO myocytes expressing WT PLM; thereby independently confirming the observations in freshly isolated myocytes. Compared to KO myocytes expressing GFP, KO myocytes expressing the cytoplasmic domain truncation mutant (TM43), the non-phosphorylatable S68A mutant, the phosphomimetic S68E mutant, and the signature PFXYD to alanine (ALL5) mutant all resulted in lower peak ICa. Expressing PLM mutants did not alter expression of α1-subunit of L-type Ca(2+) channels in cultured KO myocytes. Our results suggested that both the extracellular PFXYD motif and the transmembrane domain of PLM but not the cytoplasmic tail were necessary for regulation of peak ICa amplitude. We conclude that PLM limits Ca(2+) influx in cardiac myocytes by reducing maximal ICa and accelerating voltage-dependent inactivation.

  4. Pharmacological characteristics of liriodenine, isolated from Fissistigma glaucescens, a novel muscarinic receptor antagonist in guinea-pigs.

    PubMed

    Lin, C H; Chang, G J; Su, M J; Wu, Y C; Teng, C M; Ko, F N

    1994-09-01

    1. The pharmacological activities of liriodenine, isolated from Fissistigma glaucescens, were determined in isolated trachea, ileum and cardiac tissues of guinea-pigs. 2. Liriodenine was found to be a muscarinic receptor antagonist in guinea-pig trachea as revealed by its competitive antagonism of carbachol (pA2 = 6.22 +/- 0.08)-induced smooth muscle contraction. It was slightly more potent than methoctramine (pA2 = 5.92 +/- 0.05), but was less potent than atropine (pA2 = 8.93 +/- 0.07), pirenzepine (pA2 = 7.02 +/- 0.09) and 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, pA2 = 8.72 +/- 0.07). 3. Liriodenine was also a muscarinic antagonist in guinea-pig ileum (pA2 = 6.36 +/- 0.10) with a pA2 value that closely resembled that obtained in the trachea. 4. Liriodenine was 10 fold less potent in atrial preparations (left atria, pA2 = 5.24 +/- 0.04; right atria, pA2 = 5.35 +/- 0.09 and 5.28 +/- 0.07 for inotropic and chronotropic effects, respectively) than in smooth muscle preparations. 5. High concentration of liriodenine (300 microM) partially depressed the contractions induced by U-46619, histamine, prostaglandin F2 alpha, neurokinin A, leukotriene C4 and high K+ in the guinea-pig trachea. The inhibitions were characterized by a rightward shift in the concentration-response curves with suppression of their maximal contraction. 6. High concentration of liriodenine (300 microM) did not affect U-46619- or neurokinin A-induced tracheal contraction in the presence of nifedipine (1 microM) or in Ca(2+)-free (containing 0.2 mM EGTA) medium. 7. Neither cyclic AMP nor cyclic GMP content of guinea-pig trachealis was changed by liriodenine (30-300 microM). 8. It is concluded that liriodenine is a selective muscarinic receptor antagonist in isolated trachea, ileum and cardiac tissues of guinea-pigs. It is more potent in smooth muscle than in cardiac preparations. It also acts as a blocker of voltage-dependent Ca2+ channels at a high concentration (300 microM).

  5. Astragalosides reduce cisplatin ototoxicity in guinea pigs.

    PubMed

    Xiong, Min; He, Qinglian; Wang, Jian; Lai, Huangwen

    2011-01-01

    Cisplatin is known to cause high-frequency neurosensory hearing loss. While reactive oxygen species have been shown to play a role, reactive nitrogen species have been implicated, but not proven to be involved, in cisplatin ototoxicity. The purpose of the present study was to investigate the role of nitric oxide (NO) in cisplatin ototoxicity by administering astragalosides, a natural antioxidant, in conjunction with cisplatin. Guinea pigs were injected with cisplatin, astragalosides or both. Auditory brainstem-evoked responses (ABRs) were measured before and 3 days after cisplatin administration. The cochlear tissue was then assayed for NO and malondialdehyde (MDA), and cochleae were also examined by scanning electron microscopy. Cisplatin alone caused significant ABR threshold shifts at all stimuli tested, whereas astragalosides alone caused no shifts. There was a significant reduction in threshold shift for clicks, 8-kHz and 16-kHz tone bursts (but not 32 kHz) when astragalosides was given with cisplatin. Both the MDA concentration and the NO concentration in the astragalosides/cisplatin group were significantly lower than those of the cisplatin group. Correspondingly, the loss of outer hair cells in the astragalosides/cisplatin group was much less than that in the cisplatin group. This suggests that astragalosides reduces cisplatin ototoxicity by its antioxidant property. PMID:21494054

  6. Radiation induced micrencephaly in guinea pigs

    SciTech Connect

    Wagner, L.K.; Johnston, D.A.; Felleman, D.J.

    1991-01-01

    A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of development is consistent with the findings of small head size induced in those exposed prior to the eight week of conception at Hiroshima. This implies a mechanism for micrencephaly different from those previously suggested and lends credence to a causal relation between radiation and small head size in humans at low doses as reported by Miller and Mulvihill. 16 refs., 13 tabs.

  7. Non-terminal blood sampling techniques in guinea pigs.

    PubMed

    Birck, Malene M; Tveden-Nyborg, Pernille; Lindblad, Maiken M; Lykkesfeldt, Jens

    2014-01-01

    Guinea pigs possess several biological similarities to humans and are validated experimental animal models(1-3). However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e.g., the saphenous and jugular veins, each technique containing both advantages and disadvantages(4,5). Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals(6). All the described methods have been thoroughly tested and applied for repeated in vivo blood sampling in studies within our research facility. PMID:25350490

  8. Non-terminal blood sampling techniques in guinea pigs.

    PubMed

    Birck, Malene M; Tveden-Nyborg, Pernille; Lindblad, Maiken M; Lykkesfeldt, Jens

    2014-01-01

    Guinea pigs possess several biological similarities to humans and are validated experimental animal models(1-3). However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e.g., the saphenous and jugular veins, each technique containing both advantages and disadvantages(4,5). Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals(6). All the described methods have been thoroughly tested and applied for repeated in vivo blood sampling in studies within our research facility.

  9. Non-Terminal Blood Sampling Techniques in Guinea Pigs

    PubMed Central

    Birck, Malene M.; Tveden-Nyborg, Pernille; Lindblad, Maiken M.; Lykkesfeldt, Jens

    2014-01-01

    Guinea pigs possess several biological similarities to humans and are validated experimental animal models1-3. However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e.g., the saphenous and jugular veins, each technique containing both advantages and disadvantages4,5. Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals6. All the described methods have been thoroughly tested and applied for repeated in vivo blood sampling in studies within our research facility. PMID:25350490

  10. Hypervitaminosis D in Guinea Pigs with α-Mannosidosis

    PubMed Central

    Jensen, JanLee A; Brice, Angela K; Bagel, Jessica H; Mexas, Angela M; Yoon, Sea Young; Wolfe, John H

    2013-01-01

    A colony of guinea pigs (n = 9) with α-mannosidosis was fed a pelleted commercial laboratory guinea pig diet. Over 2 mo, all 9 guinea pigs unexpectedly showed anorexia and weight loss (11.7% to 30.0% of baseline weight), and 3 animals demonstrated transient polyuria and polydipsia. Blood chemistry panels in these 3 guinea pigs revealed high-normal total calcium, high-normal phosphate, and high ALP. Urine specific gravity was dilute (1.003, 1.009, 1.013) in the 3 animals tested. Postmortem examination of 7 animals that were euthanized after failing to respond to supportive care revealed renal interstitial fibrosis with tubular mineralization, soft tissue mineralization in multiple organs, hepatic lipidosis, and pneumonia. Analysis of the pelleted diet revealed that it had been formulated with a vitamin D3 content of more than 150 times the normal concentration. Ionized calcium and 25-hydroxyvitamin D values were both high in serum saved from 2 euthanized animals, confirming the diagnosis of hypervitaminosis D. This report discusses the clinical signs, blood chemistry results, and gross and histologic findings of hypervitaminosis D in a colony of guinea pigs. When unexpected signs occur colony-wide, dietary differentials should be investigated at an early time point. PMID:23582422

  11. An ecologically relevant guinea pig model of fetal behavior

    PubMed Central

    Bellinger, S. A.; Lucas, D.; Kleven, G. A.

    2015-01-01

    The laboratory guinea pig, Cavia porcellus, shares with humans many similarities during pregnancy and prenatal development, including precocial offspring and social dependence. These similarities suggest the guinea pig as a promising model of fetal behavioral development as well. Using innovative methods of behavioral acclimation, fetal offspring of female IAF hairless guinea pigs time mated to NIH multi-colored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To insure that the ultrasound procedure did not cause significant stress, salivary cortisol was collected both before and after each observation. Measures of fetal spontaneous movement and behavioral state were quantified from video recordings from week 3 through the last week before birth. Results from prenatal quantification of Interlimb Movement Synchrony and state organization reveal guinea pig fetal development to be strikingly similar to that previously reported for other rodents and preterm human infants. Salivary cortisol readings taken before and after sonography did not differ at any observation time point. These results suggest this model holds translational promise for studying the prenatal mechanisms of neurobehavioral development, including those that may result from adverse events. Because the guinea pig is a highly social mammal with a wide range of socially oriented vocalizations, this model may also have utility for studying the prenatal origins and trajectories of developmental disabilities with social-emotional components, such as autism. PMID:25655512

  12. Severe gastritis in guinea-pigs infected with Helicobacter pylori.

    PubMed

    Sturegård, E; Sjunnesson, H; Ho, B; Willén, R; Aleljung, P; Ng, H C; Wadström, T

    1998-12-01

    An appropriate animal model is essential to study Helicobacter pylori infection. The aim of this study was to investigate if H. pylori can colonise the guinea-pig stomach and whether the infection causes gastritis and a serological response similar to that observed in man. Guinea-pigs were infected either with fresh H. pylori isolates from human gastric biopsies or with a guinea-pig passaged strain. When the animals were killed, 3 and 7 weeks after inoculation, samples were taken for culture, histopathology and serology. H. pylori was cultured from 22 of 29 challenged animals. All culture-positive animals exhibited a specific immune response against H. pylori antigens in Western blotting and gastritis in histopathological examination. Antibody titres in enzyme immunoassay were elevated among animals challenged with H. pylori. The inflammatory response was graded as severe in most animals and consisted of both polymorphonuclear leucocytes and lymphocytes. Erosion of the gastric epithelium was found in infected animals. These results suggest that the guinea-pig is suitable for studying H. pylori-associated diseases. Moreover, guinea-pigs are probably more similar to man than any other small laboratory animal as regards gastric anatomy and physiology.

  13. An ecologically relevant guinea pig model of fetal behavior.

    PubMed

    Bellinger, S A; Lucas, D; Kleven, G A

    2015-04-15

    The laboratory guinea pig, Cavia porcellus, shares with humans many similarities during pregnancy and prenatal development, including precocial offspring and social dependence. These similarities suggest the guinea pig as a promising model of fetal behavioral development as well. Using innovative methods of behavioral acclimation, fetal offspring of female IAF hairless guinea pigs time mated to NIH multicolored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To ensure that the ultrasound procedure did not cause significant stress, salivary cortisol was collected both before and after each observation. Measures of fetal spontaneous movement and behavioral state were quantified from video recordings from week 3 through the last week before birth. Results from prenatal quantification of Interlimb Movement Synchrony and state organization reveal guinea pig fetal development to be strikingly similar to that previously reported for other rodents and preterm human infants. Salivary cortisol readings taken before and after sonography did not differ at any observation time point. These results suggest this model holds translational promise for studying the prenatal mechanisms of neurobehavioral development, including those that may result from adverse events. Because the guinea pig is a highly social mammal with a wide range of socially oriented vocalizations, this model may also have utility for studying the prenatal origins and trajectories of developmental disabilities with social-emotional components, such as autism. PMID:25655512

  14. An ecologically relevant guinea pig model of fetal behavior.

    PubMed

    Bellinger, S A; Lucas, D; Kleven, G A

    2015-04-15

    The laboratory guinea pig, Cavia porcellus, shares with humans many similarities during pregnancy and prenatal development, including precocial offspring and social dependence. These similarities suggest the guinea pig as a promising model of fetal behavioral development as well. Using innovative methods of behavioral acclimation, fetal offspring of female IAF hairless guinea pigs time mated to NIH multicolored Hartley males were observed longitudinally without restraint using noninvasive ultrasound at weekly intervals across the 10 week gestation. To ensure that the ultrasound procedure did not cause significant stress, salivary cortisol was collected both before and after each observation. Measures of fetal spontaneous movement and behavioral state were quantified from video recordings from week 3 through the last week before birth. Results from prenatal quantification of Interlimb Movement Synchrony and state organization reveal guinea pig fetal development to be strikingly similar to that previously reported for other rodents and preterm human infants. Salivary cortisol readings taken before and after sonography did not differ at any observation time point. These results suggest this model holds translational promise for studying the prenatal mechanisms of neurobehavioral development, including those that may result from adverse events. Because the guinea pig is a highly social mammal with a wide range of socially oriented vocalizations, this model may also have utility for studying the prenatal origins and trajectories of developmental disabilities with social-emotional components, such as autism.

  15. Physiological changes induced in cardiac myocytes by cytotoxic T lymphocytes

    SciTech Connect

    Hassin, D.; Fixler, R.; Shimoni, Y.; Rubinstein, E.; Raz, S.; Gotsman, M.S.; Hasin, Y.

    1987-01-01

    The lethal hit induced by viral specific, sensitized, cytotoxic T lymphocytes (CTL) attacking virus-infected heart cells is important in the pathogenesis of viral myocarditis and reflects the key role of CTL in this immune response. The mechanisms involved are incompletely understood. Studies of the physiological changes induced in mengovirus-infected, cultured, neonatal, rat heart cells by CTL that had been previously sensitized by the same virus are presented. The CTL were obtained from spleens of mengovirus-infected, major histocompatibility complex (MHC) matched adult rats. Cell wall motion was measured by an optical method, action potentials with intracellular microelectrodes, and total exchangeable calcium content by /sup 45/Ca tracer measurements after loading the myocytes with /sup 45/Ca and then exposing them to CTL. After 50 min (mean time) of exposing mengovirus-infected myocytes to the CTL, the mechanical relaxation of the myocyte was slowed, with a subsequent slowing of beating rate and a reduced amplitude of contraction. Impaired relaxation progressed, and prolonged oscillatory contractions lasting up to several seconds appeared, with accompanying oscillations in the prolonged plateau phase of the action potentials. Arrest of the myocyte contractions appeared 98 min (mean time) after exposure to CTL. It is concluded that infection of cultured myocytes with mengovirus predisposes them to attack by mengovirus specific CTL, and that persistent dysfunction of the myocyte is preceded by reversible changes in membrane potential and contraction. This is suggestive of an altered calcium handling by the myocytes possibly resulting in the cytotoxic effect.

  16. Use of a Guinea pig-specific transcriptome array for evaluation of protective immunity against genital chlamydial infection following intranasal vaccination in Guinea pigs.

    PubMed

    Wali, Shradha; Gupta, Rishein; Veselenak, Ronald L; Li, Yansong; Yu, Jieh-Juen; Murthy, Ashlesh K; Cap, Andrew P; Guentzel, M Neal; Chambers, James P; Zhong, Guangming; Rank, Roger G; Pyles, Richard B; Arulanandam, Bernard P

    2014-01-01

    Guinea pigs have been used as a second animal model to validate putative anti-chlamydial vaccine candidates tested in mice. However, the lack of guinea pig-specific reagents has limited the utility of this animal model in Chlamydia sp. vaccine studies. Using a novel guinea pig-specific transcriptome array, we determined correlates of protection in guinea pigs vaccinated with Chlamydia caviae (C. caviae) via the intranasal route, previously reported by us and others to provide robust antigen specific immunity against subsequent intravaginal challenge. C. caviae vaccinated guinea pigs resolved genital infection by day 3 post challenge. In contrast, mock vaccinated animals continued to shed viable Chlamydia up to day 18 post challenge. Importantly, at day 80 post challenge, vaccinated guinea pigs experienced significantly reduced genital pathology - a sequelae of genital chlamydial infections, in comparison to mock vaccinated guinea pigs. Sera from vaccinated guinea pigs displayed antigen specific IgG responses and increased IgG1 and IgG2 titers capable of neutralizing GPIC in vitro. Th1-cellular/inflammatory immune genes and Th2-humoral associated genes were also found to be elevated in vaccinated guinea pigs at day 3 post-challenge and correlated with early clearance of the bacterium. Overall, this study provides the first evidence of guinea pig-specific genes involved in anti-chlamydial vaccination and illustrates the enhancement of the utility of this animal model in chlamydial pathogenesis.

  17. Use of a Guinea Pig-Specific Transcriptome Array for Evaluation of Protective Immunity against Genital Chlamydial Infection following Intranasal Vaccination in Guinea Pigs

    PubMed Central

    Veselenak, Ronald L.; Li, Yansong; Yu, Jieh-Juen; Murthy, Ashlesh K.; Cap, Andrew P.; Guentzel, M. Neal; Chambers, James P.; Zhong, Guangming; Rank, Roger G.; Pyles, Richard B.; Arulanandam, Bernard P.

    2014-01-01

    Guinea pigs have been used as a second animal model to validate putative anti-chlamydial vaccine candidates tested in mice. However, the lack of guinea pig-specific reagents has limited the utility of this animal model in Chlamydia sp. vaccine studies. Using a novel guinea pig-specific transcriptome array, we determined correlates of protection in guinea pigs vaccinated with Chlamydia caviae (C. caviae) via the intranasal route, previously reported by us and others to provide robust antigen specific immunity against subsequent intravaginal challenge. C. caviae vaccinated guinea pigs resolved genital infection by day 3 post challenge. In contrast, mock vaccinated animals continued to shed viable Chlamydia up to day 18 post challenge. Importantly, at day 80 post challenge, vaccinated guinea pigs experienced significantly reduced genital pathology - a sequelae of genital chlamydial infections, in comparison to mock vaccinated guinea pigs. Sera from vaccinated guinea pigs displayed antigen specific IgG responses and increased IgG1 and IgG2 titers capable of neutralizing GPIC in vitro. Th1-cellular/inflammatory immune genes and Th2-humoral associated genes were also found to be elevated in vaccinated guinea pigs at day 3 post-challenge and correlated with early clearance of the bacterium. Overall, this study provides the first evidence of guinea pig-specific genes involved in anti-chlamydial vaccination and illustrates the enhancement of the utility of this animal model in chlamydial pathogenesis. PMID:25502875

  18. 9 CFR 3.36 - Primary enclosures used to transport live guinea pigs and hamsters.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... live guinea pigs and hamsters. 3.36 Section 3.36 Animals and Animal Products ANIMAL AND PLANT HEALTH..., Care, Treatment, and Transportation of Guinea Pigs and Hamsters Transportation Standards § 3.36 Primary enclosures used to transport live guinea pigs and hamsters. No person subject to the Animal...

  19. 9 CFR 3.36 - Primary enclosures used to transport live guinea pigs and hamsters.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... live guinea pigs and hamsters. 3.36 Section 3.36 Animals and Animal Products ANIMAL AND PLANT HEALTH..., Care, Treatment, and Transportation of Guinea Pigs and Hamsters Transportation Standards § 3.36 Primary enclosures used to transport live guinea pigs and hamsters. No person subject to the Animal...

  20. 9 CFR 3.36 - Primary enclosures used to transport live guinea pigs and hamsters.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... live guinea pigs and hamsters. 3.36 Section 3.36 Animals and Animal Products ANIMAL AND PLANT HEALTH..., Care, Treatment, and Transportation of Guinea Pigs and Hamsters Transportation Standards § 3.36 Primary enclosures used to transport live guinea pigs and hamsters. No person subject to the Animal...

  1. Novel Protective Role of Endogenous Cardiac Myocyte P2X4 Receptors in Heart Failure

    PubMed Central

    Yang, Tiehong; Shen, Jian-bing; Yang, Ronghua; Redden, John; Dodge-Kafka, Kimberly; Grady, James; Jacobson, Kenneth A.; Liang, Bruce T.

    2014-01-01

    Background Heart failure (HF), despite continuing progress, remains a leading cause of mortality and morbidity. P2X4 receptors (P2X4R) have emerged as potentially important molecules in regulating cardiac function and as potential targets for HF therapy. Transgenic P2X4R overexpression can protect against HF, but this does not explain the role of native cardiac P2X4R. Our goal is to define the physiological role of endogenous cardiac myocyte P2X4R under basal conditions and during HF induced by myocardial infarction or pressure overload. Methods and Results Mice established with conditional cardiac-specific P2X4R knockout were subjected to left anterior descending coronary artery ligation–induced postinfarct or transverse aorta constriction–induced pressure overload HF. Knockout cardiac myocytes did not show P2X4R by immunoblotting or by any response to the P2X4R-specific allosteric enhancer ivermectin. Knockout hearts showed normal basal cardiac function but depressed contractile performance in postinfarct and pressure overload models of HF by in vivo echocardiography and ex vivo isolated working heart parameters. P2X4R coimmunoprecipitated and colocalized with nitric oxide synthase 3 (eNOS) in wild-type cardiac myocytes. Mice with cardiac-specific P2X4R overexpression had increased S-nitrosylation, cyclic GMP, NO formation, and were protected from postinfarct and pressure overload HF. Inhibitor of eNOS, L-N5-(1-iminoethyl)ornithine hydrochloride, blocked the salutary effect of cardiac P2X4R overexpression in postinfarct and pressure overload HF as did eNOS knockout. Conclusions This study establishes a new protective role for endogenous cardiac myocyte P2X4R in HF and is the first to demonstrate a physical interaction between the myocyte receptor and eNOS, a mediator of HF protection. PMID:24622244

  2. Somatostatin in the human heart and comparison with guinea pig and rat heart.

    PubMed Central

    Day, S M; Gu, J; Polak, J M; Bloom, S R

    1985-01-01

    Somatostatin has been shown to have negative inotropic and chronotopic effects and to restore sinus rhythm in some cases of cardiac arrhythmia. Using acid extracts, regions of human heart were examined by radioimmunoassay to determine their somatostatin content. Mean (SD) concentrations of 4.1 (0.8) pmol/g and 2.9 (0.8) pmol/g were found in atrioventricular node and right atria respectively and were significantly higher than in other heart regions. Using fresh heart tissue from guinea pigs, somatostatin was localised to cardiac nerves by immunocytochemistry. Nerves containing somatostatin were most abundant in the atria, where the concentrations measured by radioimmunoassay were 7.6 (1.0) and 2.6 (0.4) pmol/g for right and left atria respectively. Somatostatin contained in cardiac nerves may have a physiological role in the cardiac conduction system. Images PMID:2857086

  3. Parainfluenza 3-Induced Cough Hypersensitivity in the Guinea Pig Airways.

    PubMed

    Zaccone, Eric J; Lieu, TinaMarie; Muroi, Yukiko; Potenzieri, Carl; Undem, Blair E; Gao, Peisong; Han, Liang; Canning, Brendan J; Undem, Bradley J

    2016-01-01

    The effect of respiratory tract viral infection on evoked cough in guinea pigs was evaluated. Guinea pigs were inoculated intranasally with either parainfluenza type 3 (PIV3) and cough was quantified in conscious animals. The guinea pigs infected with PIV3 (day 4) coughed nearly three times more than those treated with the viral growth medium in response to capsaicin, citric acid, and bradykinin. Since capsaicin, citric acid, and bradykinin evoked coughing in guinea pigs can be inhibited by drugs that antagonize the transient receptor potential cation channel, subfamily V, member 1 (TRPV1), it was reasoned that the virally-induced hypertussive state may involve alterations in TPRV1 activity. PIV3 infection caused a phenotypic switch in tracheal nodose Aδ "cough receptors" such that nearly 50% of neurons began to express, de novo, TRPV1 mRNA. There was also an increase TRPV1 expression in jugular C-fiber neurons as determined by qPCR. It has previously been reported that tracheal-specific nodose neurons express the BDNF receptor TrkB and jugular neurons express the NGF receptor TrkA. Jugular neurons also express the artemin receptor GFRα3. All these neurotrophic factors have been associated with increases in TRPV1 expression. In an ex vivo perfused guinea pig tracheal preparation, we demonstrated that within 8 h of PIV3 infusion there was no change in NGF mRNA expression, but there was nearly a 10-fold increase in BDNF mRNA in the tissue, and a small but significant elevation in the expression of artemin mRNA. In summary, PIV3 infection leads to elevations in TRPV1 expression in the two key cough evoking nerve subtypes in the guinea pig trachea, and this is associated with a hypertussive state with respect to various TRPV1 activating stimuli. PMID:27213574

  4. Parainfluenza 3-Induced Cough Hypersensitivity in the Guinea Pig Airways

    PubMed Central

    Lieu, TinaMarie; Muroi, Yukiko; Potenzieri, Carl; Undem, Blair E.; Gao, Peisong; Han, Liang; Canning, Brendan J.

    2016-01-01

    The effect of respiratory tract viral infection on evoked cough in guinea pigs was evaluated. Guinea pigs were inoculated intranasally with either parainfluenza type 3 (PIV3) and cough was quantified in conscious animals. The guinea pigs infected with PIV3 (day 4) coughed nearly three times more than those treated with the viral growth medium in response to capsaicin, citric acid, and bradykinin. Since capsaicin, citric acid, and bradykinin evoked coughing in guinea pigs can be inhibited by drugs that antagonize the transient receptor potential cation channel, subfamily V, member 1 (TRPV1), it was reasoned that the virally-induced hypertussive state may involve alterations in TPRV1 activity. PIV3 infection caused a phenotypic switch in tracheal nodose Aδ “cough receptors” such that nearly 50% of neurons began to express, de novo, TRPV1 mRNA. There was also an increase TRPV1 expression in jugular C-fiber neurons as determined by qPCR. It has previously been reported that tracheal-specific nodose neurons express the BDNF receptor TrkB and jugular neurons express the NGF receptor TrkA. Jugular neurons also express the artemin receptor GFRα3. All these neurotrophic factors have been associated with increases in TRPV1 expression. In an ex vivo perfused guinea pig tracheal preparation, we demonstrated that within 8 h of PIV3 infusion there was no change in NGF mRNA expression, but there was nearly a 10-fold increase in BDNF mRNA in the tissue, and a small but significant elevation in the expression of artemin mRNA. In summary, PIV3 infection leads to elevations in TRPV1 expression in the two key cough evoking nerve subtypes in the guinea pig trachea, and this is associated with a hypertussive state with respect to various TRPV1 activating stimuli. PMID:27213574

  5. Parainfluenza 3-Induced Cough Hypersensitivity in the Guinea Pig Airways.

    PubMed

    Zaccone, Eric J; Lieu, TinaMarie; Muroi, Yukiko; Potenzieri, Carl; Undem, Blair E; Gao, Peisong; Han, Liang; Canning, Brendan J; Undem, Bradley J

    2016-01-01

    The effect of respiratory tract viral infection on evoked cough in guinea pigs was evaluated. Guinea pigs were inoculated intranasally with either parainfluenza type 3 (PIV3) and cough was quantified in conscious animals. The guinea pigs infected with PIV3 (day 4) coughed nearly three times more than those treated with the viral growth medium in response to capsaicin, citric acid, and bradykinin. Since capsaicin, citric acid, and bradykinin evoked coughing in guinea pigs can be inhibited by drugs that antagonize the transient receptor potential cation channel, subfamily V, member 1 (TRPV1), it was reasoned that the virally-induced hypertussive state may involve alterations in TPRV1 activity. PIV3 infection caused a phenotypic switch in tracheal nodose Aδ "cough receptors" such that nearly 50% of neurons began to express, de novo, TRPV1 mRNA. There was also an increase TRPV1 expression in jugular C-fiber neurons as determined by qPCR. It has previously been reported that tracheal-specific nodose neurons express the BDNF receptor TrkB and jugular neurons express the NGF receptor TrkA. Jugular neurons also express the artemin receptor GFRα3. All these neurotrophic factors have been associated with increases in TRPV1 expression. In an ex vivo perfused guinea pig tracheal preparation, we demonstrated that within 8 h of PIV3 infusion there was no change in NGF mRNA expression, but there was nearly a 10-fold increase in BDNF mRNA in the tissue, and a small but significant elevation in the expression of artemin mRNA. In summary, PIV3 infection leads to elevations in TRPV1 expression in the two key cough evoking nerve subtypes in the guinea pig trachea, and this is associated with a hypertussive state with respect to various TRPV1 activating stimuli.

  6. Numerical Simulations of Calcium Ions Spiral Wave in Single Cardiac Myocyte

    NASA Astrophysics Data System (ADS)

    Bai, Yong-Qiang; Zhu, Xing

    2010-04-01

    The calcium ions (Ca2+) spark is an elementary Ca2+ release event in cardiac myocytes. It is believed to buildup cell-wide Ca2+ signals, such as Ca2+ transient and Ca2+ wave, through a Ca2+-induced Ca2+ release (CICR) mechanism. Here the excitability of the Ca2+ wave in a single cardiac myocyte is simulated by employing the fire-diffuse-fire model. By modulating the dynamic parameters of Ca2+ release and re-uptake channels, we find three Ca2+ signaling states in a single cardiac myocyte: no wave, plane wave, and spiral wave. The period of a spiral wave is variable in the different regimes. This study indicates that the spiral wave or the excitability of the system can be controlled through micro-modulation in a living excitable medium.

  7. DOCA-salts induce heart failure in the guinea pig.

    PubMed

    Tiritilli, A

    2001-10-01

    Heart failure (HF) is a common clinical problem confronting physicians and is often the final manifestation of many cardiovascular disorders. Despite recent advances in the pharmacological management of HF, it remains a highly lethal and disabling disorder. A number of animal models have been developed to study both the pathophysiology of HF and new therapeutic approaches to this complex syndrome. Only through an improved understanding of the basic biology of the early stages of the syndrome can HF be prevented or at least anticipated. With this in view, we have developed an easily realisable and inexpensive model in the guinea pig, which presents numerous structural, metabolic and biochemical similarities compared with the human heart. Thirty guinea pigs, aged 5 weeks and weighing 300 g were used. After anaesthesia, left nephrectomy was performed. After 1 week the guinea pigs were divided into: (a) control group (n=15), which received an injection of vehicle as well as tap water for 10 weeks; (b) DOCA-salts group (n=15), where the animals were treated with an IM injection of 10 mg DOCA 5 days a week for 10 weeks and with drinking water containing 9 g/l(-1) NaCl and 2 g/l(-1) KCl. Our results demonstrate that the administration of DOCA-salts to guinea pigs for 10 weeks caused a significant increase in blood pressure (BP+30%) associated with left ventricular hypertrophy (LVH), evaluated by LV weight (+37%), LV wall (+36%), by the ratio LV weight/Body weight (+23%) and by an increase in LV volume (+51%). Concerning HF, the latter was clinically evident through an increase in body weight, heart rate and dyspnoea. Indeed, guinea pigs presented pleural and/or pericardial effusion often associated with ascite. This model, which combines pressure and volume overload, results in a slow evolution towards HF. This allows a better understanding of the mechanisms in early LV remodelling which has the potential to develop into HF. Some recent studies have emphasised the value

  8. Chronic intermittent hypobaric hypoxia protects the heart against ischemia/reperfusion injury through upregulation of antioxidant enzymes in adult guinea pigs

    PubMed Central

    Guo, Hui-cai; Zhang, Zhe; Zhang, Li-nan; Xiong, Chen; Feng, Chen; Liu, Qian; Liu, Xu; Shi, Xiao-lu; Wang, Yong-li

    2009-01-01

    Aim: To investigate the protection and the anti-oxidative mechanism afforded by chronic intermittent hypobaric hypoxia (CIHH) against ischemia/reperfusion (I/R) injury in guinea pig hearts. Methods: Adult male guinea pigs were exposed to CIHH by mimicking a 5000 m high altitude (pB=404 mmHg, pO2=84 mmHg) in a hypobaric chamber for 6 h/day for 28 days. Langendorff-perfused isolated guinea pig hearts were used to measure variables of left ventricular function during baseline perfusion, ischemia and the reperfusion period. The activity and protein expression of antioxidant enzymes in the left myocardium were evaluated using biochemical methods and Western blotting, respectively. Intracellular reactive oxygen species (ROS) were assessed using ROS-sensitive fluorescence. Results: After 30 min of global no-flow ischemia followed by 60 min of reperfusion, myocardial function had better recovery rates in CIHH guinea pig hearts than in control hearts. The activity and protein expression of superoxide dismutase (SOD) and catalase (CAT) were significantly increased in the myocardium of CIHH guinea pigs. Pretreatment of control hearts with an antioxidant mixture containing SOD and CAT exerted cardioprotective effects similar to CIHH. The irreversible CAT inhibitor aminotriazole (ATZ) abolished the cardioprotection of CIHH. Cardiac contractile dysfunction and oxidative stress induced by exogenous hydrogen peroxide (H2O2) were attenuated by CIHH and CAT. Conclusions: These data suggest that CIHH protects the heart against I/R injury through upregulation of antioxidant enzymes in guinea pig. PMID:19543301

  9. Organophosphorus Pesticides Decrease M2 Muscarinic Receptor Function in Guinea Pig Airway Nerves via Indirect Mechanisms

    PubMed Central

    Proskocil, Becky J.; Bruun, Donald A.; Thompson, Charles M.; Fryer, Allison D.; Lein, Pamela J.

    2010-01-01

    Background Epidemiological studies link organophosphorus pesticide (OP) exposures to asthma, and we have shown that the OPs chlorpyrifos, diazinon and parathion cause airway hyperreactivity in guinea pigs 24 hr after a single subcutaneous injection. OP-induced airway hyperreactivity involves M2 muscarinic receptor dysfunction on airway nerves independent of acetylcholinesterase (AChE) inhibition, but how OPs inhibit neuronal M2 receptors in airways is not known. In the central nervous system, OPs interact directly with neurons to alter muscarinic receptor function or expression; therefore, in this study we tested whether the OP parathion or its oxon metabolite, paraoxon, might decrease M2 receptor function on peripheral neurons via similar direct mechanisms. Methodology/Principal Findings Intravenous administration of paraoxon, but not parathion, caused acute frequency-dependent potentiation of vagally-induced bronchoconstriction and increased electrical field stimulation (EFS)-induced contractions in isolated trachea independent of AChE inhibition. However, paraoxon had no effect on vagally-induced bradycardia in intact guinea pigs or EFS-induced contractions in isolated ileum, suggesting mechanisms other than pharmacologic antagonism of M2 receptors. Paraoxon did not alter M2 receptor expression in cultured cells at the mRNA or protein level as determined by quantitative RT-PCR and radio-ligand binding assays, respectively. Additionally, a biotin-labeled fluorophosphonate, which was used as a probe to identify molecular targets phosphorylated by OPs, did not phosphorylate proteins in guinea pig cardiac membranes that were recognized by M2 receptor antibodies. Conclusions/Significance These data indicate that neither direct pharmacologic antagonism nor downregulated expression of M2 receptors contributes to OP inhibition of M2 function in airway nerves, adding to the growing evidence of non-cholinergic mechanisms of OP neurotoxicity. PMID:20479945

  10. Pharmacometabolomic approach to predict QT prolongation in guinea pigs.

    PubMed

    Park, Jeonghyeon; Noh, Keumhan; Lee, Hae Won; Lim, Mi-sun; Seong, Sook Jin; Seo, Jeong Ju; Kim, Eun-Jung; Kang, Wonku; Yoon, Young-Ran

    2013-01-01

    Drug-induced torsades de pointes (TdP), a life-threatening arrhythmia associated with prolongation of the QT interval, has been a significant reason for withdrawal of several medicines from the market. Prolongation of the QT interval is considered as the best biomarker for predicting the torsadogenic risk of a new chemical entity. Because of the difficulty assessing the risk for TdP during drug development, we evaluated the metabolic phenotype for predicting QT prolongation induced by sparfloxacin, and elucidated the metabolic pathway related to the QT prolongation. We performed electrocardiography analysis and liquid chromatography-mass spectroscopy-based metabolic profiling of plasma samples obtained from 15 guinea pigs after administration of sparfloxacin at doses of 33.3, 100, and 300 mg/kg. Principal component analysis and partial least squares modelling were conducted to select the metabolites that substantially contributed to the prediction of QT prolongation. QTc increased significantly with increasing dose (r = 0.93). From the PLS analysis, the key metabolites that showed the highest variable importance in the projection values (>1.5) were selected, identified, and used to determine the metabolic network. In particular, cytidine-5'-diphosphate (CDP), deoxycorticosterone, L-aspartic acid and stearic acid were found to be final metabolomic phenotypes for the prediction of QT prolongation. Metabolomic phenotypes for predicting drug-induced QT prolongation of sparfloxacin were developed and can be applied to cardiac toxicity screening of other drugs. In addition, this integrative pharmacometabolomic approach would serve as a good tool for predicting pharmacodynamic or toxicological effects caused by changes in dose.

  11. Interleukin 1 and Tumor Necrosis Factor Inhibit Cardiac Myocyte β -adrenergic Responsiveness

    NASA Astrophysics Data System (ADS)

    Gulick, Tod; Chung, Mina K.; Pieper, Stephen J.; Lange, Louis G.; Schreiner, George F.

    1989-09-01

    Reversible congestive heart failure can accompany cardiac allograft rejection and inflammatory myocarditis, conditions associated with an immune cell infiltrate of the myocardium. To determine whether immune cell secretory products alter cardiac muscle metabolism without cytotoxicity, we cultured cardiac myocytes in the presence of culture supernatants from activated immune cells. We observed that these culture supernatants inhibit β -adrenergic agonist-mediated increases in cultured cardiac myocyte contractility and intracellular cAMP accumulation. The myocyte contractile response to increased extracellular Ca2+ concentration is unaltered by prior exposure to these culture supernatants, as is the increase in myocyte intracellular cAMP concentration in response to stimulation with forskolin, a direct adenyl cyclase activator. Inhibition occurs in the absence of alteration in β -adrenergic receptor density or ligand binding affinity. Suppressive activity is attributable to the macrophage-derived cytokines interleukin 1 and tumor necrosis factor. Thus, these observations describe a role for defined cytokines in regulating the hormonal responsiveness and function of contractile cells. The effects of interleukin 1 and tumor necrosis factor on intracellular cAMP accumulation may be a model for immune modulation of other cellular functions dependent upon cyclic nucleotide metabolism. The uncoupling of agonist-occupied receptors from adenyl cyclase suggests that β -receptor or guanine nucleotide binding protein function is altered by the direct or indirect action of cytokines on cardiac muscle cells.

  12. Guinea pig ductus arteriosus. II - Irreversible closure after birth.

    NASA Technical Reports Server (NTRS)

    Fay, F. S.; Cooke, P. H.

    1972-01-01

    To investigate the mechanism underlying irreversibility of ductal closure after birth, studies were undertaken to determine the exact time course for the onset of irreversible closure of the guinea pig ductus arteriosus. Parallel studies of the reactivity of ductal smooth muscle to oxygen and studies of the postpartum cellular changes within the vessel were also carried out.

  13. Measurement of cochlear acoustic pressure in guinea pigs

    NASA Astrophysics Data System (ADS)

    Franke, R.; Dancer, A.

    1983-10-01

    Guinea pig cochlear acoustic pressure was measured in the 3 to 200 Hz range. The cochlear microphonic potential was recorded. The experimental results agree with the Peterson and Bogert model. The pressure transducers and the calibrating device are confirmed to be excellent tools for this type of research.

  14. Plague in Guinea pigs and its prevention by subunit vaccines.

    PubMed

    Quenee, Lauriane E; Ciletti, Nancy; Berube, Bryan; Krausz, Thomas; Elli, Derek; Hermanas, Timothy; Schneewind, Olaf

    2011-04-01

    Human pneumonic plague is a devastating and transmissible disease for which a Food and Drug Administration-approved vaccine is not available. Suitable animal models may be adopted as a surrogate for human plague to fulfill regulatory requirements for vaccine efficacy testing. To develop an alternative to pneumonic plague in nonhuman primates, we explored guinea pigs as a model system. On intranasal instillation of a fully virulent strain, Yersinia pestis CO92, guinea pigs developed lethal lung infections with hemorrhagic necrosis, massive bacterial replication in the respiratory system, and blood-borne dissemination to other organ systems. Expression of the Y. pestis F1 capsule was not required for the development of pulmonary infection; however, the capsule seemed to be important for the establishment of bubonic plague. The mean lethal dose (MLD) for pneumonic plague in guinea pigs was estimated to be 1000 colony-forming units. Immunization of guinea pigs with the recombinant forms of LcrV, a protein that resides at the tip of Yersinia type III secretion needles, or F1 capsule generated robust humoral immune responses. Whereas LcrV immunization resulted in partial protection against pneumonic plague challenge with 250 MLD Y. pestis CO92, immunization with recombinant F1 did not. rV10, a vaccine variant lacking LcrV residues 271-300, elicited protection against pneumonic plague, which seemed to be based on conformational antibodies directed against LcrV.

  15. Survey of endoparasites in pet guinea pigs in Italy.

    PubMed

    d'Ovidio, Dario; Noviello, Emilio; Ianniello, Davide; Cringoli, Giuseppe; Rinaldi, Laura

    2015-03-01

    Little information is available on the occurrence of endoparasites in pet guinea pigs (Cavia porcellus). The purpose of this study was to evaluate the prevalence of intestinal parasites in cavies kept as pets in southern Italy. Fresh fecal samples were randomly collected from 60 guinea pigs housed in pet shops or privately owned. All fecal samples were processed using the FLOTAC pellet technique to identify and count helminthic eggs/larvae and protozoan cysts/oocysts. In addition, the specimens were analyzed also by the Remel Xpect® Giardia/Cryptosporidium immunoassay. Intestinal parasites were detected in 19 out of 60 guinea pigs (31.7 %). Paraspidodera uncinata eggs were found in 13.3 % (8/60) of the rodents examined, Nippostrongylus-like eggs in 10 % (6/60), and finally Eimeria caviae oocysts were found in 10 % (6/60) of the animals. In one case, both E. caviae oocysts and P. uncinata eggs were found. None of the samples was positive for Cryptosporidium or Giardia. To the authors' knowledge, this is the first survey of endoparasites in pet guinea pigs in Italy.

  16. Reflections on the Fiftieth Reunion of the Guinea Pigs.

    ERIC Educational Resources Information Center

    Loud, Oliver

    1988-01-01

    A member of the original faculty of the experimental Ohio State University Laboratory High School reflects at a fiftieth reunion of the first graduating class. Students were used as guinea pigs to determine the effects of providing teenagers with liberating, interesting, and customized education from university faculty. (SM)

  17. Improved Method for Culturing Guinea-Pig Macrophage Cells

    NASA Technical Reports Server (NTRS)

    Savage, J.

    1982-01-01

    Proper nutrients and periodic changes in culture medium maintain cell viability for a longer period. New method uses a thioglycolate solution, instead of mineral oil, to induce macrophage cells in guinea pigs and also uses an increased percent of fetal-calf bovine serum in cultivation medium. Macrophage cells play significant roles in the body's healing and defense systems.

  18. Carbon fiber technique for the investigation of single-cell mechanics in intact cardiac myocytes.

    PubMed

    Sugiura, Seiryo; Nishimura, Satoshi; Yasuda, Soichiro; Hosoya, Yumiko; Katoh, Kaoru

    2006-01-01

    This protocol describes a method for attaching single isolated cardiac myocytes to carbon fibers for mechanical manipulation and measurement. This method relies on cell-adhesive carbon fibers that attach easily to the cell membrane without causing damage, and is thus applicable to intact myocytes. To connect the carbon fiber to micromanipulators, a fiber holder with glass capillaries must first be fabricated. After connection of the fibers to the micromanipulators, firm attachment is easily established by gently pressing the fiber tip onto the cell membrane. Unlike other methods, this technique does not require vast technical expertise, and therefore greatly facilitates experiments. This method enables detection of the effect of drugs, genetic defects or the expression of exogenous proteins on both active and passive properties of cardiac myocytes. In combination with other experimental procedures, this technique can also be applied to the study of mechano-transduction. This protocol can be completed in 3.5 h.

  19. Fibroblast–myocyte electrotonic coupling: Does it occur in native cardiac tissue?☆

    PubMed Central

    Kohl, Peter; Gourdie, Robert G.

    2014-01-01

    Heterocellular electrotonic coupling between cardiac myocytes and non-excitable connective tissue cells has been a long-established and well-researched fact in vitro. Whether or not such coupling exists in vivo has been a matter of considerable debate. This paper reviews the development of experimental insight and conceptual views on this topic, describes evidence in favour of and against the presence of such coupling in native myocardium, and identifies directions for further study needed to resolve the riddle, perhaps less so in terms of principal presence which has been demonstrated, but undoubtedly in terms of extent, regulation, patho-physiological context, and actual relevance of cardiac myocyte–non-myocyte coupling in vivo. This article is part of a Special Issue entitled "Myocyte-Fibroblast Signalling in Myocardium." PMID:24412581

  20. Gallbladder motility and the sex of the guinea pig.

    PubMed

    Kline, Loren; Karpinski, Edward

    2016-06-01

    Progesterone (P), 17β-estradiol (E2), and dihydrotestosterone (DHT) affect gallbladder motility. When gallbladders were taken from women and men, women had more estrogen and P receptors than men. Both P and E2 had an inhibitory effect upon gallbladder contractility in men and premenopausal and postmenopausal women. Similar findings have been reported in gallbladder strips from male and female guinea pigs. In the present study, there was no significant difference in the amount of E2-, P-, or DHT-induced relaxation of CCK-induced tension when the responses in gallbladder strips from male and female guinea pigs were compared. Three metabolites of P were used: 17-hydroxyprogesterone (17-P), 20α-hydroxyprogesterone (20-P), and 21-hydroxyprogesterone (21-P). There was no significant difference in the responses from strips from male and female guinea pigs. In order to determine if the effects of E2 and P were additive, strips from male animals were exposed to either E2 or P and the amount of relaxation recorded. After recovery, the strips were exposed to E2 or P in reverse order to ensure the order of treatment had no effect. Then, the strips were treated with both E2 and P simultaneously and the relaxation recorded. This procedure was repeated with strips from female guinea pigs. The effect of E2 and P was found to be additive; however, the response of the strips from each sex were not significantly different. It is concluded that the sex of the guinea pig has no significant effect on the response to the sex hormones used. PMID:27354545

  1. Gallbladder motility and the sex of the guinea pig.

    PubMed

    Kline, Loren; Karpinski, Edward

    2016-06-01

    Progesterone (P), 17β-estradiol (E2), and dihydrotestosterone (DHT) affect gallbladder motility. When gallbladders were taken from women and men, women had more estrogen and P receptors than men. Both P and E2 had an inhibitory effect upon gallbladder contractility in men and premenopausal and postmenopausal women. Similar findings have been reported in gallbladder strips from male and female guinea pigs. In the present study, there was no significant difference in the amount of E2-, P-, or DHT-induced relaxation of CCK-induced tension when the responses in gallbladder strips from male and female guinea pigs were compared. Three metabolites of P were used: 17-hydroxyprogesterone (17-P), 20α-hydroxyprogesterone (20-P), and 21-hydroxyprogesterone (21-P). There was no significant difference in the responses from strips from male and female guinea pigs. In order to determine if the effects of E2 and P were additive, strips from male animals were exposed to either E2 or P and the amount of relaxation recorded. After recovery, the strips were exposed to E2 or P in reverse order to ensure the order of treatment had no effect. Then, the strips were treated with both E2 and P simultaneously and the relaxation recorded. This procedure was repeated with strips from female guinea pigs. The effect of E2 and P was found to be additive; however, the response of the strips from each sex were not significantly different. It is concluded that the sex of the guinea pig has no significant effect on the response to the sex hormones used.

  2. Nicotine-induced exocytotic norepinephrine release in guinea-pig heart, human atrium and bovine adrenal chromaffin cells: modulation by single components of ischaemia.

    PubMed

    Krüger, C; Haunstetter, A; Gerber, S; Serf, C; Kaufmann, A; Kübler, W; Haass, M

    1995-08-01

    The influence of single components of myocardial ischaemia, such as anoxia, substrate withdrawal, hyperkalemia and extracellular acidosis, on nicotine-induced norepinephrine (NE) release was investigated in the isolated perfused guinea-pig heart, in incubated human atrial tissue and in cultured bovine adrenal chromaffin cells (BCC). In normoxia, nicotine (1-1000 mumol/l) evoked a concentration-dependent release of NE (determined by high pressure liquid chromatography and electrochemical detection) from guinea-pig heart and human atrium. In contrast to selective anoxia (Po2 < 5 mmHg) or glucose withdrawal, respectively, anoxia in combination with glucose withdrawal (5-40 min) markedly potentiated nicotine-induced NE release both in guinea-pig heart and human atrium. The sensitization of cardiac sympathetic nerve endings to nicotine was characterized by a lower threshold concentration and an approximate two-fold increase of maximum NE release, peaking after 10 min of anoxia and glucose withdrawal. Cyanide intoxication (1 mmol/l) combined with glucose withdrawal resulted in a similar increase of nicotine-induced sympathetic transmitter release both in guinea-pig heart and human atrium. In contrast, the nicotine-induced (10 mumol/l) NE overflow was only slightly potentiated by 10 min of global ischaemia in guinea-pig heart. Both hyperkalemia ([K+] 16 mmol/l) and acidosis (pH 6.8-6.0) distinctly attenuated the stimulatory effect of nicotine in guinea-pig heart and human atrium under normoxic conditions. Consistent with an exocytotic release mechanism, NE release was dependent on the presence of extracellular calcium under all conditions tested. Furthermore, NE overflow from guinea-pig heart was accompanied by a release of the exocytosis marker neuropeptide Y (NPY; determined by radioimmunoassay). In BCC, nicotine (1-10 mumol/l) evoked a release of NE and NPY and a transient rise of [Ca2+]i (determined with fura-2) during normoxia which were both dependent on the

  3. An Experimental Model Using Cultured Cardiac Myocytes for a Study of the Generation of Premature Ventricular Contractions Under Ultrasound Exposure

    NASA Astrophysics Data System (ADS)

    Kudo, Nobuki; Yamamoto, Masaya

    2011-09-01

    It is known that use of a contrast agents in echocardiography increases the probability of generation of premature ventricular contractions (PVCs). As a basic study to elucidate the mechanisms and to reduce adverse effects, the generation of PVCs was investigated using cultured cardiac myocytes instead of the intact heart in vivo. Cardiac myocytes were isolated from neonatal rats and cultured on a cover slip. The myocyte sample was exposed to pulsed ultrasound with microbubbles adjacent to the myocytes, and generation of PVCs was examined with ultrasound exposure at various delay times after onset of myocyte contraction. The experimental results showed that generation of PVCs had a stable threshold delay time and that PVCs were generated only when myocytes were exposed to ultrasound with delay times longer than the threshold. The results indicate that the model used in this study is useful for revealing the mechanisms by which PVCs are induced by ultrasound exposure.

  4. Factors affecting radioactive microsphere measurement of blood flow in pregnant guinea pigs

    SciTech Connect

    Myers, S.; Sparks, J.W.; Makowski, E.L.

    1986-10-01

    Comparative blood flow studies were performed in pregnant guinea pigs using radioactive microspheres to test the effects of different sphere sizes on blood flow measurements and the relationship between flows obtained intraoperatively and those performed after 5 days of recovery from anesthesia and surgery. We observed that 1.5% of the cardiac output was shunted through the microcirculation of the carcass, gut, skin and endomyometrium when 15 mu microspheres were used. Intraoperative measurements of heart rate, cardiac output and placental blood flow are significantly lower than measurements made after 5 days recovery. These reductions were ameliorated with the addition of a continuous infusion of isoproterenol and the deletion of atropine from the anesthetic.

  5. Electrodeposition of anchored polypyrrole film on microelectrodes and stimulation of cultured cardiac myocytes.

    PubMed

    Nishizawa, Matsuhiko; Nozaki, Hyuma; Kaji, Hirokazu; Kitazume, Takahiro; Kobayashi, Noriyuki; Ishibashi, Takeshi; Abe, Takashi

    2007-03-01

    The electrically conducting polymer polypyrrole (PPy) was electrochemically deposited onto Pt microelectrodes on a polyimide (PI) substrate. Pre-modification of the PI surface with a self-assembled monolayer of octadecyltrichlorosilane-induced anisotropic lateral growth of PPy along the PI surface and enhanced adhesive strength of the PPy film. The lateral growth of PPy film around the electrode anchored the whole film to the substrate. External stimulation of cultured cardiac myocytes was carried out using the PPy-coated microelectrode. The myocytes on the microelectrode substrate were electrically conjugated to form a sheet, and showed synchronized beating upon stimulation. The threshold charge for effective stimulation of a 0.8 cm(2) sheet of myocytes was around 0.2 microC, roughly corresponding to a membrane depolarization of 250 mV.

  6. Effect of Hypergravity Stress on Gaseous Exchange and Survival of Young and Old Guinea Pigs

    NASA Astrophysics Data System (ADS)

    Muradian, Kh. K.; Timchenko, A. N.

    Hypergravity tolerance decreases in aging Guinea pigs, the range being lower than in other studied species of laboratory mammals - mice, hamsters, and rats. Moreover, for the gaseous exchange rate and body temperature, the decline during the stress is not characteristic for Guinea pigs of both age groups, in contrast to other species. In general, hypergravity tolerance of Guinea pigs could be more appropriate experimental models.

  7. Cell contact as an independent factor modulating cardiac myocyte hypertrophy and survival in long-term primary culture

    NASA Technical Reports Server (NTRS)

    Clark, W. A.; Decker, M. L.; Behnke-Barclay, M.; Janes, D. M.; Decker, R. S.

    1998-01-01

    Cardiac myocytes maintained in cell culture develop hypertrophy both in response to mechanical loading as well as to receptor-mediated signaling mechanisms. However, it has been shown that the hypertrophic response to these stimuli may be modulated through effects of intercellular contact achieved by maintaining cells at different plating densities. In this study, we show that the myocyte plating density affects not only the hypertrophic response and features of the differentiated phenotype of isolated adult myocytes, but also plays a significant role influencing myocyte survival in vitro. The native rod-shaped phenotype of freshly isolated adult myocytes persists in an environment which minimizes myocyte attachment and spreading on the substratum. However, these conditions are not optimal for long-term maintenance of cultured adult cardiac myocytes. Conditions which promote myocyte attachment and spreading on the substratum, on the other hand, also promote the re-establishment of new intercellular contacts between myocytes. These contacts appear to play a significant role in the development of spontaneous activity, which enhances the redevelopment of highly differentiated contractile, junctional, and sarcoplasmic reticulum structures in the cultured adult cardiomyocyte. Although it has previously been shown that adult cardiac myocytes are typically quiescent in culture, the addition of beta-adrenergic agonists stimulates beating and myocyte hypertrophy, and thereby serves to increase the level of intercellular contact as well. However, in densely-plated cultures with intrinsically high levels of intercellular contact, spontaneous contractile activity develops without the addition of beta-adrenergic agonists. In this study, we compare the function, morphology, and natural history of adult feline cardiomyocytes which have been maintained in cultures with different levels of intercellular contact, with and without the addition of beta-adrenergic agonists

  8. Homologous radioimmunoassay for guinea pig corticosteroid-binding globulin

    SciTech Connect

    Hsu, B.R.S.; Kato, E.A.; Raymoure, W.J.; Kuhn, R.W.

    1987-07-01

    A rapid, specific, and sensitive (requiring only 20 fmole of antigen equivalent to 0.007) l of serum) radioimmunoassay (RIA) was developed for the measurement of guinea pig corticosteroid-binding globulin (CBG). CBG was purified to homogeneity from guinea pig serum by affinity chromatography and used for immunization, as the standard and as the radiolabeled trace in the RIA. The antiserum to CBG was raised in rabbits. It was judged specific by immunoelectrophoresis and by comparison of RIA values with steroid-binding assay profiles obtained on serum separated on the basis of size and ion-exchange properties. The results of the radioimmunoassays agree with those of a steroid-binding assay run on identical samples. The sensitivity of the assay allows detection of CBG in serial serum samples, other biologic fluids such as milk, and cell culture supernatants.

  9. Mammary gland tumors in irradiated and untreated guinea pigs

    SciTech Connect

    Hoch-Ligeti, C.; Liebelt, A.G.; Congdon, C.C.; Stewart, H.L.

    1986-01-01

    This is a report of mammary gland tumors from 62 guinea pigs. The tumors arose in the terminal ductal-lobular units as either lobular acinar carcinoma or cystadenocarcinoma or as papillary carcinomas within large ducts near the mammilla. About half the number of the males had terminal ductal-lobular carcinomas and all but 2 of the papillary duct carcinomas also arose in males. Large tumors frequently exhibited squamous, chondromatous, osseous, fatty and myoepitheliomatous types of tissues. In 2 irradiated males and 1 female the tumors metastasized. Whole-body irradiation did not produce significant changes in the number or sex distribution or in the morphology of mammary gland tumors in inbred or outbred guinea pigs. All females had cystic ovaries without increase in granulosa cells, 24 (66.6%) had uterine tumors and 13 (34.2%) had adrenal gland tumors; all males had atrophic testes, 5 (16.5%) had testicular and 6 (22.2%) had adrenal gland tumors.

  10. Immunoreactive atrial natriuretic peptide in the guinea pig spleen

    SciTech Connect

    Vollmar, A.M.; Friedrich, A.; Schulz, R. )

    1989-01-01

    The presence of immunoreative ANP precursor-like material in the guinea pig spleen is suggested. This is based on the following experimental evidence: An acidic extract of guinea pig spleen analyzed by Sephadex G-50 gel filtration contained 4.6 pmol/g wet tissue immunoreactive atrial natriuretic peptide (IR-ANP), IR-ANP coeluting with 15 kDa synthetic ANP (2-126). Gel filtrated IR-ANP material was further submitted to reverse phase high performance liquid chromatography and monitored by radioimmunoassay employing two antisera. One antiserum recognizes the C-terminal of ANP (1-126), the second is directed against the N-terminal sequence. Both antisera revealed material eluting with synthetic ANP (2-126). Furthermore, immunohistochemical analysis suggests this ANP-like material to be localized mainly at the periphery of the white pulp of the spleen. These findings link ANP with the immune system.

  11. Predicting changes in cardiac myocyte contractility during early drug discovery with in vitro assays.

    PubMed

    Morton, M J; Armstrong, D; Abi Gerges, N; Bridgland-Taylor, M; Pollard, C E; Bowes, J; Valentin, J-P

    2014-09-01

    Cardiovascular-related adverse drug effects are a major concern for the pharmaceutical industry. Activity of an investigational drug at the L-type calcium channel could manifest in a number of ways, including changes in cardiac contractility. The aim of this study was to define which of the two assay technologies - radioligand-binding or automated electrophysiology - was most predictive of contractility effects in an in vitro myocyte contractility assay. The activity of reference and proprietary compounds at the L-type calcium channel was measured by radioligand-binding assays, conventional patch-clamp, automated electrophysiology, and by measurement of contractility in canine isolated cardiac myocytes. Activity in the radioligand-binding assay at the L-type Ca channel phenylalkylamine binding site was most predictive of an inotropic effect in the canine cardiac myocyte assay. The sensitivity was 73%, specificity 83% and predictivity 78%. The radioligand-binding assay may be run at a single test concentration and potency estimated. The least predictive assay was automated electrophysiology which showed a significant bias when compared with other assay formats. Given the importance of the L-type calcium channel, not just in cardiac function, but also in other organ systems, a screening strategy emerges whereby single concentration ligand-binding can be performed early in the discovery process with sufficient predictivity, throughput and turnaround time to influence chemical design and address a significant safety-related liability, at relatively low cost.

  12. Minocycline suppresses oxidative stress and attenuates fetal cardiac myocyte apoptosis triggered by in utero cocaine exposure

    PubMed Central

    Sinha-Hikim, Indrani; Shen, Ruoqing; Nzenwa, Ify; Gelfand, Robert; Mahata, Sushil K.

    2015-01-01

    This study investigates the molecular mechanisms by which minocycline, a second generation tetracycline, prevents cardiac myocyte death induced by in utero cocaine exposure. Timed mated pregnant Sprague-Dawley (SD) rats received one of the following treatments twice daily from embryonic (E) day 15–21 (E15–E21): (i) intraperitoneal (IP) injections of saline (control); (ii) IP injections of cocaine (15 mg/kg BW); and (iii) IP injections of cocaine + oral administration of 25 mg/kg BW of minocycline. Pups were killed on postnatal day 15 (P15). Additional pregnant dams received twice daily IP injections of cocaine (from E15–E21) + oral administration of a relatively higher (37.5 mg/kg BW) dose of minocycline. Minocycline treatment continued from E15 until the pups were sacrificed on P15. In utero cocaine exposure resulted in an increase in oxidative stress and fetal cardiac myocyte apoptosis through activation of c-Jun-NH2-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK)-mediated mitochondria-dependent apoptotic pathway. Continued minocycline treatment from E15 through P15 significantly prevented oxidative stress, kinase activation, perturbation of BAX/BCL-2 ratio, cytochrome c release, caspase activation, and attenuated fetal cardiac myocyte apoptosis after prenatal cocaine exposure. These results demonstrate in vivo cardioprotective effects of minocycline in preventing fetal cardiac myocyte death after prenatal cocaine exposure. Given its proven clinical safety and ability to cross the placental barrier and enter into the fetal circulation, minocycline may be an effective therapy for preventing cardiac consequences of in utero cocaine exposure. PMID:21424555

  13. Predicting changes in cardiac myocyte contractility during early drug discovery with in vitro assays

    SciTech Connect

    Morton, M.J.; Armstrong, D.; Abi Gerges, N.; Bridgland-Taylor, M.; Pollard, C.E.; Bowes, J.; Valentin, J.-P.

    2014-09-01

    Cardiovascular-related adverse drug effects are a major concern for the pharmaceutical industry. Activity of an investigational drug at the L-type calcium channel could manifest in a number of ways, including changes in cardiac contractility. The aim of this study was to define which of the two assay technologies – radioligand-binding or automated electrophysiology – was most predictive of contractility effects in an in vitro myocyte contractility assay. The activity of reference and proprietary compounds at the L-type calcium channel was measured by radioligand-binding assays, conventional patch-clamp, automated electrophysiology, and by measurement of contractility in canine isolated cardiac myocytes. Activity in the radioligand-binding assay at the L-type Ca channel phenylalkylamine binding site was most predictive of an inotropic effect in the canine cardiac myocyte assay. The sensitivity was 73%, specificity 83% and predictivity 78%. The radioligand-binding assay may be run at a single test concentration and potency estimated. The least predictive assay was automated electrophysiology which showed a significant bias when compared with other assay formats. Given the importance of the L-type calcium channel, not just in cardiac function, but also in other organ systems, a screening strategy emerges whereby single concentration ligand-binding can be performed early in the discovery process with sufficient predictivity, throughput and turnaround time to influence chemical design and address a significant safety-related liability, at relatively low cost. - Highlights: • The L-type calcium channel is a significant safety liability during drug discovery. • Radioligand-binding to the L-type calcium channel can be measured in vitro. • The assay can be run at a single test concentration as part of a screening cascade. • This measurement is highly predictive of changes in cardiac myocyte contractility.

  14. Autonomic Nerve Regulation of Colonic Peristalsis in Guinea Pigs

    PubMed Central

    Gribovskaja-Rupp, Irena; Babygirija, Reji; Takahashi, Toku; Ludwig, Kirk

    2014-01-01

    Background/Aims Colonic peristalsis is mainly regulated via intrinsic neurons in guinea pigs. However, autonomic regulation of colonic motility is poorly understood. We explored a guinea pig model for the study of extrinsic nerve effects on the distal colon. Methods Guinea pigs were sacrificed, their distal colons isolated, preserving pelvic nerves (PN) and inferior mesenteric ganglia (IMG), and placed in a tissue bath. Fecal pellet propagation was conducted during PN and IMG stimulation at 10 Hz, 0.5 ms and 5 V. Distal colon was connected to a closed circuit system, and colonic motor responses were measured during PN and IMG stimulation. Results PN stimulation increased pellet velocity to 24.6 ± 0.7 mm/sec (n = 20), while IMG stimulation decreased it to 2.0 ± 0.2 mm/sec (n = 12), compared to controls (13.0 ± 0.7 mm/sec, P < 0.01). In closed circuit experiments, PN stimulation increased the intraluminal pressure, which was abolished by atropine (10−6 M) and hexamethonium (10−4 M). PN stimulation reduced the incidence of non-coordinated contractions induced by NG-nitro-L-arginine methyl ester (L-NAME; 10−4 M). IMG stimulation attenuated intraluminal pressure increase, which was partially reversed by alpha-2 adrenoceptor antagonist (yohimbine; 10−6 M). Conclusions PN and IMG input determine speed of pellet progression and peristaltic reflex of the guinea pig distal colon. The stimulatory effects of PN involve nicotinic, muscarinic and nitrergic pathways. The inhibitory effects of IMG stimulation involve alpha-2 adrenoceptors. PMID:24847719

  15. Suppressed tuberculin reaction in guinea pigs following laser irradiation

    SciTech Connect

    Inoue, K.; Nishioka, J.; Hukuda, S.

    1989-01-01

    Tuberculin reactions were tested at the bilateral sites of the backs of sensitized guinea pigs. Laser irradiation at an energy fluence of 3.6 J at one site of reaction suppressed the reaction not only at the irradiated site but also at the contralateral nonirradiated site. These phenomena were observed when mononuclear cells were dominant in the perivascular cellular infiltration. The results indicate that local irradiation with a low-power laser has systemic inhibitory effects on delayed hypersensitivity reactions.

  16. Strain differences in guinea pigs' bronchial sensitivity to acetylcholine.

    PubMed

    Mikami, H; Nishibata, R; Kawamoto, Y; Ino, T

    1990-01-01

    The bronchial sensitivity to acetylcholine (ACh) of guinea pigs of various strains was investigated to clarify strain differences. Inbred Strain 2, Strain 13 and JY-1 and non-inbred Hartley strain (two colonies) were used in this experiment. (1) Guinea pigs were exposed to 0.08% ACh aerosol and the time needed to produce falling down (TNPFD) was determined. Mean +/- standard error of TNPFD (n = 14 per group) of animals was 182 +/- 28 sec, 148 +/- 22 sec, 210 +/- 30 sec, 342 +/- 24 sec and 406 +/- 36 sec in Strain 2, Strain 13, JY-1, Hartley (Japan SLC) and Hartley (Hitachi), respectively. There was a significant difference in TNPFD between inbred strains and non-inbred strains (P less than 0.05 or P less than 0.01), indicating that inbred strains had higher sensitivity. (2) Guinea pigs were exposed to 20-5000 micrograms/ml ACh for 2 min. The mean dose threshold as determined by transcutaneous oxygen pressure was 524 micrograms/ml, 424 micrograms/ml, 614 micrograms/ml, 1317 micrograms/ml and 1651 micrograms/ml (n = 14 per group) in Strain 2, Strain 13, JY-1, Hartley (Japan SLC) and Hartley (Hitachi), respectively. Inbred strains showed lower dose thresholds than non-inbred strains. (3) Isolated trachea-lungs of 5 guinea pigs were perfused with 10(-9)-10(-5) g/ml ACh to determine strain differences. Dose response curves of animals of inbred strains shifted to the left (lower concentrations), unlike those of non-inbred strains, suggesting that inbred strains had higher sensitivity to ACh than non-inbred strains.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Aging increases stiffness of cardiac myocytes measured by atomic force microscopy nanoindentation.

    PubMed

    Lieber, Samuel C; Aubry, Nadine; Pain, Jayashree; Diaz, Gissela; Kim, Song-Jung; Vatner, Stephen F

    2004-08-01

    It is well established that the aging heart exhibits left ventricular (LV) diastolic dysfunction and changes in mechanical properties, which are thought to be due to alterations in the extracellular matrix. We tested the hypothesis that the mechanical properties of cardiac myocytes significantly change with aging, which could contribute to the global changes in LV diastolic dysfunction. We used atomic force microscopy (AFM), which determines cellular mechanical property changes at nanoscale resolution in myocytes, from young (4 mo) and old (30 mo) male Fischer 344 x Brown Norway F1 hybrid rats. A measure of stiffness, i.e., apparent elastic modulus, was determined by analyzing the relationship between AFM indentation force and depth with the classical infinitesimal strain theory and by modeling the AFM probe as a blunted conical indenter. This is the first study to demonstrate a significant increase (P < 0.01) in the apparent elastic modulus of single, aging cardiac myocytes (from 35.1 +/- 0.7, n = 53, to 42.5 +/- 1.0 kPa, n = 58), supporting the novel concept that the mechanism mediating LV diastolic dysfunction in aging hearts resides, in part, at the level of the myocyte.

  18. Nicotinamide adenine dinucleotide fluorescence spectroscopy and imaging of isolated cardiac myocytes.

    PubMed Central

    Eng, J; Lynch, R M; Balaban, R S

    1989-01-01

    Nicotinamide adenine dinucleotide (NADH) plays a critical role in oxidative phosphorylation as the primary source of reducing equivalents to the respiratory chain. Using a modified fluorescence microscope, we have obtained spectra and images of the blue autofluorescence from single rat cardiac myocytes. The optical setup permitted rapid acquisition of fluorescence emission spectra (390-595 nm) or intensified digital video images of individual myocytes. The spectra showed a broad fluorescence centered at 447 +/- 0.2 nm, consistent with mitochondrial NADH. Addition of cyanide resulted in a 100 +/- 10% increase in fluorescence, while the uncoupler FCCP resulted in a 82 +/- 4% decrease. These two transitions were consistent with mitochondrial NADH and implied that the myocytes were 44 +/- 6% reduced under the resting control conditions. Intracellular fluorescent structures were observed that correlated with the distribution of a mitochondrial selective fluorescent probe (DASPMI), the mitochondrial distribution seen in published electron micrographs, and a metabolic digital subtraction image of the cyanide fluorescence transition. These data are consistent with the notion that the blue autofluorescence of rat cardiac myocytes originates from mitochondrial NADH. Images FIGURE 9 FIGURE 10 FIGURE 2 FIGURE 3 FIGURE 8 FIGURE 11 PMID:2720061

  19. Pharmacological characteristics of liriodenine, isolated from Fissistigma glaucescens, a novel muscarinic receptor antagonist in guinea-pigs.

    PubMed Central

    Lin, C H; Chang, G J; Su, M J; Wu, Y C; Teng, C M; Ko, F N

    1994-01-01

    1. The pharmacological activities of liriodenine, isolated from Fissistigma glaucescens, were determined in isolated trachea, ileum and cardiac tissues of guinea-pigs. 2. Liriodenine was found to be a muscarinic receptor antagonist in guinea-pig trachea as revealed by its competitive antagonism of carbachol (pA2 = 6.22 +/- 0.08)-induced smooth muscle contraction. It was slightly more potent than methoctramine (pA2 = 5.92 +/- 0.05), but was less potent than atropine (pA2 = 8.93 +/- 0.07), pirenzepine (pA2 = 7.02 +/- 0.09) and 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, pA2 = 8.72 +/- 0.07). 3. Liriodenine was also a muscarinic antagonist in guinea-pig ileum (pA2 = 6.36 +/- 0.10) with a pA2 value that closely resembled that obtained in the trachea. 4. Liriodenine was 10 fold less potent in atrial preparations (left atria, pA2 = 5.24 +/- 0.04; right atria, pA2 = 5.35 +/- 0.09 and 5.28 +/- 0.07 for inotropic and chronotropic effects, respectively) than in smooth muscle preparations. 5. High concentration of liriodenine (300 microM) partially depressed the contractions induced by U-46619, histamine, prostaglandin F2 alpha, neurokinin A, leukotriene C4 and high K+ in the guinea-pig trachea. The inhibitions were characterized by a rightward shift in the concentration-response curves with suppression of their maximal contraction. 6. High concentration of liriodenine (300 microM) did not affect U-46619- or neurokinin A-induced tracheal contraction in the presence of nifedipine (1 microM) or in Ca(2+)-free (containing 0.2 mM EGTA) medium. 7. Neither cyclic AMP nor cyclic GMP content of guinea-pig trachealis was changed by liriodenine (30-300 microM).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7812621

  20. Novel antitussive effect of suplatast tosilate in guinea pigs.

    PubMed

    Zhou, Jian-Rong; Syono, Ryo-ichi; Fukumi, Syu-ichi; Kimoto, Kenji; Shirasaki, Tetsuya; Soeda, Fumio; Takahama, Kazuo

    2015-01-01

    We studied the antitussive effects of suplatast, a Th2 cytokine inhibitor, and compared them with the effects of codeine using an experimental cough model in guinea pigs. Suplatast and codeine dose-dependently inhibited cough caused by mechanical stimulation of the larynx, but they did not inhibit cough caused by mechanical stimulation of the bifurcation of the trachea. In guinea pigs with bronchitis, suplatast had an antitussive effect on cough caused by stimulation of the larynx, whereas codeine did not inhibit such cough. In SO2-exposed guinea pigs, suplatast tended to inhibit cough caused by mechanical stimulation of the tracheal bifurcation. Further, suplatast inhibited citric acid-induced cough augmented by pretreatment with an angiotensin-converting enzyme inhibitor, whereas codeine did not inhibit such cough. Suplatast also inhibited bradykinin-induced discharges of airway vagal afferent nerves and significantly inhibited 4-aminopyridine-induced discharges of airway vagal afferent nerves. These findings indicate that the antitussive effects of suplatast are mediated by a novel mechanism involving the peripheral nervous system.

  1. Pathogenesis of Bolivian Hemorrhagic Fever in Guinea Pigs.

    PubMed

    Bell, T M; Bunton, T E; Shaia, C I; Raymond, J W; Honnold, S P; Donnelly, G C; Shamblin, J D; Wilkinson, E R; Cashman, K A

    2016-01-01

    Machupo virus, the cause of Bolivian hemorrhagic fever, is a highly lethal viral hemorrhagic fever with no Food and Drug Administration-approved vaccines or therapeutics. This study evaluated the guinea pig as a model using the Machupo virus-Chicava strain administered via aerosol challenge. Guinea pigs (Cavia porcellus) were serially sampled to evaluate the temporal progression of infection, gross and histologic lesions, and sequential changes in serum chemistry and hematology. The incubation period was 5 to 12 days, and complete blood counts revealed leukopenia with lymphopenia and thrombocytopenia. Gross pathologic findings included congestion and hemorrhage of the gastrointestinal mucosa and serosa, noncollapsing lungs with fluid exudation, enlarged lymph nodes, and progressive pallor and friability of the liver. Histologic lesions consisted of foci of degeneration and cell death in the haired skin, liver, pancreas, adrenal glands, lymph nodes, tongue, esophagus, salivary glands, renal pelvis, small intestine, and large intestine. Lymphohistiocytic interstitial pneumonia was also present. Inflammation within the central nervous system, interpreted as nonsuppurative encephalitis, was histologically apparent approximately 16 days postexposure and was generally progressive. Macrophages in the tracheobronchial lymph node, on day 5 postexposure, were the first cells to demonstrate visible viral antigen. Viral antigen was detected throughout the lymphoid system by day 9 postexposure, followed by prominent spread within epithelial tissues and then brain. This study provides insight into the course of Machupo virus infection and supports the utility of guinea pigs as an additional animal model for vaccine and therapeutic development. PMID:26139838

  2. Tracheal ultrastructure in kerosene treated guinea pigs. A preliminary report.

    PubMed

    Noa, N; Sanabria, J

    1984-01-01

    p6high correlation between the usage of kerosene and the appearance of asthmatic crises has been demonstrated. The ultrastructure of the upper respiratory tract of animals treated with kerosene has not been previously reported. Kerosene aerosol was administered for 15 minutes daily during 21 days to adult male guinea pigs with fragments of trachea being processed for ultrathin electron microscopical studies. Controls did not receive any treatment. Trachea of guinea pigs submitted to kerosene aerosols showed swelling, ruffling and breakdown of the ciliary membrane. The regularly arranged ciliary border was disturbed to a certain degree in some areas by the development of cytoplasmatic protrusions at the apical part of the ciliated cells. An eosinophilic infiltrate was observed deep inside the epithelium and into the lamina propria. Therefore, these ciliary alterations can be considered as one of the most important changes induced by kerosene in tracheal epithelial cells. The protrusions may represent a sign of cell alteration produced by kerosene aerosol inhalation in the guinea pig.

  3. Pathogenesis of Bolivian Hemorrhagic Fever in Guinea Pigs.

    PubMed

    Bell, T M; Bunton, T E; Shaia, C I; Raymond, J W; Honnold, S P; Donnelly, G C; Shamblin, J D; Wilkinson, E R; Cashman, K A

    2016-01-01

    Machupo virus, the cause of Bolivian hemorrhagic fever, is a highly lethal viral hemorrhagic fever with no Food and Drug Administration-approved vaccines or therapeutics. This study evaluated the guinea pig as a model using the Machupo virus-Chicava strain administered via aerosol challenge. Guinea pigs (Cavia porcellus) were serially sampled to evaluate the temporal progression of infection, gross and histologic lesions, and sequential changes in serum chemistry and hematology. The incubation period was 5 to 12 days, and complete blood counts revealed leukopenia with lymphopenia and thrombocytopenia. Gross pathologic findings included congestion and hemorrhage of the gastrointestinal mucosa and serosa, noncollapsing lungs with fluid exudation, enlarged lymph nodes, and progressive pallor and friability of the liver. Histologic lesions consisted of foci of degeneration and cell death in the haired skin, liver, pancreas, adrenal glands, lymph nodes, tongue, esophagus, salivary glands, renal pelvis, small intestine, and large intestine. Lymphohistiocytic interstitial pneumonia was also present. Inflammation within the central nervous system, interpreted as nonsuppurative encephalitis, was histologically apparent approximately 16 days postexposure and was generally progressive. Macrophages in the tracheobronchial lymph node, on day 5 postexposure, were the first cells to demonstrate visible viral antigen. Viral antigen was detected throughout the lymphoid system by day 9 postexposure, followed by prominent spread within epithelial tissues and then brain. This study provides insight into the course of Machupo virus infection and supports the utility of guinea pigs as an additional animal model for vaccine and therapeutic development.

  4. Studies of guinea pig immunoglobulin isotype, idiotype and antiidiotype

    SciTech Connect

    Tirrell, S.M.

    1988-01-01

    Immunization of Guinea pigs with diphtheria toxoid generated antibodies of the IgG class that were capable of neutralizing native toxin in vivo. Sera from these animals were used to affinity purify idiotypic antibodies (AB1). AB1 vaccines derived from the IgG1 class and from F(ab{prime}){sub 2} of IgG1 + IgG2 (IgG1/2) classes were effective in inducing a syngeneic anti-idiotype (AB2) response. Animals immunized with AB1 consisting of both IgG1/2 did not elicit a detectable AB2 response. Binding of homologous {sup 125}I-F(ab{prime}){sub 2} (AB1) to the antiidiotype was inhibited 90% in the presence of DT.F(ab{prime}){sub 2} derived from preimmune serum or had no inhibitory effects on the idiotype-antiidiotype interactions. Two groups of outbred guinea pigs were vaccinated with alum absorbed F(ab{prime}){sub 2} of anti-idiotype IgG1/2 (AB2). Of the ten animals inoculated with AB2, three tested positive by RIA against {sup 125}I-DT. Two of the RIA positive sera contained antibodies that neutralized diphtheria toxin in a rabbit intracutaneous assay. Purification of guinea pig IgG by protein A-Sepharose affinity chromatography resulted in the separation of three distinct IgG populations.

  5. Optimisation of a generic ionic model of cardiac myocyte electrical activity.

    PubMed

    Guo, Tianruo; Al Abed, Amr; Lovell, Nigel H; Dokos, Socrates

    2013-01-01

    A generic cardiomyocyte ionic model, whose complexity lies between a simple phenomenological formulation and a biophysically detailed ionic membrane current description, is presented. The model provides a user-defined number of ionic currents, employing two-gate Hodgkin-Huxley type kinetics. Its generic nature allows accurate reconstruction of action potential waveforms recorded experimentally from a range of cardiac myocytes. Using a multiobjective optimisation approach, the generic ionic model was optimised to accurately reproduce multiple action potential waveforms recorded from central and peripheral sinoatrial nodes and right atrial and left atrial myocytes from rabbit cardiac tissue preparations, under different electrical stimulus protocols and pharmacological conditions. When fitted simultaneously to multiple datasets, the time course of several physiologically realistic ionic currents could be reconstructed. Model behaviours tend to be well identified when extra experimental information is incorporated into the optimisation.

  6. A systematic approach for assessing Ca²⁺ handling in cardiac myocytes.

    PubMed

    Sipido, Karin R; Macquaide, Niall; Bito, Virginie

    2015-05-01

    In cardiac myocytes, Ca(2+) release from the sarcoplasmic reticulum (SR) Ca(2+) store through the opening of ryanodine receptors (RyRs) is the major source of Ca(2+) for activation of myofilaments and contraction. Over the past 20 years, tools have become available to study this release process in detail, allowing new insights into the regulation of SR Ca(2+) release and RyR function. To assess these processes, we recommend and here review a systematic approach that evaluates the essential transport mechanisms and Ca(2+) fluxes in isolated single cardiac myocytes by using fluorescent Ca(2+) indicators and whole-cell recording of membrane voltage and ionic currents under voltage clamp. The approach includes an assessment of the L-type Ca(2+) current as a trigger for opening of RyRs and release of SR Ca(2+), of the SR Ca(2+) content, of intrinsic properties of RyRs, and of Ca(2+)-removal systems.

  7. Comparison of the cardiostimulatory effects of acetylcholine and nicotine on the working guinea-pig heart.

    PubMed

    Rodgers, R L; Moore, J I; Hornbrook, K R

    1979-12-01

    The isolated working guinea-pig heart was used to compare the cardiostimulatory effects of acetylcholine and nicotine observed in the presence of atropine. Both agonists increased aortic pressure, left ventricular pressure, left ventricular dP/dt, cardiac output, and ventricular cyclic AMP levels. These responses were qualitatively and quantitatively similar to the effects of exogenous norepinephrine. Hexamethonium treatment abolished the responses to acetylcholine and to nicotine. However, several differences in the responses of the two agonists were also observed with respect to: 1) the effect of propranolol pretreatment, 2) selective effects on coronary and aortic flow rates, 3) coefficients of correlation between ventricular cyclic AMP and changes in dP/dt, and 4) the "autoinhibition" effect. The results support the view that the cardiostimulatory effects of acetylcholine are due entirely to endogenous catecholamine release, but that the effects of nicotine may involve an additional action.

  8. Nuclear Compartmentalization of α1-Adrenergic Receptor Signaling in Adult Cardiac Myocytes

    PubMed Central

    Wu, Steven C.

    2015-01-01

    Abstract: Although convention dictates that G protein-coupled receptors localize to and signal at the plasma membrane, accumulating evidence suggests that G protein-coupled receptors localize to and signal at intracellular membranes, most notably the nucleus. In fact, there is now significant evidence indicating that endogenous alpha-1 adrenergic receptors (α1-ARs) localize to and signal at the nuclei in adult cardiac myocytes. Cumulatively, the data suggest that α1-ARs localize to the inner nuclear membrane, activate intranuclear signaling, and regulate physiologic function in adult cardiac myocytes. Although α1-ARs signal through Gαq, unlike other Gq-coupled receptors, α1-ARs mediate important cardioprotective functions including adaptive/physiologic hypertrophy, protection from cell death (survival signaling), positive inotropy, and preconditioning. Also unlike other Gq-coupled receptors, most, if not all, functional α1-ARs localize to the nuclei in adult cardiac myocytes, as opposed to the sarcolemma. Together, α1-AR nuclear localization and cardioprotection might suggest a novel model for compartmentalization of Gq-coupled receptor signaling in which nuclear Gq-coupled receptor signaling is cardioprotective. PMID:25264754

  9. Improving cardiac myocytes performance by carbon nanotubes platforms†

    PubMed Central

    Martinelli, Valentina; Cellot, Giada; Fabbro, Alessandra; Bosi, Susanna; Mestroni, Luisa; Ballerini, Laura

    2013-01-01

    The application of nanotechnology to the cardiovascular system has increasingly caught scientists' attention as a potentially powerful tool for the development of new generation devices able to interface, repair, or boost the performance of cardiac tissue. Carbon nanotubes (CNTs) are considered as promising materials for nanomedicine applications in general and have been recently tested toward excitable cell growth. CNTs are cylindrically shaped structures made up of rolled-up graphene sheets, with unique electrical, thermal, and mechanical properties, able to effectively conducting electrical current in electrochemical interfaces. CNTs-based scaffolds have been recently found to support the in vitro growth of cardiac cells: in particular, their ability to improve cardiomyocytes proliferation, maturation, and electrical behavior are making CNTs extremely attractive for the development and exploitation of interfaces able to impact on cardiac cells physiology and function. PMID:24027533

  10. Cardiac fibroblasts are predisposed to convert into myocyte phenotype: Specific effect of transforming growth factor. beta

    SciTech Connect

    Eghbali, M.; Tomek, R.; Woods, C.; Bhambi, B. )

    1991-02-01

    Cardiac fibroblasts are mainly responsible for the synthesis of major extracellular matrix proteins in the heart, including fibrillar collagen types I and III and fibronectin. In this report we show that these cells, when stimulated by transforming growth factor {beta}{sub 1} (TGF-{beta}{sub 1}), acquire certain myocyte-specific properties. Cultured cardiac fibroblasts from adult rabbit heart were treated with TGF-{beta}{sub 1}, (10-15 ng/ml) for different periods of time. Northern hybridization analysis of total RNA showed that cells treated with TGF-{beta}{sub 1} became stained with a monoclonal antibody to muscle-specific actin. After treatment of quiescent cells with TGF-{beta}{sub 1}, cell proliferation (as measured by ({sup 3}H)thymidine incorporation) was moderately increased. Cultured cardiac fibroblasts at the subconfluent stage, when exposed to TGF-{beta}{sub 1} in the presence of 10% fetal bovine serum, gave rise to a second generation of slowly growing cells that expressed muscle-specific actin filaments. The findings demonstrate that cardiac fibroblasts can be made to differentiate into cells that display many characteristics of cardiac myocytes. TGF-{beta}{sub 1} seems to be a specific inducer of such conversion.

  11. Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus).

    PubMed

    Field, Kristin L; Beauchamp, Gary K; Kimball, Bruce A; Mennella, Julie A; Bachmanov, Alexander A

    2010-11-01

    Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity. PMID:21090891

  12. Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus).

    PubMed

    Field, Kristin L; Beauchamp, Gary K; Kimball, Bruce A; Mennella, Julie A; Bachmanov, Alexander A

    2010-11-01

    Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity.

  13. Infection of Guinea Pigs with Vesicular Stomatitis New Jersey Virus Transmitted by Culicoides sonorensis (Diptera: Ceratopogonidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Interpretive Biting midges,Culicoides sonorensis were shown to be capable of transmitting vesicular stomatitis New Jersey virus (VSNJV) to guinea pigs. Despite seroconversion for VSNJV, none of the guinea pigs developed clinical signs when infected in the abdomen by either infected insects or by nee...

  14. Dioxin in soil: bioavailability after ingestion by rats and guinea pigs

    SciTech Connect

    McConnell, E.E.; Lucier, G.W.; Rumbaugh, R.C.; Albro, P.W.; Harvan, D.J.; Hass, J.R.; Harris, M.W.

    1984-03-09

    Soil environmentally contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was given by gavage to guinea pigs and rats. The development of a characteristic clinicopathologic syndrome in guinea pigs, the induction of aryl hydrocarbon hydroxylase in rats, and the presence of TCDD in the livers of both species show that TCDD in soil exhibits high biological availability after ingestion.

  15. Renal failure in a guinea pig (Cavia porcellus) following ingestion of oxalate containing plants

    PubMed Central

    Holowaychuk, Marie K.

    2006-01-01

    A 1-year-old guinea pig presented with anorexia, lethargy, and weight loss, 1 week after ingesting a peace lily leaf. Laboratory findings were suggestive of renal failure and included elevated blood urea nitrogen and creatinine with concurrent isosthenuria. The guinea pig was euthanized 1 month later due to worsening clinical signs. PMID:16933558

  16. Comparative study of Helicobacter pylori infection in guinea pigs and mice - elevation of acute-phase protein C3 in infected guinea pigs.

    PubMed

    Sjunnesson, H; Sturegård, E; Grubb, A; Willén, R; Wadström, T

    2001-03-01

    Eighteen Dunkin-Hartley guinea pigs and 50 NMRI mice were inoculated with Helicobacter pylori and the infection followed by culture, histopathology, antibody response, and plasma levels of the acute-phase proteins albumin, C3, and transferrin for up to 7 weeks. The immune response to H. pylori surface proteins was studied by an enzyme immunoassay (EIA) and Western immunoblot and the plasma levels of albumin, C3, and transferrin were analyzed by single radial immunodiffusion. Guinea pigs had a more severe gastritis and a higher EIA immune response than NMRI mice. Serum C3 levels were elevated in infected guinea pigs after 3 and 7 weeks indicating a systemic inflammatory response and a possible link between H. pylori infection and extragastric manifestations such as vasculitis associated with atherosclerosis. Serum cholesterol levels were analyzed in guinea pigs at 7 weeks and indicated a higher level in H. pylori-infected than in control animals, but this difference was not statistically significant.

  17. Pannexin 1 Constitutes the Large Conductance Cation Channel of Cardiac Myocytes

    PubMed Central

    Kienitz, Marie-Cecile; Bender, Kirsten; Dermietzel, Rolf; Pott, Lutz; Zoidl, Georg

    2011-01-01

    A large conductance (∼300 picosiemens) channel (LCC) of unknown molecular identity, activated by Ca2+ release from the sarcoplasmic reticulum, particularly when augmented by caffeine, has been described previously in isolated cardiac myocytes. A potential candidate for this channel is pannexin 1 (Panx1), which has been shown to form large ion channels when expressed in Xenopus oocytes and mammalian cells. Panx1 function is implicated in ATP-mediated auto-/paracrine signaling, and a crucial role in several cell death pathways has been suggested. Here, we demonstrate that after culturing for 4 days LCC activity is no longer detected in myocytes but can be rescued by adenoviral gene transfer of Panx1. Endogenous LCCs and those related to expression of Panx1 share key pharmacological properties previously used for identifying and characterizing Panx1 channels. These data demonstrate that Panx1 constitutes the LCC of cardiac myocytes. Sporadic openings of single Panx1 channels in the absence of Ca2+ release can trigger action potentials, suggesting that Panx1 channels potentially promote arrhythmogenic activities. PMID:21041301

  18. Cell-specific promoter in adenovirus vector for transgenic expression of SERCA1 ATPase in cardiac myocytes.

    PubMed

    Inesi, G; Lewis, D; Sumbilla, C; Nandi, A; Strock, C; Huff, K W; Rogers, T B; Johns, D C; Kessler, P D; Ordahl, C P

    1998-03-01

    Adenovirus-mediated transfer of cDNA encoding the chicken skeletal muscle sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA1) yielded selective expression in cultured chick embryo cardiac myocytes under control of a segment (-268 base pair) of the cell-specific cardiac troponin T (cTnT) promoter or nonselective expression in myocytes and fibroblasts under control of a constitutive viral [cytomegalovirus (CMV)] promoter. Under optimal conditions nearly all cardiac myocytes in culture were shown to express transgenic SERCA1 ATPase. Expression was targeted to intracellular membranes and was recovered in subcellular fractions with a pattern identical to that of the endogenous SERCA2a ATPase. Relative to control myocytes, transgenic SERCA1 expression increased up to four times the rates of ATP-dependent (and thapsigargin-sensitive) Ca2+ transport activity of cell homogenates. Although the CMV promoter was more active than the cTnT promoter, an upper limit for transgenic expression of functional enzyme was reached under control of either promoter by adjustment of the adenovirus plaque-forming unit titer of infection media. Cytosolic Ca2+ concentration transients and tension development of whole myocytes were also influenced to a similar limit by transgenic expression of SERCA1 under control of either promoter. Our experiments demonstrate that a cell-specific protein promoter in recombinant adenovirus vectors yields highly efficient and selective transgene expression of a membrane-bound and functional enzyme in cardiac myocytes.

  19. High frequency stimulation of cardiac myocytes: a theoretical and computational study.

    PubMed

    Weinberg, Seth H

    2014-12-01

    High-frequency stimulation (HFS) has recently been identified as a novel approach for terminating life-threatening cardiac arrhythmias. HFS elevates myocyte membrane potential and blocks electrical conduction for the duration of the stimulus. However, low amplitude HFS can induce rapidly firing action potentials, which may reinitiate an arrhythmia. The cellular level mechanisms underlying HFS-induced electrical activity are not well understood. Using a multiscale method, we show that a minimal myocyte model qualitatively reproduces the influence of HFS on cardiac electrical activity. Theoretical analysis and simulations suggest that persistent activation and de-inactivation of ionic currents, in particular a fast inward window current, underlie HFS-induced action potentials and membrane potential elevation, providing hypotheses for future experiments. We derive analytical expressions to describe how HFS modifies ionic current amplitude and gating dynamics. We show how fast inward current parameters influence the parameter regimes for HFS-induced electrical activity, demonstrating how the efficacy of HFS as a therapy for terminating arrhythmias may depend on the presence of pathological conditions or pharmacological treatments. Finally, we demonstrate that HFS terminates cardiac arrhythmias in a one-dimensional ring of cardiac tissue. In this study, we demonstrate a novel approach to characterize the influence of HFS on ionic current gating dynamics, provide new insight into HFS of the myocardium, and suggest mechanisms underlying HFS-induced electrical activity.

  20. High frequency stimulation of cardiac myocytes: A theoretical and computational study

    NASA Astrophysics Data System (ADS)

    Weinberg, Seth H.

    2014-12-01

    High-frequency stimulation (HFS) has recently been identified as a novel approach for terminating life-threatening cardiac arrhythmias. HFS elevates myocyte membrane potential and blocks electrical conduction for the duration of the stimulus. However, low amplitude HFS can induce rapidly firing action potentials, which may reinitiate an arrhythmia. The cellular level mechanisms underlying HFS-induced electrical activity are not well understood. Using a multiscale method, we show that a minimal myocyte model qualitatively reproduces the influence of HFS on cardiac electrical activity. Theoretical analysis and simulations suggest that persistent activation and de-inactivation of ionic currents, in particular a fast inward window current, underlie HFS-induced action potentials and membrane potential elevation, providing hypotheses for future experiments. We derive analytical expressions to describe how HFS modifies ionic current amplitude and gating dynamics. We show how fast inward current parameters influence the parameter regimes for HFS-induced electrical activity, demonstrating how the efficacy of HFS as a therapy for terminating arrhythmias may depend on the presence of pathological conditions or pharmacological treatments. Finally, we demonstrate that HFS terminates cardiac arrhythmias in a one-dimensional ring of cardiac tissue. In this study, we demonstrate a novel approach to characterize the influence of HFS on ionic current gating dynamics, provide new insight into HFS of the myocardium, and suggest mechanisms underlying HFS-induced electrical activity.

  1. A First Generation Comparative Chromosome Map between Guinea Pig (Cavia porcellus) and Humans

    PubMed Central

    Romanenko, Svetlana A.; Perelman, Polina L.; Trifonov, Vladimir A.; Serdyukova, Natalia A.; Li, Tangliang; Fu, Beiyuan; O’Brien, Patricia C. M.; Ng, Bee L.; Nie, Wenhui; Liehr, Thomas; Stanyon, Roscoe; Graphodatsky, Alexander S.; Yang, Fengtang

    2015-01-01

    The domesticated guinea pig, Cavia porcellus (Hystricomorpha, Rodentia), is an important laboratory species and a model for a number of human diseases. Nevertheless, genomic tools for this species are lacking; even its karyotype is poorly characterized. The guinea pig belongs to Hystricomorpha, a widespread and important group of rodents; so far the chromosomes of guinea pigs have not been compared with that of other hystricomorph species or with any other mammals. We generated full sets of chromosome-specific painting probes for the guinea pig by flow sorting and microdissection, and for the first time, mapped the chromosomal homologies between guinea pig and human by reciprocal chromosome painting. Our data demonstrate that the guinea pig karyotype has undergone extensive rearrangements: 78 synteny-conserved human autosomal segments were delimited in the guinea pig genome. The high rate of genome evolution in the guinea pig may explain why the HSA7/16 and HSA16/19 associations presumed ancestral for eutherians and the three syntenic associations (HSA1/10, 3/19, and 9/11) considered ancestral for rodents were not found in C. porcellus. The comparative chromosome map presented here is a starting point for further development of physical and genetic maps of the guinea pig as well as an aid for genome assembly assignment to specific chromosomes. Furthermore, the comparative mapping will allow a transfer of gene map data from other species. The probes developed here provide a genomic toolkit, which will make the guinea pig a key species to unravel the evolutionary biology of the Hystricomorph rodents. PMID:26010445

  2. A First Generation Comparative Chromosome Map between Guinea Pig (Cavia porcellus) and Humans.

    PubMed

    Romanenko, Svetlana A; Perelman, Polina L; Trifonov, Vladimir A; Serdyukova, Natalia A; Li, Tangliang; Fu, Beiyuan; O'Brien, Patricia C M; Ng, Bee L; Nie, Wenhui; Liehr, Thomas; Stanyon, Roscoe; Graphodatsky, Alexander S; Yang, Fengtang

    2015-01-01

    The domesticated guinea pig, Cavia porcellus (Hystricomorpha, Rodentia), is an important laboratory species and a model for a number of human diseases. Nevertheless, genomic tools for this species are lacking; even its karyotype is poorly characterized. The guinea pig belongs to Hystricomorpha, a widespread and important group of rodents; so far the chromosomes of guinea pigs have not been compared with that of other hystricomorph species or with any other mammals. We generated full sets of chromosome-specific painting probes for the guinea pig by flow sorting and microdissection, and for the first time, mapped the chromosomal homologies between guinea pig and human by reciprocal chromosome painting. Our data demonstrate that the guinea pig karyotype has undergone extensive rearrangements: 78 synteny-conserved human autosomal segments were delimited in the guinea pig genome. The high rate of genome evolution in the guinea pig may explain why the HSA7/16 and HSA16/19 associations presumed ancestral for eutherians and the three syntenic associations (HSA1/10, 3/19, and 9/11) considered ancestral for rodents were not found in C. porcellus. The comparative chromosome map presented here is a starting point for further development of physical and genetic maps of the guinea pig as well as an aid for genome assembly assignment to specific chromosomes. Furthermore, the comparative mapping will allow a transfer of gene map data from other species. The probes developed here provide a genomic toolkit, which will make the guinea pig a key species to unravel the evolutionary biology of the Hystricomorph rodents.

  3. Ozone-Induced Hypertussive Responses in Rabbits and Guinea Pigs.

    PubMed

    Clay, Emlyn; Patacchini, Riccardo; Trevisani, Marcello; Preti, Delia; Branà, Maria Pia; Spina, Domenico; Page, Clive

    2016-04-01

    Cough remains a major unmet clinical need, and preclinical animal models are not predictive for new antitussive agents. We have investigated the mechanisms and pharmacological sensitivity of ozone-induced hypertussive responses in rabbits and guinea pigs. Ozone induced a significant increase in cough frequency and a decrease in time to first cough to inhaled citric acid in both conscious guinea pigs and rabbits. This response was inhibited by the established antitussive drugs codeine and levodropropizine. In contrast to the guinea pig, hypertussive responses in the rabbit were not inhibited by bronchodilator drugs (β2 agonists or muscarinic receptor antagonists), suggesting that the observed hypertussive state was not secondary to bronchoconstriction in this species. The ozone-induced hypertussive response in the rabbit was inhibited by chronic pretreatment with capsaicin, suggestive of a sensitization of airway sensory nerve fibers. However, we could find no evidence for a role of TRPA1 in this response, suggesting that ozone was not sensitizing airway sensory nerves via activation of this receptor. Whereas the ozone-induced hypertussive response was accompanied by a significant influx of neutrophils into the airway, the hypertussive response was not inhibited by the anti-inflammatory phosphodiesterase 4 inhibitor roflumilast at a dose that clearly exhibited anti-inflammatory activity. In summary, our results suggest that ozone-induced hypertussive responses to citric acid may provide a useful model for the investigation of novel drugs for the treatment of cough, but some important differences were noted between the two species with respect to sensitivity to bronchodilator drugs.

  4. Ozone-Induced Hypertussive Responses in Rabbits and Guinea Pigs

    PubMed Central

    Clay, Emlyn; Patacchini, Riccardo; Trevisani, Marcello; Preti, Delia; Branà, Maria Pia; Spina, Domenico

    2016-01-01

    Cough remains a major unmet clinical need, and preclinical animal models are not predictive for new antitussive agents. We have investigated the mechanisms and pharmacological sensitivity of ozone-induced hypertussive responses in rabbits and guinea pigs. Ozone induced a significant increase in cough frequency and a decrease in time to first cough to inhaled citric acid in both conscious guinea pigs and rabbits. This response was inhibited by the established antitussive drugs codeine and levodropropizine. In contrast to the guinea pig, hypertussive responses in the rabbit were not inhibited by bronchodilator drugs (β2 agonists or muscarinic receptor antagonists), suggesting that the observed hypertussive state was not secondary to bronchoconstriction in this species. The ozone-induced hypertussive response in the rabbit was inhibited by chronic pretreatment with capsaicin, suggestive of a sensitization of airway sensory nerve fibers. However, we could find no evidence for a role of TRPA1 in this response, suggesting that ozone was not sensitizing airway sensory nerves via activation of this receptor. Whereas the ozone-induced hypertussive response was accompanied by a significant influx of neutrophils into the airway, the hypertussive response was not inhibited by the anti-inflammatory phosphodiesterase 4 inhibitor roflumilast at a dose that clearly exhibited anti-inflammatory activity. In summary, our results suggest that ozone-induced hypertussive responses to citric acid may provide a useful model for the investigation of novel drugs for the treatment of cough, but some important differences were noted between the two species with respect to sensitivity to bronchodilator drugs. PMID:26837703

  5. Chlamydial infection of subcutaneous conjunctival transplants in guinea pigs.

    PubMed

    Pham, R T; Sung, M; Dawson, C R; Schachter, J

    1990-07-01

    The development and testing of candidate vaccines for trachoma are constrained because only humans and nonhuman primates are susceptible to conjunctival infection with Chlamydia trachomatis. Guinea pig inclusion conjunctivitis (GPIC), an analogous disease of guinea pigs, provides a useful, less expensive model to study ocular chlamydial infections. GPIC is caused by a Chlamydia psittaci strain whose external constituents are very similar to those of C. trachomatis. To develop a better model for studying GPIC immunity, conjunctival pockets were established under the abdominal skin of guinea pigs by subcutaneous implantation. Up to six implants could be produced in each animal. The success rate of implantation was 79.0% (n = 148). These pockets were then infected with GPIC. The organism was recovered from the autografts indicating local replication, and tests for serum antibody by microimmunofluorescence showed production of GPIC-specific antibody of IgG and IgM classes after infection. There was minimal antibody response after moderate inoculating doses to the implants, and the titers increased more slowly than after eye infection with GPIC; with higher concentration of the inoculum, however, the antibody response increased to the same levels as with the ocular challenge but more slowly. Inoculation of pockets with GPIC also produced acute inflammatory changes in infected autografts (n = 101). Histologic examination of infected grafts showed chlamydial inclusions in epithelial cells and significant infiltration with lymphocytes and polymorphonuclear cells. Subcutaneous autografts may provide a useful model for chronologic studies of chlamydial infection. The delayed immunologic response, however, suggests that these pockets of implanted epithelium do not have full access to the immune system.

  6. Chlamydiales in guinea-pigs and their zoonotic potential.

    PubMed

    Lutz-Wohlgroth, L; Becker, A; Brugnera, E; Huat, Z L; Zimmermann, D; Grimm, F; Haessig, M; Greub, G; Kaps, S; Spiess, B; Pospischil, A; Vaughan, L

    2006-05-01

    The aim was to detect and characterize chlamydial infections in guinea-pigs (GP) with ocular disease, study their pathogenicity and zoonotic potential and to test for the presence of Acanthamoebae spp. in GP eyes and to investigate whether they could act as vectors for Chlamydia-like organisms. Overall 126 GP, of which 77 were symptomatic, were screened by clinical examination, cytology, gross pathology, histology, immunohistochemistry, polymerase chain reaction (PCR) and bacteriology. A new Chlamydiaceae-specific intergenic spacer rRNA gene PCR, designed to amplify this segment linking the 16S and 23S regions, was performed. DNA samples were also received from one owner including samples of his cat and rabbit. Guinea-pigs: 48 of 75 symptomatic, but only 11 of 48 asymptomatic GP were positive by PCR for Chlamydophila caviae guinea-pig inclusion conjunctivitis (GPIC) (P < 0.0001). Eighteen of 75 or 15/48, respectively, were positive for DNA from Chlamydia-like organisms. Acanthamoebae-DNA could be found in two GP, of which one was symptomatic. Owner, cat and rabbit: Samples of all three species were positive by PCR for C. caviae GPIC and the owner's one-day disposable contact lenses showed a positive PCR result for the Chlamydia-like organism Parachlamydia acanthamoebae. No Acanthamoebae-DNA could be detected. This study is the first to describe Chlamydia-like organisms in GP and to detect C. caviae GPIC in human, cat and rabbit. Therefore, C. caviae GPIC could pose a zoonotic potential. We believe that the finding of C. caviae GPIC in species other than GP is probably not unique.

  7. Growth failure after recurrent fever in young guinea pigs.

    PubMed

    Madu, S C; Faurie, A; Pettifor, J M; Laburn, H P

    2007-03-16

    Infection causes fever and suppression of appetite, a combination of effects which threatens normal growth in infected children. We have used an animal model to study the effects on growth of recurrent simulated Gram-positive bacterial infection. After weaning, 10 guinea pig pups underwent surgery under general anaesthesia for the implantation of temperature-sensitive radiotelemeters and thereafter were assigned to receive intramuscular injections of either 50 microg/kg muramyl dipeptide (MDP), or sterile saline. During a 30-day period corresponding to their rapid growth phase, the pups were given eight injections. MDP resulted in fevers of about 1.5 degrees C on each occasion, but no significant change in body temperature occurred after saline injections. Food intake was suppressed during each febrile episode such that 24-h intake was significantly lower on days of injections of MDP, compared to days between MDP injections in the same animals, and compared to that of animals injected with saline. The rate of weight gain of the MDP-injected guinea pigs was significantly lower than that of the control group and failed even to achieve a rate similar to the saline-injected group in their more adult-like growth phase. Plasma zinc concentration was significantly lower in MDP-compared to saline-injected animals sampled 8 days after the last injection. Our results show that recurrent fever during the growth phase of young guinea pigs results in irreversible growth failure, and that reduced food intake on days when the animals were febrile was at least partly responsible for this reduced rate of growth.

  8. Ozone-Induced Hypertussive Responses in Rabbits and Guinea Pigs.

    PubMed

    Clay, Emlyn; Patacchini, Riccardo; Trevisani, Marcello; Preti, Delia; Branà, Maria Pia; Spina, Domenico; Page, Clive

    2016-04-01

    Cough remains a major unmet clinical need, and preclinical animal models are not predictive for new antitussive agents. We have investigated the mechanisms and pharmacological sensitivity of ozone-induced hypertussive responses in rabbits and guinea pigs. Ozone induced a significant increase in cough frequency and a decrease in time to first cough to inhaled citric acid in both conscious guinea pigs and rabbits. This response was inhibited by the established antitussive drugs codeine and levodropropizine. In contrast to the guinea pig, hypertussive responses in the rabbit were not inhibited by bronchodilator drugs (β2 agonists or muscarinic receptor antagonists), suggesting that the observed hypertussive state was not secondary to bronchoconstriction in this species. The ozone-induced hypertussive response in the rabbit was inhibited by chronic pretreatment with capsaicin, suggestive of a sensitization of airway sensory nerve fibers. However, we could find no evidence for a role of TRPA1 in this response, suggesting that ozone was not sensitizing airway sensory nerves via activation of this receptor. Whereas the ozone-induced hypertussive response was accompanied by a significant influx of neutrophils into the airway, the hypertussive response was not inhibited by the anti-inflammatory phosphodiesterase 4 inhibitor roflumilast at a dose that clearly exhibited anti-inflammatory activity. In summary, our results suggest that ozone-induced hypertussive responses to citric acid may provide a useful model for the investigation of novel drugs for the treatment of cough, but some important differences were noted between the two species with respect to sensitivity to bronchodilator drugs. PMID:26837703

  9. Speckle based configuration for simultaneous in vitro inspection of mechanical contractions of cardiac myocyte cells

    NASA Astrophysics Data System (ADS)

    Golberg, Mark; Fixler, Dror; Shainberg, Asher; Zlochiver, Sharon; Micó, Vicente; Garcia, Javier; Beiderman, Yevgeny; Zalevsky, Zeev

    2013-04-01

    In this manuscript we propose optical lensless configuration for a remote non-contact measuring of mechanical contractions of vast number of cardiac myocytes. All the myocytes were taken from rats, and the measurements were done in an in vitro mode. The optical method is based on temporal analysis of secondary reflected speckle patterns generated in lensless microscope configuration. The processing involves analyzing the movement and the change in the statistics of the generated secondary speckle patterns that are created on top of the cell culture when it is illuminated by a spot of laser beam. The main advantage of the proposed system is the ability to measure many cells simultaneously (approximately one thousand cells) and to extract the statistical data of their movement at once. The presented experimental results also include investigation the effect of isoproteranol on cells contraction process.

  10. Allergy to guinea pigs: II Identification of specific allergens in guinea pig dust by crossed radio-immunoelectrophoresis and investigation of the possible origin.

    PubMed

    Walls, A F; Newman Taylor, A J; Longbottom, J L

    1985-11-01

    An extract of dust from the air-vent filters of a room housing guinea pigs was analysed by quantitative immunoelectrophoretic procedures and compared with extracts of various materials derived from guinea pigs. Crossed radio-immunoelectrophoresis (CRIE) of the dust, performed with sera from twenty asthmatic patients who were positive by skin testing and RAST to guinea pig extracts, identified fourteen IgE-binding constituents. Although responses varied, most sera reacted with four particular allergens, antigens 2, 3, 10 and Sl. The numbers of allergens recognized by individual patients correlated with the RAST score, but not with total serum IgE. All seventeen dust constituents detected by crossed immunoelectrophoresis (and all four major allergens), were also present in extracts of guinea pig dander, fur, saliva and urine; several of these components were absent in an epithelial extract, and there were even less in preparations of shaved pelt, serum or faeces. None of the dust extract antigens were detected in materials used in animal husbandry, dust samples from rooms without guinea pigs, or a D. pteronyssinus extract. These findings suggest that inhalant allergens may be derived predominantly from material shed from the guinea pig coat after contamination with saliva, and possibly to a lesser extent, urine. PMID:2416489

  11. Common Emergencies in Rabbits, Guinea Pigs, and Chinchillas.

    PubMed

    DeCubellis, Julie

    2016-05-01

    Rabbits, guinea pigs, and chinchillas are some of the more common exotic pets seen in emergency clinics. They frequently present with acute illnesses that are the result of several chronic conditions, most related to inadequate diet and husbandry. This article reviews the diagnosis and treatment of some of the more common acute illnesses. It also discusses the predisposing factors that culminate in acute presentations, so that emergency providers can recognize and be mindful of underlying causes of disease before treatment of acute illnesses. PMID:26948264

  12. Anatomy and Disorders of the Oral Cavity of Guinea Pigs.

    PubMed

    Legendre, Loic

    2016-09-01

    Acquired dental disease represents the most common oral disorder of guinea pigs. Most patients are presented with nonspecific clinical signs and symptoms, such as weight loss, reduced food intake, difficulty chewing and/or swallowing. The physical examination must be followed by standard radiography and/or computed tomography, and thorough inspection under general anesthesia. Several complications may follow, including periodontal disease, subluxation of the temporomandibular joint, periapical infection, and abscessation. The dental treatment is aimed to restore the proper length and shape of both the incisor and cheek teeth, associated with medical and supportive treatment. Abscesses should be surgically addressed by complete excision. PMID:27497208

  13. ATP-sensitive potassium channel modulation of the guinea pig ventricular action potential and contraction.

    PubMed

    Nichols, C G; Ripoll, C; Lederer, W J

    1991-01-01

    The role of ATP-sensitive potassium (KATP) channels in modulating the action potential and contraction of guinea pig ventricular myocytes was investigated. Under voltage clamp, the maximum whole-cell KATP channel conductance was estimated (195 +/- 10 nS, n = 6) by exposing the cells to complete metabolic blockade (2 mM cyanide in the presence of 10 mM 2-deoxy-glucose). In isolated inside-out membrane patches, the ATP dependence of KATP channel activity under relevant conditions was measured (half-maximal inhibition at 114 microM). Under current clamp (with intracellular ATP concentration = 5 mM), the effect of graded KATP channel activation on the action potential and the twitch was estimated by injection of a current (proportional to voltage) that simulated the KATP conductance. As this "conductance" was increased, the action potential was shortened, and contractile amplitude declined, as expected. From the results of these experiments, the quantitative dependence of the action potential duration on intracellular ATP concentration was estimated, without relying on a mathematical model of the cell membrane. The results imply that KATP-dependent action potential shortening is likely to occur if ATP concentration falls below normal levels (approximately 5 mM), as may happen regionally, or globally, during myocardial ischemia.

  14. Comparison of SERCA1 and SERCA2a expressed in COS-1 cells and cardiac myocytes.

    PubMed

    Sumbilla, C; Cavagna, M; Zhong, L; Ma, H; Lewis, D; Farrance, I; Inesi, G

    1999-12-01

    Cultured COS-1 cells, as well as chicken embryonic and neonatal rat cardiac myocytes, were infected with recombinant adenovirus vectors to define limiting factors in the expression and Ca2+ transport function of recombinant sarcoplasmic-endoplasmic reticulum Ca(2+) (SERCA) isoforms. Titration experiments showed that all COS-1 cells and myocytes in culture could be infected by an adenovirus titer of 10 plaque-forming units (pfu) per seeded cell. Raising the adenovirus titer further yielded higher protein expression up to an asymptotic limit for functional, membrane-bound SERCA protein. The asymptotic behavior of SERCA expression was not transcription related but was due to posttranscriptional events. The minimal (-268) cardiac troponin T (cTnT) promoter was a convenient size for adenovirus vector construction and manifested tight muscle specificity. However, its efficiency was lower than that of the nonspecific cytomegalovirus (CMV) promoter. At any rate, identical maximal levels of SERCA expression were obtained with the CMV and the cTnT promoter, as long as the viral titer was adjusted to compensate for transcription efficiency. A maximal threefold increase of total SERCA protein expression over the level of the endogenous SERCA of control myocytes was reached (a sevenfold increase compared with the endogenous SERCA of the same infected myocytes due to reduction of endogenous SERCA after infection). In contrast with previous reports [Ji et al. Am. J. Physiol. 276 (Heart Circ. Physiol. 45): H89-H97, 1999], a higher kinetic turnover was demonstrated for the SERCA1 compared with the SERCA2a isoform as shown by a 5.0- versus 2.6-fold increase in calcium uptake rate accompanying maximal expression of recombinant SERCA1 or SERCA2a, respectively. This information is deemed necessary for studies attempting to modify myocardial cell function by manipulation of SERCA expression.

  15. Optimal range for parvalbumin as relaxing agent in adult cardiac myocytes: gene transfer and mathematical modeling.

    PubMed Central

    Coutu, Pierre; Metzger, Joseph M

    2002-01-01

    Parvalbumin (PV) has recently been shown to increase the relaxation rate when expressed in intact isolated cardiac myocytes via adenovirus gene transfer. We report here a combined experimental and mathematical modeling approach to determine the dose-response and the sarcomere length (SL) shortening-frequency relationship of PV in adult rat cardiac myocytes in primary culture. The dose-response was obtained experimentally by observing the PV-transduced myocytes at different time points after gene transfer. Calcium transients and unloaded mechanical contractions were measured. The results were as follows. At low estimated [PV] (approximately 0.01 mM), contractile parameters were unchanged; at intermediate [PV], relaxation rate of the mechanical contraction and the decay rate of the calcium transient increased with little effects on amplitude; and at high [PV] (approximately 0.1 mM), relaxation rate was further increased, but the amplitudes of the mechanical contraction and the calcium transient were diminished when compared with control myocytes. The SL shortening-frequency relationship exhibited a biphasic response to increasing stimulus frequency in controls (decrease in amplitude and re-lengthening time from 0.2 to 1.0 Hz followed by an increase in these parameters from 2.0 to 4.0 Hz). The effect of PV was to flatten this frequency response. This flattening effect was partly explained by a reduction in the variation in fractional binding of PV to calcium during beats at high frequency. In conclusion, experimental results and mathematical modeling indicate that there is an optimal PV range for which relaxation rate is increased with little effect on contractile amplitude and that PV effectiveness decreases as the stimulus frequency increases. PMID:11964244

  16. Interferon-γ Causes Cardiac Myocyte Atrophy via Selective Degradation of Myosin Heavy Chain in a Model of Chronic Myocarditis

    PubMed Central

    Cosper, Pippa F.; Harvey, Pamela A.; Leinwand, Leslie A.

    2013-01-01

    Interferon-γ (IFN-γ), a proinflammatory cytokine, has been implicated in the pathogenesis of a number of forms of heart disease including myocarditis and congestive heart failure. In fact, overexpression of IFN-γ in mice causes dilated cardiomyopathy. However, the direct effects of IFN-γ on cardiac myocytes and the mechanism by which it causes cardiac dysfunction have not been described. Here, we present the molecular pathology of IFN-γ exposure and its effect on myofibrillar proteins in isolated neonatal rat ventricular myocytes. Treatment with IFN-γ caused cardiac myocyte atrophy attributable to a specific decrease in myosin heavy chain protein. This selective degradation of myosin heavy chain was not accompanied by a decrease in total protein synthesis or by an increase in total protein degradation. IFN-γ increased both proteasome and immunoproteasome activity in cardiac myocytes and their inhibition blocked myosin heavy chain loss and myocyte atrophy, whereas inhibition of the lysosome or autophagosome did not. Collectively, these results provide a mechanism by which IFN-γ causes cardiac pathology in the setting of chronic inflammatory diseases. PMID:23058369

  17. High Speed Striation Pattern Recognition In Contracting Cardiac Myocytes

    NASA Astrophysics Data System (ADS)

    Roos, Kenneth P.; Bliton, A. Christyne; Lubell, Bradford A.; Parker, John M.; Patton, Mark J.; Taylor, Stuart R.

    1989-06-01

    The understanding of muscle contraction and relaxation requires the quantitation of movement at the sub-micron level in living cells. Two complementary non-RS-170 imaging systems used for authentic real time measurement of contractile dynamics are described and compared. Images from isolated skeletal or cardiac muscle cells are projected by an optical microscope onto single line or area charge-coupled device (CCD) photodiode arrays. These data are digitized and stored for subsequent image processing and analysis. The inherently low contrast muscle striation patterns are enhanced and their rapid movement measured with an accuracy at least an order of magnitude greater than traditional limits of optical resolution. The features of each image format are complementary and when combined provide the maximum overall information in time and space.

  18. Hypertrophy, gene expression, and beating of neonatal cardiac myocytes are affected by microdomain heterogeneity in 3D

    PubMed Central

    Curtis, Matthew W.; Sharma, Sadhana; Desai, Tejal A.

    2011-01-01

    Cardiac myocytes are known to be influenced by the rigidity and topography of their physical microenvironment. It was hypothesized that 3D heterogeneity introduced by purely physical microdomains regulates cardiac myocyte size and contraction. This was tested in vitro using polymeric microstructures (G′=1.66 GPa) suspended with random orientation in 3D by a soft Matrigel matrix (G′=22.9 Pa). After 10 days of culture, the presence of 100 μm-long microstructures in 3D gels induced fold increases in neonatal rat ventricular myocyte size (1.61±0.06, p<0.01) and total protein/cell ratios (1.43± 0.08, p<0.05) that were comparable to those induced chemically by 50 μM phenylephrine treatment. Upon attachment to microstructures, individual myocytes also had larger cross-sectional areas (1.57±0.05, p<0.01) and higher average rates of spontaneous contraction (2.01±0.08, p<0.01) than unattached myocytes. Furthermore, the inclusion of microstructures in myocyte-seeded gels caused significant increases in the expression of beta-1 adrenergic receptor (β1-AR, 1.19±0.01), cardiac ankyrin repeat protein (CARP, 1.26±0.02), and sarcoplasmic reticulum calcium-ATPase (SERCA2, 1.59±0.12, p<0.05), genes implicated in hypertrophy and contractile activity. Together, the results demonstrate that cardiac myocyte behavior can be controlled through local 3D microdomains alone. This approach of defining physical cues as independent features may help to advance the elemental design considerations for scaffolds in cardiac tissue engineering and therapeutic microdevices. PMID:20668947

  19. Effect of thrombin on purine metabolism in the guinea pig heart

    SciTech Connect

    Whelton, B.K.; Thompson, C.I.; Sparks, H.V.

    1986-03-01

    In vitro coronary endothelial cells (EC) release adenosine (ADO) in response to thrombin (THR). The authors tested the hypothesis that THR causes the release of ADO from in situ EC of isolated guinea pig hearts. The authors preferentially labelled the EC by infusing 2,8-/sup 3/H-ADO (ADO; 5 x 10/sup -8/ M) into the heart for 30 minutes. Then THR (1 U/ml) or THR plus allopurinol (2.4 x 10-/sup 4M) was infused into the heart. Venous effluent samples analyzed for ADO, ADO and /sup 3/H-H/sub 2/O. THR increased the release of ADO from 32 +/- 11 pm/min/g to 175 +/- 47 after 4 minutes (p < 0.02, n = 5). Despite the increase in total ADO release, ADO did not increase. Release of H/sub 2/O increased from 10.1 +/- 10/sup 3/ dpm/min/g to 23.5 +/- 5.7 x 10/sup 3/ at 4 minutes. In the presence of the xanthine oxidase/dehydrogenase inhibitor allopurinol, H/sub 2/O release in response to THR fell to 3.6 +/- 1.2 x 10 dpm/min/gm. The authors conclude that the labelled EC are not the source of ADO released in response to THR. Instead the ADO released by THR comes from an unlabelled compartment, most likely the myocytes. This suggests that ADO release from myocytes may be a mechanism to regulate thrombogenesis. The THR-induced increase in H/sub 2/O release and it's inhibition by allopurinol indicates that THR enhances purine catabolism in EC.

  20. Gaining myocytes or losing fibroblasts: Challenges in cardiac fibroblast reprogramming for infarct repair.

    PubMed

    Nagalingam, Raghu S; Safi, Hamza A; Czubryt, Michael P

    2016-04-01

    Unlike most somatic tissues, the heart possesses a very limited inherent ability to repair itself following damage. Attempts to therapeutically salvage the myocardium after infarction, either by sparing surviving myocytes or by injection of exogenous cells of varied provenance, have met with limited success. Cardiac fibroblasts are numerous, resistant to hypoxia, and amenable to phenotype reprogramming to cardiomyocytes - a potential panacea to an intractable problem. However, the long-term effects of mass conversion of fibroblasts are as-yet unknown. Since fibroblasts play key roles in normal cardiac function, treating these cells as a ready source of replacements for myocytes may have the effect of swapping one problem for another. This review briefly examines the roles of cardiac fibroblasts, recaps the strides made so far in their reprogramming to cardiomyocytes both in vitro and in vivo, and discusses the potential ramifications of large-scale cellular identity swapping. While such therapy offers great promise, the potential repercussions require consideration and careful study. PMID:26640115

  1. Early afterdepolarizations in cardiac myocytes: beyond reduced repolarization reserve

    PubMed Central

    Qu, Zhilin; Xie, Lai-Hua; Olcese, Riccardo; Karagueuzian, Hrayr S.; Chen, Peng-Sheng; Garfinkel, Alan; Weiss, James N.

    2013-01-01

    Early afterdepolarizations (EADs) are secondary voltage depolarizations during the repolarizing phase of the action potential, which can cause lethal cardiac arrhythmias. The occurrence of EADs requires a reduction in outward current and/or an increase in inward current, a condition called reduced repolarization reserve. However, this generalized condition is not sufficient for EAD genesis and does not explain the voltage oscillations manifesting as EADs. Here, we summarize recent progress that uses dynamical theory to build on and advance our understanding of EADs beyond the concept of repolarization reserve, towards the goal of developing a holistic and integrative view of EADs and their role in arrhythmogenesis. We first introduce concepts from nonlinear dynamics that are relevant to EADs, namely, Hopf bifurcation leading to oscillations and basin of attraction of an equilibrium or oscillatory state. We then present a theory of phase-2 EADs in nonlinear dynamics, which includes the formation of quasi-equilibrium states at the plateau voltage, their stabilities, and the bifurcations leading to and terminating the oscillations. This theory shows that the L-type calcium channel plays a unique role in causing the nonlinear dynamical behaviours necessary for EADs. We also summarize different mechanisms of phase-3 EADs. Based on the dynamical theory, we discuss the roles of each of the major ionic currents in the genesis of EADs, and potential therapeutic targets. PMID:23619423

  2. Inorganic polyphosphate in cardiac myocytes: from bioenergetics to the permeability transition pore and cell survival.

    PubMed

    Dedkova, Elena N

    2016-02-01

    Inorganic polyphosphate (polyP) is a linear polymer of Pi residues linked together by high-energy phosphoanhydride bonds as in ATP. PolyP is present in all living organisms ranging from bacteria to human and possibly even predating life of this planet. The length of polyP chain can vary from just a few phosphates to several thousand phosphate units long, depending on the organism and the tissue in which it is synthesized. PolyP was extensively studied in prokaryotes and unicellular eukaryotes by Kulaev's group in the Russian Academy of Sciences and by the Nobel Prize Laureate Arthur Kornberg at Stanford University. Recently, we reported that mitochondria of cardiac ventricular myocytes contain significant amounts (280±60 pmol/mg of protein) of polyP with an average length of 25 Pi and that polyP is involved in Ca(2+)-dependent activation of the mitochondrial permeability transition pore (mPTP). Enzymatic polyP depletion prevented Ca(2+)-induced mPTP opening during ischaemia; however, it did not affect reactive oxygen species (ROS)-mediated mPTP opening during reperfusion and even enhanced cell death in cardiac myocytes. We found that ROS generation was actually enhanced in polyP-depleted cells demonstrating that polyP protects cardiac myocytes against enhanced ROS formation. Furthermore, polyP concentration was dynamically changed during activation of the mitochondrial respiratory chain and stress conditions such as ischaemia/reperfusion (I/R) and heart failure (HF) indicating that polyP is required for the normal heart metabolism. This review discusses the current literature on the roles of polyP in cardiovascular health and disease. PMID:26862184

  3. Synaptic localization of. kappa. opioid receptors in guinea pig neostriatum

    SciTech Connect

    Jomary, C.; Beaudet, A. ); Gairin, J.E. )

    1992-01-15

    Distribution of {kappa} opioid receptors was examined by EM radioautography in sections of guinea pig neostriatum with the selective {sup 125}I-labeled dynorphin analog (D-Pro{sup 10})dynorphin-(1-11). Most specifically labeled binding sites were found by probability circle analysis to be associated with neuronal membrane appositions. Because of limitations in resolution of the method, the radioactive sources could not be ascribed directly to either one of the apposed plasma membranes. Nevertheless, three lines of evidence favored a predominant association of ligand with dendrites of intrinsic striatal neurons: (1) the high frequency with which labeled interfaces implicated a dendrite, (2) the enrichment of dendrodendritic interfaces, and (3) the occurrence of dendritic profiles labeled at several contact points along their plasma membranes. A small proportion of labeled sites was associated with axo-axonic interfaces, which may subserve the {kappa} opioid-induced regulation of presynaptic dopamine and acetylcholine release documented in guinea pig neostriatum. These results support the hypothesis that in mammalian brain {kappa} opioid receptors are conformationally and functionally distinct from {mu} and {delta} types.

  4. Spasmolytic effect of traditional herbal formulation on guinea pig ileum

    PubMed Central

    Kumar, Dushyant; Ganguly, Kuntal; Hegde, H. V.; Patil, P. A.; Kholkute, S. D.

    2015-01-01

    Background: The herbal formulation consisting of Andrographis paniculata Nees., Cassia fistula L., Foeniculum vulgare Mill. and Cuminum cyminum L. is widely used by the local traditional practitioners in rural Northern Karnataka for spasmodic abdominal pain. Objective: The present study was undertaken to evaluate safety and spasmolytic effect of poly-herbal formulation. Materials and Methods: Acute toxicity studies were carried out in Swiss mice, as per the Organization for Economic Co-operation and Development (OECD) guidelines. The spasmolytic activity of the formulation was studied in isolated guinea pig ileum model using histamine and acetylcholine as agonists. The data were analyzed by one-way ANOVA, followed by Dunnetts post-hoc test and P ≤ 0.05 was considered as significant. Results: The formulation did not show any adverse toxic effects and found to be safe. It also showed significant (P < 0.05) relaxation in different agonist like histamine and acetylcholine-induced contractions in guinea pig ileum. Conclusion: Antispasmodic activity of the herbal formulation can be attributed to its atropine-like activity. The present findings, therefore, support its utility in spasmodic abdominal pain. PMID:26604555

  5. Pulmonary effects of acid sulfate inhalation in the guinea pig

    SciTech Connect

    Silbaugh, S.A.; Mauderly, J.L.; Wolff, R.K.; Carpenter, R.L.; Brownstein, D.G.; Harkema, J.R.; Rothenberg, S.J.

    1982-07-01

    Guinea pigs were exposed by inhalation for 1 to 8 hours to sulfuric acid aerosols of various sizes and concentrations in order to provide quantitative information for standards setting. The effects of sulfuric acid aerosols were examined to determine acute mortality, changes in respiratory function and morphology, response mechanisms, differences in individual sensitivity and changes in airway response to bronchoconstrictors. An aerosol generator for another sulfur-containing pollutant, ammonium bisulfite, was developed for use in animal exposures. Also, lung lesions which simulate human emphysema were produced by intratracheal elastase instillation to investigate a potential impaired animal model for sulfur pollutant exposures. Pulmonary mechanics, lung morphology, and histamine sensitivity data all suggest that the guinea pig reacts to sulfuric acid aerosols with a nearly all-or-none airway constrictive response. Results also indicate that the concentration at which this response occurs is affected by aerosol size, exposure profile and individual animal sensitivity. No acute pulmonary function changes were noted at concentrations below 15 mg/m/sup 3/. The reason for these differences is unknown.

  6. THE FINE STRUCTURE OF TESTICULAR INTERSTITIAL CELLS IN GUINEA PIGS

    PubMed Central

    Christensen, A. Kent

    1965-01-01

    In guinea pig testes perfused with either glutaraldehyde or osmium tetroxide fixative, the cytoplasm of the interstitial cells contains an exceptionally abundant agranular endoplasmic reticulum. The reticulum in central regions of the cell is a network of interconnected tubules, but in extensive peripheral areas the reticulum is commonly organized into closely packed, flattened cisternae which are fenestrated. Occasional small patches of the granular reticulum occur in the cytoplasm and connect freely with the agranular reticulum. The mitochondria have a dense matrix and contain cristae and some tubules. The Golgi complex is disperse and shows no evidence of secretory material. The cytoplasm also contains lipid droplets. Lipofuscin pigment granules are probably polymorphic residual bodies and contain three components: (1) a dense material which at high magnification shows a 75-A periodicity; (2) a medium-sized lipid droplet; and (3) a cap-like structure. In glutaraldehyde-perfused testis the interstitial cell cytoplasm appears to have the same density from cell to cell, and the agranular reticulum is tubular or cisternal but not in the form of empty vesicles. Thus the "dark" and "light" cells and the vesicular agranular reticulum sometimes encountered in other fixations may be artifacts. Biochemical results from other laboratories, correlated with the present findings, indicate that the membranes of the agranular endoplasmic reticulum in guinea pig interstitial cells are the site of at least two enzymes of androgen biosynthesis, the 17-hydroxylase and the 17-desmolase. PMID:19866687

  7. Noninvasive detection of airway constriction in awake guinea pigs

    SciTech Connect

    Silbaugh, S.A.; Mauderly, J.L.

    1984-01-01

    Tidal volume measured by the barometric method is very sensitive to increases in compression and expansion of alveolar gas, such as would be expected to occur during airway narrowing or closure. By comparing a barometric method tidal volume signal (VT') with a reference tidal volume (VT) obtained with a head-out pressure plethysmograph, a simple index related to gas compressibility effects was calculated (VT/VT'). Changes in this index were compared with decreases in dynamic compliance (Cdyn) during histamine aerosol challenge of 15 Charles River Hartley guinea pigs. Decreases in VT/VT' occurred during all aerosol challenges and were correlated with decreases in Cdyn. Decreases in VT/VT' were most marked at Cdyn values of less than 50% of base line. At Cdyn of less than 15% of base line, VT' was 3.1-4.8 times the VT reference signal. No increase in total pulmonary resistance was noted, and Cdyn and VT/VT' returned to base line after histamine exposure was stopped. The authors conclude that gas compressibility effects become substantial during histamine-induced airway constriction in the guinea pig and that the VT/VT' ratio appears to provide a simple noninvasive method of detecting these changes.

  8. Low barometric pressure aggravates neuropathic pain in guinea pigs.

    PubMed

    Sato, Jun; Itano, Yuya; Funakubo, Megumi; Mizoguchi, Hiroyuki; Itoh, Mariko; Mori, Rarami

    2011-10-01

    Several clinical studies have demonstrated a consistent relationship between changes in meteorological factors, particularly barometric pressure, and pain intensity in subjects with chronic pain. We have previously demonstrated that exposure to artificially low barometric pressure (LP) intensifies pain-related behaviors in rats with neuropathic pain. In the present study, guinea pigs with unilateral L5 spinal nerve ligation (SNL) were placed in a pressure-controlled chamber and subjected to LP of 10 or 27hPa below the ambient pressure. The SNL surgery led to increased hindpaw withdrawal frequencies to 34-, 59-, and 239-mN von Frey filaments (VFFs). When the SNL animals were subjected to both LP exposures consecutively, the hindpaw withdrawal frequencies further increased; the effect was most significant when the animals were exposed to LP 27hPa below ambient pressure. In contrast, no change was seen in a group of sham-operated control animals. These results indicate that fluctuations in LP within the range of natural weather patterns can potentiate neuropathic pain in guinea pigs.

  9. Chlamydial salpingitis in female guinea pigs receiving oral contraceptives.

    PubMed

    Barron, A L; Pasley, J N; Rank, R G; White, H J; Mrak, R E

    1988-01-01

    Female guinea pigs were given daily doses of a combination of oral contraceptive (OC) agents, consisting of mestranol and norethynodrel suspended in sesame oil or distilled H2O, and were infected in the genital tract with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC). Counts of chlamydial inclusions in cells of vaginal smears collected during infection, showed prolongation and enhancement of infection in OC-treated animals as compared with controls. Appearance of IgG and IgA antibodies to GPIC in genital secretions, as determined by enzyme-linked immunosorbent assay (ELISA), was also delayed in OC-treated animals as compared with controls. OC-treated infected animals were killed on days 15 and 43, and gross pathological evidence for ascending infection culminating in salpingitis was found in all of five and four of five animals, respectively. On the other hand, among untreated infected controls on each sacrifice day, only one of five animals had any evidence for ascending infection. Chlamydiae were detected by light and electron microscopy in fallopian tube tissue collected on day 15 following OC-treatment but not in tissue from control animals.

  10. Cutaneous sensitization to some polyisocyanate prepolymers in guinea pigs.

    PubMed

    Zissu, D; Binet, S; Limasset, J C

    1998-11-01

    Isocyanates are used extensively in the polyurethane industry. Pulmonary and dermal sensitization resulting from exposure to diisocyanates has frequently been reported, but the potential effects of polyisocyanates on health are less well known. Thus, since 1978, occupational exposure limits have been established for diisocyanates only. Nevertheless, respiratory diseases and dermatitis have been reported in the polyurethane industry after accidental isocyanate contact during spills or splashes. The aim of this experimental work was to assess the dermal hypersensitivity of guinea pigs to some polyisocyanate prepolymers by means of a well-conducted standard predictive Buehler test. Our results showed that dicyclohexylmethane 4,4'-diisocyanate (HMDI), toluylene 2,4-diisocyanate (TDI), TDI adduct triol, TDI isocyanurate, 1,6-hexamethylene diisocyanate (HDI), HDI isocyanurate, HDI biuret and isophorone diisocyanate (IPDI) induced dermal sensitization while IPDI isocyanurate did not. In conclusion, the dermal hypersensitivity of guinea pigs to some polyisocyanates was similar to those of their corresponding monomers except for IPDI isocyanurate, suggesting that the results from diisocyanate monomers could not be a valuable approach for the detection of the sensitization potency of the corresponding prepolymers.

  11. Five month persistence of Helicobacter pylori infection in guinea pigs.

    PubMed

    Sjunnesson, Hakan; Sturegard, Erik; Hynes, Sean; Willen, Roger; Feinstein, Ricardo; Wadstrom, Torkel

    2003-06-01

    Seven Dunkin-Hartley guinea pigs were infected with the Sydney strain of H. pylori (SS1). Gastric histopathology was evaluated and serum antibody response to H. pylori cell-surface proteins was analysed by enzyme immunoassay (EIA) and immunoblot. Tissue and faecal samples from five control animals were analysed for the presence of naturally occurring Helicobacter spp. infection by culture and Helicobacter genus-specific PCR. The H. pylori infection persisted for 5 months, in most animals accompanied by a histologically severe antral gastritis, exhibiting focal degeneration and necrosis of gastric crypt epithelium. Increased numbers of mitotic figures were observed in the gastric epithelium, indicating a regenerative process. Infected animals displayed specific antibodies towards H. pylori cell-surface proteins in immunoblot, whereas EIA was of dubious value creating false-positive results. Serum complement C3 and cholesterol levels appeared to be elevated in infected animals. Helicobacter spp. infection was not detected in the control animals. The persistent infection, accompanied by severe gastritis and a prominent serum antibody response, and the apparent absence of a natural Helicobacter spp. infection makes the guinea pig model useful in H. pylori research.

  12. Cortical evoked potentials recorded from the guinea pig without averaging.

    PubMed

    Walloch, R A

    1975-01-01

    Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.

  13. Bambuterol: uptake and metabolism in guinea pig isolated lungs

    SciTech Connect

    Ryrfeldt, A.; Nilsson, E.; Tunek, A.; Svensson, L.A.

    1988-03-01

    The lung uptake and biotransformation of /sup 3/H-bambuterol, a prodrug to terbutaline, were studied using isolated perfused and ventilated guinea pig lungs. /sup 14/C-Sucrose was used as an extracellular marker. The lung uptake of bambuterol was significantly (0.05 greater than or equal to P greater than or equal to 0.001) higher than that found for sucrose in single-pass perfusion experiments. High-performance liquid chromatographic (HPLC) analysis showed that 95.6 +/- 3.6% of the effluent /sup 3/H radioactivity was attributable to bambuterol. In recirculating experiments (120 min) the lung biotransformation of /sup 3/H-bambuterol (8.5 pmol/ml) was studied. Both oxidative and hydrolytic metabolism took place. The dominating metabolites were hydroxylated bambuterol and the monocarbamate derivative which is a product of hydrolysis of bambuterol. Traces of terbutaline were also formed. The results show that bambuterol has a certain affinity to lung tissue and that the drug is, to some extent, biotransformed in the guinea pig lung.

  14. Characterization of gastrin receptors on guinea pig pancreatic acini

    SciTech Connect

    Yu, Dahong; Noguchi, Masato; Zhou, Zhichao; Villanueva, M.L.; Gardner, J.D.; Jensen, R.T. )

    1987-12-01

    Recent studies have demonstrated gastrin receptors in some pancreatic tumors and that gastrin is a potent stimulant of pancreatic Na{sup +}-H{sup +} exchange. In the present study the authors used {sup 125}I-labeled gastrin ({sup 125}I-gastrin) to characterize gastrin receptors on guinea pig pancreatic acini. Binding of {sup 125}I-gastrin was temperature dependent, saturable, and specific for gastrin-related peptides. Analysis demonstrated a single class of receptors with high affinity for gastrin and a binding capacity of 1 fmol/mg protein. Binding of {sup 125}I-gastrin was inhibited with the following relative potencies: cholecystokinin octapeptide (CCK-8) > gastrin-17-I = gastrin-34-I > pentagastrin > desulfated (des(SO{sub 3}))CCK-8 > CCK-4 and by the receptor antagonists CBZ-CCK-27-32-NH{sub 2} > proglumide analogue 10 > asperlicin > Bt{sub 2}-guanosine 3{prime},5{prime}-cyclic monophosphate. The present results demonstrate that guinea pig pancreatic acini possess gastrin receptors that have a high affinity for gastrin and are distinct from CCK receptors previously described. Only occupation of the CCK receptors results in enzyme secretion. Gastrin receptors on pancreatic acini resemble those described in parietal cells and gastric glands; however, their function is unknown.

  15. Evidence for independent evolution of functional progesterone withdrawal in primates and guinea pigs

    PubMed Central

    Nnamani, Mauris C.; Plaza, Silvia; Romero, Roberto; Wagner, Günter P.

    2013-01-01

    Background and objectives: Cervix remodeling (CRM) is a critical process in preparation for parturition. Early cervix shortening is a powerful clinical predictor of preterm birth, and thus understanding how CRM is regulated is important for the prevention of prematurity. Humans and other primates differ from most other mammals by the maintenance of high levels of systemic progesterone concentrations. Humans have been hypothesized to perform functional progesterone withdrawal (FPW). Guinea pigs are similar to humans in maintaining high-progesterone concentrations through parturition, thus making them a prime model for studying CRM. Here, we analyze the phylogenetic history of FPW and document gene expression in the guinea pig uterine cervix. Methodology: Data on progesterone withdrawal were collected from the literature, and character evolution was analyzed. Uterine cervix samples were collected from non-pregnant, mid-pregnant and late pregnant guinea pigs. RNA was extracted and sequenced. Relative transcript levels were estimated and compared among sample groups. Results: The phylogenetic analysis shows that FPW evolved independently in primates and guinea pigs. The transcriptome data confirms that guinea pigs down-regulate progesterone receptor toward parturition, in contrast to humans. Some of the similarities between human and guinea pig are: down-regulation of estrogen receptor, up-regulation of VCAN and IGFBP4 as well as likely involvement of prostaglandins. Conclusions and implications: (i) FPW in guinea pigs evolved independently from that in primates. (ii) A small set of conserved gene regulatory changes has been detected. PMID:24481205

  16. Temperature Preference in IAF Hairless and Hartley Guinea Pigs (Cavia porcellus)

    PubMed Central

    Kleven, Gale A; Joshi, Prianca

    2016-01-01

    The Hairless strain of guinea pigs (Cavia porcellus) is the result of a spontaneous recessive mutation first identified at the Institute Armand Frappier (IAF) in 1978. Despite the longstanding availability of this strain, little is known about its thermoregulatory behavior. The aim of this study was to determine temperature preference in Hartley and Hairless guinea pigs by observing each strain in a ring-shaped apparatus containing a nonlinear temperature gradient. Temperatures were maintained by separately controlled heating mats lining the apparatus. Set point temperatures ranged from 24 to 38 °C. Guinea pigs (Hartley female, Hairless female, and Hairless male guinea pigs; n = 8 each group) were placed either singly or in pairs at 1 of the 8 randomized starting points within the apparatus. Subjects were observed for 30 min and coded for location within the temperature gradient by both frequency and duration. When placed singly in the apparatus, all 3 groups spent more time in the 30 °C zones. However, when placed as pairs with a cagemate, Hartley female guinea pigs spent more time in the cooler range of temperatures from 24 to 30 °C, whereas Hairless guinea pigs preferred a range of 30 to 38 °C. These results confirm a temperature preference of 30 ± 2 °C for both Hartley and Hairless guinea pigs when singly housed. However, data from the paired housing condition suggest that context plays an important role in thermoregulatory behavior. PMID:27025807

  17. Investigation Into the Humaneness of Slaughter Methods for Guinea Pigs (Cavia porcelus) in the Andean Region

    PubMed Central

    Limon, Georgina; Gonzales-Gustavson, Eloy A.; Gibson, Troy J.

    2016-01-01

    Guinea pigs (Cavia porcelus) are an important source of nonhuman animal protein in the Andean region of South America. Specific guidelines regarding the welfare of guinea pigs before and during slaughter have yet to be developed. This study critically assessed the humaneness of 4 different stunning/slaughter methods for guinea pigs: cervical neck dislocation (n = 60), electrical head-only stunning (n = 83), carbon dioxide (CO2) stunning (n = 21), and penetrating captive bolt (n = 10). Following cervical neck dislocation, 97% of guinea pigs had at least 1 behavioral or cranial/spinal response. Six percent of guinea pigs were classified as mis-stunned after electrical stunning, and 1% were classified as mis-stunned after captive bolt. Increased respiratory effort was observed during CO2 stunning. Apart from this finding, there were no other obvious behavioral responses that could be associated with suffering. Of the methods assessed, captive bolt was deemed the most humane, effective, and practical method of stunning guinea pigs. Cervical neck dislocation should not be recommended as a slaughter method for guinea pigs. PMID:26963642

  18. Cardiac intercellular communication: are myocytes and fibroblasts fair-weather friends?

    PubMed

    Martin, Melissa L; Blaxall, Burns C

    2012-12-01

    The cardiac fibroblast (CF) has historically been thought of as a quiescent cell of the heart, passively maintaining the extracellular environment for the cardiomyocytes (CM), the functional cardiac cell type. The increasingly appreciated role of the CF, however, extends well beyond matrix production, governing many aspects of cardiac function including cardiac electrophysiology and contractility. Importantly, its contributions to cardiac pathophysiology and pathologic remodeling have created a shift in the field's focus from the CM to the CF as a therapeutic target in the treatment of cardiac diseases. In response to cardiac injury, the CF undergoes a pathologic phenotypic transition into a myofibroblast, characterized by contractile smooth muscle proteins and upregulation of collagens, matrix proteins, and adhesion molecules. Further, the myofibroblast upregulates expression and secretion of a variety of pro-inflammatory, profibrotic mediators, including cytokines, chemokines, and growth factors. These mediators act in both an autocrine fashion to further activate CFs, as well as in a paracrine manner on both CMs and circulating inflammatory cells to induce myocyte dysfunction and chronic inflammation, respectively. Together, cell-specific cytokine-induced effects exacerbate pathologic remodeling and progression to HF. A better understanding of this dynamic intercellular communication will lead to novel targets for the attenuation of cardiac remodeling. Current strategies aimed at targeting cytokines have been largely unsuccessful in clinical trials, lending insights into ways that such intercellular cross talk can be more effectively attenuated. This review will summarize the current knowledge regarding CF functions in the heart and will discuss the regulation and signaling behind CF-mediated cytokine production and function. We will then highlight clinical trials that have exploited cytokine cross talk in the treatment of heart failure and provide novel

  19. Pathogenesis of a Chinese strain of bovine adenovirus type 3 infection in albino guinea pigs.

    PubMed

    Shi, Hong-Fei; Zhu, Yuan-Mao; Yan, Hao; Ma, Lei; Wang, Xue-Zhi; Xue, Fei

    2014-12-01

    Bovine adenovirus type 3 (BAV-3) is considered one of the most important respiratory tract agents of cattle and is widespread among cattle around the world. A BAV-3 strain was isolated from a bovine nasal swab for the first time in China in 2009 and named HLJ0955. Subsequently, BAV-3 has frequently been isolated from calves with respiratory diseases in China. To date, only limited study on the pathogenesis of BAV-3 infection in cotton rats has been conducted, and the pathogenesis of BAV-3 infection in guinea pigs has not been reported. Therefore, sixteen albino guinea pigs were inoculated intranasally with HLJ0955. All of the infected guinea pigs had apparently elevated rectal temperatures (39.2 °C-39.9 °C) at 2-7 days post-inoculation (PI). Consolidation and petechial hemorrhage were also observed in guinea pigs experimentally infected with HLJ0955. Viral replication was detectable by virus isolation and titration and by immunohistochemistry in the lungs of guinea pigs as early as 24 h PI. Viral DNA was detectable in the lungs of infected guinea pigs during 11 days of observation by real-time PCR. Virus-neutralizing antibodies against BAV-3 were detectable from 11 days PI and reached a peak titer at 15 days PI. Histopathological changes mainly occurred in the lungs of infected guinea pigs and were characterized by thickening of alveolar septa, mononuclear cell infiltration, hemorrhage and alveolar epithelial necrosis. These results indicate that HLJ0955 can replicate in the lungs of guinea pigs and cause fever and gross and histological lesions. The guinea pig infection model of BAV-3 would serve as a useful system for monitoring the infection process and pathogenesis of the Chinese BAV-3 strain HLJ0955, as well as immune responses to BAV-3 vaccines.

  20. Therapeutic efficacy of oral lactobacillus preparation for antibiotic-associated enteritis in guinea pigs.

    PubMed

    Wasson, K; Criley, J M; Clabaugh, M B; Koch, M A; Peper, R L

    2000-01-01

    Enteritis is a potential complication of antimicrobial agent use, particularly in certain species of rodents. The organism most frequently implicated in this disease is Clostridium difficile. Anecdotal information suggests that administration of yogurt or other Lactobacillus-containing products in conjunction with antimicrobial agents will prevent or minimize the effects of antibiotic-associated enteritis. We wanted to determine whether a single subcutaneous injection of clindamycin phosphate could induce enteritis in guinea pigs and whether a commercial Lactobacillus preparation would ameliorate the clinical effects of antibiotic administration in these animals. Juvenile male guinea pigs were divided into three treatment groups. Group 1 guinea pigs (n=8) received a single saline injection followed by an oral Lactobacillus preparation twice daily; group 2 (n=8) received a single antibiotic injection followed by an oral Lactobacillus preparation twice daily; group 3 (n=8) received a single antibiotic injection. Attitude, body temperature, body weight, and feed and water consumption were recorded for each guinea pig 7 days prior to and after treatment. Fecal samples were collected and necropsies performed on each guinea pig at the time of euthanasia. C. difficile and other enteric pathogens were not isolated from any group before or after treatment, although some guinea pigs receiving the antibiotic developed enteritis. There were no significant clinical differences between guinea pigs receiving antibiotics with the oral Lactobacillus preparation, and those receiving antibiotics alone. The results of this study suggest that a single injection of clindamycin phosphate can induce enteritis in guinea pigs and that oral administration of a Lactobacillus-containing product is ineffective in preventing clinical disease in guinea pigs administered clindamycin phosphate.

  1. Natural infection of guinea pigs exposed to patients with highly drug-resistant tuberculosis

    PubMed Central

    Dharmadhikari, Ashwin S.; Basaraba, Randall J.; Van Der Walt, Martie L.; Weyer, Karin; Mphahlele, Matsie; Venter, Kobus; Jensen, Paul A.; First, Melvin W.; Parsons, Sydney; McMurray, David N.; Orme, Ian M.; Nardell, Edward A.

    2012-01-01

    A natural TB infection model using guinea pigs may provide useful information for investigating differences in transmission efficiency and establishment of active disease by clinical TB strains in a highly susceptible host under controlled environmental conditions. We sought to examine the capacity of naturally transmitted multidrug-resistant M. tuberculosis to establish infection and produce active disease in guinea pigs. Guinea pigs were continuously exposed for 4 months to the exhaust air of a 6-bed multidrug-resistant tuberculosis inpatient hospital ward in South Africa. Serial tuberculin skin test reactions were measured to determine infection. All animals were subsequently evaluated for histologic disease progression at necropsy. Although 75% of the 362 exposed guinea pigs had positive skin test reactions [≥6mm], only 12% had histopathologic evidence of active disease. Reversions (≥ 6 mm change) in skin test reactivity were seen in 22% of animals, exclusively among those with reactions of 6 to 13 mm. Only two of 86 guinea pigs with reversion had histological evidence of disease compared to 47% (31/66) of guinea pigs with large, non-reverting reactions. Immunosuppression of half the guinea pigs across all skin test categories did not significantly accelerate disease progression. In guinea pigs that reverted a skin test, a second positive reaction in 27 (33%) of them strongly suggested re-infection due to ongoing exposure. These results show that a large majority of guinea pigs naturally exposed to human-source strains of multidrug-resistant tuberculosis became infected, but that many resolved their infection and a large majority failed to progress to detectable disease. PMID:21478054

  2. Cardiac sodium channel palmitoylation regulates channel availability and myocyte excitability with implications for arrhythmia generation

    PubMed Central

    Pei, Zifan; Xiao, Yucheng; Meng, Jingwei; Hudmon, Andy; Cummins, Theodore R.

    2016-01-01

    Cardiac voltage-gated sodium channels (Nav1.5) play an essential role in regulating cardiac electric activity by initiating and propagating action potentials in the heart. Altered Nav1.5 function is associated with multiple cardiac diseases including long-QT3 and Brugada syndrome. Here, we show that Nav1.5 is subject to palmitoylation, a reversible post-translational lipid modification. Palmitoylation increases channel availability and late sodium current activity, leading to enhanced cardiac excitability and prolonged action potential duration. In contrast, blocking palmitoylation increases closed-state channel inactivation and reduces myocyte excitability. We identify four cysteines as possible Nav1.5 palmitoylation substrates. A mutation of one of these is associated with cardiac arrhythmia (C981F), induces a significant enhancement of channel closed-state inactivation and ablates sensitivity to depalmitoylation. Our data indicate that alterations in palmitoylation can substantially control Nav1.5 function and cardiac excitability and this form of post-translational modification is likely an important contributor to acquired and congenital arrhythmias. PMID:27337590

  3. Immunity to vaginal reinfection in female guinea pigs infected sexually with Chlamydia of guinea pig inclusion conjunctivitis.

    PubMed

    Lamont, H C; Semine, D Z; Leveille, C; Nichols, R L

    1978-03-01

    Guinea pig boars were inoculated intraurethrally with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC). At the heights of their urethral infections, they were caged with sows in estrus. Whereas some of the sows had not been previously exposed to GPIC agent, others had received an intravaginal inoculation 5 to 8 weeks earlier. Those sows for which infected boars provided the first exposure were challenged by intravaginal inoculation 5 to 8 weeks later. Vaginal and conjunctival scrapings were taken regularly and stained for chlamydial inclusions. Titers of serum anti-GPIC antibodies and of vaginal secretory IgA anti-GPIC antibodies were determined by immunofluorescence. Our results show for the first time that a sexually acquired vaginal GPIC infection induces immunity to manual reinfection of the vagina. Because of the high incidence of secondary conjunctival infections among the vaginally infected sows, we could not provide a sound statistical basis for our tentative conclusion that manual infection of the vagina induces immunity to sexual reinfection. The results of our antibody titrations confirm previous work showing that vaginal GPIC infection induces formation of both serum antibody and vaginal secretory immunoglobulin A antibody.

  4. Lead acetate action on anaphylactic response of guinea pig smooth muscle.

    PubMed

    Gijón, E; Cartas, L; García, X

    2001-01-01

    Experiments were performed to evaluate lead acetate effects on the anaphylactic contraction in guinea pigs smooth muscles. Aortic rings from guinea pigs exposed to lead acetate developed an anaphylactic contraction significantly lower than the contraction induced by the antigen in controls. In the smooth muscle of the intestine, lead acetate did not modify the anaphylactic response. Lead induced immunosuppression of the anaphylactic response of aortic rings, whereas sodium acetate had no effect on the anaphylactic reaction of the guinea pig smooth muscle. The amplitude of the norepinephrine contraction was not modified by lead nor by sodium acetate.

  5. Heat production of quiescent ventricular trabeculae isolated from guinea-pig heart.

    PubMed Central

    Daut, J; Elzinga, G

    1988-01-01

    1. A new calorimetric technique has been developed which allows continuous measurement of the rate of energy expenditure in superfused preparations of cardiac muscle. Thin trabeculae of guinea-pig ventricular muscle were mounted in a Perspex tube of 0.8 mm inner diameter and the temperature difference of the perfusate upstream and downstream of the preparation was measured. 2. The resting heat rate of trabeculae of 240-575 microns diameter from guinea-pig heart was determined repeatedly for up to 6 h after cardiectomy. It did not vary with time during the course of the experiment. 3. The average resting heat rate measured in HEPES-buffered Tyrode solution containing 20 mM-glucose and 2 mM-pyruvate as substrates was 130 +/- 29 mW/g dry weight or 36 +/- 8 mW/cm3 of tissue (n = 15). This is an order of magnitude larger than the resting heat rate reported in the literature for isolated cardiac preparations. 4. After omitting the pyruvate from the superfusate the resting heat rate decreased to 60-70% of its steady value within 4 min. After readmission of pyruvate this effect was reversed. The average resting heat rate with glucose as sole substrate was 23 +/- 4 mW/cm3. 5. Uncoupling of the mitochondria by 50 microM-2,4-dinitrophenol (DNP) increased the heat rate up to 170 mW/cm3. This effect could be maintained for several minutes and was fully reversible. Raising the external K+ concentration to 150 mM (NaCl replaced by KCl) induced a transient rise in the rate of heat production up to 115 mW/cm3. 6. The heat production during uncoupling of the mitochondria and during potassium contractures was inversely related to the diameter of the preparation. Calculation based on Hill's equation (Hill, 1928) indicated that this was caused by the development of anoxia at the core of the preparation. 7. In contrast, the rate of heat production of quiescent preparations was not correlated with diameter and calculation indicated that at rest there was no anoxic core. The high value of

  6. An integrative model of the cardiac ventricular myocyte incorporating local control of Ca2+ release.

    PubMed Central

    Greenstein, Joseph L; Winslow, Raimond L

    2002-01-01

    The local control theory of excitation-contraction (EC) coupling in cardiac muscle asserts that L-type Ca(2+) current tightly controls Ca(2+) release from the sarcoplasmic reticulum (SR) via local interaction of closely apposed L-type Ca(2+) channels (LCCs) and ryanodine receptors (RyRs). These local interactions give rise to smoothly graded Ca(2+)-induced Ca(2+) release (CICR), which exhibits high gain. In this study we present a biophysically detailed model of the normal canine ventricular myocyte that conforms to local control theory. The model formulation incorporates details of microscopic EC coupling properties in the form of Ca(2+) release units (CaRUs) in which individual sarcolemmal LCCs interact in a stochastic manner with nearby RyRs in localized regions where junctional SR membrane and transverse-tubular membrane are in close proximity. The CaRUs are embedded within and interact with the global systems of the myocyte describing ionic and membrane pump/exchanger currents, SR Ca(2+) uptake, and time-varying cytosolic ion concentrations to form a model of the cardiac action potential (AP). The model can reproduce both the detailed properties of EC coupling, such as variable gain and graded SR Ca(2+) release, and whole-cell phenomena, such as modulation of AP duration by SR Ca(2+) release. Simulations indicate that the local control paradigm predicts stable APs when the L-type Ca(2+) current is adjusted in accord with the balance between voltage- and Ca(2+)-dependent inactivation processes as measured experimentally, a scenario where common pool models become unstable. The local control myocyte model provides a means for studying the interrelationship between microscopic and macroscopic behaviors in a manner that would not be possible in experiments. PMID:12496068

  7. NFAT transcription factor regulation by urocortin II in cardiac myocytes and heart failure.

    PubMed

    Walther, Stefanie; Awad, Sawsan; Lonchyna, Vassyl A; Blatter, Lothar A

    2014-03-01

    Urocortin II (UcnII), a cardioactive peptide with beneficial effects in normal and failing hearts, is also arrhythmogenic and prohypertrophic. We demonstrated that cardiac effects are mediated by a phosphatidylinositol-3 kinase (PI3K)/Akt kinase (Akt)/endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) signaling pathways. Nuclear factor of activated T-cells (NFAT) transcription factors play a key role in the regulation of gene expression in cardiac development, maintenance of an adult differentiated cardiac phenotype, and remodeling processes in cardiac hypertrophy and heart failure (HF). We tested the hypothesis that UcnII differentially regulates NFAT activity in cardiac myocytes from both normal and failing hearts through the PI3K/Akt/eNOS/NO pathway. Isoforms NFATc1 and NFATc3 revealed different basal subcellular distribution in normal and HF rabbit ventricular myocytes with a nuclear NFATc1 and a cytosolic localization of NFATc3. However, in HF, the nuclear localization of NFATc1 was less pronounced, whereas the nuclear occupancy of NFATc3 was increased. In normal myocytes, UcnII induced nuclear export of NFATc1 and attenuated NFAT-dependent transcriptional activity but did not affect the distribution of NFATc3. In HF UcnII facilitated nuclear export of both isoforms and reduced transcriptional activity. NFAT regulation was mediated by a PI3K/Akt/eNOS/NO signaling cascade that converged on the activation of several kinases, including glycogen synthase kinase-3β (GSK3β), c-Jun NH2-terminal kinase (JNK), p38 mitogen-activated kinase (p38), and PKG, resulting in phosphorylation, deactivation, and nuclear export of NFAT. In conclusion, while NFATc1 and NFATc3 reveal distinct subcellular distribution patterns, both are regulated by the UcnII-PI3K/Akt/eNOS/NO pathway that converges on the activation of NFAT kinases and NFAT inactivation. The data reconcile cardioprotective and prohypertrophic UcnII effects mediated by different NFAT isoforms.

  8. Sarcolemmal ATP-sensitive potassium channel protects cardiac myocytes against lipopolysaccharide-induced apoptosis.

    PubMed

    Zhang, Xiaohui; Zhang, Xiaohua; Xiong, Yiqun; Xu, Chaoying; Liu, Xinliang; Lin, Jian; Mu, Guiping; Xu, Shaogang; Liu, Wenhe

    2016-09-01

    The sarcolemmal ATP-sensitive K+ (sarcKATP) channel plays a cardioprotective role during stress. However, the role of the sarcKATP channel in the apoptosis of cardiomyocytes and association with mitochondrial calcium remains unclear. For this purpose, we developed a model of LPS-induced sepsis in neonatal rat cardiomyocytes (NRCs). The TUNEL assay was performed in order to detect the apoptosis of cardiac myocytes and the MTT assay was performed to determine cellular viability. Exposure to LPS significantly decreased the viability of the NRCs as well as the expression of Bcl-2, whereas it enhanced the activity and expression of the apoptosis-related proteins caspase-3 and Bax, respectively. The sarcKATP channel blocker, HMR-1098, increased the apoptosis of NRCs, whereas the specific sarcKATP channel opener, P-1075, reduced the apoptosis of NRCs. The mitochondrial calcium uniporter inhibitor ruthenium red (RR) partially inhibited the pro-apoptotic effect of HMR-1098. In order to confirm the role of the sarcKATP channel, we constructed a recombinant adenovirus vector carrying the sarcKATP channel mutant subunit Kir6.2AAA to inhibit the channel activity. Kir6.2AAA adenovirus infection in NRCs significantly aggravated the apoptosis of myocytes induced by LPS. Elucidating the regulatory mechanisms of the sarcKATP channel in apoptosis may facilitate the development of novel therapeutic targets and strategies for the management of sepsis and cardiac dysfunction. PMID:27430376

  9. Transforming growth factor-{beta}2 enhances differentiation of cardiac myocytes from embryonic stem cells

    SciTech Connect

    Kumar, Dinender . E-mail: Dinender.Kumar@uvm.edu; Sun, Baiming

    2005-06-24

    Stem cell therapy holds great promise for the treatment of injured myocardium, but is challenged by a limited supply of appropriate cells. Three different isoforms of transforming growth factor-{beta} (TGF-{beta}) -{beta}1, -{beta}2, and -{beta}3 exhibit distinct regulatory effects on cell growth, differentiation, and migration during embryonic development. We compared the effects of these three different isoforms on cardiomyocyte differentiation from embryonic stem (ES) cells. In contrast to TGF-{beta}1, or -{beta}3, treatment of mouse ES cells with TGF-{beta}2 isoform significantly increased embryoid body (EB) proliferation as well as the extent of the EB outgrowth that beat rhythmically. At 17 days, 49% of the EBs treated with TGF-{beta}2 exhibited spontaneous beating compared with 15% in controls. Cardiac myocyte specific protein markers sarcomeric myosin and {alpha}-actin were demonstrated in beating EBs and cells isolated from EBs. In conclusion, TGF-{beta}2 but not TGF-{beta}1, or -{beta}3 promotes cardiac myocyte differentiation from ES cells.

  10. Sarcolemmal ATP-sensitive potassium channel protects cardiac myocytes against lipopolysaccharide-induced apoptosis

    PubMed Central

    Zhang, Xiaohui; Zhang, Xiaohua; Xiong, Yiqun; Xu, Chaoying; Liu, Xinliang; Lin, Jian; Mu, Guiping; Xu, Shaogang; Liu, Wenhe

    2016-01-01

    The sarcolemmal ATP-sensitive K+ (sarcKATP) channel plays a cardioprotective role during stress. However, the role of the sarcKATP channel in the apoptosis of cardiomyocytes and association with mitochondrial calcium remains unclear. For this purpose, we developed a model of LPS-induced sepsis in neonatal rat cardiomyocytes (NRCs). The TUNEL assay was performed in order to detect the apoptosis of cardiac myocytes and the MTT assay was performed to determine cellular viability. Exposure to LPS significantly decreased the viability of the NRCs as well as the expression of Bcl-2, whereas it enhanced the activity and expression of the apoptosis-related proteins caspase-3 and Bax, respectively. The sarcKATP channel blocker, HMR-1098, increased the apoptosis of NRCs, whereas the specific sarcKATP channel opener, P-1075, reduced the apoptosis of NRCs. The mitochondrial calcium uniporter inhibitor ruthenium red (RR) partially inhibited the pro-apoptotic effect of HMR-1098. In order to confirm the role of the sarcKATP channel, we constructed a recombinant adenovirus vector carrying the sarcKATP channel mutant subunit Kir6.2AAA to inhibit the channel activity. Kir6.2AAA adenovirus infection in NRCs significantly aggravated the apoptosis of myocytes induced by LPS. Elucidating the regulatory mechanisms of the sarcKATP channel in apoptosis may facilitate the development of novel therapeutic targets and strategies for the management of sepsis and cardiac dysfunction. PMID:27430376

  11. Important role of energy-dependent mitochondrial pathways in cultured rat cardiac myocyte apoptosis.

    PubMed

    Shiraishi, J; Tatsumi, T; Keira, N; Akashi, K; Mano, A; Yamanaka, S; Matoba, S; Asayama, J; Yaoi, T; Fushiki, S; Fliss, H; Nakagawa, M

    2001-10-01

    Recent studies have suggested that apoptosis and necrosis share common features in their signaling pathway and that apoptosis requires intracellular ATP for its mitochondrial/apoptotic protease-activating factor-1 suicide cascade. The present study was, therefore, designed to examine the role of intracellular energy levels in determining the form of cell death in cardiac myocytes. Neonatal rat cardiac myocytes were first incubated for 1 h in glucose-free medium containing oligomycin to achieve metabolic inhibition. The cells were then incubated for another 4 h in similar medium containing staurosporine and graded concentrations of glucose to manipulate intracellular ATP levels. Under ATP-depleting conditions, the cell death caused by staurosporine was primarily necrotic, as determined by creatine kinase release and nuclear staining with ethidium homodimer-1. However, under ATP-replenishing conditions, staurosporine increased the percentage of apoptotic cells, as determined by nuclear morphology and DNA fragmentation. Caspase-3 activation by staurosporine was also ATP dependent. However, loss of mitochondrial transmembrane potential (DeltaPsi(m)), Bax translocation, and cytochrome c release were observed in both apoptotic and necrotic cells. Moreover, cyclosporin A, an inhibitor of mitochondrial permeability transition, attenuated staurosporine-induced apoptosis and necrosis through the inhibition of DeltaPsi(m) reduction, cytochrome c release, and caspase-3 activation. Our data therefore suggest that staurosporine induces cell demise through a mitochondrial death signaling pathway and that the presence of intracellular ATP favors a shift from necrosis to apoptosis through caspase activation. PMID:11557554

  12. Glucose deprivation causes oxidative stress and stimulates aggresome formation and autophagy in cultured cardiac myocytes.

    PubMed

    Marambio, Paola; Toro, Barbra; Sanhueza, Carlos; Troncoso, Rodrigo; Parra, Valentina; Verdejo, Hugo; García, Lorena; Quiroga, Clara; Munafo, Daniela; Díaz-Elizondo, Jessica; Bravo, Roberto; González, María-Julieta; Diaz-Araya, Guilermo; Pedrozo, Zully; Chiong, Mario; Colombo, María Isabel; Lavandero, Sergio

    2010-06-01

    Aggresomes are dynamic structures formed when the ubiquitin-proteasome system is overwhelmed with aggregation-prone proteins. In this process, small protein aggregates are actively transported towards the microtubule-organizing center. A functional role for autophagy in the clearance of aggresomes has also been proposed. In the present work we investigated the molecular mechanisms involved on aggresome formation in cultured rat cardiac myocytes exposed to glucose deprivation. Confocal microscopy showed that small aggregates of polyubiquitinated proteins were formed in cells exposed to glucose deprivation for 6 h. However, at longer times (18 h), aggregates formed large perinuclear inclusions (aggresomes) which colocalized with gamma-tubulin (a microtubule-organizing center marker) and Hsp70. The microtubule disrupting agent vinblastine prevented the formation of these inclusions. Both small aggregates and aggresomes colocalized with autophagy markers such as GFP-LC3 and Rab24. Glucose deprivation stimulates reactive oxygen species (ROS) production and decreases intracellular glutathione levels. ROS inhibition by N-acetylcysteine or by the adenoviral overexpression of catalase or superoxide dismutase disrupted aggresome formation and autophagy induced by glucose deprivation. In conclusion, glucose deprivation induces oxidative stress which is associated with aggresome formation and activation of autophagy in cultured cardiac myocytes. PMID:20176105

  13. Leukotriene B4 receptors on guinea pig alveolar eosinophils

    SciTech Connect

    Maghni, K.; de Brum-Fernandes, A.J.; Foeldes-Filep, E.G.; Gaudry, M.; Borgeat, P.; Sirois, P. )

    1991-09-01

    The existence of receptors for LTB4 on highly purified guinea pig alveolar eosinophils was investigated. Massive infiltration of eosinophils in alveolar spaces was induced in guinea pigs by i.v. injections of Sephadex beads G50 (16 mg/kg). Alveolar eosinophils (50 {times} 10(6) cells) were purified to approximately 98% by Percoll continuous density gradient centrifugation. The binding studies indicated that alveolar eosinophils bind LTB4 in a saturable, reversible and specific manner. Scatchard analysis indicated the existence of high-affinity binding sites (Kd1 = 1.00 {plus minus} 0.22 nM; Bmax1 = 966 {plus minus} 266 sites/cell) and low-affinity binding sites (Kd2 = 62.5 {plus minus} 8.9 nM; Bmax2 = 5557 {plus minus} 757 sites/cell). The metabolism of LTB4 by alveolar eosinophils in binding conditions was assessed by RP-HPLC and no significant degradation of (3H)LTB4 was observed. LTB4 dose-dependently stimulated eosinophil migration in both chemokinesis and chemotaxis assays with an EC50 value of 1.30 {plus minus} 0.14 and 18.14 {plus minus} 1.57 nM, respectively. LTB4 caused a dose-dependent increase in the production of superoxide anion with an apparent EC50 value of 50 {times} 10(-9) M in the authors experimental conditions. LTB4 also induced a dose-dependent increase in the generation of TxA2 with an EC50 value of 46.2 {times} 10(-9) M. Taken together, their results demonstrated that guinea pig alveolar eosinophils express two classes of specific receptors for LTB4. The high-affinity binding sites seem associated to chemokinesis and chemotaxis whereas the low-affinity binding sites seem associated to superoxide anion production and generation of TxA2. The existence of LTB4 receptors in eosinophils could explain the presence of these cells in hypersensitivity reactions.

  14. Dilated cardiomyopathy mutations in δ-sarcoglycan exert a dominant-negative effect on cardiac myocyte mechanical stability.

    PubMed

    Campbell, Matthew D; Witcher, Marc; Gopal, Anoop; Michele, Daniel E

    2016-05-01

    Delta-sarcoglycan is a component of the sarcoglycan subcomplex within the dystrophin-glycoprotein complex located at the plasma membrane of muscle cells. While recessive mutations in δ-sarcoglycan cause limb girdle muscular dystrophy 2F, dominant mutations in δ-sarcoglycan have been linked to inherited dilated cardiomyopathy (DCM). The purpose of this study was to investigate functional cellular defects present in adult cardiac myocytes expressing mutant δ-sarcoglycans harboring the dominant inherited DCM mutations R71T or R97Q. This study demonstrates that DCM mutant δ-sarcoglycans can be stably expressed in adult rat cardiac myocytes and traffic similarly to wild-type δ-sarcoglycan to the plasma membrane, without perturbing assembly of the dystrophin-glycoprotein complex. However, expression of DCM mutant δ-sarcoglycan in adult rat cardiac myocytes is sufficient to alter cardiac myocyte plasma membrane stability in the presence of mechanical strain. Upon cyclical cell stretching, cardiac myocytes expressing mutant δ-sarcoglycan R97Q or R71T have increased cell-impermeant dye uptake and undergo contractures at greater frequencies than myocytes expressing normal δ-sarcoglycan. Additionally, the R71T mutation creates an ectopic N-linked glycosylation site that results in aberrant glycosylation of the extracellular domain of δ-sarcoglycan. Therefore, appropriate glycosylation of δ-sarcoglycan may also be necessary for proper δ-sarcoglycan function and overall dystrophin-glycoprotein complex function. These studies demonstrate that DCM mutations in δ-sarcoglycan can exert a dominant negative effect on dystrophin-glycoprotein complex function leading to myocardial mechanical instability that may underlie the pathogenesis of δ-sarcoglycan-associated DCM.

  15. Cardiac myocyte dysfunction induced by streptolysin O is membrane pore and calcium dependent

    PubMed Central

    Bolz, Devin D.; Li, Zhi; McIndoo, Eric R.; Tweten, Rodney K.; Bryant, Amy E.; Stevens, Dennis L.

    2014-01-01

    Septic cardiomyopathy is a severe complication among some patients who develop group A streptococcal toxic shock syndrome (StrepTSS). Despite the importance of cardiac dysfunction in determining prognosis, very little is known about mechanisms that reduce cardiac output in association with streptococcal infection. Here, we investigated the effects of streptococcal extracellular toxins on mechanical contractility of electrically paced primary murine cardiomyocytes. Our data demonstrate that Streptolysin O (SLO) is the major streptococcal toxin responsible for cardiomyocyte contractile dysfunction. SLO dose-dependently affected cardiac myocyte function in discrete stages. Exposure to SLO caused a failure of cardiac cells to respond to electrical pacing, followed by spontaneous dysregulated contractions and augmented strength of contraction. Central to these SLO-mediated effects is a marked influx of calcium into the cytosol through SLO-mediated pores in the cytoplasmic membrane. Such calcium mobilization in response to SLO correlated temporally with hypercontractility and unpaced contractions. During continued exposure to SLO, cardiomyocytes exhibited periods of reversion to normal electrical pacing suggestive of membrane lesion repair and restoration of calcium handling. Together, these observations are consistent with the clinical observation that septic cardiomyopathy is a reversible condition in patients that survive StrepTSS. These data provide strong evidence that streptococcal exotoxins, specifically SLO, can directly impact cardiac mechanical function. PMID:25243426

  16. 17β-Aminoestrogens induce guinea pig airway smooth muscle hyperresponsiveness through L-type Ca(2+) channels activation.

    PubMed

    Flores-Soto, Edgar; Martínez-Villa, Inocencio; Solís-Chagoyán, Héctor; Sommer, Bettina; Lemini, Cristina; Montaño, Luis M

    2015-09-01

    Therapy with estrogens is frequently used in menopausal women and as hormonal contraception. Because of its thrombotic effects, long term estrogen administration used in hormonal replacement therapy (HRT) and contraception could represent a health hazard. In this regard, 17β-aminoestrogens such as aminoestrol, butolame and pentolame have shown promising HRT potential, because they have a weak agonist estrogenic action and antithrombotic activity. Additionally, estrogens play a protective role in airway smooth muscle, but the effect of 17β-aminoestrogens on the airway smooth muscle has not been tested yet. In guinea pig tracheal smooth muscle pentolame and butolame induced hyperresponsiveness to histamine (His), carbachol (Cch) and KCl. Interestingly, aminoestrol did not show this effect at the highest concentration studied, it even lowered the contraction induced by Cch. The hyperresponsiveness induced by pentolame to His was abolished by nifedipine. In single tracheal myocytes, KCl induced an increment in the intracellular Ca(2+) concentration [Ca(2+)]i, pentolame also showed an increase in [Ca(2+)]i and the addition of KCl in the plateau of this rise further significantly augmented the [Ca(2+)]i response. Additionally, in patch clamp experiments pentolame increased the L-type Ca(2+) currents. Thus, 17β-aminoestrogens such as pentolame and butolame, but not aminoestrol, activate L-type Ca(2+) channel to induced hyperresponsiveness to Cch, His and KCl in guinea pig tracheal smooth muscle. Due to its lack of effect on airways and to its anticoagulant characteristics, aminoestrol seems to be the best alternative in the HRT among the 17β-aminoestrogens studied.

  17. Role of endothelial cell hyperpolarization in EDHF-mediated responses in the guinea-pig carotid artery

    PubMed Central

    Quignard, J -F; Félétou, M; Edwards, G; Duhault, J; Weston, A H; Vanhoutte, P M

    2000-01-01

    Experiments were performed to identify the potassium channels involved in the acetylcholine-induced endothelium-dependent hyperpolarization of the guinea-pig internal carotid artery. Smooth muscle and endothelial cell membrane potentials were recorded in isolated arteries with intracellular microelectrodes. Potassium currents were recorded in freshly-dissociated smooth muscle cells using patch clamp techniques. In single myocytes, iberiotoxin (0.1 μM)-, charybdotoxin (0.1 μM)-, apamin (0.5 μM)- and 4-aminopyridine (5 mM)-sensitive potassium currents were identified indicating the presence of large- and small-conductance calcium-sensitive potassium channels (BKCa and SKCa) as well as voltage-dependent potassium channels (KV). Charybdotoxin and iberiotoxin inhibited the same population of BKCa but a conductance specifically sensitive to the combination of charybdotoxin plus apamin could not be detected. 4-aminopyridine (0.1–25 mM) induced a concentration-dependent inhibition of KV without affecting the iberiotoxin- or the apamin-sensitive currents. In isolated arteries, both the endothelium-dependent hyperpolarization of smooth muscle and the hyperpolarization of endothelial cells induced by acetylcholine or by substance P were inhibited by 5 mM 4-aminopyridine. These results indicate that in the vascular smooth muscle cells of the guinea-pig carotid artery, a conductance specifically sensitive to the combination of charybdotoxin plus apamin could not be detected, comforting the hypothesis that the combination of these two toxins should act on the endothelial cells. Furthermore, the inhibition by 4-aminopyridine of both smooth muscle and endothelial hyperpolarizations, suggests that in order to observe an endothelium-dependent hyperpolarization of the vascular smooth muscle cells, the activation of endothelial potassium channels is likely to be required. PMID:10725258

  18. Audiometric effects of simulated sonic booms in guinea pigs

    NASA Astrophysics Data System (ADS)

    Reinis, S.; Weiss, D. S.; Featherstone, J. W.; Tsaros, C.

    1987-03-01

    Changes of hearing thresholds have been studied in guinea pigs following exposure to 100 simulated sonic booms. Simulated sonic booms increased the hearing thresholds at frequencies above 30 kHz. The only early structural change observed was an appearance of a small blood clot in the scala tympani of the basal turn of the cochlea. Although these changes may be specific for small laboratory animals only, they indicate that caution is necessary in exposing people to repeated or intense sonic booms. Also, the data indicate that, following the exposure to the sonic booms, the high frequency hearing is influenced first. Therefore, audiometric testing following the sonic boom exposure should not be limited to the routine audiometric curve ending at 8 kHz.

  19. Mycoplasma pneumoniae induces cytotoxic activity in guinea pig bronchoalveolar cells

    SciTech Connect

    Kist, M.; Koester, H.; Bredt, W.

    1985-06-01

    Precultured guinea pig alveolar macrophages (AM) and freshly harvested alveolar cells (FHAC) activated by interaction with Mycoplasma pneumoniae were cytotoxic for xenogeneic /sup 75/selenomethionine-labeled tumor target cells. Phagocytosis of whole opsonized or nonopsonized M. pneumoniae cells was more effective in eliciting cytotoxicity than uptake of sonicated microorganisms. The addition of living mycoplasma cells to the assay system enhanced the cytotoxic effect considerably. Target cells were significantly more susceptible to the cytotoxic action of phagocytes if they were coated with mycoplasma antigen or cocultured together with M. pneumoniae. The activation of the phagocytes could be inhibited by 2-deoxy-D-glucose but not by antimicrobial substances suppressing mycoplasma protein synthesis. It was accompanied by /sup 51/Cr release without detectable signs of cell damage. The supernatants of activated cells were cytotoxic for approximately 24 h. Inhibition, release, and cytotoxic activity indicate the necessity of an intact metabolism of the effector cells and suggest a secretion of cytotoxic substances.

  20. Studies on contact hypersensitivity in the guinea pig.

    PubMed

    Tsuchiya, S; Kondo, M; Okamoto, K; Takase, Y

    1982-07-01

    A method to determine the quantitative induction and challenge of the allergenicity of externally applied toiletories and cosmetics, including their components, is described. The experiment used oil-soluble cinnamic aldehyde and water-soluble formalin as allergens, and guinea pigs as the experimental animals. A high sensitization method resulted, carried out as follows. A 24-h closed patch is attached to the skin every other day over a period of 2 weeks (a total of 4 applications). Freund's complete adjuvant is administered intradermally just before the 3rd application of the patch. The challenge step is performed by directly applying the test material. This method was compared with other allergenicity evaluation methods. As a result, this method was found to be in no way inferior in sensitization performance to the other methods. The method was used on perfume mixtures and tested for its evaluation effectiveness. It proved to be satisfactory.

  1. Assay of contact photosensitivity to musk ambrette in guinea pigs.

    PubMed

    Kochever, I E; Zalar, G L; Einbinder, J; Harber, L C

    1979-08-01

    This study reports the induction of contact photodermatitis to musk ambrette, 2-methoxy-3,5-dinitro-4-methyl-t-butylbenzene, in guinea pigs. Photoallergic contact dermatitis was assayed using 2 alternative induction methods. Successful photosensitization was achieved only when the nuchal skin was stripped with scotch tape before application of musk ambrette and ultraviolet radiation. Induction methods utilizing nonstripped nuchal skin which induce photosensitivity to potent photoallergens were ineffective for musk ambrette. Phtotoxicity tests to musk ambrette at concentrations between 1 and 50% and a dose of 10.2 joules/cm2 from "Black Light" fluorescent tubes were all negative. Under identical irradiation conditions, anthracene at 0.9% and 8-methoxypsoralen at 1% were consistently positive. The mechanism of photosensitivity to musk ambrette appears to be photoallergic rather than phototoxic. The requirement for skin abrasion to induce photosensitization parallels the clinical reports of photosensitivity to musk ambrette in man.

  2. Naegleria: another pathogenic ameba studies in germfree guinea pigs.

    PubMed

    Phillips, B P

    1974-09-01

    Free-living amebas of the genus Naegleria, of world-wide distribution and long considered harmless, have been linked etiologically with 57 fatal cases of primary amebic meningoencephalitis during the last decade. Naegleria from cultures derived from one of these fatal cases in Richmond, Virginia, have been inoculated intranasally, intraorally, into the conjunctival sac near the inner canthus of the eyes, and into induced skin lesions in adult germfree guinea pigs. Of 33 animals inoculated intranasally with 18 to 31 amebas, 31 developed a fatal encephalitis. There was considerable destruction of tissues of the cerebellum and the cerebrum and including the olfactory lobes. The meninges were involved to varying degrees in most of the animals. None of the animals inoculated by the three other routes developed either symptoms or lesions. PMID:4451226

  3. Infrared neural stimulation: beam path in the guinea pig cochlea.

    PubMed

    Moreno, Laura E; Rajguru, Suhrud M; Matic, Agnella Izzo; Yerram, Nitin; Robinson, Alan M; Hwang, Margaret; Stock, Stuart; Richter, Claus-Peter

    2011-12-01

    It has been demonstrated that INS can be utilized to stimulate spiral ganglion cells in the cochlea. Although neural stimulation can be achieved without direct contact of the radiation source and the tissue, the presence of fluids or bone between the target structure and the radiation source may lead to absorption or scattering of the radiation, which may limit the efficacy of INS. The present study demonstrates the neural structures in the radiation beam path that can be stimulated. Histological reconstructions and microCT of guinea pig cochleae stimulated with an infrared laser suggest that the orientation of the beam from the optical fiber determined the site of stimulation in the cochlea. Best frequencies of the INS-evoked neural responses obtained from the central nucleus of the inferior colliculus matched the histological sites in the spiral ganglion.

  4. Interactions of trimebutine with guinea-pig opioid receptors.

    PubMed

    Roman, F; Pascaud, X; Taylor, J E; Junien, J L

    1987-05-01

    Affinities of trimebutine (TMB) and N-desmethyl trimebutine (NDTMB) for mu, delta and kappa opioid receptor subtypes have been examined using specific 3H-ligands and guinea-pig membrane. TMB and NDTMB showed a relative higher affinity for the mu receptor subtype although they were, respectively, 30- and 48-fold less active than morphine. The receptor selectivity index for mu, delta and kappa were 100:12:14.4 for TMB, 100:32:25 for NDTMB and 100:5:5 for morphine. The sodium shift ratio was 14 for TMB, 10 for NDTMB and 37 for morphine. These data show that (unlike morphine, a pure mu agonist) TMB and NDTMB can be classified as weak opioid agonists and confirm that peripheral opioid receptors mediate their gastrointestinal motility effects. PMID:2886594

  5. Oxygen radicals stimulate guinea pig gallbladder glycoprotein secretion in vitro

    SciTech Connect

    Hale, W.B.; Turner, B.; LaMont, J.T. )

    1987-11-01

    In several animal models of cholelithiasis, and in humans with gallstones, hypersecretion of gallbladder mucin is observed. This study was undertaken to determine the effect of oxygen radicals on guinea pig gallbladder glycoprotein secretion in organ culture. Mucosal explants were incubated with ({sup 3}H)glucosamine hydrochloride to label glycoproteins, then exposed to oxygen radicals generated by chelated ferric iron and ascorbic acid. Marked stimulation of glycoprotein release was observed after a 30-min exposure to the oxygen radical-generating system, and the effect was inhibited by mannitol. The stimulatory effect of hydroxyl radical was not accompanied by leakage of intracellular lactate dehydrogenase. Parallel experiments with human granulocytes activated with f-Met-Leu-Phe and coincubated with gallbladder explants revealed similar results. These results indicate that oxygen radicals, especially the hydroxyl radical (OH), are capable of stimulating rapid release of mucous-type glycoproteins from gallbladder epithelium.

  6. Papular dermatitis induced in guinea pigs by the biting midge Culicoides sonorensis (Diptera: Ceratopogonidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histological, ultrastructural, and virological examinations were performed on abdominal skin from guinea pigs after a blood meal by colony-bred biting midges, Culicoides sonorensis. Small, superficial, cutaneous, crateriform ulcers with necrosis of superficial dermis developed at feeding sites and ...

  7. The effect of restraining on the heart rate in guinea pigs

    NASA Technical Reports Server (NTRS)

    Mikiskova, H.

    1980-01-01

    The emotional effect of different applications of electrodes and the fixation for cariographic examination was investigated using guinea pigs. The effect of the stress is discussed in terms of heart rhythm and behavior.

  8. Induction of follicular luteinization by equine chorionic gonadotropin in cyclic guinea pigs*

    PubMed Central

    Li, Jun-rong; Wang, Wei; Shi, Fang-xiong

    2015-01-01

    The effects of equine chorionic gonadotropin (eCG) on follicular development and ovulation in cyclic guinea pigs were investigated by histological and immunohistochemical analyses. Three groups of guinea pigs (n=12) were administrated subcutaneously with saline, 20 or 50 IU of eCG, respectively, on cyclic Day 12 (Day 1=vaginal openings). Ovaries were collected at 4 and 8 d after administration (6 animals per group each time). The eCG administration induced significant and distinct morphological changes in the ovaries, as it promoted the luteinization of granulosa cells, but not follicular development. In addition, proliferating cell nuclear antigen (PCNA) and steroidogenic acute regulatory protein (StAR) were immunolocalized specifically in luteinized follicles. Our experiments together indicate that eCG administration can induce follicular luteinization but not superovulation in guinea pigs. The eCG in cyclic guinea pigs functions similar to that of luteinizing hormone (LH), but not follicle-stimulating hormone (FSH). PMID:26642181

  9. 9 CFR 3.36 - Primary enclosures used to transport live guinea pigs and hamsters.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... lifting shall be provided on the exterior of the primary enclosure to enable the primary enclosure to be... guinea pig Weight (grams) Square centimeters Square inches Up to 350 193.6 30 350 to 600 290.3 45...

  10. 9 CFR 3.36 - Primary enclosures used to transport live guinea pigs and hamsters.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... lifting shall be provided on the exterior of the primary enclosure to enable the primary enclosure to be... guinea pig Weight (grams) Square centimeters Square inches Up to 350 193.6 30 350 to 600 290.3 45...

  11. Chronic estrogen exposure maintains elevated levels of progesterone receptor mRNA in guinea pig hypothalamus.

    PubMed

    Bayliss, D A; Millhorn, D E

    1991-05-01

    We performed in situ hybridization on hypothalamic sections from ovariectomized guinea pig using a cocktail of three 35S-labeled oligonucleotides complementary to mammalian progesterone receptor (PR) cDNA. PR mRNA was readily detected in hypothalamic neurons from guinea pigs pretreated with 17 beta-estradiol benzoate (E2B), but not from animals which did not receive supplemental E2B. The distribution of PR mRNA-containing cells corresponded well with previous localizations of PR in guinea pig. In contrast to earlier reports of E2B regulation of PR mRNA in rat hypothalamus, however, we found that PR mRNA remained elevated during chronic exposure to E2B (up to 10 days) in guinea pig. PMID:2072827

  12. Cortical representation of species-specific vocalizations in Guinea pig.

    PubMed

    Suta, Daniel; Popelář, Jiří; Burianová, Jana; Syka, Josef

    2013-01-01

    We investigated the representation of four typical guinea pig vocalizations in the auditory cortex (AI) in anesthetized guinea pigs with the aim to compare cortical data to the data already published for identical calls in subcortical structures - the inferior colliculus (IC) and medial geniculate body (MGB). Like the subcortical neurons also cortical neurons typically responded to many calls with a time-locked response to one or more temporal elements of the calls. The neuronal response patterns in the AI correlated well with the sound temporal envelope of chirp (an isolated short phrase), but correlated less well in the case of chutter and whistle (longer calls) or purr (a call with a fast repetition rate of phrases). Neuronal rate vs. characteristic frequency profiles provided only a coarse representation of the calls' frequency spectra. A comparison between the activity in the AI and those of subcortical structures showed a different transformation of the neuronal response patterns from the IC to the AI for individual calls: i) while the temporal representation of chirp remained unchanged, the representations of whistle and chutter were transformed at the thalamic level and the response to purr at the cortical level; ii) for the wideband calls (whistle, chirp) the rate representation of the call spectra was preserved in the AI and MGB at the level present in the IC, while in the case of low-frequency calls (chutter, purr), the representation was less precise in the AI and MGB than in the IC; iii) the difference in the response strength to natural and time-reversed whistle was found to be smaller in the AI than in the IC or MGB.

  13. Acute and subchronic dermal toxicity of nanosilver in guinea pig.

    PubMed

    Korani, M; Rezayat, S M; Gilani, K; Arbabi Bidgoli, S; Adeli, S

    2011-01-01

    Silver has been used as an antimicrobial agent for a long time in different forms, but silver nanoparticles (nanosilver) have recently been recognized as potent antimicrobial agents. Although nanosilver is finding diverse medical applications such as silver-based dressings and silver-coated medical devices, its dermal and systemic toxicity via dermal use has not yet been identified. In this study, we analyzed the potential toxicity of colloidal nanosilver in acute and subchronic guinea pigs. Before toxicity assessments, the size of colloidal nanosilver was recorded in sizes <100 nm by X-ray diffraction and transmission electron microscopy. For toxicological assessments, male guinea pigs weighing 350 to 400 g were exposed to two different concentrations of nanosilver (1000 and 10,000 μg/mL) in an acute study and three concentrations of nanosilver (100, 1000, and 10,000 μg/mL) in a subchronic study. Toxic responses were assessed by clinical and histopathologic parameters. In all experimental animals the sites of exposure were scored for any type of dermal toxicity and compared with negative control and positive control groups. In autopsy studies during the acute test, no significant changes in organ weight or major macroscopic changes were detected, but dose-dependent histopathologic abnormalities were seen in skin, liver, and spleen of all test groups. In addition, experimental animals subjected to subchronic tests showed greater tissue abnormalities than the subjects of acute tests. It seems that colloidal nanosilver has the potential to provide target organ toxicities in a dose- and time-dependent manner.

  14. Guinea Pig Lung Lavage Cells After Intranasal BCG Sensitization

    PubMed Central

    Terai, T.; Ganguly, Rama; Waldman, Robert H.

    1979-01-01

    Recent studies have suggested that intranasal administration of antigen can induce local cell-mediated immunity in lung lavage cells. The present study was designed to examine the changes in composition of lung lavage cells and their capacity to produce the lymphokine migration inhibitory factor after intranasal immunization with BCG in guinea pigs. Results indicate that guinea pigs responded to respiratory tract BCG infection with an increase in immunocompetent cells in the bronchoalveolar tract and with production of migration inhibitory factor. After local pulmonary BCG administration, the total number of cells increased as compared with that of the uninfected animals, the increase being statistically significant within 2 weeks. This marked increase in the total cell population is due to a more than doubling of the number of macrophages in the lavage fluid. Animals also developed at this time positive delayed hypersensitivity to intradermally administered purified protein derivative. A significant increase in the total lymphoid cells and macrophage population was observed again at 6 weeks after sensitization, suggesting that the response is biphasic in nature. At 6 weeks, however, there was also a significant rise in total lymphocytes and T cell population in addition to macrophage numbers. This increase in T cells correlated with an increase in production of migration inhibitory factor in the presence of purified protein derivative. These data suggest that the immune response of the respiratory tract after BCG challenge involves increased recruitment of immunocompetent cells locally at the site of infection and that these cells are capable of producing effector molecules in terms of the elaboration of migration inhibitory factor. PMID:387595

  15. Processing of communication calls in Guinea pig auditory cortex.

    PubMed

    Grimsley, Jasmine M S; Shanbhag, Sharad J; Palmer, Alan R; Wallace, Mark N

    2012-01-01

    Vocal communication is an important aspect of guinea pig behaviour and a large contributor to their acoustic environment. We postulated that some cortical areas have distinctive roles in processing conspecific calls. In order to test this hypothesis we presented exemplars from all ten of their main adult vocalizations to urethane anesthetised animals while recording from each of the eight areas of the auditory cortex. We demonstrate that the primary area (AI) and three adjacent auditory belt areas contain many units that give isomorphic responses to vocalizations. These are the ventrorostral belt (VRB), the transitional belt area (T) that is ventral to AI and the small area (area S) that is rostral to AI. Area VRB has a denser representation of cells that are better at discriminating among calls by using either a rate code or a temporal code than any other area. Furthermore, 10% of VRB cells responded to communication calls but did not respond to stimuli such as clicks, broadband noise or pure tones. Area S has a sparse distribution of call responsive cells that showed excellent temporal locking, 31% of which selectively responded to a single call. AI responded well to all vocalizations and was much more responsive to vocalizations than the adjacent dorsocaudal core area. Areas VRB, AI and S contained units with the highest levels of mutual information about call stimuli. Area T also responded well to some calls but seems to be specialized for low sound levels. The two dorsal belt areas are comparatively unresponsive to vocalizations and contain little information about the calls. AI projects to areas S, VRB and T, so there may be both rostral and ventral pathways for processing vocalizations in the guinea pig. PMID:23251604

  16. Cortical representation of species-specific vocalizations in Guinea pig.

    PubMed

    Suta, Daniel; Popelář, Jiří; Burianová, Jana; Syka, Josef

    2013-01-01

    We investigated the representation of four typical guinea pig vocalizations in the auditory cortex (AI) in anesthetized guinea pigs with the aim to compare cortical data to the data already published for identical calls in subcortical structures - the inferior colliculus (IC) and medial geniculate body (MGB). Like the subcortical neurons also cortical neurons typically responded to many calls with a time-locked response to one or more temporal elements of the calls. The neuronal response patterns in the AI correlated well with the sound temporal envelope of chirp (an isolated short phrase), but correlated less well in the case of chutter and whistle (longer calls) or purr (a call with a fast repetition rate of phrases). Neuronal rate vs. characteristic frequency profiles provided only a coarse representation of the calls' frequency spectra. A comparison between the activity in the AI and those of subcortical structures showed a different transformation of the neuronal response patterns from the IC to the AI for individual calls: i) while the temporal representation of chirp remained unchanged, the representations of whistle and chutter were transformed at the thalamic level and the response to purr at the cortical level; ii) for the wideband calls (whistle, chirp) the rate representation of the call spectra was preserved in the AI and MGB at the level present in the IC, while in the case of low-frequency calls (chutter, purr), the representation was less precise in the AI and MGB than in the IC; iii) the difference in the response strength to natural and time-reversed whistle was found to be smaller in the AI than in the IC or MGB. PMID:23785425

  17. Involvement of chymase in allergic conjunctivitis of guinea pigs.

    PubMed

    Nabe, Takeshi; Kijitani, Yurie; Kitagawa, Yuriko; Sakano, Emi; Ueno, Tomoko; Fujii, Masanori; Nakao, Shintaro; Sakai, Masaru; Takai, Shinji

    2013-08-01

    It has been reported that chymase activity was increased in allergic conjunctivitis patients and this activity was correlated with the severity of the disease. However, the precise roles of chymase in allergic conjunctivitis are unclear, and whether chymase inhibitors are effective for allergic conjunctivitis has not been reported even in experimental animal models. In this study, the roles of chymase in the pathogenesis were evaluated using a selective chymase inhibitor, ONO-WH-236, in a guinea pig model of allergic conjunctivitis induced by cedar pollen. Sensitized guinea pigs were challenged by the pollen, followed by assessing redness and edema in the conjuntiva, and counting the frequency of eye scratching as an itch-associated response. Treatment with the ONO-WH-236 (40 and 80 mg/kg, p.o.) dose-dependently inhibited the induction of redness, edema and scratching behavior. An anti-histaminic drug, ketotifen (3 mg/kg, p.o.), also significantly inhibited conjunctivitis symptoms. Chymase activity was increased in ophthalmic lavage fluid immediately after the pollen challenge. The increase in chymase activity was inhibited by in vivo treatment with ONO-WH-236. Interestingly, increased histamine in the ophthalmic lavage fluid immediately after the challenge was also inhibited by the chymase inhibitor. Administration of human recombinant chymase by eye dropping (0.09 and 0.9 μg/eye) dose-dependently induced scratching behavior, which was inhibited by not only ONO-WH-236 but also ketotifen; however, chymase administration induced only weak redness in the conjunctiva, which was resistant to treatment with anti-histaminic drugs. In conclusion, it was suggested that chymase was released from mast cells after antigen challenge, followed by the induction of conjunctivitis symptoms through histamine release from mast cells. Thus, chymase could be a potential target for pharmacotherapy for allergic conjunctivitis.

  18. Blast cells transfer experimental hypersensitivity pneumonitis in guinea pigs

    SciTech Connect

    Schuyler, M.; Cook, C.; Listrom, M.; Fengolio-Preiser, C.

    1988-06-01

    We previously demonstrated that experimental hypersensitivity pneumonitis (HP) can be transferred by lymph node cells (LNC) cultured in vitro with antigen. The purpose of this study was to identify the cells responsible for transfer and to determine if pulmonary cells can transfer HP. We cultured LNC from sensitized Strain 2 guinea pigs with a soluble extract of Micropolyspora faeni for 72 h, separated lymphoblasts from small lymphocytes, and transferred both subpopulations intravenously to syngeneic recipients. We also transferred irradiated lymphoblasts (1,500 rads), macrophage-depleted, lymphoblast-enriched populations, and pulmonary cells either without culture or after culture with M. faeni. Control animals received an equal volume of medium. All recipient animals were challenged intratracheally (i.t.) with M. faeni 48 h after the cell transfer, and they were killed 4 days after i.t. challenge. Randomly selected microscopic fields of the lung (250/animal) were judged to be normal or abnormal without knowledge of treatment. This measurement was reproducible (r = 0.95 for duplicate measurements, n = 55). All guinea pigs were maintained in HEPA-filtered air. There was a low level of pulmonary response to an i.t. challenge of M. faeni in animals that received medium. Animals that received pulmonary cells, either cultured or noncultured, did not differ from those in the control group. There was a substantial increase (p less than 0.01) in the extent of pulmonary abnormalities in the recipients of the lymphoblast population, with significant correlation (r = 0.87, p less than 0.01) between the number of lymphoblasts transferred and the extent of pulmonary abnormalities.

  19. Pharmacokinetics of activated protein C in guinea pigs

    SciTech Connect

    Berger, H. Jr.; Kirstein, C.G.; Orthner, C.L. )

    1991-05-15

    Protein C is a vitamin K-dependent zymogen of the serine protease, activated protein C (APC), an important regulatory enzyme in hemostasis. In view of the potential of human APC as an anticoagulant and profibrinolytic agent, the pharmacokinetics and tissue distribution of APC were studied in guinea pigs. The plasma elimination of a trace dose of {sup 125}I-APC was biphasic following an initial rapid elimination of approximately 15% of the injected dose within 1 to 2 minutes. This rapid removal of {sup 125}I-APC from the circulation was found to be a result of an association with the liver regardless of the route of injection. Essentially identical results were obtained with active site-blocked forms of APC generated with either diisopropylfluorophosphate or D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone, which indicates that the active site was not essential for the liver association. Accumulation of all three forms of APC in the liver peaked at 30 minutes and then declined as increasing amounts of degraded radiolabeled material appeared in the gastrointestinal tract and urine. Removal of the gamma-carboxyglutamic acid (gla) domain of diisopropylphosphoryl-APC resulted in a 50% reduction in the association with liver and an accumulation in the kidneys. Protein C and protein S were cleared from the circulation at rates approximately one-half and one-fourth, respectively, that of APC. Both in vitro and in vivo, APC was found to form complexes with protease inhibitors present in guinea pig plasma. Complex formation resulted in a more rapid disappearance of the enzymatic activity of APC than elimination of the protein moiety. These findings indicate two distinct mechanisms for the elimination of APC. One mechanism involves reaction with plasma protease inhibitors and subsequent elimination by specific hepatic receptors. (Abstract Truncated)

  20. Ozone-induced modulation of airway hyperresponsiveness in guinea pigs.

    PubMed

    Schlesinger, Richard B; Cohen, Mitchell; Gordon, Terry; Nadziejko, Christine; Zelikoff, Judith T; Sisco, Maureen; Regal, Jean F; Ménache, Margaret G

    2002-06-01

    Although acute exposure to ozone (03*) has been shown to influence the severity and prevalence of airway hyperresponsiveness, information has been lacking on effects due to long-term exposure at relatively low exposure concentrations. The goals of this study were to determine whether long-term repeated ozone exposures could induce nonspecific hyperresponsiveness in normal, nonatopic (nonsensitized) animals, whether such exposure could exacerbate the preexisting hyperresponsive state in atopic (sensitized) animals, or both. The study was also designed to determine whether gender modulated airway responsiveness related to ozone exposure. Airway responsiveness was measured during and after exposure to 0.1 and 0.3 ppm ozone for 4 hours/day, 4 days/week for 24 weeks in normal, nonsensitized guinea pigs, in guinea pigs sensitized to an allergen (ovalbumin) prior to initiation of ozone exposures, and in animals sensitized concurrently with ozone exposures. Both male and female animals were studied. Ozone exposure did not produce airway hyperresponsiveness in nonsensitized animals. Ozone exposure did exacerbate airway hyperresponsiveness to specific and nonspecific bronchoprovocation in both groups of sensitized animals, and this effect persisted at least 4 weeks after the end of the exposures. Although the overall degree of airway responsiveness did differ between genders (males had more responsive airways than did females), the airway response to ozone exposure did not differ between the two groups. Ozone-induced effects upon airway responsiveness were not associated with the number of pulmonary eosinophils or with any chronic pulmonary inflammatory response. Levels of antigen-specific antibodies increased in sensitized animals, and a significant correlation was observed between airway responsiveness and antibody levels. The results of this study provide support for a role of ambient ozone exposure in exacerbation of airway dysfunction in persons with atopy.

  1. Immunologically induced neuromodulation of guinea pig nodose ganglion neurons.

    PubMed

    Undem, B J; Hubbard, W; Weinreich, D

    1993-07-01

    The influence of specific antigen challenge on the excitability of C-cells in nodose ganglia isolated from actively sensitized guinea pigs was evaluated using intracellular recording techniques. Antigen (ovalbumin) caused a significant depolarization (approximately 8 mV) of the resting membrane potential. Antigen exposure had differing effects on the membrane input impedance; decreasing it in 15 neurons, increasing it in 6 neurons, and having no effect in 8 neurons. About 20% of guinea pig nodose C-cells reveal a long-lasting after-spike hyperpolarization (AHPslow). Antigen challenge reversibly blocked the AHPslow in 4 of 18 neurons studied in 18 ganglia. About 30% of the nodose ganglion neurons display a time- and voltage-dependent inward rectification at membrane potentials more negative than -75 mV. Exposing the ganglion to the sensitizing antigen consistently blocked this response in 8 of 8 neurons. Histological assessment of toluidine blue stained cells revealed that the nodose ganglion contained approximately 100 mast cells. Exposing the ganglion to ovalbumin stimulated mast cell degranulation, as measured by a decrease in number of stained cells, and evoked the release of histamine, PGD2, and immunoreactive peptidoleukotrienes from the tissue. The results support the hypothesis that endogenous inflammatory mediators released during the immediate hypersensitivity (allergic) reactions can modulate the excitability of primary C-fiber afferents. Mechanisms underlying antigen-induced neuromodulation of these neurons include depolarization of the resting membrane potential, changes in membrane resistance, blockade of a time- and voltage-dependent anomalous rectifier, and, in some cells, blockade of the AHPslow.

  2. Cardiac Myocyte Alternans in Intact Heart: Influence of Cell-Cell Coupling and β-Adrenergic Stimulation

    PubMed Central

    Hammer, Karin P.; Ljubojevic, Senka; Ripplinger, Crystal M.; Pieske, Burkert M.; Bers, Donald M.

    2015-01-01

    Background Cardiac alternans are proarrhythmic and mechanistically link cardiac mechanical dysfunction and sudden cardiac death. Beat-to-beat alternans occur when beats with large Ca2+ transients and long action potential duration (APD) alternate with the converse. APD alternans are typically driven by Ca2+ alternans and sarcoplasmic reticulum (SR) Ca2+ release alternans. But the effect of intercellular communication via gap junctions (GJ) on alternans in intact heart remains unknown. Objective We assessed the effects of cell-to-cell coupling on local alternans in intact Langen-dorff-perfused mouse hearts, measuring single myocyte [Ca2+] alternans synchronization among neighboring cells, and effects of β-adrenergic receptor (β-AR) activation and reduced GJ coupling. Methods and Results Mouse hearts (C57BL/6) were retrogradely perfused and loaded with Fluo-8 AM to record cardiac myocyte [Ca2+] in situ with confocal microscopy. Single cell resolution allowed analysis of alternans within the intact organ during alternans induction. Carbenoxolone (25 μM), a GJ inhibitor, significantly increased the occurrence and amplitude of alternans in single cells within the intact heart. Alternans were concordant between neighboring cells throughout the field of view, except transiently during onset. β-AR stimulation only reduced Ca2+ alternans in tissue that had reduced GJ coupling, matching effects seen in isolated myocytes. Conclusions Ca2+ alternans among neighboring myocytes is predominantly concordant, likely because of electrical coupling between cells. Consistent with this, partial GJ uncoupling increased propensity and amplitude of Ca2+ alternans, and made them more sensitive to reversal by β-AR activation, as in isolated myocytes. Electrical coupling between myocytes may thus limit the alternans initiation, but also allow alternans to be more stable once established. PMID:25828762

  3. A Pilot Study of Uterine Artery Embolization with Tris-Acryl Gelatin Microspheres in Guinea Pigs

    SciTech Connect

    Zhuang Wenquan; Tan Guosheng; Guo Wenbo; Yang Jianyong

    2012-06-15

    Objective: This study was designed to establish guinea pigs as an animal model for uterine artery embolization (UAE) with tris-acryl gelatin microspheres (TAGM). Methods: Twenty-five female adult guinea pigs were randomly divided into two groups, including a uterine artery casting mould group (n = 10) and a UAE group (n = 15). Pelvic angiography and vascular casting mould were performed in the first group. The anatomical characters of the pelvic cavity in guinea pigs were described. In the second group, the technical feasibility of performing UAE with TAGM in guinea pigs was investigated. The histopathological slides of the uterus of guinea pigs after UAE were examined to inspect the outcomes of UAE. Results: The uterine artery springs from the internal iliac artery, ascends tortuously along the cervix, and gives off vertically 8-10 branches to the cervix uteri and uterine horns. The diameters of the trunk of the uterine artery and its first branch were 0.32 {+-} 0.027 mm and 0.14 {+-} 0.01 mm, respectively. For UAE animals, the dosages of 40-120 and 100-300 {mu}m TAGM were 0.033 {+-} 0.003 ml and 0.015 {+-} 0.002 ml, respectively. On histopathological slides, embosphere particles were found in the first branches of the uterine artery, the subserous arteries, and the intramural arteries. Inflammatory reactions in the uterus were common in guinea pigs after UAE. Local or dispersed areas of necrosis in uterus also were observed in a few guinea pigs. Conclusions: Guinea pigs are an appropriate and feasible model for UAE with TAGM.

  4. Bitter avoidance in Guinea Pigs (Cavia porcellus) and Mice (Mus musculus and Peromyscus leucopus)

    PubMed Central

    Field, Kristin L.; Beauchamp, Gary K.; Kimball, Bruce A.; Mennella, Julie A.; Bachmanov, Alexander A.

    2010-01-01

    Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two non-herbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of QHCl than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity. PMID:21090891

  5. Behavioral responses of deafened guinea pigs to intracochlear electrical stimulation: a new rapid psychophysical procedure.

    PubMed

    Agterberg, Martijn J H; Versnel, Huib

    2014-07-01

    In auditory research the guinea pig is often preferred above rats and mice because of the easily accessible cochlea and because the frequency range of its hearing is more comparable to that of humans. Studies of the guinea-pig auditory system primarily apply histological and electrophysiological measures. Behavioral animal paradigms, in particular in combination with these histological and electrophysiological methods, are necessary in the development of new therapeutic interventions. However, the guinea pig is not considered an attractive animal for behavioral experiments. Therefore, the purpose of this study was to develop a behavioral task suitable for guinea pigs, that can be utilized in cochlear-implant related research. Guinea pigs were trained in a modified shuttle-box in which a stream of air was used as unconditioned stimulus (UCS). A stream of air was preferred over conventionally used methods as electric foot-shocks since it produces less stress, which is a confounding factor in behavioral experiments. Hearing guinea pigs were trained to respond to acoustic stimuli. They responded correctly within only five sessions of ten minutes. The animals maintained their performance four weeks after the right cochlea was implanted with an electrode array. After systemic deafening, the animals responded in the first session immediately to intracochlear electrical stimulation. These responses were not affected by daily chronic electrical stimulation (CES). In conclusion, the present study demonstrates that guinea pigs can be trained relatively fast to respond to acoustic stimuli, and that the training has a lasting effect, which generalizes to intracochlear electrical stimulation after deafening. Furthermore, it demonstrates that bilaterally deafened guinea pigs with substantial (∼50%) loss of spiral ganglion cells (SGCs), detect intracochlear electrical stimulation.

  6. Cross talk between cardiac myocytes and fibroblasts: from multiscale investigative approaches to mechanisms and functional consequences

    PubMed Central

    Zhang, P.; Su, J.

    2012-01-01

    The heart is comprised of a syncytium of cardiac myocytes (CM) and surrounding nonmyocytes, the majority of which are cardiac fibroblasts (CF). CM and CF are highly interspersed in the myocardium with one CM being surrounded by one or more CF. Bidirectional cross talk between CM and CF plays important roles in determining cardiac mechanical and electrical function in both normal and diseased hearts. Genetically engineered animal models and in vitro studies have provided evidence that CM and CF can regulate each other's function. Their cross talk contributes to structural and electrical remodeling in both atria and ventricles and appears to be involved in the pathogenesis of various heart diseases that lead to heart failure and arrhythmia disorders. Mechanisms of CM-CF cross talk, which are not yet fully understood, include release of paracrine factors, direct cell-cell interactions via gap junctions and potentially adherens junctions and nanotubes, and cell interactions with the extracellular matrix. In this article, we provide an overview of the existing multiscale experimental and computational approaches for the investigation of cross talk between CM and CF and review recent progress in our understanding of the functional consequences and underlying mechanisms. Targeting cross talk between CM and CF could potentially be used therapeutically for the modulation of the cardiac remodeling response in the diseased heart and may lead to new strategies for the treatment of heart failure or rhythm disturbances. PMID:23064834

  7. Immunisation of guinea-pigs with circulating immune complexes from patients with rheumatoid arthritis.

    PubMed

    Hack, C E; Lim, H G; Aalberse, R C

    1984-10-01

    Sixteen guinea-pigs were immunised with immune complexes isolated from serum of nine patients with rheumatoid arthritis. The resulting antisera were analysed by radioimmunoassays. All guinea-pig sera were extensively absorbed with normal human serum. After this absorption eight guinea-pig sera contained antibodies specific for immune complexes isolated from the sera of three patients. One of these antisera reacted not only with immune complexes (and serum) from the corresponding patient but also with immune complexes (and sera) from other patients with rheumatoid arthritis. The antigen(s) to which the guinea-pig antibodies were directed sedimented as IgM, and they bound to IgG Sepharose. Therefore the guinea-pig sera were absorbed with IgM-rheumatoid factors isolated from the serum of the corresponding patient. After this absorption, the guinea-pig sera had lost their reactivity with immune complexes. We conclude that these antisera did not detect an exogenous antigen in immune complexes from patients with rheumatoid arthritis. The positive reactions found were due to antibodies specific for (idiotypic?) antigenic determinants on IgM-rheumatoid factors.

  8. Pathogenesis of aerosolized Eastern Equine Encephalitis virus infection in guinea pigs

    PubMed Central

    Roy, Chad J; Reed, Douglas S; Wilhelmsen, Catherine L; Hartings, Justin; Norris, Sarah; Steele, Keith E

    2009-01-01

    Mice and guinea pigs were experimentally exposed to aerosols containing regionally-distinct strains (NJ1959 or ArgM) of eastern equine encephalitis virus (EEEV) at two exclusive particle size distributions. Mice were more susceptible to either strain of aerosolized EEEV than were guinea pigs; however, clinical signs indicating encephalitis were more readily observed in the guinea pigs. Lower lethality was observed in both species when EEEV was presented at the larger aerosol distribution (> 6 μm), although the differences in the median lethal dose (LD50) were not significant. Virus isolation and immunohistochemistry indicated that virus invaded the brains of guinea pigs within one day postexposure, regardless of viral strain or particle size distribution. Immunohistochemistry further demonstrated that neuroinvasion occurred through the olfactory system, followed by transneuronal spread to all regions of the brain. Olfactory bipolar neurons and neurons throughout the brain were the key viral targets. The main microscopic lesions in infected guinea pigs were neuronal necrosis, inflammation of the meninges and neuropil of the brain, and vasculitis in the brain. These results indicate that guinea pigs experimentally infected by aerosolized EEEV recapitulate several key features of fatal human infection and thus should serve as a suitable animal model for aerosol exposure to EEEV. PMID:19852817

  9. Characterization of fetal growth by repeated ultrasound measurements in the wild guinea pig (Cavia aperea).

    PubMed

    Schumann, K; Guenther, A; Göritz, F; Jewgenow, K

    2014-08-01

    Fetal growth during pregnancy has previously been studied in the domesticated guinea pig (Cavia aperea f. porcellus) after dissecting pregnant females, but there are no studies describing the fetal growth in their wild progenitor, the wild guinea pig (C aperea). In this study, 50 pregnancies of wild guinea pig sows were investigated using modern ultrasound technique. The two most common fetal growth parameters (biparietal diameter [BPD] and crown-rump-length [CRL]) and uterine position were measured. Data revealed similar fetal growth patterns in the wild guinea pig and domesticated guinea pig in the investigated gestation period, although they differ in reproductive milestones such as gestation length (average duration of pregnancy 68 days), average birth weight, and litter mass. In this study, pregnancy lasted on average 60.2 days with a variance of less than a day (0.96 days). The measured fetal growth parameters are strongly correlated with each (R = 0.91; P < 0.001) other and with gestational age (BPD regression equation y = 0.04x - 0.29; P < 0.001 and CRL regression equation y = 0.17x - 2.21; P < 0.01). Furthermore, fetuses in the most frequent uterine positions did not differ in their growth parameters and were not influenced by the mother ID. Our results imply that ultrasound measurement of a single fetal growth parameter is sufficient to reliably estimate gestational age in the wild guinea pig.

  10. Chlamydia caviae infection alters abundance but not composition of the guinea pig vaginal microbiota

    PubMed Central

    Neuendorf, Elizabeth; Gajer, Pawel; Bowlin, Anne K.; Marques, Patricia X.; Ma, Bing; Yang, Hongqiu; Fu, Li; Humphrys, Michael S.; Forney, Larry J.; Myers, Garry S.A.; Bavoil, Patrik M.; Rank, Roger G.; Ravel, Jacques

    2015-01-01

    In humans, the vaginal microbiota is thought to be the first line of defense again pathogens including Chlamydia trachomatis. The guinea pig has been extensively used as a model to study chlamydial infection because it shares anatomical and physiological similarities with humans, such as a squamous vaginal epithelium as well as some of the long-term outcomes caused by chlamydial infection. In this study, we aimed to evaluate the guinea pig-C. caviae model of genital infection as a surrogate for studying the role of the vaginal microbiota in the early steps of C. trachomatis infection in humans. We used culture-independent molecular methods to characterize the relative and absolute abundance of bacterial phylotypes in the guinea pig vaginal microbiota in animals non-infected, mock-infected or infected by C. caviae. We showed that the guinea pig and human vaginal microbiotas are of different bacterial composition and abundance. Chlamydia caviae infection had a profound effect on the absolute abundance of bacterial phylotypes but not on the composition of the guinea pig vaginal microbiota. Our findings compromise the validity of the guinea pig-C. caviae model to study the role of the vaginal microbiota during the early steps of sexually transmitted infection. PMID:25761873

  11. Evaluation of Rhesus Monkey and Guinea Pig Hepatic Cytosol Fractions as Models for Human Aldehyde Oxidase

    PubMed Central

    Choughule, Kanika V.; Barr, John T.

    2013-01-01

    Aldehyde oxidase (AOX) is a cytosolic enzyme expressed across a wide range of species, including guinea pig and rhesus monkey. These species are believed to be the best preclinical models for studying human AOX-mediated metabolism. We compared AOX activity in rhesus monkeys, guinea pigs, and humans using phthalazine and N-[2-(dimethylamino)ethyl]acridone-4-carboxamide (DACA) as substrates and raloxifene as an inhibitor. Michaelis-Menten kinetics was observed for phthalazine oxidation in rhesus monkey, guinea pig, and human liver cytosol, whereas substrate inhibition was seen with DACA oxidase activity in all three livers. Raloxifene inhibited phthalazine and DACA oxidase activity uncompetitively in guinea pig, whereas mixed-mode inhibition was seen in rhesus monkey. Our analysis of the primary sequence alignment of rhesus monkey, guinea pig, and human aldehyde oxidase isoform 1 (AOX1) along with homology modeling has led to the identification of several amino acid residue differences within the active site and substrate entrance channel of AOX1. We speculate that some of these residues might be responsible for the differences observed in activity. Overall, our data indicate that rhesus monkeys and guinea pigs would overestimate intrinsic clearance in humans and would be unsuitable to use as animal models. Our study also showed that AOX metabolism in species is substrate-dependent and no single animal model can be reliably used to predict every drug response in humans. PMID:23918666

  12. Viral strain dependent differences in experimental Argentine hemorrhagic fever (Junin virus) infection of guinea pigs.

    PubMed

    Kenyon, R H; Green, D E; Maiztegui, J I; Peters, C J

    1988-01-01

    Guinea pigs infected with low-passage Junin virus of human origin showed viral strain dependent differences in mortality, LD50, time to death, and in viral spread and distribution. Different Junin strains appeared to cause at least two broad patterns of Argentine hemorrhagic fever in guinea pigs. A number of strains of Junin virus caused a viscerotropic type of illness in which virus replicated predominantly in lymph nodes, spleen, and bone marrow. With the most severe visceral forms of Argentine hemorrhagic fever, the guinea pigs became viremic, developed necrosis of spleen, lymph nodes, and bone marrow, showed gastric hemorrhages, and all animals died within 13-15 days. Other Junin strains induced a neurological type of illness with transient viral replication in and lymphocyte depletion of spleen and lymph nodes, with no detectable viremia or viral replication in bone marrow. Subsequently, virus was found in the brain with varying severities of polioencephalitis, and the guinea pigs frequently showed rear leg paralysis before death occurred 28-34 days after inoculation. Not all animals infected with a neurotropic strain developed all these signs. One viral strain induced some signs characteristic of both patterns of illness. Although the disease forms in the guinea pig model did not strictly correlate with those observed in the humans from which these strains were obtained, the different strains of Junin virus consistently caused very different patterns of illness in infected guinea pigs.

  13. Immunosuppression of experimental allergic encephalomyelitis in guinea pigs by antibrain and antithymocyte heteroantisera.

    PubMed

    Rauch, H C; Tom, B H

    1980-01-01

    Experimental allergic encephalomyelitis (EAE), induced by central nervous system (CNS) myelin basic protein (MBP) in adjuvant, is considered a thymus dependent autoimmune disease. Brain contains the thymic antigen, thy 1. The possibility that brain associated anti thy 1 immunoglobulin may be provoked in certain pathologic conditions of the CNS suggested a comparative evaluation of brain and thymocyte antisera on the development of EAE. Antisera produced in rabbits against brain from guinea pigs, rats and mice or fetal guinea pig thymus were highly reactive against thy 1 containing cells when assessed by indirect immunofluorescent staining or complement-mediated cell lysis. Treatment of guinea pigs with heteroantisera to guinea pig and mouse, but not to rat brain, for 3 days around the time of MBP sensitization markedly reduced physical signs of disease, particularly paralysis, but had little effect on the development of inflammatory lesions in the CNS. Anti-guinea pig thymocyte sera eliminated all physical signs of EAE with only residual pathology. These results establish the relative immunosuppressive effect of brain and thymocyte antisera in EAE and corroborate the thymus-dependent nature of EAE in guinea pigs.

  14. Increased Severity of Tuberculosis in Guinea Pigs with Type 2 Diabetes

    PubMed Central

    Podell, Brendan K.; Ackart, David F.; Obregon-Henao, Andres; Eck, Sarah P.; Henao-Tamayo, Marcela; Richardson, Michael; Orme, Ian M.; Ordway, Diane J.; Basaraba, Randall J.

    2015-01-01

    Impaired glucose tolerance and type 2 diabetes were induced in guinea pigs to model the emerging comorbidity of Mycobacterium tuberculosis infection in diabetic patients. Type 2 diabetes mellitus was induced by low-dose streptozotocin in guinea pigs rendered glucose intolerant by first feeding a high-fat, high-carbohydrate diet before M. tuberculosis exposure. M. tuberculosis infection of diabetic guinea pigs resulted in severe and rapidly progressive tuberculosis (TB) with a shortened survival interval, more severe pulmonary and extrapulmonary pathology, and a higher bacterial burden compared with glucose-intolerant and nondiabetic controls. Compared with nondiabetics, diabetic guinea pigs with TB had an exacerbated proinflammatory response with more severe granulocytic inflammation and higher gene expression for the cytokines/chemokines interferon-γ, IL-17A, IL-8, and IL-10 in the lung and for interferon-γ, tumor necrosis factor-α, IL-8, and monocyte chemoattractant protein-1 in the spleen. TB disease progression in guinea pigs with impaired glucose tolerance was similar to that of nondiabetic controls in the early stages of infection but was more severe by day 90. The guinea pig model of type 2 diabetes–TB comorbidity mimics important features of the naturally occurring disease in humans. This model will be beneficial in understanding the complex pathogenesis of TB in diabetic patients and to test new strategies to improve TB and diabetes control when the two diseases occur together. PMID:24492198

  15. Chlamydia caviae infection alters abundance but not composition of the guinea pig vaginal microbiota.

    PubMed

    Neuendorf, Elizabeth; Gajer, Pawel; Bowlin, Anne K; Marques, Patricia X; Ma, Bing; Yang, Hongqiu; Fu, Li; Humphrys, Michael S; Forney, Larry J; Myers, Garry S A; Bavoil, Patrik M; Rank, Roger G; Ravel, Jacques

    2015-06-01

    In humans, the vaginal microbiota is thought to be the first line of defense again pathogens including Chlamydia trachomatis. The guinea pig has been extensively used as a model to study chlamydial infection because it shares anatomical and physiological similarities with humans, such as a squamous vaginal epithelium as well as some of the long-term outcomes caused by chlamydial infection. In this study, we aimed to evaluate the guinea pig-C. caviae model of genital infection as a surrogate for studying the role of the vaginal microbiota in the early steps of C. trachomatis infection in humans. We used culture-independent molecular methods to characterize the relative and absolute abundance of bacterial phylotypes in the guinea pig vaginal microbiota in animals non-infected, mock-infected or infected by C. caviae. We showed that the guinea pig and human vaginal microbiotas are of different bacterial composition and abundance. Chlamydia caviae infection had a profound effect on the absolute abundance of bacterial phylotypes but not on the composition of the guinea pig vaginal microbiota. Our findings compromise the validity of the guinea pig-C. caviae model to study the role of the vaginal microbiota during the early steps of sexually transmitted infection.

  16. Immunogenicity of guinea pig cells transformed in culture by chemical carcinogens

    SciTech Connect

    Ohanian, S.H.; McCabe, R.P.; Evans, C.H.

    1981-12-01

    The immunogenicity of inbred strain 2/N guinea pig fibroblasts transformed to the malignant state in vitro by chemical carcinogens was evaluated with the use of a variety of in vivo and in vitro methods including delayed-type hypersensitivity skin and tumor transplantation tests and analysis of antibody production by immunofluorescence, complement fixation, and staphylococcal protein A binding tests. Neoplastic transformation was induced by direct treatment of cells in culture with benzo(a)pyrene, 3-methylcholanthrene, or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or by the host-mediated method by which fetuses were exposed to diethylnitrosamine or MNNG in vivo prior to cell culture. Rabbits and syngeneic guinea pigs were inoculated with unirradiated and X-irradiated clonally derived cells. Delayed hypersensitivity skin reactions to immunizing or other cells were equivalent in immunized or control guinea pigs, and no protection to tumor outgrowth from a challenge inoculum of immunizing cells was observed. Antibody activity induced in the sera of immunized guinea pigs was cross-reactive and removed by absorption with nontumorigenic cells. Rabbit anitsera after absorption with fetal guinea pig cells were nonreactive with the specific immunizing or other cultured cells. Chemical carcinogen-induced neoplastic transformation of guinea pig cells can, therefore, occur without formation of detectable, individually distinct cell surface tumor-specific neoantigens.

  17. Immunogenicity of guinea pig cells transformed in culture by chemical carcinogens

    SciTech Connect

    Ohanian, S.H.; McCabe, R.P.; Evans, C.H.

    1981-12-01

    The immunogenicity of inbred strain 2/N guinea pig fibroblasts transformed to the malignant state in vitro by chemical carcinogens was evaluated with the use of a variety of in vivo and in vitro methods including delayed-type hypersensitivity skin and tumor transplantation tests and analysis of antibody production by immunofluorescence, complement fixation, and staphylococcal protein A binding tests. Neoplastic transformation was induced by direct treatment of cells in culture with benzo(a)pyrene, 3-methylcholanthrene, or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or by the host-mediated method by which fetuses were exposed to diethylnitrosamine or MNNG in vivo prior to cell culture. Rabbits and syngeneic guinea pigs were inoculated with unirradiated and X-irradiated clonally derived cells. Delayed hypersensitivity skin reactions to immunizing or other cells were equivalent in immunized or control guinea pigs, and no protection to tumor outgrowth from a challenge inoculum of immunizing cells was observed. Antibody activity induced in the sera of immunized guinea pigs was cross-reactive and removed by absorption with nontumorigenic cells. Rabbit antisera after absorption with fetal guinea pig cells were nonreactive with the specific immunizing or other culture cells. Chemical carcinogen-induced neoplastic transformation of guinea pig cells can, therefore, occur without formation of detectable, individually distinct cell surface tumor-specific neoantigens.

  18. T-cell-activating monoclonal antibodies, reacting with both leukocytes and erythrocytes, recognize the guinea pig Thy-1 differentiation antigen: characterization and cloning of guinea pig CD90.

    PubMed

    Schäfer, H; Bartels, T; Hahn, G; Otto, A; Burger, R

    1999-11-01

    A glycophosphatidylinositol (GPI)-linked differentiation antigen expressed on guinea pig T and B lymphocytes was identified by several monoclonal antibodies; it has been shown previously that this membrane protein induced strong polyclonal T cell proliferation upon antibody binding and costimulation by PMA. Purification by immunoadsorption and microsequencing revealed that this T-cell-activating protein is the homologue of Thy-1 or CD90. In contrast to the Thy-1 antigen of most other species, guinea pig Thy-1 has a much higher molecular weight, which is due to a more extensive N-linked glycosylation, bringing the molecular weight of the total antigen up to 36 kDa. Molecular cloning of guinea pig Thy-1 indicated that the deduced molecular weight of the protein backbone is 12,777 after removal of an N-terminal 19-amino-acid leader peptide and cleavage of the 31 amino acids for GPI anchoring the C-terminal end. Sequence comparison showed that guinea pig Thy-1 has an 82% homology to human and a 72% homology to mouse Thy-1 on the amino acid level. Immunohistological staining of cryostat sections revealed intensive staining with the monoclonal antibody H154 on fibroblasts, fibrocytes, Kupffer cells, alveolar macrophages, and mesangial cells. As observed in the human, mouse, and rat, Thy-1 is abundant in the guinea pig brain. Unlike Thy-1 expression in other species, guinea pig Thy-1 is strongly expressed on most resting, nonactivated B cells and, to a lesser extent, on erythrocytes. While treatment of erythrocytes and lymphocytes with GPI-specific phospholipase C largely decreased reactivity with mAb H154, T cells retained the proliferative response to antibody and phorbol esters.

  19. Modeling beta-adrenergic control of cardiac myocyte contractility in silico

    NASA Technical Reports Server (NTRS)

    Saucerman, Jeffrey J.; Brunton, Laurence L.; Michailova, Anushka P.; McCulloch, Andrew D.; McCullough, A. D. (Principal Investigator)

    2003-01-01

    The beta-adrenergic signaling pathway regulates cardiac myocyte contractility through a combination of feedforward and feedback mechanisms. We used systems analysis to investigate how the components and topology of this signaling network permit neurohormonal control of excitation-contraction coupling in the rat ventricular myocyte. A kinetic model integrating beta-adrenergic signaling with excitation-contraction coupling was formulated, and each subsystem was validated with independent biochemical and physiological measurements. Model analysis was used to investigate quantitatively the effects of specific molecular perturbations. 3-Fold overexpression of adenylyl cyclase in the model allowed an 85% higher rate of cyclic AMP synthesis than an equivalent overexpression of beta 1-adrenergic receptor, and manipulating the affinity of Gs alpha for adenylyl cyclase was a more potent regulator of cyclic AMP production. The model predicted that less than 40% of adenylyl cyclase molecules may be stimulated under maximal receptor activation, and an experimental protocol is suggested for validating this prediction. The model also predicted that the endogenous heat-stable protein kinase inhibitor may enhance basal cyclic AMP buffering by 68% and increasing the apparent Hill coefficient of protein kinase A activation from 1.0 to 2.0. Finally, phosphorylation of the L-type calcium channel and phospholamban were found sufficient to predict the dominant changes in myocyte contractility, including a 2.6x increase in systolic calcium (inotropy) and a 28% decrease in calcium half-relaxation time (lusitropy). By performing systems analysis, the consequences of molecular perturbations in the beta-adrenergic signaling network may be understood within the context of integrative cellular physiology.

  20. Cell-Specific Cardiac Electrophysiology Models

    PubMed Central

    Groenendaal, Willemijn; Ortega, Francis A.; Kherlopian, Armen R.; Zygmunt, Andrew C.; Krogh-Madsen, Trine; Christini, David J.

    2015-01-01

    The traditional cardiac model-building paradigm involves constructing a composite model using data collected from many cells. Equations are derived for each relevant cellular component (e.g., ion channel, exchanger) independently. After the equations for all components are combined to form the composite model, a subset of parameters is tuned, often arbitrarily and by hand, until the model output matches a target objective, such as an action potential. Unfortunately, such models often fail to accurately simulate behavior that is dynamically dissimilar (e.g., arrhythmia) to the simple target objective to which the model was fit. In this study, we develop a new approach in which data are collected via a series of complex electrophysiology protocols from single cardiac myocytes and then used to tune model parameters via a parallel fitting method known as a genetic algorithm (GA). The dynamical complexity of the electrophysiological data, which can only be fit by an automated method such as a GA, leads to more accurately parameterized models that can simulate rich cardiac dynamics. The feasibility of the method is first validated computationally, after which it is used to develop models of isolated guinea pig ventricular myocytes that simulate the electrophysiological dynamics significantly better than does a standard guinea pig model. In addition to improving model fidelity generally, this approach can be used to generate a cell-specific model. By so doing, the approach may be useful in applications ranging from studying the implications of cell-to-cell variability to the prediction of intersubject differences in response to pharmacological treatment. PMID:25928268

  1. Irregularly Appearing Early Afterdepolarizations in Cardiac Myocytes: Random Fluctuations or Dynamical Chaos?

    PubMed Central

    Sato, Daisuke; Xie, Lai-Hua; Nguyen, Thao P.; Weiss, James N.; Qu, Zhilin

    2010-01-01

    Irregularly occurring early afterdepolarizations (EADs) in cardiac myocytes are traditionally hypothesized to be caused by random ion channel fluctuations. In this study, we combined 1), patch-clamp experiments in which action potentials were recorded at different pacing cycle lengths from isolated rabbit ventricular myocytes under several experimental conditions inducing EADs, including oxidative stress with hydrogen peroxide, calcium overload with BayK8644, and ionic stress with hypokalemia; 2), computer simulations using a physiologically detailed rabbit ventricular action potential model, in which repolarization reserve was reduced to generate EADs and random ion channel or path cycle length fluctuations were implemented; and 3), iterated maps with or without noise. By comparing experimental, modeling, and bifurcation analyses, we present evidence that noise-induced transitions between bistable states (i.e., between an action potential with and without an EAD) is not sufficient to account for the large variation in action potential duration fluctuations observed in experimental studies. We conclude that the irregular dynamics of EADs is intrinsically chaotic, with random fluctuations playing a nonessential, auxiliary role potentiating the complex dynamics. PMID:20682253

  2. Na+ Transport in Cardiac Myocytes; Implications for Excitation-Contraction Coupling

    PubMed Central

    Bers, Donald M.; Despa, Sanda

    2009-01-01

    Intracellular Na+ concentration ([Na+]i) is very important in modulating the contractile and electrical activity of the heart. Upon electrical excitation of the myocardium, voltage-dependent Na+ channels open, triggering the upstroke of the action potential (AP). During the AP, Ca2+ enters the myocytes via L-type Ca2+ channels. This triggers Ca2+ release from the sarcoplasmic reticulum (SR) and thus activates contraction. Relaxation occurs when cytosolic Ca2+ declines, mainly due to re-uptake into the SR via SR Ca2+-ATPase and extrusion from the cell via the Na+/Ca2+ exchanger (NCX). NCX extrudes one Ca2+ ion in exchange for three Na+ ions and its activity is critically regulated by [Na+]i. Thus, via NCX, [Na+]i is centrally involved in the regulation of intracellular [Ca2+] and contractility. Na+ brought in by Na+ channels, NCX and other Na+ entry pathways is extruded by the Na+/K+ pump (NKA) to keep [Na+]i low. NKA is regulated by phospholemman, a small sarcolemmal protein that associates with NKA. Unphosphorylated phospholemman inhibits NKA by decreasing the pump affinity for internal Na+ and this inhibition is relieved upon phosphorylation. Here we discuss the main characteristics of the Na+ transport pathways in cardiac myocytes and their physiological and pathophysiological relevance. PMID:19243007

  3. Restoration of β -Adrenergic Signaling in Failing Cardiac Ventricular Myocytes via Adenoviral-Mediated Gene Transfer

    NASA Astrophysics Data System (ADS)

    Akhter, Shahab A.; Skaer, Christine A.; Kypson, Alan P.; McDonald, Patricia H.; Peppel, Karsten C.; Glower, Donald D.; Lefkowitz, Robert J.; Koch, Walter J.

    1997-10-01

    Cardiovascular gene therapy is a novel approach to the treatment of diseases such as congestive heart failure (CHF). Gene transfer to the heart would allow for the replacement of defective or missing cellular proteins that may improve cardiac performance. Our laboratory has been focusing on the feasibility of restoring β -adrenergic signaling deficiencies that are a characteristic of chronic CHF. We have now studied isolated ventricular myocytes from rabbits that have been chronically paced to produce hemodynamic failure. We document molecular β -adrenergic signaling defects including down-regulation of myocardial β -adrenergic receptors (β -ARs), functional β -AR uncoupling, and an upregulation of the β -AR kinase (β ARK1). Adenoviral-mediated gene transfer of the human β 2-AR or an inhibitor of β ARK1 to these failing myocytes led to the restoration of β -AR signaling. These results demonstrate that defects present in this critical myocardial signaling pathway can be corrected in vitro using genetic modification and raise the possibility of novel inotropic therapies for CHF including the inhibition of β ARK1 activity in the heart.

  4. Heart Rate and Extracellular Sodium and Potassium Modulation of Gap Junction Mediated Conduction in Guinea Pigs

    PubMed Central

    Entz, Michael; George, Sharon A.; Zeitz, Michael J.; Raisch, Tristan; Smyth, James W.; Poelzing, Steven

    2016-01-01

    Background: Recent studies suggested that cardiac conduction in murine hearts with narrow perinexi and 50% reduced connexin43 (Cx43) expression is more sensitive to relatively physiological changes of extracellular potassium ([K+]o) and sodium ([Na+]o). Purpose: Determine whether similar [K+]o and [Na+]o changes alter conduction velocity (CV) sensitivity to pharmacologic gap junction (GJ) uncoupling in guinea pigs. Methods: [K+]o and [Na+]o were varied in Langendorff perfused guinea pig ventricles (Solution A: [K+]o = 4.56 and [Na+]o = 153.3 mM. Solution B: [K+]o = 6.95 and [Na+]o = 145.5 mM). Gap junctions were inhibited with carbenoxolone (CBX) (15 and 30 μM). Epicardial CV was quantified by optical mapping. Perinexal width was measured with transmission electron microscopy. Total and phosphorylated Cx43 were evaluated by western blotting. Results: Solution composition did not alter CV under control conditions or with 15μM CBX. Decreasing the basic cycle length (BCL) of pacing from 300 to 160 ms decreased CV uniformly with both solutions. At 30 μM CBX, a change in solution did not alter CV either longitudinally or transversely at BCL = 300 ms. However, reducing BCL to 160 ms caused CV to decrease more in hearts perfused with Solution B than A. Solution composition did not alter perinexal width, nor did it change total or phosphorylated serine 368 Cx43 expression. These data suggest that the solution dependent CV changes were independent of altered perinexal width or GJ coupling. Action potential duration was always shorter in hearts perfused with Solution B than A, independent of pacing rate and/or CBX concentration. Conclusions: Increased heart rate and GJ uncoupling can unmask small CV differences caused by changing [K+]o and [Na+]o. These data suggest that modulating extracellular ionic composition may be a novel anti-arrhythmic target in diseases with abnormal GJ coupling, particularly when heart rate cannot be controlled. PMID:26869934

  5. Mst1 promotes cardiac myocyte apoptosis through phosphorylation and inhibition of Bcl-xL

    PubMed Central

    Del Re, Dominic P.; Matsuda, Takahisa; Zhai, Peiyong; Maejima, Yasuhiro; Jain, Mohit Raja; Liu, Tong; Li, Hong; Hsu, Chiao-Po; Sadoshima, Junichi

    2014-01-01

    SUMMARY The Hippo pathway, evolutionarily conserved from flies to mammals, promotes cell death and inhibits cell proliferation to regulate organ size. The core component of this cascade, Mst1 in mammalian cells, is sufficient to promote apoptosis. However, the mechanisms underlying both its activation and its ability to elicit cell death remain largely undefined. We here identify a novel signaling cassette in cardiac myocytes consisting of K-Ras, the scaffold RASSF1A and Mst1 that is localized to mitochondria and promotes Mst1 activation in response to oxidative stress. Activated Mst1 phosphorylates Bcl-xL at Ser14, which resides in the BH4 domain, thereby antagonizing Bcl-xL-Bax binding. This, in turn, causes activation of Bax and subsequent mitochondria-mediated apoptotic death. Our findings demonstrate mitochondrial localization of Hippo signaling and identify a novel target of this cascade, Bcl-xL, which is directly modified to promote apoptosis. PMID:24813943

  6. Using models of the myocyte for functional interpretation of cardiac proteomic data

    PubMed Central

    Winslow, Raimond L; Cortassa, Sonia; Greenstein, Joseph L

    2005-01-01

    There has been significant progress towards the development of highly integrative computational models of the cardiac myocyte over the past decade. Models now incorporate descriptions of voltage-gated ionic currents and membrane transporters, mechanisms of calcium-induced calcium release and intracellular calcium cycling, mitochondrial ATP production and its coupling to energy-requiring membrane transport processes and mechanisms of force generation. There is an extensive literature documenting both the reconstructive and predictive abilities of these models and there is no question that an interplay between quantitative modelling and experimental investigation has become a central component of modern cardiovascular research. As data regarding the cardiovascular proteome in both health and disease emerge, integrative models of the myocyte are becoming useful tools for interpreting the functional significance of changes in protein expression and post-translational modifications (PTMs). Data of particular importance include information on: (a) changes of expressed protein level, (b) changes of protein PTMs, (c) protein localization, and (d) protein–protein interactions, as it is often possible to incorporate and interpret the functional significance of such findings using computational models. We provide two examples of how models may be used in this fashion. In the first example, we show how information on altered expression of the sarcoplasmic reticulum Ca2+-ATPase, when interpreted through the use of a computational model, has provided key insights into fundamental mechanisms regulating cardiac action potential duration. In the second example, we show how information on the effects of phosphorylation of L-type Ca2+ channels, when interpreted through the use of a model, provides insights on how this post-translational modification alters the properties of excitation–contraction coupling and risk for arrhythmia. PMID:15611013

  7. The Multi-Domain Fibroblast/Myocyte Coupling in the Cardiac Tissue: A Theoretical Study.

    PubMed

    Greisas, Ariel; Zlochiver, Sharon

    2016-09-01

    Cardiac fibroblast proliferation and concomitant collagenous matrix accumulation (fibrosis) develop during multiple cardiac pathologies. Recent studies have demonstrated direct electrical coupling between myocytes and fibroblasts in vitro, and assessed the electrophysiological implications of such coupling. However, in the living tissues, such coupling has not been demonstrated, and only indirect coupling via the extracellular space is likely to exist. In this study we employed a multi-domain model to assess the modulation of the cardiac electrophysiological properties by neighboring fibroblasts assuming only indirect coupling. Numerical simulations in 1D and 2D human atrial models showed that extracellular coupling sustains a significant impact on conduction velocity (CV) and a less significant effect on the action potential duration. Both CV and the slope of the CV restitution increased with increasing fibroblast density. This effect was more substantial for lower extracellular conductance. In 2D, spiral waves exhibited reduced frequency with increasing fibroblast density, and the propensity of wavebreaks and complex dynamics at high pacing rates significantly increased. PMID:27150222

  8. Curvature effects on activation speed and repolarization in an ionic model of cardiac myocytes

    NASA Astrophysics Data System (ADS)

    Comtois, P.; Vinet, A.

    1999-10-01

    Reentry is a major mechanism underlying the initiation and perpetuation of many cardiac arrhythmias 12345. Stimulated ventricular myocytes give action potential characterized by a fast upstroke, a long-lasting plateau, and a late repolarization phase. The plateau phase determines the action potential duration (APD) during which the system remains refractory, a property essential to the synchronization of the heart cycle. The APD varies much with prematurity and this change has been shown to be the main determinant of the dynamics in models of paced cells and cable, and during reentry in the one-dimensional loop. Curvature has also been shown to be an important factor for propagation in experimental and theoretical cardiac extended tissue. The objective of this paper is to combine both curvature and prematurity effects in a kinematical model of propagation in cardiac tissue. First, an approximation of the ionic model is used to obtain the effects of curvature and prematurity on the speed of propagation, the APD, and the absolute refractory period. Two versions of the ionic model are studied that differ in their rate of excitability recovery. The functions are used in a kinematical model describing the propagation of period-1 solutions around an annulus.

  9. Four-and-a-half LIM domains proteins are novel regulators of the protein kinase D pathway in cardiac myocytes.

    PubMed

    Stathopoulou, Konstantina; Cuello, Friederike; Candasamy, Alexandra J; Kemp, Elizabeth M; Ehler, Elisabeth; Haworth, Robert S; Avkiran, Metin

    2014-02-01

    PKD (protein kinase D) is a serine/threonine kinase implicated in multiple cardiac roles, including the phosphorylation of the class II HDAC5 (histone deacetylase isoform 5) and thereby de-repression of MEF2 (myocyte enhancer factor 2) transcription factor activity. In the present study we identify FHL1 (four-and-a-half LIM domains protein 1) and FHL2 as novel binding partners for PKD in cardiac myocytes. This was confirmed by pull-down assays using recombinant GST-fused proteins and heterologously or endogenously expressed PKD in adult rat ventricular myocytes or NRVMs (neonatal rat ventricular myocytes) respectively, and by co-immunoprecipitation of FHL1 and FHL2 with GFP-PKD1 fusion protein expressed in NRVMs. In vitro kinase assays showed that neither FHL1 nor FHL2 is a PKD1 substrate. Selective knockdown of FHL1 expression in NRVMs significantly inhibited PKD activation and HDAC5 phosphorylation in response to endothelin 1, but not to the α₁-adrenoceptor agonist phenylephrine. In contrast, selective knockdown of FHL2 expression caused a significant reduction in PKD activation and HDAC5 phosphorylation in response to both stimuli. Interestingly, neither intervention affected MEF2 activation by endothelin 1 or phenylephrine. We conclude that FHL1 and FHL2 are novel cardiac PKD partners, which differentially facilitate PKD activation and HDAC5 phosphorylation by distinct neurohormonal stimuli, but are unlikely to regulate MEF2-driven transcriptional reprogramming.

  10. Electrophysiological effects of the aqueous extract of Averrhoa carambola L. leaves on the guinea pig heart.

    PubMed

    Vasconcelos, C M L; Araújo, M S; Conde-Garcia, E A

    2006-07-01

    This work aims to describe some electrophysiological changes promoted by the aqueous extract (AEx) from Averrhoa carambola leaves in guinea pig heart. The experiments were carried out on isolated heart or on right atrium-ventricle preparations. In 6 hearts, the extract induced many kinds of atrioventricular blocks (1st, 2nd, and 3rd degrees); increased the QT interval from 229+/-23 to 264+/-19 ms; increased the QRS complex duration from 27+/-3.1 to 59+/-11 ms, and depressed the cardiac rate from 136+/-17 to 89+/-14b pm. Furthermore, it decreased the conduction velocity of atrial impulse (17+/-3%); reduced the intraventricular pressure (86+/-6%), and increased the conduction time between the right atrium and the His bundle (27+/-6.5%). The conduction time from the His bundle to the right ventricle was not altered. Atropine sulfate did not change either the electrocardiographic parameters or the intraventricular pressure effects promoted by the A. carambola AEx. Based on these results, the popular use of such extracts should be avoided because it can promote electrical and mechanical changes in the normal heart.

  11. Quinidine elicits proarrhythmic changes in ventricular repolarization and refractoriness in guinea-pig.

    PubMed

    Osadchii, Oleg E

    2013-04-01

    Quinidine is a class Ia Na(+) channel blocker that prolongs cardiac repolarization owing to the inhibition of I(Kr), the rapid component of the delayed rectifier current. Although quinidine may induce proarrhythmia, the contributing mechanisms remain incompletely understood. This study examined whether quinidine may set proarrhythmic substrate by inducing spatiotemporal abnormalities in repolarization and refractoriness. The monophasic action potential duration (APD), effective refractory periods (ERPs), and volume-conducted electrocardiograms (ECGs) were assessed in perfused guinea-pig hearts. Quinidine was found to produce the reverse rate-dependent prolongation of ventricular repolarization, which contributed to increased steepness of APD restitution. Throughout the epicardium, quinidine elicited a greater APD increase in the left ventricular chamber compared with the right ventricle, thereby enhancing spatial repolarization heterogeneities. Quinidine prolonged APD to a greater extent than ERP, thus extending the vulnerable window for ventricular re-excitation. This change was attributed to increased triangulation of epicardial action potential because of greater APD lengthening at 90% repolarization than at 30% repolarization. Over the transmural plane, quinidine evoked a greater ERP prolongation at endocardium than epicardium and increased dispersion of refractoriness. Premature ectopic beats and monomorphic ventricular tachycardia were observed in 50% of quinidine-treated heart preparations. In summary, abnormal changes in repolarization and refractoriness contribute greatly to proarrhythmic substrate upon quinidine infusion.

  12. CaMKII Negatively Regulates Calcineurin-NFAT Signaling in Cardiac Myocytes

    PubMed Central

    MacDonnell, Scott M.; Weisser-Thomas, Jutta; Kubo, Hajime; Hanscome, Marie; Liu, Qinghang; Jaleel, Naser; Berretta, Remus; Chen, Xiongwen; Brown, Joan H.; Sabri, Abdel-Karim; Molkentin, Jeffery D.; Houser, Steven R.

    2009-01-01

    Rationale Pathologic cardiac myocyte hypertrophy is thought to be induced by the persistent increases in intracellular Ca2+ needed to maintain cardiac function when systolic wall stress is increased. Hypertrophic Ca2+ binds to calmodulin (CaM) and activates the phosphatase calcineurin (Cn) and CaM kinase (CaMKII). Cn dephosphorylates cytoplasmic nuclear factor of activated T-cells (NFAT), inducing its translocation to the nucleus where it activates anti-apoptotic and hypertrophic target genes. Cytoplasmic CaMKII regulates Ca2+ handling proteins but whether or not it is directly involved in hypertrophic and survival signaling is not known. Objective This study explored the hypothesis that cytoplasmic CaMKII reduces NFAT nuclear translocation by inhibiting the phosphatase activity of Cn. Methods and Results GFP-tagged NFATc3 was used to determine the cellular location of NFAT in cultured neonatal rat ventricular myocytes (NRVM) and adult feline ventricular myocytes. Constitutively active (CaMKII-CA) or dominant negative (CaMKII-DN) mutants of cytoplasmic targeted CaMKIIδc were used to activate and inhibit cytoplasmic CaMKII activity. In NRVM CaMKII-DN (48.5±3%, P<0.01 vs control) increased while CaMKII-CA decreased (5.9±1%, P<0.01 vs control) NFAT nuclear translocation (Control: 12.3±1%). Cn inhibitors were used to show that these effects were caused by modulation of Cn activity. Increasing Ca2+ increased Cn-dependent NFAT translocation (to 71.7±7%, p<0.01) and CaMKII-CA reduced this effect (to 17.6±4%). CaMKII-CA increased TUNEL and caspase-3 activity (P<0.05). CaMKII directly phosphorylated Cn at Ser197 in CaMKII-CA infected NRVM and in hypertrophied feline hearts. Conclusion These data show that activation of cytoplasmic CaMKII inhibits NFAT nuclear translocation by phosphorylation and subsequent inhibition of Cn. PMID:19608982

  13. Heterokaryons of cardiac myocytes and fibroblasts reveal the lack of dominance of the cardiac muscle phenotype.

    PubMed Central

    Evans, S M; Tai, L J; Tan, V P; Newton, C B; Chien, K R

    1994-01-01

    The molecular characterization of a cardiac determination gene has been an elusive goal for the past several years. Prior to cloning of the skeletal muscle determination factor MyoD, the presence of a dominantly acting skeletal muscle determination factor had been inferred from the observation that the skeletal muscle phenotype was dominant in skeletal muscle-fibroblast heterokaryons (H. M. Blau, G. K. Pavlath, E. C. Hardeman, C.-P. Chiu, L. Siberstein, S. G. Webster, S. C. Miller, and D. Webster, Science 230:758-766, 1985). In these experiments, we have examined cardiac-fibroblast heterokaryons to investigate the existence of a dominantly acting cardiac determination factor. We have employed a novel experimental approach using primary embryonic fibroblasts from transgenic mice as a means of assaying for the activation of a cardiac promoter-luciferase reporter transgene within fibroblast nuclei. This approach provides a potential means of genetic selection for a dominantly acting positive factor and can be generalized to other systems. We have examined the expression of three markers of the cardiac lineage: a myofibrillar protein promoter (MLC2), a secreted protein (ANF), and a transcription factor (MEF2). MEF2 is specific to both cardiac and skeletal muscle cells. Our results indicate that in a majority of heterokaryons with an equal ratio of cardiac to fibroblast nuclei, none of these cardiac markers are expressed, indicating that the cardiac phenotype is not dominant over the embryonic fibroblast phenotype. The distinction from previous results with skeletal muscle is emphasized by our results with MEF2, which is dominantly expressed in skeletal muscle-fibroblast but not cardiac-fibroblast heterokaryons, supporting its divergent regulation in the two cell types. Images PMID:8196663

  14. The ototoxic effect of boric acid solutions applied into the middle ear of guinea pigs.

    PubMed

    Oztürkcan, Sedat; Dündar, Riza; Katilmis, Hüseyin; Ilknur, Ali Ekber; Aktaş, Sinem; Haciömeroğlu, Senem

    2009-05-01

    This study analyzed the ototoxic effects of boric acid solutions. Boric acid solutions have been used as otologic preparations for many years. Boric acid is commonly found in solutions prepared with alcohol or distilled water but can also be found in a powder form. These preparations are used for both their antiseptic and acidic qualities in external and middle ear infections. We investigated the ototoxic effect of boric acid solutions on guinea pigs. We are unaware of any similar, previously published study of this subject in English. The study was conducted on 28 young albino guinea pigs. Prior to application of the boric acid solution under general anesthesia, an Auditory Brainstem Response (ABRs) test was applied to the right ear of the guinea pigs. Following the test, a perforation was created on the tympanic membrane of the right ear of each guinea pig and small gelfoam pieces were inserted into the perforated area. Test solutions were administered to the middle ear for 10 days by means of a transcanal route. Fifteen days after inserting the gelfoams in all of the guinea pigs, we anasthesized the guinea pigs and removed the gelfoams from the perforated region of the ear and then performed an ABRs on each guinea pig. The ABRs were within the normal range before the applications. After the application, no significant changes were detected in the ABRs thresholds in neither the saline group nor the group administered boric acid and distilled water solution; however, significant changes were detected in the ABRs thresholds of the Gentamicine and boric acid and alcohol solution groups. We believe that a 4% boric acid solution prepared with distilled water can be a more reliable preparation than a 4% boric acid solution prepared with alcohol.

  15. Effect of KOB03, a polyherbal medicine, on ovalbumin-induced allergic rhinitis in guinea pigs

    PubMed Central

    2012-01-01

    Background KOB03 is a polyherbal medicine that originated from the oriental prescription for the treatment of chronic allergic diseases such as rhinitis and asthma. This study aims to evaluate the effect of KOB03 on ovalbumin (OVA)-induced allergic rhinitis (AR) in guinea pigs. Methods Hartley guinea pigs were sensitized to OVA by intraperitoneal injection on days 0, 7, and 14 and challenged with intranasal exposure to OVA three times for 7 days after the last sensitization. KOB03 at doses of 200 and 500 mg/kg were orally administrated to guinea pigs once daily during challenge. The serum levels of histamine, OVA-specific immunoglobulin (Ig) E, eosinophil cationic protein (ECP) and cytokines (TNF-α, IL-4 and IFN-γ) in OVA sensitization/challenge-induced AR guinea pigs were measured. We also observed histological changes in nasal tissues of AR guinea pigs by staining with H&E, Periodic acid-Schiff, and toluidine blue. Results The administration of KOB03 at a dose of 500 mg/kg significantly decreased the serum levels of histamine (P = 0.001), OVA-specific IgE (P = 0.0017), ECP (P = 0.008), and TNF-α (P = 0.0003) in OVA-sensitized/challenged guinea pigs compared with controls. KOB03 significantly decreased the serum levels of a Th2 cytokine, IL-4 (P = 0.017), while significantly increasing the levels of a Th1 cytokine, IFN-γ (P = 0.0006) in OVA-sensitized/challenged guinea pigs compared with controls. In addition, KOB03 suppressed the epithelial destruction, goblet cell hyperplasia and eosinophilic infiltration into nasal mucosa associated with AR. Conclusion KOB03 may regulate allergic inflammation in AR by inhibiting nasal damage, the release of allergic mediators and modulating the balance of Th1/Th2 cytokines. PMID:23253436

  16. Acoustic stimulation promotes DNA fragmentation in the Guinea pig cochlea.

    PubMed

    Kamio, Tomonobu; Watanabe, Ken-Ichi; Okubo, Kimihiro

    2012-01-01

    Apoptosis can be described as programmed cell death. Apoptosis regulates cell turnover and is involved in various pathological conditions. The characteristic features of apoptosis are shrinkage of the cell body, chromatin condensation, and nucleic acid fragmentation. During apoptosis, double-stranded DNA is broken down into single-stranded DNA (ssDNA) by proteases. Acoustic trauma is commonly encountered in otorhinolaryngology clinics. Intense noise can cause inner ear damage, such as hearing disturbance, tinnitus, ear fullness, and decreased speech discrimination. In this study, we used immunohistochemical and electrophysiological methods to examine the fragmentation of DNA in the cochleas of guinea pigs that had been exposed to intense noise. Twenty-four guinea pigs weighing 250 to 350 g were used. The animals were divided into 4 groups: (I) a control group (n=6), (II) a group that was exposed to noise for 2 hours (n=6), (III) a group that was exposed to noise for 5 hours (n=6), and (IV) a group that was exposed to noise for 20 hours. The stimulus was a pure tone delivered at a frequency of 2 kHz. The sound pressure level was 120 dBSPL. No threshold shifts were apparent in group I. Group II showed a significant elevation of the hearing threshold (ANOVA, p<0.05(*)). The ABR threshold level was also significantly elevated immediately after the acoustic stimulation in groups III and IV (ANOVA, p<0.01(**)). In groups I, II, and IV, the lateral wall of the ear did not show immunoreactivity to ssDNA but did in group III. No immunoreactivity was apparent in the organ of Corti in group I or II. However, the supporting cells and outer hair cells in groups III and IV showed reactions for ssDNA. The fine structure of the organ of Corti had been destroyed in group IV. The lateral wall showed immunoreactivity for ssDNA only in group III, whereas the organ of Corti showed reactions for ssDNA in groups III and IV. Our study suggests that apoptotic changes occur in patients that

  17. Acoustic stimulation promotes DNA fragmentation in the Guinea pig cochlea.

    PubMed

    Kamio, Tomonobu; Watanabe, Ken-Ichi; Okubo, Kimihiro

    2012-01-01

    Apoptosis can be described as programmed cell death. Apoptosis regulates cell turnover and is involved in various pathological conditions. The characteristic features of apoptosis are shrinkage of the cell body, chromatin condensation, and nucleic acid fragmentation. During apoptosis, double-stranded DNA is broken down into single-stranded DNA (ssDNA) by proteases. Acoustic trauma is commonly encountered in otorhinolaryngology clinics. Intense noise can cause inner ear damage, such as hearing disturbance, tinnitus, ear fullness, and decreased speech discrimination. In this study, we used immunohistochemical and electrophysiological methods to examine the fragmentation of DNA in the cochleas of guinea pigs that had been exposed to intense noise. Twenty-four guinea pigs weighing 250 to 350 g were used. The animals were divided into 4 groups: (I) a control group (n=6), (II) a group that was exposed to noise for 2 hours (n=6), (III) a group that was exposed to noise for 5 hours (n=6), and (IV) a group that was exposed to noise for 20 hours. The stimulus was a pure tone delivered at a frequency of 2 kHz. The sound pressure level was 120 dBSPL. No threshold shifts were apparent in group I. Group II showed a significant elevation of the hearing threshold (ANOVA, p<0.05(*)). The ABR threshold level was also significantly elevated immediately after the acoustic stimulation in groups III and IV (ANOVA, p<0.01(**)). In groups I, II, and IV, the lateral wall of the ear did not show immunoreactivity to ssDNA but did in group III. No immunoreactivity was apparent in the organ of Corti in group I or II. However, the supporting cells and outer hair cells in groups III and IV showed reactions for ssDNA. The fine structure of the organ of Corti had been destroyed in group IV. The lateral wall showed immunoreactivity for ssDNA only in group III, whereas the organ of Corti showed reactions for ssDNA in groups III and IV. Our study suggests that apoptotic changes occur in patients that

  18. Long-term hypothermic preservation of cardiac myocytes isolated from the neonatal rat ventricle: a comparison of various crystalloid solutions.

    PubMed

    Orita, H; Fukasawa, M; Uchino, H; Uchida, T; Shiono, S; Washio, M

    1995-01-01

    In this study, the functional and biochemical effects of crystalloid solutions on immature cardiac myocytes incubated under hypothermic conditions were evaluated. Cardiac myocytes were isolated from neonatal rat ventricles and cultured for 4 days, following which 12.5 x 10(5) myocytes per flask were incubated at 4 degrees C for 3, 6, 12, and 18 h in five types of crystalloid solutions: lactated Ringer's (LR), St. Thomas' Hospital (ST), University of Wisconsin (UW), 5% glucose-based potassium (GK), and normal saline (NS). The levels of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in the solutions were measured after each hypothermic incubation, following which the myocytes were cultured for an additional 24 h at 37 degrees C to evaluate the recovery of the myocyte beating rate. In the LR, UW, and NS groups, the recovery ratios of the myocyte beating rate were over 95% of the control (the beating rate prior to hypothermic incubation) at 3 h, but decreased to 20.3, 15.1, and 0%, respectively, at 18 h. The ST and GK groups had significantly lower recovery ratios than the other three groups (72.9% and 63.4%, respectively) at 3 h. The release of CPK and LDH in the LR, UW, and NS groups was significantly suppressed compared to the ST and GK groups, with the greatest suppression observed in the LR group. Moreover, the ST and GK groups had the highest CPK and LDH levels, respectively. Thus, LR solution had the least cytotoxic effects, indicating that it could be the most suitable basic solution of the various cardioplegic or preservation solutions during the neonatal period. PMID:7640455

  19. Isoform- and tissue-specific regulation of the Ca(2+)-sensitive transcription factor NFAT in cardiac myocytes and heart failure.

    PubMed

    Rinne, Andreas; Kapur, Nidhi; Molkentin, Jeffery D; Pogwizd, Steven M; Bers, Donald M; Banach, Kathrin; Blatter, Lothar A

    2010-06-01

    Nuclear factors of activated T cells (NFATs) are Ca(2+)-sensitive transcription factors that have been implicated in hypertrophy, heart failure (HF), and arrhythmias. Cytosolic NFAT is activated by dephosphorylation by the Ca(2+)-sensitive phosphatase calcineurin, resulting in translocation to the nucleus, which is opposed by kinase activity, rephosphorylation, and nuclear export. Four different NFAT isoforms are expressed in the heart. The activation and regulation of NFAT in adult cardiac myocytes, which may depend on the NFAT isoform and cell type, are not fully understood. This study compared basal localization, import, and export of NFATc1 and NFATc3 in adult atrial and ventricular myocytes to identify isoform- and tissue-specific regulatory mechanisms of NFAT activation under physiological conditions and in HF. NFAT-green fluorescent protein fusion proteins and NFAT immunocytochemistry were used to analyze NFAT regulation in adult cat and rabbit myocytes. NFATc1 displayed basal nuclear localization in atrial and ventricular myocytes, an effect that was attenuated by reducing intracellular Ca(2+) concentration and inhibiting calcineurin, and enhanced by the inhibition of nuclear export. In contrast, NFATc3 was localized to the cytoplasm but could be driven to the nucleus by angiotensin II and endothelin-1 stimulation in atrial, but not ventricular, cells. Inhibition of nuclear export (by leptomycin B) facilitated nuclear localization in both cell types. Ventricular myocytes from HF rabbits showed increased basal nuclear localization of endogenous NFATc3 and reduced responsiveness of NFAT translocation to phenylephrine stimulation. In control myocytes, Ca(2+) overload, leading to spontaneous Ca(2+) waves, induced substantial translocation of NFATc3 to the nucleus. We conclude that the activation of NFAT in adult cardiomyocytes is isoform and tissue specific and is tightly controlled by nuclear export. NFAT is activated in myocytes from HF animals and may be

  20. PGC-1{alpha} accelerates cytosolic Ca{sup 2+} clearance without disturbing Ca{sup 2+} homeostasis in cardiac myocytes

    SciTech Connect

    Chen, Min; Wang, Yanru; Qu, Aijuan

    2010-06-11

    Energy metabolism and Ca{sup 2+} handling serve critical roles in cardiac physiology and pathophysiology. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1{alpha}) is a multi-functional coactivator that is involved in the regulation of cardiac mitochondrial functional capacity and cellular energy metabolism. However, the regulation of PGC-1{alpha} in cardiac Ca{sup 2+} signaling has not been fully elucidated. To address this issue, we combined confocal line-scan imaging with off-line imaging processing to characterize calcium signaling in cultured adult rat ventricular myocytes expressing PGC-1{alpha} via adenoviral transduction. Our data shows that overexpressing PGC-1{alpha} improved myocyte contractility without increasing the amplitude of Ca{sup 2+} transients, suggesting that myofilament sensitivity to Ca{sup 2+} increased. Interestingly, the decay kinetics of global Ca{sup 2+} transients and Ca{sup 2+} waves accelerated in PGC-1{alpha}-expressing cells, but the decay rate of caffeine-elicited Ca{sup 2+} transients showed no significant change. This suggests that sarcoplasmic reticulum (SR) Ca{sup 2+}-ATPase (SERCA2a), but not Na{sup +}/Ca{sup 2+} exchange (NCX) contribute to PGC-1{alpha}-induced cytosolic Ca{sup 2+} clearance. Furthermore, PGC-1{alpha} induced the expression of SERCA2a in cultured cardiac myocytes. Importantly, overexpressing PGC-1{alpha} did not disturb cardiac Ca{sup 2+} homeostasis, because SR Ca{sup 2+} load and the propensity for Ca{sup 2+} waves remained unchanged. These data suggest that PGC-1{alpha} can ameliorate cardiac Ca{sup 2+} cycling and improve cardiac work output in response to physiological stress. Unraveling the PGC-1{alpha}-calcium handing pathway sheds new light on the role of PGC-1{alpha} in the therapy of cardiac diseases.

  1. Absorption Kinetics of Subcutaneously Administered Ceftazidime in Hypoperfused Guinea Pigs

    PubMed Central

    Ebihara, Tsuyoshi; Oshima, Shinji; Okita, Mitsuyoshi; Shiina, Sayumi; Negishi, Akio; Ohara, Kousuke; Ohshima, Shigeru; Iwasaki, Hiroyuki; Yoneyama, Akira; Kitazumi, Eiji; Kobayashi, Daisuke

    2014-01-01

    Background Pneumonia is the most common cause of death in patients with severe motor and intellectual disabilities (SMID), and intravenous ceftazidime (CAZ) is a widely used treatment for such infections. However, intravenous administration in patients with SMID may be difficult because of insufficient vascular development. Objectives The aim of our study was to determine the feasibility of subcutaneous drug administration by mentholated warm compresses (WMCs) as an alternative delivery method for ceftazidime in patients with SMID. Methods CAZ was subcutaneously administered to the abdominal region of naphazoline-treated hypoperfused guinea pigs, which were used as a hemodynamic model of patients with SMID. MWCs or warm compresses (WCs) were applied to the injection site to increase blood flow. We calculated the cumulative CAZ absorption over time by using the deconvolution method. Results Application of MWCs or WCs increased blood flow at the administration site and increased CAZ plasma levels. Application of MWCs or WCs after subcutaneous CAZ injection led to higher CAZ plasma levels than the mutant prevention concentration for a longer period than was observed for CAZ administration without the application of MWCs or WCs. Conclusions The application of MWCs or WCs enhanced subcutaneous CAZ absorption by increasing blood flow. MWCs and WCs are considered to be safe and routine methods to induce defecation after surgery on the digestive system; thus, the combination of these methods and subcutaneous CAZ administration is a potential method for treating pneumonia in patients with SMID. PMID:26649076

  2. Visual evoked potentials in guinea pigs with brain lesion.

    PubMed

    Takeuchi, T; Suzuki, M; Sitizyo, K; Isobe, R; Saito, T; Umemura, T; Shimada, A

    1992-10-01

    Visual evoked potentials (VEPs) were recorded in 10 adult male guinea pigs with brain lesion. Lesions were produced in 5 animals by superficial suction of the occipital lobe. The other 5 animals were orally administered with hexachlorophene (about 35 mg/kg/day) for 28 days. In the VEP following the ablation of the occipital lobe, the peaks P10, N20, P55, N75, N140 and P200 disappeared in many cases. The amplitude of the peak N40 decreased to approximately one half its control VEP. In the VEP obtained from the animals administered with hexachlorophene, the peak latencies of N20, P30, P55, N75 and P100 were slightly prolonged after the 7th day following the first administration. On the other hand, there was no change in the latency of N40 during the whole period of administration. The peak-to-peak amplitude showed some variability in different peaks. Histologically, diffuse status spongiosis were found in the white matter of the cerebrum, cerebellum, and brain stem. As described above, the ablation of the occipital lobe caused markedly depressed VEPs, however, the responses to the photic stimulation persisted after the injury. On the other hand, the VEPs of animals administered with hexachlorophene showed a high probability of peak appearance, and a decrease in amplitude was not marked.

  3. Experimental microembolism induces localized neuritic pathology in guinea pig cerebrum.

    PubMed

    Li, Jian-Ming; Cai, Yan; Liu, Fei; Yang, La; Hu, Xia; Patrylo, Peter R; Cai, Huaibin; Luo, Xue-Gang; Xiao, Dong; Yan, Xiao-Xin

    2015-05-10

    Microbleeds are a common finding in aged human brains. In Alzheimer's disease (AD), neuritic plaques composed of β-amyloid (Aβ) deposits and dystrophic neurites occur frequently around cerebral vasculature, raising a compelling question as to whether, and if so, how, microvascular abnormality and amyloid/neuritic pathology might be causally related. Here we used a guinea pig model of cerebral microembolism to explore a potential inductive effect of vascular injury on neuritic and amyloid pathogenesis. Brains were examined 7-30 days after experimental microvascular embolization occupying ~0.5% of total cortical area. Compared to sham-operated controls, glial fibrillary acidic protein immunoreactivity was increased in the embolized cerebrum, evidently around intracortical vasculature. Swollen/sprouting neurites exhibiting increased reactivity of nicotinamide adenine dinucleotide phosphate diaphorase, parvalbumin, vesicular glutamate transporter 1 and choline acetyltransferase appeared locally in the embolized brains in proximity to intracortical vasculature. The embolization-induced swollen/sprouting neurites were also robustly immunoreactive for β-amyloid precursor protein and β-secretase-1, the substrate and initiating enzyme for Aβ genesis. These experimental data suggest that microvascular injury can induce multisystem neuritic pathology associated with an enhanced amyloidogenic potential in wild-type mammalian brain.

  4. Cross-links between stereocilia in the guinea pig cochlea.

    PubMed

    Furness, D N; Hackney, C M

    1985-05-01

    Cross-links between stereocilia on guinea pig cochlear hair cells have been examined using high resolution scanning (SEM) and transmission electron microscopy (TEM), confirming recent descriptions of these structures. Links from the tips of shorter stereocilia to the sides of the adjacent taller stereocilia (upward-pointing links), between stereocilia of the same row (side-to-side links) and between adjacent rows (row-to-row links), have been observed on inner and outer hair cells. These links have been seen in material fixed using (1) glutaraldehyde only, (2) glutaraldehyde/osmium and (3) glutaraldehyde/osmium/thiocarbohydrazide (a technique which makes gold coating unnecessary). Upward-pointing links were seen less frequently, and the surfaces of stereocilia and microvilli were smoother after fixation (3) compared with fixations (1) and (2) in which they were usually roughened in appearance. In TEM, side-to-side and row-to-row links form a regular lattice between stereocilia, and consist of a number of strands. Upward-pointing links consist of a single strand, the ends of which are associated with electron-dense material. This lies between the stereociliary membrane and the actin filament bundle, at the tip of the shorter stereocilium and the side of the taller stereocilium.

  5. In vivo imaging and vibration measurement of Guinea pig cochlea

    NASA Astrophysics Data System (ADS)

    Choudhury, Niloy; Chen, Fangyi; Zheng, Jiefu; Nuttall, Alfred L.; Jacques, Steven L.

    2008-02-01

    An optical coherence tomography (OCT) system was built to acquire in vivo, both images and vibration measurements of the organ of Corti of the guinea pig. The organ of Corti was viewed through a ~500-μm diameter hole in the bony wall of the scala tympani of the first cochlear turn. In imaging mode, the image was acquired as reflectance R(x,z). In vibration mode, the basilar membrane (BM) or reticular lamina (RL) was selected based on the image. Under software control, the system would move the scanning mirrors to bring the sensing volume of the measurement to the desired tissue location. To address the gain stability problem of the homodyne OCT system, arising from the system moving in and out of the quadrature point and also to resolve the 180 degree ambiguity in the phase measurement using an interferometer, a vibration calibration method is developed by adding a vibrating source to the reference arm to monitor the operating point of the interferometric system. Amplitude gain and phase of various cochlear membranes was measured for different sound pressure level (SPL) varying from 65dB SPL to 93 dB SPL.

  6. Antitussive effect of Carum copticum in guinea pigs.

    PubMed

    Boskabady, M H; Jandaghi, P; Kiani, S; Hasanzadeh, L

    2005-02-10

    Several therapeutic effects including anti-asthma and dyspnea have been described for the seeds of Carum copticum In previous studies the relaxant and anticholinergic (functional antagonism) effects, histamine (H(1)) inhibitory effect of Carum copticum have been demonstrated on guinea pig tracheal chains. In the present study the antitussive effect of this plant was evaluated. The antitussive effects of aerosols of two different concentrations of aqueous and macerated extracts and carvacrol, codeine, and saline were tested by counting the number of coughs produced due to aerosol of citric acid 10 min after exposing animals to aerosols of different solutions (for carvacrol n=5 and for other solutions n=6). The results showed significant reduction of cough number obtained in the presence of both concentrations of aqueous and macerated extracts and codeine (p<0.001 for extracts and p<0.01 for codeine). The cough number obtained in the presence of higher concentration of aqueous and macerated extracts was significantly less than those of lower concentrations (p<0.05 for both extracts). In addition the cough number obtained in the presence of both concentrations of aqueous and macerated extracts was significantly lower than that of codeine (p<0.05 to 0.001). However, carvacrol did not show any antitussive effect. These results indicated an antitussive effect of Carum copticum which was even greater than that of codeine at concentrations used. In addition the antitussive effect of Carum copticum was not due to its main constituent, carvacrol.

  7. Biosynthesis of glucagon in isolated pancreatic islets of guinea pigs

    PubMed Central

    Hellerström, Claes; Howell, Simon L.; Edwards, John C.; Andersson, Arne; Östenson, Claes-Göran

    1974-01-01

    1. The biosynthesis of glucagon in guinea-pig A2 cells was investigated by incubation of isolated islets of Langerhans in the presence of [3H]tryptophan for periods of up to 14 days. Proteins were extracted from islets and incubation media and analysed by gel filtration. 2. In addition to very-high-molecular-weight (100000) proteins, the principal tryptophan-containing biosynthetic product after incubation for up to 17h was a protein of minimum mol.wt. 9000, which co-eluted on gel filtration with a peak of glucagon-like immunoreactivity, but was apparently devoid of biological activity in a fat-cell assay. A discrete peak of labelled glucagon was only recovered after incubation for at least 6 days. Losses of glucagon during the extraction and rapid secretion of newly synthesized glucagon into incubation media were excluded as reasons for the lack of recovery of labelled hormone from islets after shorter incubations. 3. The 9000-mol.wt. protein was localized to A2 cells in experiments using B-cell-depleted islets, and to A2-cell granules by subcellular fractionation and electron-microscopic radioautography. Only glucagon was secreted into the incubation medium. 4. Possible relationships between the 9000-mol.wt. protein and glucagon are discussed in the light of postulated mechanisms of glucagon biosynthesis. PMID:4615708

  8. Gene Targeting to the Uteroplacental Circulation of Pregnant Guinea Pigs.

    PubMed

    Mehta, Vedanta; Ofir, Keren; Swanson, Anna; Kloczko, Ewa; Boyd, Michael; Barker, Hannah; Avdic-Belltheus, Adnan; Martin, John; Zachary, Ian; Peebles, Donald; David, Anna L

    2016-08-01

    Our study aimed to target adenoviral gene therapy to the uteroplacental circulation of pregnant guinea pigs in order to develop a novel therapy for fetal growth restriction. Four methods of delivery of an adenovirus encoding β-galactosidase (Ad.LacZ) were evaluated: intravascular injection using phosphate-buffered saline (PBS) into (1) uterine artery (UtA) or (2) internal iliac artery or external administration in (3) PBS or (4) pluronic F-127 gel (Sigma Aldrich). Postmortem examination was performed 4 to 7 days after gene transfer. Tissue transduction was assessed by X-gal histochemistry and enzyme-linked immunosorbent assay. External vascular application of the adenovirus vector in combination with pluronic gel had 91.7% success rate in terms of administration (85% maternal survival) and gave the best results for maternal/fetal survival and local transduction efficiency without any spread to maternal or fetal tissues. This study suggests an optimal method of gene delivery to the UtAs of a small rodent for preclinical studies.

  9. Sulfur Mustard Induces Immune Sensitization in Hairless Guinea Pigs

    PubMed Central

    Mishra, Neerad C.; Rir-sima-ah, Jules; March, Thomas; Weber, Waylon; Benson, Janet; Jaramillo, Richard; Seagrave, Jean-Clare; Schultz, Gregory; Grotendorst, Gary; Sopori, Mohan

    2009-01-01

    Sulfur mustard (SM, bis-(2-chloroethyl) sulfide) is a well known chemical warfare agent that may cause long-term debilitating injury. Because of the ease of production and storage, it has a strong potential for chemical terrorism; however, the mechanism by which SM causes chronic tissue damage is essentially unknown. SM is a potent protein alkylating agent, and we tested the possibility that SM modifies cellular antigens, leading to an immunological response to “altered self” and a potential long-term injury. To that end, in this communication, we show that dermal exposure of euthymic hairless guinea pigs induced infiltration of both CD4+ and CD8+ T cells into the SM-exposed skin and strong upregulated expression of proinflammatory cytokines and chemokines (TNF-α, IFN-γ, and IL-8) in distal tissues such as the lung and the lymph nodes. Moreover, we present evidence for the first time that SM induces a specific delayed-type hypersensitivity response that is associated with splenomegaly, lymphadenopathy, and proliferation of cells in these tissues. These results clearly suggest that dermal exposure to SM leads to immune activation, infiltration of T cells into the SM-exposed skin, delayed-type hypersensitivity response, and molecular imprints of inflammation in tissues distal from the site of SM exposure. These immunological responses may contribute to the long-term sequelae of SM toxicity. PMID:19887117

  10. Demonstration of a specific C3a receptor on guinea pig platelets

    SciTech Connect

    Fukuoka, Y.; Hugli, T.E.

    1988-05-15

    Guinea pig platelets reportedly contain receptors specific for the anaphylatoxin C3a based on both ligand-binding studies and functional responses. A portion of the human 125I-C3a that binds to guinea pig platelets is competitively displaced by excess unlabeled C3a; however, the majority of ligand uptake was nonspecific. Uptake of 125I-C3a by guinea pig platelets is maximal in 1 min, and stimulation of guinea pig platelets by thrombin, ADP, or the Ca2+ ionophore A23187 showed little influence on binding of the ligand. Scatchard analysis indicated that approximately 1200 binding sites for C3a exist per cell with an estimated Kd of 8 x 10(-10) M. Human C3a des Arg also binds to guinea pig platelets, but Scatchard analysis indicated that no specific binding occurred. Because the ligand-binding studies were complicated by high levels of nonspecific uptake, we attempted to chemically cross-link the C3a molecule to a specific component on the platelet surface. Cross-linkage of 125I-C3a to guinea pig platelets with bis(sulfosuccinimidyl)suberate revealed radioactive complexes at 105,000 and 115,000 m.w. on SDS-PAGE gels by autoradiographic analysis. In the presence of excess unlabeled C3a, complex formation was inhibited. No cross-linkage could be demonstrated between the inactive 125I-C3a des Arg and the putative C3a-R on guinea pig platelets. Human C3a, but not C3a des Arg induces serotonin release and aggregation of the guinea pig platelets. Human C3a was unable to induce either serotonin release or promote aggregation of human platelets. Uptake of human 125I-C3a by human platelets was not saturable, and Scatchard analysis was inconclusive. Attempts to cross-link 125I-C3a to components on the surface of human platelets also failed to reveal a ligand-receptor complex. Therefore, we conclude that guinea pig platelets have specific surface receptors to C3a and that human platelets appear devoid of receptors to the anaphylatoxin.

  11. A simple numerical model of calcium spark formation and detection in cardiac myocytes.

    PubMed Central

    Smith, G D; Keizer, J E; Stern, M D; Lederer, W J; Cheng, H

    1998-01-01

    The elementary events of excitation-contraction coupling in heart muscle are Ca2+ sparks, which arise from one or more ryanodine receptors in the sarcoplasmic reticulum (SR). Here a simple numerical model is constructed to explore Ca2+ spark formation, detection, and interpretation in cardiac myocytes. This model includes Ca2+ release, cytosolic diffusion, resequestration by SR Ca2+-ATPases, and the association and dissociation of Ca2+ with endogenous Ca2+-binding sites and a diffusible indicator dye (fluo-3). Simulations in a homogeneous, isotropic cytosol reproduce the brightness and the time course of a typical cardiac Ca2+ spark, but underestimate its spatial size (approximately 1.1 micron vs. approximately 2.0 micron). Back-calculating [Ca2+]i by assuming equilibrium with indicator fails to provide a good estimate of the free Ca2+ concentration even when using blur-free fluorescence data. A parameter sensitivity study reveals that the mobility, kinetics, and concentration of the indicator are essential determinants of the shape of Ca2+ sparks, whereas the stationary buffers and pumps are less influential. Using a geometrically more complex version of the model, we show that the asymmetric shape of Ca2+ sparks is better explained by anisotropic diffusion of Ca2+ ions and indicator dye rather than by subsarcomeric inhomogeneities of the Ca2+ buffer and transport system. In addition, we examine the contribution of off-center confocal sampling to the variance of spark statistics. PMID:9649364

  12. Functional Coupling of Ca2+ Channels and Ryanodine Receptors in Cardiac Myocytes

    NASA Astrophysics Data System (ADS)

    Sham, James S. K.; Cleemann, Lars; Morad, Martin

    1995-01-01

    In skeletal muscle, dihydropyridine receptors are functionally coupled to ryanodine receptors of the sarcoplasmic reticulum in triadic or diadic junctional complexes. In cardiac muscle direct physical or functional couplings have not been demonstrated. We have tested the hypothesis of functional coupling of L-type Ca2+ channels and ryanodine receptors in rat cardiac myocytes by comparing the efficacies of Ca2+ in triggering Ca2+ release when the ion enters the cell via the Ca2+ channels or the Na^+/Ca2+ exchanger. Ca2+ transported through the Ca2+ channels was 20-160 times more effective than Ca2+ influx via the Na^+/Ca2+ exchanger in gating Ca2+ release from the sarcoplasmic reticulum, suggesting privileged communication between Ca2+ channels and ryanodine receptors. In support of this hypothesis we found that Ca2+ channels were inactivated by Ca2+ release from the sarcoplasmic reticulum, even though the myoplasmic Ca2+ concentrations were buffered with 10 mM EGTA. The data thus suggest privileged cross signaling between the dihydropyridine and ryanodine receptors such that Ca2+ flux through either the Ca2+ channel or the ryanodine receptor alters the gating kinetics of the other channel.

  13. Breathing responses of unanesthetized man and guinea pigs to increased transrespiratory pressure.

    PubMed

    Gillespie, J R; Bruce, E; Alexander, J; Mead, J

    1979-07-01

    We compared the breathing responses of unanesthetized men and guinea pigs to externally imposed shifts in lung volume produced by steady pressures applied to the body surface while the mouth remained near atmospheric pressure. Lung inflation caused no consistent or significant changes either in frequency or end-tidal CO2 in the three men. In contrast, during lung inflation the guinea pigs breathed at low frequencies and smaller tidal volumes and showed consistent increases in arterial PCO2 lasting up to 10 min. The changes seen immediately on application of pressure, namely apneic periods followed by breathing in which inspiratory duration was shortened while expiratory duration was substantially increased, indicates that conscious guinea pigs have active inflation reflexes. We concluded that the reflex responses rather than mechanical factors probably account for the underventilation in the guinea pigs and that guinea pigs are not nearly as well equipped as is man to defend gas exchange in the face of nonmetabolic shifts in lung volume. PMID:381262

  14. Reduced noise susceptibility in littermate offspring from heterozygous animals of the German waltzing guinea pig.

    PubMed

    Skjönsberg, Åsa; Mannström, Paula

    2015-07-01

    The German waltzing guinea pig is a spontaneously mutated strain with severe auditory and vestibular impairment caused by a so far unknown genetic mutation. The animals are born deaf and show a circling behavior. The heterozygote animals of this guinea pig strain have functionally normal hearing and balance. However, these animals have, in earlier studies, shown an increased resistance to noise compared with normal wild-type guinea pigs. In the present study, we explored the functional hearing with auditory brainstem response thresholds before and at different time points after noise exposure. Symptom-free littermates from heterozygote couples of the German waltzing guinea pigs were exclusively used for the study, which, after the hearing test, were sent back for breeding to confirm their genotype (i.e. heterozygote or normal). The aim of this paper was to ascertain that the previously shown reduced susceptibility to noise trauma in the heterozygote animals of the German waltzing guinea pig was also evident when littermates were used as control animals. The findings are important for further analysis of the heterozygote animals of this strain and for future investigations of the underlying mechanisms behind the diverse susceptibility to exposures of loud sound.

  15. Reduced noise susceptibility in littermate offspring from heterozygous animals of the German waltzing guinea pig.

    PubMed

    Skjönsberg, Åsa; Mannström, Paula

    2015-07-01

    The German waltzing guinea pig is a spontaneously mutated strain with severe auditory and vestibular impairment caused by a so far unknown genetic mutation. The animals are born deaf and show a circling behavior. The heterozygote animals of this guinea pig strain have functionally normal hearing and balance. However, these animals have, in earlier studies, shown an increased resistance to noise compared with normal wild-type guinea pigs. In the present study, we explored the functional hearing with auditory brainstem response thresholds before and at different time points after noise exposure. Symptom-free littermates from heterozygote couples of the German waltzing guinea pigs were exclusively used for the study, which, after the hearing test, were sent back for breeding to confirm their genotype (i.e. heterozygote or normal). The aim of this paper was to ascertain that the previously shown reduced susceptibility to noise trauma in the heterozygote animals of the German waltzing guinea pig was also evident when littermates were used as control animals. The findings are important for further analysis of the heterozygote animals of this strain and for future investigations of the underlying mechanisms behind the diverse susceptibility to exposures of loud sound. PMID:26053702

  16. Isolation and characterization of guinea-pig serum amyloid P component.

    PubMed Central

    Maudsley, S; Hind, C R; Munn, E A; Buttress, N; Pepys, M B

    1986-01-01

    A pentraxin was isolated from acute-phase guinea-pig serum by calcium-dependent affinity chromatography on agarose. It was immunochemically identical to guinea-pig amyloid P component and therefore has been called guinea-pig serum amyloid P component (SAP). Guinea-pig SAP has an apparent MW of between 265,000 and 300,000 by different techniques, and is composed of 10 noncovalently associated subunits arranged in two pentameric annular discs interacting face-to-face. It is apparently composed of two types of subunit, which run as a closely spaced doublet on reduced sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). At least one type of subunit is glycosylated. The serum concentration was 16 +/- 4 mg/l in outbred animals, rising to 25 +/- 4 mg/l in an acute-phase response. Binding to agarose correlated with the agarose pyruvate content and was completely abolished by diazomethane treatment of the agarose, which methylates the pyruvate carboxylic moiety. Binding was also inhibited in the presence of free methyl 4,6-o-(carboxyethylidine)-beta-D-galactopyranoside. No protein resembling C-reactive protein (CRP) was obtained by calcium-dependent affinity chromatography of acute-phase guinea-pig serum on phosphorylcholine (PC)-Sepharose, and it not clear whether a counterpart of CRP exists in this species. Images Figure 1 Figure 2 PMID:3770806

  17. Late effects of radiation on the lumbar spinal cord of guinea pigs: Re-treatment tolerance

    SciTech Connect

    Mason, K.A. ); Withers, H.R.; Chiang, Chi-Shiun )

    1993-07-15

    Using a guinea pig model of lumbar myelopathy, various factors affecting the tolerance of spinal cord to irradiation were assessed: (a) extent of initial injury; (b) time interval between priming and test doses; and (c) animal age at the time of initial radiation treatment. A 3 cm section of lumbar spinal cord of guinea pigs was irradiated with fractionated doses of 4.5 Gy gamma rays given as 9 fractions per week. Guinea pigs were primed with 9 x 4.5 Gy in 7 days which is 60% of the ED[sub 50] for a continuous course of treatment. After 28 or 40 weeks, animal were retreated with 6-14 fractions of 4.5 Gy. Animals were observed for 2 years following the priming dose and both the incidence and latency of myelopathy recorded. Young adult guinea pigs (8 wk old) showed both a decreased radiation tolerance and latency compared to old individuals (40 wk old). At 28 or 40 wk after 9 x 4.5 Gy, only about 8% of the initial injury was remembered in young adult guinea pigs. The amount of residual injury was dependent on the initial damage as a proportion of the tolerance dose. The spinal cord shows a greater capacity for long-term recovery than generally appreciated and re-treatment doses clinically prescribed may be lower than necessary. 8 refs., 3 figs., 2 tabs.

  18. Actin isoform synthesis by cultured cardiac myocytes: effects of actinomycin D and mithramycin

    SciTech Connect

    Lewis, W.; Gonzalez, B.

    1986-03-01

    Cultured neonatal rat myocardial cells (CMC) were incubated with the Actinomycin D (ACT) and mithramycin (MIT) in concentrations of 1 x 10/sup -8/M to 1 x 10/sup -5/M in medium containing 35..mu..Ci of /sup 35/S-methionine to determine incorporation into myocardial contractile proteins. After 24h, cells were harvested in buffer with Triton X-100, homogenized and subjected to centrifugation. Protein content of the centrifuged extracts was determined and equivalent amounts of protein were applied to 8-15% gradient sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS PAGE). Similar aliquots were subjected to isoelectric focusing and to gel electrophoresis in the second dimension. Electrophoretic gels were autoradiographed and were quantified densitometrically. A concentration-dependent effect of ACT and MIT on protein and on actin synthesis was found in cultured myocytes with decreased intensity of the radiolabeled actin band in CMC exposed to 1 x 10/sup -8/M to 1 x 10/sup -5/M ACT of 1 x 10/sup -7/M to 1 x 10/sup -5/M MIT. Autoradiography of gels showed focusing of actin isoforms but decreased intensity of iso-actin spots in extracts from CMC exposed to 1 x 10/sup -7/M ACT. ACT and MIT decreased CMC protein and synthesis by 20% at 1 x 10/sup -8/M respectively. The effect of MIT and ACT on CMC actin synthesis and synthesis of other proteins in heart cells is not as specific as the effect of anthracycline antineoplastics on cardiac myocyte proteins and actin.

  19. Phosphatidic acid stimulates inositol 1,4,5-trisphosphate production in adult cardiac myocytes.

    PubMed

    Kurz, T; Wolf, R A; Corr, P B

    1993-03-01

    The cellular content of phosphatidic acid can increase in response to several agonists either by phosphorylation of diacylglycerol after phospholipase C-catalyzed hydrolysis of phospholipids or directly through activation of phospholipase D. Although previous findings indicated that the generation of phosphatidic acid was exclusively a means of regulation of the cellular concentration of diacylglycerol, more recent studies have indicated that phosphatidic acid may also directly regulate several cellular functions. Accordingly, the present study was performed to assess whether phosphatidic acid could stimulate cardiac phospholipase C in intact adult rabbit ventricular myocytes. The mass of inositol 1,4,5-trisphosphate [Ins (1,4,5)P3] was determined by a specific and sensitive binding protein assay and by direct mass measurement using anion exchange chromatography for separation of selected inositol phosphates and gas chromatography and mass spectrometry for quantification of inositol monophosphate (IP1), inositol bisphosphate (IP2), inositol trisphosphate (IP3), and inositol tetrakisphosphate (IP4). Phosphatidic acid (10(-9)-10(-6) M) elicited a rapid concentration-dependent increase in Ins (1,4,5)P3 accumulation, with the peak fourfold to fivefold increase at 30 seconds of stimulation; the concentration required for 50% of maximal stimulation was 4.4 x 10(-8) M. The time course of individual inositol phosphates indicated a successive increase in the mass of IP3, IP4, IP2, and IP1 in response to stimulation with phosphatidic acid. The production of Ins (1,4,5)P3 in response to phosphatidic acid was not altered in the absence of extracellular calcium or in the presence of extracellular EGTA (10(-3) M). Thus, these findings indicate that phosphatidic acid is a potent activator of inositol phosphate production in adult ventricular myocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Spot-on Treatments of Diflubenzuron and Permethrin to Control a Guinea Pig Louse, Gliricola Porcelli (Phthiraptera: Gyropidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Guinea pigs (Cavia porcellus (L.)) (Rodentia: Caviidae) are pets and laboratory animals. They can be infested by a chewing louse, Gliricola porcelli (Schrank) (Phthiraptera: Gyropidae), which is fairly common in some animal rearing facilities, pet stores, and on wild guinea pigs. Infestation with G....

  1. Volatile anaesthetic effects on Na+-Ca2+ exchange in rat cardiac myocytes

    PubMed Central

    Seckin, Inanc; Sieck, Gary C; Prakash, Y S

    2001-01-01

    We examined the influence of two clinically relevant concentrations (1 and 2 MAC (minimum alveolar concentration)) of halothane and sevoflurane on both efflux and reverse modes of Na+-Ca2+ exchange (NCX) in enzymatically dissociated adult rat cardiac myocytes. We hypothesised that a volatile anaesthetic-induced decrease in myocardial contractility is mediated by a reduction in intracellular calcium concentration ([Ca2+]i) via inhibition of NCX. Cells were exposed to cyclopiazonic acid and zero extracellular Na+ and Ca2+ to block sacroplasmic reticulum (SR) re-uptake and NCX efflux, respectively. As [Ca2+]i increased under these conditions, extracellular Na+ was rapidly (< 300 ms) reintroduced in the presence or absence of a volatile anaesthetic to selectively promote Ca2+ efflux via NCX. Other cells exposed to cyclopiazonic acid and ryanodine to inhibit SR Ca2+ re-uptake and release were Na+ loaded in zero extracellular Ca2+. The reintroduction of extracellular Ca2+ was used to selectively activate Ca2+ influx via NCX. Compared to controls, both 1 and 2 MAC halothane as well as sevoflurane reduced NCX-mediated efflux. The reduction in NCX-mediated influx was concentration dependent, but comparable between the two anaesthetics. Both anaesthetics at each concentration also shifted the relationship between extracellular Na+ (or extent of Na+ loading) and NCX-mediated efflux (or influx) to the right. These data indicate that despite inhibition of NCX-mediated Ca2+ efflux, volatile anaesthetics produce myocardial depression. However, the inhibition of NCX-mediated Ca2+ influx may contribute to decreased cardiac contractility. The overall effect of volatile anaesthetics on the [Ca2+]i profile is likely to be determined by the relative contributions of influx vs. efflux via NCX during each cardiac cycle. PMID:11283227

  2. Enhancement of the responsiveness of vas deferens and ileum smooth muscle in sensitized guinea pigs: in vitro study.

    PubMed

    Bidon, J C; Blin, M; Gogny, M; Vu, A T; Jondet, A

    1994-05-01

    Changes in the reactivity of the ileum (to histamine and barium chloride) and vas deferens (to acetylcholine and barium chloride), isolated from actively egg albumen-sensitized guinea pigs, have been investigated. The study was performed on 2 guinea pig strains: the Dunkin-Hartley strain, usually used as an airway allergic model, and the BFA strain. In actively sensitized guinea pigs of both strains, concentration-response curves exhibited a significant dose-dependent upward shift compared to those obtained in control guinea pigs. The maximal contraction strength calculated from these curves was significantly enhanced in both sensitized guinea pig strains, without a change in EC50 values. This study showed that the active antigen sensitization procedure involved several smooth muscle functions, and not exclusively the trachea. PMID:7950408

  3. Nonuniform elasticity of titin in cardiac myocytes: a study using immunoelectron microscopy and cellular mechanics.

    PubMed Central

    Granzier, H; Helmes, M; Trombitás, K

    1996-01-01

    Titin (also known as connectin) is a muscle-specific giant protein found inside the sarcomere, spanning from the Z-line to the M-line. The I-band segment of titin is considered to function as a molecular spring that develops tension when sarcomeres are stretched (passive tension). Recent studies on skeletal muscle indicate that it is not the entire I-band segment of titin that behaves as a spring; some sections are inelastic and do not take part in the development of passive tension. To better understand the mechanism of passive tension development in the heart, where passive tension plays an essential role in the pumping function, we investigated titin's elastic segment in cardiac myocytes using structural and mechanical techniques. Single cardiac myocytes were stretched by various amounts and then immunolabeled and processed for electron microscopy in the stretched state. Monoclonal antibodies that recognize different titin epitopes were used, and the locations of the titin epitopes in the sarcomere were studied as a function of sarcomere length. We found that only a small region of the I-band segment of titin is elastic; its contour length is estimated at approximately 75 nm, which is only approximately 40% of the total I-band segment of titin. Passive tension measurements indicated that the fundamental determinant of how much passive tension the heart develops is the strain of titin's elastic segment. Furthermore, we found evidence that in sarcomeres that are slack (length, approximately 1.85 microns) the elastic titin segment is highly folded on top of itself. Based on the data, we propose a two-stage mechanism of passive tension development in the heart, in which, between sarcomere lengths of approximately 1.85 microns and approximately 2.0 microns, titin's elastic segment straightens and, at lengths longer than approximately 2.0 microns, the molecular domains that make up titin's elastic segment unravel. Sarcomere shortening to lengths below slack

  4. Contraction and relaxation of isolated cardiac myocytes of the frog under varying mechanical loads.

    PubMed

    Parikh, S S; Zou, S Z; Tung, L

    1993-02-01

    The mechanics of cardiac systole and relaxation have been studied primarily at the level of the whole heart or intact muscle. End-systolic pressure-volume relations of frog hearts have been found to be load dependent, whereas those of the mammal are relatively load independent. On the other hand, myocardial relaxation as studied at the muscle level is load independent in the frog but markedly load dependent in the mammal. Interpretation of these studies is complicated because of the unknown contribution of extracellular connective tissue, neurohumoral factors, and, in the case of the heart, the complex chamber geometry. Therefore, it is valuable to study cardiac mechanics at the level of the basic unit of contractile activity--the isolated myocyte. The goal of this study was to subject isolated frog cardiomyocytes to mechanical loading paradigms that mimic those presented to the cells within the heart. In the first part of this study, the afterload and preload of contracting cells were varied to study their effects on the end-systolic force-length relation, which was consistently found to be load independent over the range of isotonic shortening tested (typically 5%). We also investigated the force-length-time response of the cells to test the concept of the heart behaving as a time-varying elastance. Our results suggest that in this regard the frog myocyte behaves like mammalian muscle, and they are consistent with the presence of a small viscosity within the cell. We conclude that the tissue structure of the frog heart may contribute to disparity in mechanical behavior at the different structural levels. In the second part of this study, we subjected isolated frog cardiomyocytes to four different loading paradigms to test the hypothesis that myocardial relaxation in the frog is independent of load. These sequences consisted of afterloaded contractions followed by conventional isotonic-isometric relaxation (ACCR) or afterloaded contractions followed by

  5. Respiration and glucose oxidation in human and guinea pig leukocytes: comparative studies

    PubMed Central

    Baehner, Robert L.; Gilman, Neal; Karnovsky, Manfred L.

    1970-01-01

    A comparison has been made of the metabolic shifts in human and guinea pig leukocytes when they phagocytize. Respiration of guinea pig polymorphonuclear leukocytes (PMN) and the increment during phagocytosis were each about 2½-fold that of human PMN. This was also true of the direct oxidation of glucose-6-P (hexose monophosphate shunt). Enzymes potentially responsible for these phenomena have been compared in each species. Cyanide-insensitive NADH oxidase and NADPH oxidase were measured and only the formed exhibited adequate activity to account for the respiratory stimulus durintg phagocytosis. The hydrogen peroxide formed by this enzyme stimulates the hexose monophosphate shunt by oxidizing glutathione which upon reduction by an NADPH-linked glutathione reductase provides NADP to drive the hexose monophosphate shunt. Other linkages between respiratory stimulation and that of the hexose monophosphate shunt also pertain in the guinea pig. PMID:4392648

  6. Influence of body condition on reproductive output in the guinea pig.

    PubMed

    Michel, Catherine Louise; Bonnet, Xavier

    2012-01-01

    Reproduction is expensive. Substantial body reserves (i.e. high body condition) are usually required for females to undertake offspring production. In many vertebrates, maternal body condition positively influences reproductive output, and emaciated individuals skip reproduction. However, the impact of extremely high body condition, more specifically obesity, on animal reproductive performance remains poorly understood and research has generated contradictory results. For instance, obesity negatively affects fertility in women, but does not influence reproductive capacity or reproductive output in laboratory rodents. We examined the influence of high body condition on reproductive status and reproductive output in the guinea pig. In captivity, when fed ad libitum, guinea pigs store large amounts of fat tissues and exhibit a tendency for obesity. Our results show that obesity negatively affected reproduction in this species: both the proportion of fertile females and litter size were lower in the fattest females. Therefore, guinea pigs may represent suitable organisms to better understand the negative effect of obesity on reproduction.

  7. Chronic prenatal ethanol exposure increases disinhibition and perseverative responding in the adult guinea pig.

    PubMed

    Olmstead, Mary C; Martin, Amanda; Brien, James F; Reynolds, James N

    2009-09-01

    Cognitive and behavioural deficits, including increased impulsivity and perseveration, are associated with chronic prenatal ethanol exposure (CPEE) in humans. We tested whether these same deficits occur in the guinea pig after CPEE treatment. Pregnant guinea pigs received oral administration of ethanol (4 g/kg maternal body weight/day), or isocaloric-sucrose/pair-feeding throughout gestation. Young adult offspring were trained in lever-pressing paradigms to work for a sucrose-pellet food reward. CPEE increased No-Go, but not Go, responses in the Go/No-Go paradigm, indicative of a disinhibition deficit in these animals. Perseverative responses in the Cued Alternation task were also increased in CPEE offspring. These data show that CPEE induces behavioural deficits in the guinea pig that are remarkably similar to the executive function deficits that follow prenatal ethanol exposure in humans.

  8. Naturally occurring Parelaphostrongylus tenuis-associated choriomeningitis in a guinea pig with neurologic signs.

    PubMed

    Southard, T; Bender, H; Wade, S E; Grunenwald, C; Gerhold, R W

    2013-05-01

    An adult male guinea pig (Cavia porcellus) with a 1-month history of hind limb paresis, torticollis, and seizures was euthanized and submitted for necropsy. Gross examination was unremarkable, but histologic examination revealed multifocal eosinophilic and lymphoplasmacytic choriomeningitis and cross sections of nematode parasites within the leptomeninges of the midbrain and diencephalon. Morphologic features of the nematode were consistent with a metastrongyle, and the parasite was identified as Parelaphostrongylus tenuis by polymerase chain reaction testing and nucleotide sequencing. Further questioning of the owner revealed that the guinea pig was fed grass from a yard often grazed by white-tailed deer (Odocoileus virginianus). To the authors' knowledge, this is the first report of a naturally occurring P. tenuis infection in a guinea pig.

  9. Worm recovery and precipitin antibody response in guinea pigs and rats infected with Clonorchis sinensis.

    PubMed

    Su, K E; Wang, F Y; Chi, P Y

    1998-12-01

    Guinea pigs (Hartley strain) and rats (Wistar strain) were each fed 200 and 100 Clonorchis sinensis metacercariae, respectively. Five animals from each species were sacrificed weekly between 1-8 weeks postinfection (WPI) and then at 12, 16, 20 and 30 WPI for collection of worms, bile and sera. The overall worm recovery rates for guinea pigs and rats were 18.7% and 12.4%, respectively. Only one of the five rats examined at 20 WPI still harbored one worm, while all were worm-free at 30 WPI. By a double diffusion test, no antibodies were detected against C. sinensis adult antigens in the bile juice. Serum antibodies were detected in at least 95% of the infected guinea pigs between 4-30 WPI and rats between 3-16 WPI. Precipitin antibodies seemed to be correlated with the presence of live worms in rats that had been infected for more than 12 weeks.

  10. Resistance to reinfection with a chlamydial agent (guinea pig inclusion conjunctivitis agent).

    PubMed

    Ahmad, A; Dawson, C R; Yoneda, C; Togni, B; Schachter, J

    1977-06-01

    Although most chlamydial infections are chronic or recurrent, infection of the guinea pig's eye with guinea pig inclusion conjunctivitis (GPIC) agent induces a marked resistance to reinfection. To characterize this resistance to GPIC agent, we compared the disease and infection in previously infected guinea pigs with that in animals infected for the first time. In animals experiencing primary infection, even the lowest dose (10 egg-lethal doses [ELD50]) produced the disease and chlamydial inclusions in conjunctival smears, but the incubation period became progressively shorter with the highest inocula (10(4) and 10(5) ELD50). In animals with previous infection only these two highest inocula produced disease and infection, but the disease was short-lived, and replication of the agent was severely limited. The mechanism of this resistance may be due to secretory antibody in the tears, cellular immunity, or other local factors.

  11. Cystitis associated with chlamydial infection of the genital tract in male guinea pigs.

    PubMed

    Rank, R G; White, H J; Soloff, B L; Barron, A L

    1981-01-01

    Male guinea pigs were infected with the chlamydial agent of guinea pig inclusion conjunctivitis (GPIC) by intraurethral injection of chlamydiae or by placement of a drop of chlamydial suspension on the meatus of the extruded penis. Transient urethritis and cystitis were observed in animals infected by either method. The production of cystitis by the drop-on technique indicated that chlamydiae are able to ascend the urethra and that the bladder may be a target organ of chlamydial infection. When infected animals were immunosuppressed with cyclophosphamide, the number of guinea pigs with cystitis was increased, and chlamydiae could be detected in the bladder for as long as 50 days after infection. In contrast, GPIC was not detected in the bladders of untreated animals after day 18.

  12. Comparative study of 2 surgical techniques for castration of guinea pigs (Cavia porcellus)

    PubMed Central

    Guilmette, Josée; Langlois, Isabelle; Hélie, Pierre; de Oliveira El Warrak, Alexander

    2015-01-01

    The objective of this study was to compare 2 surgical approaches (scrotal or abdominal) for castration of guinea pigs and to investigate post-operative infection rates with either technique. Forty-eight guinea pigs were castrated by scrotal or abdominal technique after being randomly assigned to 1 of 2 groups (n = 24). Individuals were either castrated by an experienced exotic animal surgeon (n = 12) or by an experienced small animal surgeon (n = 12). Surgical wounds were evaluated daily before euthanasia for histological evaluation 2 wks after surgery. Post-operative infection rate was significantly higher in the scrotal group than in the abdominal group, with a higher rate for the experienced small animal surgeon. Castration of guinea pigs with the abdominal technique is significantly faster and has a significantly lower post-operative infection rate than the scrotal technique. PMID:26424914

  13. Pathological and virological features of arenavirus disease in guinea pigs. Comparison of two Pichinde virus strains.

    PubMed Central

    Aronson, J. F.; Herzog, N. K.; Jerrells, T. R.

    1994-01-01

    A guinea pig passage-adapted strain of the arena-virus Pichinde (adPIC) is highly virulent in inbred guinea pigs, whereas the related strain PIC3739 is attenuated. Both viruses were macrophage tropic and infected peritoneal, splenic, liver, and alveolar macrophages during experimental Pichinde virus infection. Infection with the virulent strain was associated with unlimited viral replication in the face of exaggerated delayed-type hypersensitivity response, manifested by the macrophage disappearance reaction. Histopathological lesions unique to adPIC-infected guinea pigs included intestinal villus blunting with mucosal infiltration by pyknotic debris-laden macrophages and apoptosis of crypt epithelial cells. Splenic red pulp necrosis was also significantly associated with adPIC infection but not PIC3739 infection. These findings may provide clues to the pathogenesis of a group of poorly understood human viral hemorrhagic fevers. Images Figure 6 Figure 7 PMID:8030751

  14. Inhibition of gastric secretion in guinea pig by relatively low dose ionizing radiation

    SciTech Connect

    Batzri, S.; Catravas, G.

    1988-11-01

    We evaluated the effect of a single dose of ionizing radiation on gastric secretion in awake guinea pigs equipped with a permanent gastric cannula. Changes in gastric secretion were measured using a dye dilution technique. Infusion of histamine increased acid and fluid output and there was a positive correlation (r = 0.93) between the two. Total body irradiation with 400 cGy, like cimetidine, suppressed acid and fluid secretion under basal conditions and during histamine stimulation by 50-90%. Recovery from the radiation damage was only partial after one week. Irradiation inhibited the rise in gastric juice volume during histamine stimulation and also reduced the normal gain in body weight of the guinea pig. These results demonstrate that ionizing radiations have an immediate and long lasting effects on the gastric mucosal function of the guinea pig.

  15. Adenosine transport systems on dissociated brain cells from mouse, guinea-pig, and rat

    SciTech Connect

    Johnston, M.E.; Geiger, J.D. )

    1990-09-01

    The kinetics and sodium dependence of adenosine transport were determined using an inhibitor-stop method on dissociated cell body preparations obtained from mouse, guinea-pig and rat brain. Transport affinity (KT) values for the high affinity adenosine transport systems KT(H) were significantly different between these three species; mean +/- SEM values were 0.34 +/- 0.1 in mouse, 0.9 +/- 0.2 in rat, and 1.5 +/- 0.5 microM in guinea-pig. The KT values for the low affinity transport system KT(L) were not different between the three species. Brain cells from rat displayed a significantly greater maximal capacity to accumulate (3H)adenosine (Vmax) than did mouse or guinea-pig for the high affinity system, or than did mouse for the low affinity system. When sodium chloride was replaced in the transport medium with choline chloride, the KT(H) values for guinea-pig and rat were both increased by approximately 100%; only in rat did the change reach statistical significance. The sodium-dependence of adenosine transport in mouse brain was clearly absent. The differences between KT(H) values in mouse and those in guinea-pig or rat were accentuated in the absence of sodium. The differences in kinetic values, ionic requirements, and pharmacological characteristics between adenosine transporters in CNS tissues of mouse, guinea-pig and rat may help account for some of the variability noted among species in terms of their physiological responses to adenosine.

  16. Species differences in the localization and number of CNS beta adrenergic receptors: Rat versus guinea pig

    SciTech Connect

    Booze, R.M.; Crisostomo, E.A.; Davis, J.N.

    1989-06-01

    The localization and number of beta adrenergic receptors were directly compared in the brains of rats and guinea pigs. The time course of association and saturability of (125I)cyanopindolol (CYP) binding to slide-mounted tissue sections was similar in rats (Kd = 17 pM) and guinea pigs (Kd = 20 pM). The beta-1 and beta-2 receptor subtypes were examined through the use of highly selective unlabeled receptor antagonists, ICI 118,551 (50 nM) and ICI 89,406 (70 nM). Dramatic species differences between rats and guinea pigs were observed in the neuroanatomical regional localization of the beta adrenergic receptor subtypes. For example, in the thalamus prominent beta-1 and beta-2 receptor populations were identified in the rat; however, the entire thalamus of the guinea pig had few, if any, beta adrenergic receptors of either subtype. Hippocampal area CA1 had high levels of beta-2 adrenergic receptors in both rats and guinea pigs but was accompanied by a widespread distribution of beta-2 adrenergic receptors only in rats. Quantitative autoradiographic analyses of 25 selected neuroanatomical regions (1) confirmed the qualitative differences in CNS beta adrenergic receptor localization, (2) determined that guinea pigs had significantly lower levels of beta adrenergic receptors than rats and (3) indicated a differential pattern of receptor subtypes between the two species. Knowledge of species differences in receptor patterns may be useful in designing effective experiments as well as in exploring the relationships between receptor and innervation patterns. Collectively, these data suggest caution be used in extrapolation of the relationships of neurotransmitters and receptors from studies of a single species.

  17. Differences in the distribution and characteristics of tachykinin NK1 binding sites between human and guinea pig lung.

    PubMed Central

    Walsh, D A; Salmon, M; Featherstone, R; Wharton, J; Church, M K; Polak, J M

    1994-01-01

    1. The distribution and characteristics of tachykinin NK1 binding sites have been compared in human and guinea pig lung using quantitative in vitro receptor autoradiography with [125I]-Bolton Hunter-labelled substance P ([125I]-BH-SP). In addition, the effects on these sites of ovalbumin sensitization and challenge have been determined in guinea pig lung. 2. [125I]-BH-SP bound specifically and with high affinity to microvascular endothelium in both human and guinea pig lung, but to bronchial smooth muscle and pulmonary artery media in only guinea pig lung. 3. Specific binding of [125I]-BH-SP to guinea pig bronchial smooth muscle was positively correlated with airway diameter in the range 150-800 microns and was less dense in trachea than in main bronchi. 4. [125I]-BH-SP binding was inhibited by tachykinins with rank orders of affinity of SP > NKA > NKB (human microvessels) and SP > NKA = NKB (guinea pig bronchi and pulmonary arteries). NKA displayed a higher affinity for [125I]-BH-SP binding sites in human microvessels than in guinea pig tissues (P < 0.0001), indicating differences in selectivity for tachykinins between human and guinea pig NK1 receptors. 5. In both human and guinea pig lung, [125I]-BH-SP binding was inhibited by the specific tachykinin receptor antagonists FK888 (NK1 selective antagonist) and FK224 (mixed NK1/NK2 antagonist), with FK888 displaying equal affinity to SP and > 500 times higher affinity than FK224. SP, NKA, NKB and FK888 exhibited similar affinities for [125I]-BH-SP binding sites in both guinea pig arteries and bronchi.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 1 Figure 2 PMID:7534186

  18. Apparent lack of beta 3-adrenoceptors and of insulin regulation of glucose transport in brown adipose tissue of guinea pigs.

    PubMed

    Himms-Hagen, J; Triandafillou, J; Begin-Heick, N; Ghorbani, M; Kates, A L

    1995-01-01

    Norepinephrine-induced thermogenesis was substantial in adipocytes from brown adipose tissue (BAT) of cold-acclimated guinea pigs but absent in adipocytes from BAT of warm-acclimated guinea pigs. There was no thermogenic response to any beta 3-adrenergic agonist (CL-316,243, ZD-7114, BRL-28410, CGP-12177). The receptor was characterized as a beta 1-adrenoceptor. Adrenergic agonists stimulated adenylate cyclase in membranes from BAT of both warm- and cold-acclimated guinea pigs also via a beta 1-adrenoceptor; beta 3-adrenergic agonists had no effect. Glucose transport by brown adipocytes from warm-acclimated guinea pigs was not stimulated by either norepinephrine or insulin. Cold acclimation induced the appearance of stimulation of glucose transport by norepinephrine in association with the appearance of a large capacity for thermogenesis, but there was little improvement in response to insulin. GLUT4 was present in membranes from BAT of both warm- and cold-acclimated guinea pigs. Insulin is known to have an antilipolytic effect on both BAT and white adipose tissue of guinea pigs. Thus there is a selective lack of insulin-regulated glucose transport that is not improved by cold acclimation. Guinea pigs may have a mutated component of the translocation mechanism for GLUT4. beta 3-Adrenoceptors appear to be absent in brown adipocytes of adult guinea pigs, as in white adipocytes of guinea pigs, yet are known to be present in the gut. Tissue-specific expression of beta 3-adrenergic receptors in guinea pigs may differ from that in rats, in which receptors are expressed in the adipose tissues and gut. PMID:7840345

  19. Purification and characterization of guinea pig liver morphine 6-dehydrogenase.

    PubMed

    Yamano, S; Kageura, E; Ishida, T; Toki, S

    1985-05-10

    Morphine 6-dehydrogenase, which catalyzes the dehydrogenation of morphine to morphinone, has been purified about 440-fold from the soluble fraction of guinea pig liver with a yield of 38%. The purified enzyme was a homogeneous protein on polyacrylamide gel disc electrophoresis and isoelectric focusing. The molecular weight and isoelectric point of the enzyme were 29,000 and 7.6, respectively. The enzyme utilizes both NAD and NADP as a cofactor, and the Km values were 0.12 mM for NAD and 0.42 mM for NADP. The Vmax values for morphine were 588 milliunits/mg of protein (with NAD) and 1600 milliunits/mg of protein (with NADP). The Km values for morphine were 0.12 mM (with NAD) and 0.49 mM (with NADP). The enzyme also exhibited activity for morphine-related compounds: nalorphine, normorphine, codeine, and ethylmorphine; however, 7,8-saturated congeners such as dihydromorphine and dihydrocodeine were poor substrates. The enzyme was inactivated by removal of 2-mercaptoethanol from the enzyme solution. The inactivated enzyme was rapidly recovered by the addition of 2-mercaptoethanol. Phenylarsine oxide and CdCl2 (dithiol modifiers) inhibited competitively toward cofactor binding and noncompetitively toward morphine binding. These results suggest that the enzyme possesses the essential thiol groups, probably vicinal dithiol, at or near the cofactor-binding site. Using the partially purified enzyme, 8-(2-hydroxyethylthio)dihydromorphinone was isolated as the product and identified by UV, mass, and NMR spectra. It was confirmed that morphinone proposed as the dehydrogenation product was nonenzymatically and covalently bound to 2-mercaptoethanol. Accordingly, the isolated morphinone-2-mercaptoethanol conjugate must be formed by two steps: enzymatic production of morphinone from morphine and then nonenzymatic binding of 2-mercaptoethanol to morphinone. PMID:2580834

  20. [+]-Huperzine A protects against soman toxicity in guinea pigs.

    PubMed

    Wang, Ying; Wei, Yanling; Oguntayo, Samuel; Jensen, Neil; Doctor, Bhupendra P; Nambiar, Madhusoodana P

    2011-12-01

    The chemical warfare nerve agent (CWNA) soman irreversibly inhibits acetylcholinesterase (AChE) causing seizure, neuropathology and neurobehavioral deficits. Pyridostigmine bromide (PB), the currently approved pretreatment for soman, is a reversible AChE inhibitor that does not cross the blood-brain barrier (BBB) to protect against central nervous system damage. [-]-Huperzine A, a natural reversible AChE inhibitor, rapidly passes through the BBB and has numerous neuroprotective properties that are beneficial for protection against soman. However, [-]-Huperzine A is toxic at higher doses due to potent AChE inhibition which limits the utilization of its neuroprotective properties. [+]-Huperzine A, a synthetic stereoisomer of [-]-Huperzine A and a weak inhibitor of AChE, is non-toxic. In this study, we evaluated the efficacy of [+]-Huperzine A for protection against soman toxicity in guinea pigs. Pretreatments with [+]-Huperzine A, i.m., significantly increased the survival rate in a dose-dependent manner against 1.2× LD(50) soman exposures. Behavioral signs of soman toxicity were significantly reduced in 20 and 40 mg/kg [+]-Huperzine A treated animals at 4 and 24 h compared to vehicle and PB controls. Electroencephalogram (EEG) power spectral analysis showed that [+]-Huperzine A significantly reduces soman-induced seizure compared to PB. [+]-Huperzine A (40 mg/kg) preserved higher blood and brain AChE activity compared to PB in soman exposed animals. These data suggest that [+]-Huperzine A protects against soman toxicity stronger than PB and warrant further development as a potent medical countermeasure against CWNA poisoning.

  1. Vagal non-adrenergic inhibition of guinea-pig stomach

    PubMed Central

    Beani, L.; Bianchi, Clementina; Crema, A.

    1971-01-01

    1. The effect of vagal and sympathetic stimulation on the mechanical and electrical activity (intracellular recording) of the body of the guinea-pig stomach was investigated in vitro. 2. Following atropine, 1 × 10-6-1 × 10-7 g/ml., vagal responses were reversed from excitatory to inhibitory. 3. Sympathetic blockade, produced by α- and β-receptor antagonists and adrenergic neurone-blocking agents, reduced or abolished sympathetic, but not vagal inhibition. 4. Hexamethonium (5 × 10-5 g/ml.) reduced vagal relaxation to 11-30% according to the stimulation rate. The residual response was maintained in the presence of 5-hydroxytryptamine tachyphylaxis. 5. Many muscle cells were observed to be under the influence of both vagus and sympathetic nerves: the effect of sympathetic stimulation was always inhibitory in nature, but high stimulation rates were required. The effect of vagal stimulation was both excitatory and inhibitory even in the absence of atropine: low stimulation rates gave rise either to E.J.P.s (excitatory junctional potentials), often followed by spikes, or to I.J.P.s (inhibitory junctional potentials). 6. In some spontaneously firing cells the interruption of electrical activity produced by vagal stimulation at 2/sec and sympathetic stimulation at 20/sec was recorded for a long enough time to check the effect of guanethedine (5 × 10-6 g/ml.): the drug selectively blocked sympathetic inhibition. 7. The significance of the inhibitory non-adrenergic transmitter, released by the intramural neurones activated by preganglionic vagal fibres, is discussed. PMID:4398576

  2. Beam-Beam Interaction Simulations with Guinea Pig (LCC-0125)

    SciTech Connect

    Sramek, C

    2003-11-20

    At the interaction point of a particle accelerator, various phenomena occur which are known as beam-beam effects. Incident bunches of electrons (or positrons) experience strong electromagnetic fields from the opposing bunches, which leads to electron deflection, beamstrahlung and the creation of electron/positron pairs and hadrons due to two-photon exchange. In addition, the beams experience a ''pinch effect'' which focuses each beam and results in either a reduction or expansion of their vertical size. Finally, if a beam's disruption parameter is too large, the beam can develop a sinusoidal distortion, or two-stream (kink) instability. This project simulated and studied these effects as they relate to luminosity, deflection angles and energy loss in order to optimize beam parameters for the Next Linear Collider (NLC). Using the simulation program Guinea Pig, luminosity, deflection angle and beam energy data was acquired for different levels of beam offset and distortion. Standard deflection curves and luminosity plots agreed with theoretical models but also made clear the difficulties of e-e- feedback. Simulations emphasizing kink instability in modulated and straight beam collisions followed qualitative behavioral predictions and roughly fit recent analytic calculations. A study of e-e- collisions under design constraints for the NLC provided new estimates of how luminosity, beamstrahlung energy loss, upsilon parameter and deflection curve width scale with beam cross-sections ({sigma}{sub x}, {sigma}{sub y}, {sigma}{sub z}) and number of particles per bunch (N). Finally, this same study revealed luminosity maxima at large N and small {sigma}{sub y} which may merit further investigation.

  3. Stimulation of anti-tumour immunity in guinea-pigs by methanol extraction residue of BCG.

    PubMed Central

    Wainberg, M. A.; Deutsch, V.; Weiss, D. W.

    1976-01-01

    The immunoprophylactic effects of the methanol extraction residue (MER) of BCG were investigated in Strain 2 guinea-pigs injected with cells of the transplantable, diethylnitrosamine-induced, Line 10 hepatocarcinoma. Pretreatment with MER at times ranging from 18 to 182 days prior to tumour implantation protected approximately 40% of guinea-pigs from progressive neoplastic disease. In addition, MER-treated animals developed specific cell-mediated anti-tumour immunity both more rapidly and at higher levels than did non-MER-treated tumour-bearing controls. It was not possible, however, to prognosticate from the results of such laboratory studies to the outcome of immunoprophylaxis. PMID:187207

  4. Digesta retention and fibre digestion in maras (Dolichotis patagonum) and guinea-pigs.

    PubMed

    Sakaguchi, E; Nippashi, K; Endoh, G

    1992-04-01

    1. Digestibilities of feed and turnover time (1/k), transit time (TT) and mean retention time (MRT: 1/k+TT) of fluid and particle markers were measured in maras (Dolichotis patagonum) and guinea-pigs (Cavia procellus) fed a diet containing 50% alfalfa. 2. The digestibility of fibre was similar in both animals, however, the digestibilities of crude protein (nitrogen x 6.25) and crude ash were lower in the mara than in the guinea-pig. 3. 1/k of the digesta markers were similar in both animals, suggesting that the two animals possess similar dilution and retention time of digesta in their caecum and proximal colon. PMID:1351463

  5. Limited survey of genital infection by guinea pig inclusion conjunctivitis agent.

    PubMed

    Reed, C; Campbell, L H; Soave, O A

    1977-09-01

    Cervical or urethral scrapings were collected from 245 guinea pigs that had clinical signs of guinea pig inclusion conjunctivitis (GPIC) or were parents of newborn young having clinical signs of GPIC. Giemsa-stained smears were examined for cytoplasmic inclusion bodies, and samples were passaged in 6-day-old embryonating eggs. Complement-fixation tests were performed on 44 samples passaged through eggs in an effort to detect the presence of GPIC antigen. Unequivocal evidence of chlamydial infection of the genital tract was not found.

  6. Biolistic-mediated gene expression in guinea pigs and cattle tissue in vivo.

    PubMed

    Rech, E L; De-Bem, A R; Aragão, F J

    1996-10-01

    Foreign genes were introduced and expressed in vivo in guinea pigs and cattle utilizing a new hand-held device based on high-pressure helium gas to accelerate DNA-coated microparticles. Guinea pigs were used to evaluate the physical parameters to introduce and express the exogenous DNA. The best conditions were applied to conduct bombardments in cattle. The results showed a high frequency of gene expression in all the bombarded cattle. This procedure could be used to study the immune responses in cattle and in a wide variety of animals through genetic immunization. PMID:9181095

  7. Evidence for a non-opioid sigma binding site din the guinea-pig myenteric plexus

    SciTech Connect

    Roman, F.; Pascaud, X.; Vauche, D.; Junien, J.

    1988-01-01

    The presence of a binding site to (+)-(/sup 3/H)SKF 10,047 was demonstrated in a guinea-pig myenteric plexus (MYP) membrane preparation. Specific binding to this receptor was saturable, reversible, linear with protein concentration and consisted of two components, a high affinity site and a low affinity site. Morphine and naloxone 10/sup -4/M were unable to displace (+)-(/sup 3/H)SKF 10,047 binding. Haloperidol, imipramine, ethylketocyclazocine and propranolol were among the most potent compounds to inhibit this specific binding. These results suggest the presence of a non-opioid haloperidol sensitive sigma receptor in the MYP of the guinea-pig.

  8. Replication and Transmission of the Novel Bovine Influenza D Virus in a Guinea Pig Model

    PubMed Central

    Sreenivasan, Chithra; Thomas, Milton; Sheng, Zizhang; Hause, Ben M.; Collin, Emily A.; Knudsen, David E. B.; Pillatzki, Angela; Nelson, Eric; Wang, Dan; Kaushik, Radhey S.

    2015-01-01

    ABSTRACT Influenza D virus (FLUDV) is a novel influenza virus that infects cattle and swine. The goal of this study was to investigate the replication and transmission of bovine FLUDV in guinea pigs. Following direct intranasal inoculation of animals, the virus was detected in nasal washes of infected animals during the first 7 days postinfection. High viral titers were obtained from nasal turbinates and lung tissues of directly inoculated animals. Further, bovine FLUDV was able to transmit from the infected guinea pigs to sentinel animals by means of contact and not by aerosol dissemination under the experimental conditions tested in this study. Despite exhibiting no clinical signs, infected guinea pigs developed seroconversion and the viral antigen was detected in lungs of animals by immunohistochemistry. The observation that bovine FLUDV replicated in the respiratory tract of guinea pigs was similar to observations described previously in studies of gnotobiotic calves and pigs experimentally infected with bovine FLUDV but different from those described previously in experimental infections in ferrets and swine with a swine FLUDV, which supported virus replication only in the upper respiratory tract and not in the lower respiratory tract, including lung. Our study established that guinea pigs could be used as an animal model for studying this newly emerging influenza virus. IMPORTANCE Influenza D virus (FLUDV) is a novel emerging pathogen with bovine as its primary host. The epidemiology and pathogenicity of the virus are not yet known. FLUDV also spreads to swine, and the presence of FLUDV-specific antibodies in humans could indicate that there is a potential for zoonosis. Our results showed that bovine FLUDV replicated in the nasal turbinate and lungs of guinea pigs at high titers and was also able to transmit from an infected animal to sentinel animals by contact. The fact that bovine FLUDV replicated productively in both the upper and lower respiratory tracts

  9. In vitro metabolism of cannabinol in rat, mouse, rabbit, guinea pig, hamster, gerbil and cat.

    PubMed

    Brown, N K; Harvey, D J

    1990-01-01

    Metabolism of cannabinol (CBN) was studied in hepatic microsomal incubates from mouse, rat, rabbit, guinea pig, cat, hamster and gerbil. Metabolites were extracted with ethyl acetate, concentrated by chromatography on Sephadex LH-20 and identified by GC/MS as TMS derivatives. Six monohydroxy metabolites were identified. These had hydroxy groups at C-11 and at all positions of the pentyl side-chain. Metabolism varied considerably between the species. 11-Hydroxylation was the most prominent route in the majority of species, but in the hamster and cat the major metabolic pathway was 4'-hydroxylation. Metabolites hydroxylated in the pentyl chain were generally more abundant in guinea pig, hamster and cat. PMID:2253656

  10. Optic nerve head and intraocular pressure in the guinea pig eye.

    PubMed

    Ostrin, Lisa A; Wildsoet, Christine F

    2016-05-01

    The guinea pig is becoming an increasingly popular model for studying human myopia, which carries an increased risk of glaucoma. As a step towards understanding this association, this study sought to characterize the normal, developmental intraocular pressure (IOP) profiles, as well as the anatomy of the optic nerve head (ONH) and adjacent sclera of young guinea pigs. IOP was tracked in pigmented guinea pigs up to 3 months of age. One guinea pig was imaged in vivo with OCT and one with a fundus camera. The eyes of pigmented and albino guinea pigs (ages 2 months) were enucleated and sections from the posterior segment, including the ONH and surrounding sclera, processed for histological analyses - either hematoxylin and eosin (H&E) staining of paraffin embedded, sectioned tissue (n = 1), or cryostat sectioned tissue, processed for immunohistochemistry (n = 3), using primary antibodies against collagen types I-V, elastin, fibronectin and glial fibrillary acidic protein (GFAP). Transmission and scanning electron microscopy (TEM, SEM) studies of ONHs were also undertaken (n = 2 & 5 respectively). Mean IOPs ranged from 17.33 to 22.7 mmHg, increasing slightly across the age range studied, and the IOPs of individual animals also exhibited diurnal variations, peaking in the early morning (mean of 25.8, mmHg, ∼9 am), and decreasing across the day. H&E-stained sections showed retinal ganglion cell axons organized into fascicles in the prelaminar and laminar region of the ONHs, with immunostained sections revealing collagen types I, III, IV and V, as well as elastin, GFAP and fibronectin in the ONHs. SEM revealed a well-defined lamina cribrosa (LC), with radially-oriented collagen beams. TEM revealed collagen fibrils surrounding non-myelinated nerve fiber bundles in the LC region, with myelination and decreased collagen posterior to the LC. The adjacent sclera comprised mainly crimped collagen fibers in a crisscross arrangement. Both the sclera and LC were

  11. Cardiac Non-myocyte Cells Show Enhanced Pharmacological Function Suggestive of Contractile Maturity in Stem Cell Derived Cardiomyocyte Microtissues

    PubMed Central

    Ravenscroft, Stephanie M.; Pointon, Amy; Williams, Awel W.; Cross, Michael J.; Sidaway, James E.

    2016-01-01

    The immature phenotype of stem cell derived cardiomyocytes is a significant barrier to their use in translational medicine and pre-clinical in vitro drug toxicity and pharmacological analysis. Here we have assessed the contribution of non-myocyte cells on the contractile function of co-cultured human embryonic stem cell derived cardiomyocytes (hESC-CMs) in spheroid microtissue format. Microtissues were formed using a scaffold free 96-well cell suspension method from hESC-CM cultured alone (CM microtissues) or in combination with human primary cardiac microvascular endothelial cells and cardiac fibroblasts (CMEF microtissues). Contractility was characterized with fluorescence and video-based edge detection. CMEF microtissues displayed greater Ca2+ transient amplitudes, enhanced spontaneous contraction rate and remarkably enhanced contractile function in response to both positive and negative inotropic drugs, suggesting a more mature contractile phenotype than CM microtissues. In addition, for several drugs the enhanced contractile response was not apparent when endothelial cell or fibroblasts from a non-cardiac tissue were used as the ancillary cells. Further evidence of maturity for CMEF microtissues was shown with increased expression of genes that encode proteins critical in cardiac Ca2+ handling (S100A1), sarcomere assembly (telethonin/TCAP) and β-adrenergic receptor signalling. Our data shows that compared with single cell-type cardiomyocyte in vitro models, CMEF microtissues are superior at predicting the inotropic effects of drugs, demonstrating the critical contribution of cardiac non-myocyte cells in mediating functional cardiotoxicity. PMID:27125969

  12. On the degradability and exocytosis of ceroid/lipofuscin in cultured rat cardiac myocytes.

    PubMed

    Terman, A; Brunk, U T

    1998-01-30

    The accumulation of lipofuscin (LF)--a polymeric, electron-dense, autofluorescent substance--within postmitotic cells is a characteristic manifestation of aging. It is generally believed that LF is undegradable and formed due to peroxidative alterations of various macromolecules under intralysosomal autophagic degradation. We report here that a short-term exposure of cultured neonatal rat cardiac myocytes to the thiol protease-inhibitor leupeptin, causes an accumulation of numerous electron-dense autophagic lysosomes within the cells. Although very similar to LF by ultrastructure, these inclusions do not display LF-specific, yellow-orange autofluorescence when excited with blue light. Moreover, they rapidly disappear from the cells upon re-establishment of normal culture conditions. In contrast, prolonged leupeptin treatment results in an accumulation of dense lysosomes that also show LF-typical autofluorescence. This autofluorescent material remains in the cells after the end of leupeptin action. The results suggest that: (i) a certain amount of time is needed for autophagocytosed material to become peroxidized, autofluorescent and undegradable, i.e. to acquire properties typical of LF; (ii) protease-inhibition by itself does not lead to LF-formation but rather allows the prolonged time needed for oxidative modification of autophagocytosed material; (iii) mature LF is probably not subjected to either degradation or exocytosis.

  13. Hematological changes and nitric oxide levels accompanying high-dose artemether-lumefantrine administration in male guinea pigs: Effect of unsweetened natural cocoa powder

    PubMed Central

    Asiedu-Gyekye, Isaac Julius; Antwi-Boasiako, Charles; Oppong, Seth; Arthur, Stella; Sarkodie, Joseph Edusei

    2016-01-01

    Background: Unsweetened natural cocoa powder (UNCP), prepared after removal of the cocoa butter, is a common beverage in Ghana. It possesses antimalarial prophylactic property and has a beneficial effect on blood components. Aim: The aim of this study was to determine whether regular dietary supplement of UNCP mitigates high-dose (HD) artemether-lumefantrine (A-L)-induced hematological disorders and to determine the effect on nitric oxide (NO) levels. Materials and Methods: Adult male guinea pigs (300 g - 350 g) were randomly divided into 5 groups of 6 guinea pigs each. Among the 5 groups, 3 groups were treated with UNCP (300, 900, and 1500 mg/kg body weight) for 14 days. A-L (75 mg/kg) was administered from the 12th to 14th day. One of the remaining 2 groups received distilled water only, i.e., vehicle control group (VCG) while the other received 75 mg/kg A-L only, i.e., negative control group (NCG). Blood samples from all groups were obtained by cardiac puncture (day 15) followed by hematological and NO analysis. Results: A-L reduced white blood cells (WBC) by 31.87%, lymphocyte count by 45.99%, hemoglobin by 11.72%, hematocrit by 18.56%, and platelet count by 33.08% in the NCG. Administration of various doses of UNCP increased WBC and lymphocyte count (P > 0.05) compared to the NCG. UNCP and A-L combination caused an increase in NO levels when compared to the VCG. Conclusion: Regular consumption of UNCP by guinea pigs increases plasma NO and restores some hematological disorders induced by a 3-day HD A-L administration. PMID:27757264

  14. Adiponectin mediates cardioprotection in oxidative stress-induced cardiac myocyte remodeling

    PubMed Central

    Essick, Eric E.; Ouchi, Noriyuki; Wilson, Richard M.; Ohashi, Koji; Ghobrial, Joanna; Shibata, Rei; Pimentel, David R.

    2011-01-01

    Reactive oxygen species (ROS) induce matrix metalloproteinase (MMP) activity that mediates hypertrophy and cardiac remodeling. Adiponectin (APN), an adipokine, modulates cardiac hypertrophy, but it is unknown if APN inhibits ROS-induced cardiomyocyte remodeling. We tested the hypothesis that APN ameliorates ROS-induced cardiomyocyte remodeling and investigated the mechanisms involved. Cultured adult rat ventricular myocytes (ARVM) were pretreated with recombinant APN (30 μg/ml, 18 h) followed by exposure to physiologic concentrations of H2O2 (1–200 μM). ARVM hypertrophy was measured by [3H]leucine incorporation and atrial natriuretic factor (ANF) and brain natriuretic peptide (BNP) gene expression by RT-PCR. MMP activity was assessed by in-gel zymography. ROS was induced with angiotensin (ANG)-II (3.2 mg·kg−1·day−1 for 14 days) in wild-type (WT) and APN-deficient (APN-KO) mice. Myocardial MMPs, tissue inhibitors of MMPs (TIMPs), p-AMPK, and p-ERK protein expression were determined. APN significantly decreased H2O2-induced cardiomyocyte hypertrophy by decreasing total protein, protein synthesis, ANF, and BNP expression. H2O2-induced MMP-9 and MMP-2 activities were also significantly diminished by APN. APN significantly increased p-AMPK in both nonstimulated and H2O2-treated ARVM. H2O2-induced p-ERK activity and NF-κB activity were both abrogated by APN pretreatment. ANG II significantly decreased myocardial p-AMPK and increased p-ERK expression in vivo in APN-KO vs. WT mice. ANG II infusion enhanced cardiac fibrosis and MMP-2-to-TIMP-2 and MMP-9-to-TIMP-1 ratios in APN-KO vs. WT mice. Thus APN inhibits ROS-induced cardiomyocyte remodeling by activating AMPK and inhibiting ERK signaling and NF-κB activity. Its effects on ROS and ultimately on MMP expression define the protective role of APN against ROS-induced cardiac remodeling. PMID:21666115

  15. Carbon nanotubes instruct physiological growth and functionally mature syncytia: nongenetic engineering of cardiac myocytes.

    PubMed

    Martinelli, Valentina; Cellot, Giada; Toma, Francesca Maria; Long, Carlin S; Caldwell, John H; Zentilin, Lorena; Giacca, Mauro; Turco, Antonio; Prato, Maurizio; Ballerini, Laura; Mestroni, Luisa

    2013-07-23

    Myocardial tissue engineering currently represents one of the most realistic strategies for cardiac repair. We have recently discovered the ability of carbon nanotube scaffolds to promote cell division and maturation in cardiomyocytes. Here, we test the hypothesis that carbon nanotube scaffolds promote cardiomyocyte growth and maturation by altering the gene expression program, implementing the cell electrophysiological properties and improving networking and maturation of functional syncytia. In our study, we combine microscopy, biological and electrophysiological methodologies, and calcium imaging, to verify whether neonatal rat ventricular myocytes cultured on substrates of multiwall carbon nanotubes acquire a physiologically more mature phenotype compared to control (gelatin). We show that the carbon nanotube substrate stimulates the induction of a gene expression profile characteristic of terminal differentiation and physiological growth, with a 2-fold increase of α-myosin heavy chain (P < 0.001) and upregulation of sarcoplasmic reticulum Ca(2+) ATPase 2a. In contrast, markers of pathological hypertrophy remain unchanged (β-myosin heavy chain, skeletal α-actin, atrial natriuretic peptide). These modifications are paralleled by an increase of connexin-43 gene expression, gap junctions and functional syncytia. Moreover, carbon nanotubes appear to exert a protective effect against the pathologic stimulus of phenylephrine. Finally, cardiomyocytes on carbon nanotubes demonstrate a more mature electrophysiological phenotype of syncytia and intracellular calcium signaling. Thus, carbon nanotubes interacting with cardiomyocytes have the ability to promote physiological growth and functional maturation. These properties are unique in the current vexing field of tissue engineering, and offer unprecedented perspectives in the development of innovative therapies for cardiac repair.

  16. Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

    PubMed

    Lichter, Justin G; Carruth, Eric; Mitchell, Chelsea; Barth, Andreas S; Aiba, Takeshi; Kass, David A; Tomaselli, Gordon F; Bridge, John H; Sachse, Frank B

    2014-07-01

    Sarcomeres are the basic contractile units of cardiac myocytes. Recent studies demonstrated remodeling of sarcomeric proteins in several diseases, including genetic defects and heart failure. Here we investigated remodeling of sarcomeric α-actinin in two models of heart failure, synchronous (SHF) and dyssynchronous heart failure (DHF), as well as a model of cardiac resynchronization therapy (CRT). We applied three-dimensional confocal microscopy and quantitative methods of image analysis to study isolated cells from our animal models. 3D Fourier analysis revealed a decrease of the spatial regularity of the α-actinin distribution in both SHF and DHF versus control cells. The spatial regularity of α-actinin in DHF cells was reduced when compared with SHF cells. The spatial regularity of α-actinin was partially restored after CRT. We found longitudinal depositions of α-actinin in SHF, DHF and CRT cells. These depositions spanned adjacent Z-disks and exhibited a lower density of α-actinin than in the Z-disk. Differences in the occurrence of depositions between the SHF, CRT and DHF models versus control were significant. Also, CRT cells exhibited a higher occurrence of depositions versus SHF, but not DHF cells. Other sarcomeric proteins did not accumulate in the depositions to the same extent as α-actinin. We did not find differences in the expression of α-actinin protein and its encoding gene in our animal models. In summary, our studies indicate that HF is associated with two different types of remodeling of α-actinin and only one of those was reversed after CRT. We suggest that these results can guide us to an understanding of remodeling of structures and function associated with sarcomeres.

  17. Electron microscopic observations concerning the in vivo uptake and release of the agent of guinea-pig inclusion conjunctivitis (Chlamydia psittaci) in guinea-pig exocervix.

    PubMed

    Soloff, B L; Rank, R G; Barron, A L

    1985-07-01

    This report details electron-microscopical observations concerning C. psittaci infection in vivo. The model employed was that of the guinea-pig infected at the exocervical region with the agent of guinea-pig inclusion conjunctivitis (GPIC). Our observations indicate that chlamydial particles gain access to their target cells by the mechanism of endocytosis. Single GPIC elementary bodies were seen to be positioned within individual endosomes. The observations reported here provide evidence that chlamydial particles that had undergone their developmental cycle within the exocervical epithelial cells may leave the epithelium in 2 ways; within entire infected cells that had been shed into the lumen of the cervix and by means of the liberation of chlamydial particles from disrupted cells. The mechanism of cell disruption and shedding is thought to involve the large number of PMNs observed to be present within the enlarged intercellular spaces of the infected epithelium.

  18. Cell-mediated and humoral immune responses to chlamydial antigens in guinea pigs infected ocularly with the agent of guinea pig inclusion conjunctivitis.

    PubMed

    Senyk, G; Kerlan, R; Stites, D P; Schanzlin, D J; Ostler, H B; Hanna, L; Keshishyan, H; Jawetz, E

    1981-04-01

    Cell-mediated immune response and humoral response to chlamydial antigens were investigated in guinea pigs infected with the agent of guinea pig inclusion conjunctivitis (GPIC). Pronounced cell-mediated immune response to the homologous antigen, as well as to two other chlamydial antigens, 6BC (Chlamydia psittaci) and LB-1 (C. trachomatis), occurred in all infected animals. Cell-mediated immune response to GPIC, and to a lesser extent to 6BC and LB-1 as well, was enhanced with time after infection even without the re-inoculation of the infectious agent. Extensive cross-reactions among the three chlamydial antigens during the cell-mediated immune response appeared to be due to shared species-specific and group-reactive antigens. Serum antibody response was pronounced and uniform to GPIC; it was less marked to 6BC and LB-1, with fewer cross-reactions than seen in tests for cell-mediated immunity.

  19. Development of a novel, guinea pig-specific IFN-γ ELISPOT assay and characterization of guinea pig cytomegalovirus GP83-specific cellular immune responses following immunization with a modified vaccinia virus Ankara (MVA)-vectored GP83 vaccine

    PubMed Central

    Gillis, Peter A.; Hernandez-Alvarado, Nelmary; Gnanandarajah, Josephine S.; Wussow, Felix; Diamond, Don J.; Schleiss, Mark R.

    2014-01-01

    The guinea pig (Cavia porcellus) provides a useful animal model for studying the pathogenesis of many infectious diseases, and for preclinical evaluation of vaccines. However, guinea pig models are limited by the lack of immunological reagents required for characterization and quantification of antigen-specific T cell responses. To address this deficiency, an enzyme-linked immunospot (ELISPOT) assay for guinea pig interferon (IFN)-γ was developed to measure antigen/epitope-specific T cell responses to guinea pig cytomegalovirus (GPCMV) vaccines. Using splenocytes harvested from animals vaccinated with a modified vaccinia virus Ankara (MVA) vector encoding the GPCMV GP83 (homolog of human CMV pp65 [gpUL83]) protein, we were able to enumerate and map antigen-specific responses, both in vaccinated as well as GPCMV-infected animals, using a panel of GP83-specific peptides. Several potential immunodominant GP83-specific peptides were identified, including one epitope, LGIVHFFDN, that was noted in all guinea pigs that had a detectable CD8+ response to GP83. Development of a guinea pig IFN-γ ELISPOT should be useful in characterization of additional T cell-specific responses to GPCMV, as well as other pathogens. This information in turn can help focus future experimental evaluation of immunization strategies, both for GPCMV as well as for other vaccine-preventable illnesses studied in the guinea pig model. PMID:24856783

  20. Development of a novel, guinea pig-specific IFN-γ ELISPOT assay and characterization of guinea pig cytomegalovirus GP83-specific cellular immune responses following immunization with a modified vaccinia virus Ankara (MVA)-vectored GP83 vaccine.

    PubMed

    Gillis, Peter A; Hernandez-Alvarado, Nelmary; Gnanandarajah, Josephine S; Wussow, Felix; Diamond, Don J; Schleiss, Mark R

    2014-06-30

    The guinea pig (Cavia porcellus) provides a useful animal model for studying the pathogenesis of many infectious diseases, and for preclinical evaluation of vaccines. However, guinea pig models are limited by the lack of immunological reagents required for characterization and quantification of antigen-specific T cell responses. To address this deficiency, an enzyme-linked immunospot (ELISPOT) assay for guinea pig interferon (IFN)-γ was developed to measure antigen/epitope-specific T cell responses to guinea pig cytomegalovirus (GPCMV) vaccines. Using splenocytes harvested from animals vaccinated with a modified vaccinia virus Ankara (MVA) vector encoding the GPCMV GP83 (homolog of human CMV pp65 [gpUL83]) protein, we were able to enumerate and map antigen-specific responses, both in vaccinated as well as GPCMV-infected animals, using a panel of GP83-specific peptides. Several potential immunodominant GP83-specific peptides were identified, including one epitope, LGIVHFFDN, that was noted in all guinea pigs that had a detectable CD8+ response to GP83. Development of a guinea pig IFN-γ ELISPOT should be useful in characterization of additional T cell-specific responses to GPCMV, as well as other pathogens. This information in turn can help focus future experimental evaluation of immunization strategies, both for GPCMV as well as for other vaccine-preventable illnesses studied in the guinea pig model.

  1. Paradoxical effect of salbutamol in a model of acute organophosphates intoxication in guinea pigs: role of substance P release.

    PubMed

    Chávez, Jaime; Segura, Patricia; Vargas, Mario H; Arreola, José Luis; Flores-Soto, Edgar; Montaño, Luis M

    2007-04-01

    Organophosphates induce bronchoobstruction in guinea pigs, and salbutamol only transiently reverses this effect, suggesting that it triggers additional obstructive mechanisms. To further explore this phenomenon, in vivo (barometric plethysmography) and in vitro (organ baths, including ACh and substance P concentration measurement by HPLC and immunoassay, respectively; intracellular Ca2+) measurement in single myocytes) experiments were performed. In in vivo experiments, parathion caused a progressive bronchoobstruction until a plateau was reached. Administration of salbutamol during this plateau decreased bronchoobstruction up to 22% in the first 5 min, but thereafter airway obstruction rose again as to reach the same intensity as before salbutamol. Aminophylline caused a sustained decrement (71%) of the parathion-induced bronchoobstruction. In in vitro studies, paraoxon produced a sustained contraction of tracheal rings, which was fully blocked by atropine but not by TTX, omega-conotoxin (CTX), or epithelium removal. During the paraoxon-induced contraction, salbutamol caused a temporary relaxation of approximately 50%, followed by a partial recontraction. This paradoxical recontraction was avoided by the M2- or neurokinin-1 (NK1)-receptor antagonists (methoctramine or AF-DX 116, and L-732138, respectively), accompanied by a long-lasting relaxation. Forskolin caused full relaxation of the paraoxon response. Substance P and, to a lesser extent, ACh released from tracheal rings during 60-min incubation with paraoxon or physostigmine, respectively, were significantly increased when salbutamol was administered in the second half of this period. In myocytes, paraoxon did not produce any change in the intracellular Ca2+ basal levels. Our results suggested that: 1) organophosphates caused smooth muscle contraction by accumulation of ACh released through a TTX- and CTX-resistant mechanism; 2) during such contraction, salbutamol relaxation is functionally antagonized by the

  2. A model of calcium dynamics in cardiac myocytes based on the kinetics of ryanodine-sensitive calcium channels.

    PubMed Central

    Tang, Y; Othmer, H G

    1994-01-01

    The ryanodine-sensitive calcium channels are pivotal to signal transduction and cell function in many cell types, including cardiac myocytes. In this paper a kinetic model is proposed for these channels. In the model there are two Ca regulatory sites on the channel protein, one positive and the other negative. Cytoplasmic Ca binds to these regulatory sites independently It is assumed that the binding of Ca to the positive site is a much faster process than binding to the negative site. At steady state, the channel opening as a function of the Ca concentration is a bell-shaped curve. The model predicts the adaptation of channels to constant Ca stimulus. When this model is applied to cardiac myocytes, it predicts excitability with respect to Ca perturbations, smoothly graded responses, and Ca oscillations in certain pathological circumstances. In a spatially distributed system, traveling Ca waves in individual myocytes exist under certain conditions. This model can also be applied to other systems where the ryanodine-sensitive channels have been identified. Images FIGURE 1 FIGURE 15 PMID:7696464

  3. The Expression and Role of Protein Kinase C in Neonatal Cardiac Myocyte Attachment, Cell Volume, and Myofibril Formation Is Dependent on the Composition of the Extracellular Matrix

    NASA Astrophysics Data System (ADS)

    Bullard, Tara A.; Borg, Thomas K.; Price, Robert L.

    2005-06-01

    The extracellular matrix (ECM) is a dynamic component of tissues that influences cellular phenotype and behavior. We sought to determine the role of specific ECM substrates in the regulation of protein kinase C (PKC) isozyme expression and function in cardiac myocyte attachment, cell volume, and myofibril formation. PKC isozyme expression was ECM substrate specific. Increasing concentrations of the PKC [delta] inhibitor rottlerin attenuated myocyte attachment to randomly organized collagen (1, 5, and 10 [mu]M), laminin (5 and 10 [mu]M), aligned collagen (5 and 10 [mu]M), and fibronectin (10 [mu]M). Rottlerin significantly decreased cell volume on laminin and randomly organized collagen, and inhibited myofibril formation on laminin. The PKC [alpha] inhibitor Gö 6976 inhibited attachment to randomly organized collagen at 6 nM but did not affect cell volume. The general PKC inhibitor Bisindolylmalemide I (10 and 30 [mu]M) did not affect myocyte attachment; however, it significantly decreased cell volume on randomly organized collagen. Our data indicate that PKC isozymes are expressed and utilized by neonatal cardiac myocytes during attachment, cell growth, and myofibril formation. Specifically, it appears that PKC [delta] and/or its downstream effectors play an important role in the interaction between cardiac myocytes and laminin, providing further evidence that the ECM influences cardiac myocyte behavior.

  4. Mitochondrial membrane potential in single living adult rat cardiac myocytes exposed to anoxia or metabolic inhibition.

    PubMed Central

    Di Lisa, F; Blank, P S; Colonna, R; Gambassi, G; Silverman, H S; Stern, M D; Hansford, R G

    1995-01-01

    1. The relation between mitochondrial membrane potential (delta psi m) and cell function was investigated in single adult rat cardiac myocytes during anoxia and reoxygenation. delta psi m was studied by loading myocytes with JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'- tetra-ethylbenzimidazolylcarbocyanine iodide), a fluorescent probe characterized by two emission peaks (539 and 597 nm with excitation at 490 nm) corresponding to monomer and aggregate forms of the dye. 2. De-energizing conditions applied to mitochondria, cell suspensions or single cells decreased the aggregate emission and increased the monomer emission. This latter result cannot be explained by changes of JC-1 concentration in the aqueous mitochondrial matrix phase indicating that hydrophobic interaction of the probe with membranes has to be taken into account to explain JC-1 fluorescence properties in isolated mitochondria or intact cells. 3. A different sensitivity of the two JC-1 forms to delta psi m changes was shown in isolated mitochondria by the effects of ADP and FCCP and the calibration with K+ diffusion potentials. The monomer emission was responsive to values of delta psi m below 140 mV, which hardly modified the aggregate emission. Thus JC-1 represents a unique double sensor which can provide semi-quantitative information in both low and high potential ranges. 4. At the onset of glucose-free anoxia the epifluorescence of individual myocytes studied in the single excitation (490 nm)-double emission (530 and 590 nm) mode showed a gradual decline of the aggregate emission, which reached a plateau while electrically stimulated (0.2 Hz) contraction was still retained. The subsequent failure of contraction was followed by the rise of the emission at 530 nm, corresponding to the monomer form of the dye, concomitantly with the development of rigor contracture. 5. The onset of the rigor was preceded by the increase in intracellular Mg2+ concentration ([Mg2+]i) monitored by mag-indo-1 epifluorescence

  5. Regulation of L-type calcium current by intracellular magnesium in rat cardiac myocytes

    PubMed Central

    Wang, Min; Tashiro, Michiko; Berlin, Joshua R

    2004-01-01

    The effects of changing cytosolic [Mg2+] ([Mg2+]i) on l-type Ca2+ currents were investigated in rat cardiac ventricular myocytes voltage-clamped with patch pipettes containing salt solutions with defined [Mg2+] and [Ca2+]. To control [Mg2+]i and cytosolic [Ca2+] ([Ca2+]i), the pipette solution included 30 mm citrate and 10 mm ATP along with 5 mm EGTA (slow Ca2+ buffer) or 15 mm EGTA plus 5 mm BAPTA (fast Ca2+ buffer). With pipette [Ca2+] ([Ca2+]p) set at 100 nm using a slow Ca2+ buffer and pipette [Mg2+] ([Mg2+]p) set at 0.2 mm, peak l-type Ca2+ current density (ICa) was 17.0 ± 2.2 pA pF−1. Under the same conditions, but with [Mg2+]p set to 1.8 mm, ICa was 5.6 ± 1.0 pA pF−1, a 64 ± 2.8% decrease in amplitude. This decrease in ICa was accompanied by an acceleration and a –8 mV shift in the voltage dependence of current inactivation. The [Mg2+]p-dependent decrease in ICa was not significantly different when myocytes were preincubated with 10 μm forskolin and 300 μm 3-isobutyl-1-methylxanthine and voltage-clamped with pipettes containing 50 μm okadaic acid, to maximize Ca2+ channel phosphorylation. However, when myocytes were voltage-clamped with pipettes containing protein phosphatase 2A, to promote channel dephosphorylation, ICa decreased only 25 ± 3.4% on changing [Mg2+]p from 0.2 to 1.8 mm. In the presence of 0.2 mm[Mg2+]p, changing channel phosphorylation conditions altered ICa over a 4-fold range; however, with 1.8 mm[Mg2+]p, these same manoeuvres had a much smaller effect on ICa. These data suggest that [Mg2+]i can antagonize the effects of phosphorylation on channel gating kinetics. Setting [Ca2+]p to 1, 100 or 300 nm also showed that the [Mg2+]p-induced reduction of ICa was smaller at the lowest [Ca2+]p, irrespective of channel phosphorylation conditions. This interaction between [Ca2+]i and [Mg2+]i to modulate ICa was not significantly affected by ryanodine, fast Ca2+ buffers or inhibitors of calmodulin, calmodulin-dependent kinase and

  6. Na(+)-K+ pump cycle during beta-adrenergic stimulation of adult rat cardiac myocytes.

    PubMed

    Dobretsov, M; Hastings, S L; Stimers, J R

    1998-03-01

    1. The mechanisms underlying the increase in Na(+)-K+ pump current (Ip) caused by adrenergic stimulation were investigated in cultured adult rat cardiac myocytes using the whole-cell patch-clamp technique at 31-33 degrees C. 2. In myocytes perfused internally with 50 mM Na+ (0 K+i, 20 nM Ca2+, caesium aspartate solution) and externally with 5.4 mM K+o, noradrenaline (NA) and isoprenaline (Iso) (1-50 microM) stimulated Ip by 40-45%. 3. Na(+)-dependent transient Ip measurements with 0 mM K+i and 0 mM K+o revealed no change in the total charge transferred by the Na(+)-K+ pump during the conformational change, suggesting that the pump site density was not changed by adrenergic stimulation (2630 +/- 370 pumps micron-2 in control and 2540 +/- 190 pumps micron-2 in the presence of 10 microM NA). 4. With saturating Na+i or K+o (150 and 15-20 mM, respectively), Ip was still stimulated by NA and Iso. Thus, there was no indication that adrenergic activation of the Na(+)-K+ pump was mediated by accumulation of Na+i and K+o or changes in the Na(+)-K+ pump affinity for Na+i and K+o. 5. Both Ip and its increase under adrenergic stimulation were found to depend on [K+]i. While steady-state Ip decreased from 2.2 +/- 0.1 to 1.2 +/- 0.1 pA pF-1 (P < 0.05), the stimulation of Ip by 10 microM Iso increased from 0.38 +/- 0.04 to 0.67 +/- 0.06 pA pF-1 (P < 0.05) with an increase in [K+]i from 0 to 100 mM. 6. Under conditions that cause the Ip-Vm (membrane potential) relationship to express a positive slope ([Na+]o, 150 mM; [K+]o, 5.4 mM) or a negative slope ([Na+]o, 0; [K+]o, 0.3 mM) Iso stimulated Ip with no change in the shape of Ip-Vm curves. Thus, adrenergic stimulation of the Na(+)-K+ pump was not due to an alteration of voltage-dependent steps of the pump cycle. 7. Simulation of these data with a six-step model of the Na(+)-K+ pump cycle suggested that in rat ventricular myocytes a signal from adrenergic receptors increased the Na(+)-K+ pump rate by modulating the rate of K+ de

  7. Immunization with extracellular proteins of Mycobacterium tuberculosis induces cell-mediated immune responses and substantial protective immunity in a guinea pig model of pulmonary tuberculosis.

    PubMed Central

    Pal, P G; Horwitz, M A

    1992-01-01

    We have studied the capacity of a selected fraction of Mycobacterium tuberculosis extracellular proteins (EP) released into broth culture by mid-logarithmic-growth-phase organisms to induce cell-mediated immune responses and protective immunity in a guinea pig model of pulmonary tuberculosis. Guinea pigs infected with M. tuberculosis by aerosol but not uninfected control guinea pigs exhibit strong cell-mediated immune responses to EP, manifest by dose-dependent cutaneous delayed-type hypersensitivity and splenic lymphocyte proliferation. Guinea pigs immunized subcutaneously with EP but not sham-immunized control guinea pigs also develop strong cell-mediated immune responses to EP, manifest by dose-dependent cutaneous delayed-type hypersensitivity and splenic lymphocyte proliferation. EP is nonlethal and nontoxic to guinea pigs upon subcutaneous immunization. Guinea pigs immunized with EP and then challenged with aerosolized M. tuberculosis exhibit protective immunity. In five independent experiments, EP-immunized guinea pigs were consistently protected against clinical illness, including weight loss. Compared with EP-immunized guinea pigs, sham-immunized control guinea pigs lost 12.9 +/- 2.0% (mean +/- SE) of their total weight. EP-immunized guinea pigs also had a 10-fold reduction in viable M. tuberculosis bacilli in their lungs and spleens (P = 0.004 and 0.001, respectively) compared with sham-immunized control animals. In the two experiments in which some guinea pigs died after aerosol challenge, EP-immunized animals were protected from death. Whereas all 12 (100%) EP-immunized guinea pigs survived challenge with aerosolized M. tuberculosis, only 6 of 12 (50%) sham-immunized control guinea pigs survived challenge (P = 0.007, Fisher exact test). This study demonstrates that actively growing M. tuberculosis cells release immunoprotective molecules extracellularly, that a subunit vaccine against tuberculosis is feasible, and that extracellular molecules of M

  8. Allergy to guinea pigs: I. Allergenic activities of extracts derived from the pelt, saliva, urine and other sources.

    PubMed

    Walls, A F; Newman Taylor, A J; Longbottom, J L

    1985-05-01

    Guinea pig-sensitive patients with asthma and rhinitis were skin test positive to extracts of several materials derived from guinea pigs. A radioallergosorbent test (RAST) was developed to measure serum IgE specific for the dander, urine, saliva and also for dust from the air-vent filters of a room housing guinea pigs. A strong correlation was found between positive skin test reactions, and raised serum IgE to these extracts. Furthermore, the relative allergenic potency of extracts was similar when determined by skin-prick testing and by inhibition of the RAST to guinea pig dust. Non-guinea pig-derived extracts such as the hay, sawdust and diet had negligible activity in skin testing and RAST inhibition; and preparations of Dermatophagoides pteronyssinus, house dust and rat dust did not inhibit the RAST for guinea pig room dust. The guinea pig dust, dander, fur, urine and saliva were the more potent extracts; while whole pelt, faeces and serum were considerably less active. Extracts from different sexes were not appreciably different in potency. The results of skin testing, RAST and RAST inhibition suggest cross-allergenicity between the various extracts. Although material shed from the pelt may have been derived from saliva, or even urine, allergenic activities of urinary and salivary preparations were found to be less than those of the dander, fur or dust. This suggests that allergens have become concentrated on the pelt. PMID:4006174

  9. Influence of gender on ethanol-induced ventricular myocyte contractile depression in transgenic mice with cardiac overexpression of alcohol dehydrogenase.

    PubMed

    Duan, Jinhong; Esberg, Lucy B; Ye, Gang; Borgerding, Anthony J; Ren, Bonnie H; Aberle, Nicholas S; Epstein, Paul N; Ren, Jun

    2003-03-01

    Acute ethanol exposure depresses ventricular contractility and contributes to alcoholic cardiomyopathy in both men and women chronically consuming ethanol. However, a gender-related difference in the severity of myopathy exists with female being more sensitive to ethanol-induced tissue damage. Acetaldehyde (ACA), the major oxidized product of ethanol, has been implicated to play a role in the pathogenesis and gender-related difference of alcoholic cardiomyopathy, possibly due to its direct cardiac effect and interaction with estrogen. This study was designed to compare the effects of cardiac overexpression of alcohol dehydrogenase (ADH), which converts ethanol into ACA, on the cardiac contractile response to ethanol in ventricular myocytes isolated from age-matched adult male and female transgenic (ADH) and wild-type (FVB) mice. Mechanical properties were measured with an IonOptix SoftEdge system. ACA production was assessed by gas chromatography. The ADH myocytes from both genders exhibited similar mechanical properties but a higher efficacy to produce ACA compared to FVB myocytes. Exposure to ethanol (80-640 mg/dl) for 60 min elicited concentration-dependent decrease of cell shortening in both FVB and ADH groups. The ethanol-induced depression on cell shortening was significantly augmented in female but not male ADH group. ADH transgene did not exacerbate the ethanol-induced inhibition of maximal velocity of shortening/relengthening in either gender. In addition, neither ethanol nor ADH transgene affect the duration of shortening and relengthening in male or female mice. These data suggest that females may be more sensitive to ACA-induced cardiac contractile depression than male, which may attribute to the gender-related difference of alcoholic cardiomyopathy.

  10. The cannabinoid receptor type 2 promotes cardiac myocyte and fibroblast survival and protects against ischemia/reperfusion-induced cardiomyopathy.

    PubMed

    Defer, Nicole; Wan, Jinghong; Souktani, Richard; Escoubet, Brigitte; Perier, Magali; Caramelle, Philippe; Manin, Sylvie; Deveaux, Vanessa; Bourin, Marie-Claude; Zimmer, Andreas; Lotersztajn, Sophie; Pecker, Françoise; Pavoine, Catherine

    2009-07-01

    Post-myocardial infarction (MI) heart failure is a major public health problem in Western countries and results from ischemia/reperfusion (IR)-induced cell death, remodeling, and contractile dysfunction. Ex vivo studies have demonstrated the cardioprotective anti-inflammatory effect of the cannabinoid type 2 (CB2) receptor agonists within hours after IR. Herein, we evaluated the in vivo effect of CB2 receptors on IR-induced cell death, fibrosis, and cardiac dysfunction and investigated the target role of cardiac myocytes and fibroblasts. The infarct size was increased 24 h after IR in CB2(-/-) vs. wild-type (WT) hearts and decreased when WT hearts were injected with the CB2 agonist JWH133 (3 mg/kg) at reperfusion. Compared with WT hearts, CB2(-/-) hearts showed widespread injury 3 d after IR, with enhanced apoptosis and remodeling affecting the remote myocardium. Finally, CB2(-/-) hearts exhibited exacerbated fibrosis, associated with left ventricular dysfunction 4 wk after IR, whereas their WT counterparts recovered normal function. Cardiac myocytes and fibroblasts isolated from CB2(-/-) hearts displayed a higher H(2)O(2)-induced death than WT cells, whereas 1 microM JWH133 triggered survival effects. Furthermore, H(2)O(2)-induced myofibroblast activation was increased in CB2(-/-) fibroblasts but decreased in 1 microM JWH133-treated WT fibroblasts, compared with that in WT cells. Therefore, CB2 receptor activation may protect against post-IR heart failure through direct inhibition of cardiac myocyte and fibroblast death and prevention of myofibroblast activation.

  11. Recognition of Modified Conditioning Sounds by Competitively Trained Guinea Pigs.

    PubMed

    Ojima, Hisayuki; Horikawa, Junsei

    2015-01-01

    The guinea pig (GP) is an often-used species in hearing research. However, behavioral studies are rare, especially in the context of sound recognition, because of difficulties in training these animals. We examined sound recognition in a social competitive setting in order to examine whether this setting could be used as an easy model. Two starved GPs were placed in the same training arena and compelled to compete for food after hearing a conditioning sound (CS), which was a repeat of almost identical sound segments. Through a 2-week intensive training, animals were trained to demonstrate a set of distinct behaviors solely to the CS. Then, each of them was subjected to generalization tests for recognition of sounds that had been modified from the CS in spectral, fine temporal and tempo (i.e., intersegment interval, ISI) dimensions. Results showed that they discriminated between the CS and band-rejected test sounds but had no preference for a particular frequency range for the recognition. In contrast, sounds modified in the fine temporal domain were largely perceived to be in the same category as the CS, except for the test sound generated by fully reversing the CS in time. Animals also discriminated sounds played at different tempos. Test sounds with ISIs shorter than that of the multi-segment CS were discriminated from the CS, while test sounds with ISIs longer than that of the CS segments were not. For the shorter ISIs, most animals initiated apparently positive food-access behavior as they did in response to the CS, but discontinued it during the sound-on period probably because of later recognition of tempo. Interestingly, the population range and mean of the delay time before animals initiated the food-access behavior were very similar among different ISI test sounds. This study, for the first time, demonstrates a wide aspect of sound discrimination abilities of the GP and will provide a way to examine tempo perception mechanisms using this animal species

  12. Recognition of Modified Conditioning Sounds by Competitively Trained Guinea Pigs

    PubMed Central

    Ojima, Hisayuki; Horikawa, Junsei

    2016-01-01

    The guinea pig (GP) is an often-used species in hearing research. However, behavioral studies are rare, especially in the context of sound recognition, because of difficulties in training these animals. We examined sound recognition in a social competitive setting in order to examine whether this setting could be used as an easy model. Two starved GPs were placed in the same training arena and compelled to compete for food after hearing a conditioning sound (CS), which was a repeat of almost identical sound segments. Through a 2-week intensive training, animals were trained to demonstrate a set of distinct behaviors solely to the CS. Then, each of them was subjected to generalization tests for recognition of sounds that had been modified from the CS in spectral, fine temporal and tempo (i.e., intersegment interval, ISI) dimensions. Results showed that they discriminated between the CS and band-rejected test sounds but had no preference for a particular frequency range for the recognition. In contrast, sounds modified in the fine temporal domain were largely perceived to be in the same category as the CS, except for the test sound generated by fully reversing the CS in time. Animals also discriminated sounds played at different tempos. Test sounds with ISIs shorter than that of the multi-segment CS were discriminated from the CS, while test sounds with ISIs longer than that of the CS segments were not. For the shorter ISIs, most animals initiated apparently positive food-access behavior as they did in response to the CS, but discontinued it during the sound-on period probably because of later recognition of tempo. Interestingly, the population range and mean of the delay time before animals initiated the food-access behavior were very similar among different ISI test sounds. This study, for the first time, demonstrates a wide aspect of sound discrimination abilities of the GP and will provide a way to examine tempo perception mechanisms using this animal species

  13. Papular Dermatitis Induced in Guinea Pig by Biting Midge Culicoides Sonorensis (Diptera: Ceratopogonidaie)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histological, ultrastructural, and virological examinations were performed on abdominal skin from guinea pigs after a blood meal by colony-bred biting midges, Culicoides sonorensis. Small, superficial, cutaneous, crateriform ulcers with necrosis of superficial dermis developed at feeding sites and h...

  14. T-lymphocyte responses in guinea pigs vaccinated with foot-and-mouth disease virus.

    PubMed

    Bartels, T; Schäfer, H; Liebermann, H; Burger, R; Beyer, J

    1994-03-01

    The guinea pig provides an alternative experimental model for analysis of the immune response against foot-and-mouth disease virus (FMDV). The cellular immune response against FMDV in this experimental animal is unknown and was analyzed by in vivo and in vitro studies. In guinea pigs immunized with an FMDV A5 vaccine, a marked change in T-lymphocyte count appeared. For analyzing which functional T-cell compartment was affected, immunofluorescence studies, using monoclonal antibodies directed against differentiation antigens on guinea pig lymphoid cells, were performed. The proliferating T-cells were predominantly CD4-positive and, therefore, helper cells. T-cells from these animals were re-stimulated in vitro with homologous inactivated virus. The antigen-specific proliferative response of the T-cells in vitro was measured using the thymidine incorporation assay. A proliferative response to FMDV was observed that depended on the dose of the antigen. High concentration of virus had an inhibitory effect on T-cell proliferation. These data indicate that the guinea pig is a useful model for analysis of T-cell mediated mechanisms in the pathogenesis and immunity of foot-and-mouth disease. PMID:7909182

  15. Pathogenesis of endometritis and salpingitis in a guinea pig model of chlamydial genital infection.

    PubMed Central

    Rank, R. G.; Sanders, M. M.

    1992-01-01

    The development of tubal obstruction and subsequent infertility is a major sequelum of upper genital tract infection with Chlamydia trachomatis; however, little is known about the pathogenesis of the infection. In this investigation, the authors present a detailed study of the progression of ascending chlamydial infection in female guinea pigs resulting from intravaginal inoculation of the Chlamydia psittaci agent of guinea pig inclusion conjunctivitis (GPIC). Isolation of chlamydiae from different tissues of the genital tract revealed definitive evidence for ascending infection that was not dose-related. By 7 days after infection, GPIC was isolated from the endometrium and oviducts of 78% of the animals. Pathologic changes analogous to those seen in human chlamydial disease, including polymorphonuclear, mononuclear, and plasma cell infiltration, were seen in the endometrium and oviducts, although not all isolation positive animals developed overt tubal disease. Long-term fibrosis, often in combination with hydrosalpinx, was noted in the mesosalpingeal tissue in 20% of the animals. Thus, the guinea pig:GPIC system represents a model for ascending chlamydial infection resulting from vaginal inoculation of normal guinea pigs that closely approximates the disease as seen in humans and can be used to study the pathogenesis of chlamydial genital infection. Images Figure 4 Figure 7 Figure 8 Figure 9 Figure 10 PMID:1562052

  16. Effects of polylactic acid film on middle ear mucosa and cochlear function in Guinea pigs.

    PubMed

    Ensari, Nuray; Tutar, Hakan; Ekinci, Ozgur; Ugur, Mehmet Birol; Bayazıt, Yıldırım A; Gokdogan, Cagil; Goksu, Nebil

    2015-05-01

    Our aim was to assess the effects of polylactic acid (PLA) on middle ear mucosa and cochlea, to be used as a film barrier for postoperative adhesion prevention in the middle ear. Twenty-one albino Guinea pigs were included in the study. A window was opened on both tympanic bulla and on one side PLA material was placed in the middle ear and on the other side only fenestration was performed and used as a control. All Guinea pigs underwent evaluation of tympanic membranes microscopically; functional hearing was analyzed by auditory brainstem responses preoperatively, in the first and the sixth month. All Guinea pigs were killed on the sixth month for histopathologic evaluation of their temporal bones. There was no statistical difference between both groups regarding hearing thresholds, interpeak wave latencies preoperatively and on first and the sixth months postoperatively. Histopathological evaluation revealed no specific changes. There was a mild local inflammation both in the PLA implanted and control ears. PLA film barrier most likely has no toxic effects on Guinea pig middle ear and does not show any ototoxic side effects.

  17. Contractile properties of synthetic cationic polypeptides in guinea-pig isolated trachea.

    PubMed Central

    Spina, D.; Goldie, R. G.

    1994-01-01

    1. The synthetic polypeptides, poly-L-arginine, poly-L-lysine and poly-D-lysine contract guinea-pig isolated trachea in a concentration-dependent, epithelium-independent manner. Indomethacin augmented the contractile response to poly-L-arginine. 2. The contractile response to poly-L-arginine was not significantly inhibited by nicardipine, a selective L-type calcium channel blocker or by the histamine H1-receptor antagonist, mepyramine nor significantly augmented by the neutral endopeptidase inhibitor, phosphoramidon. 3. The contractile response to poly-L-arginine was inhibited in a concentration-dependent manner by prior incubation of guinea-pig tracheal rings with a number of anionic polypeptides including, low molecular weight heparin, poly-L-aspartic acid and bovine serum albumin. 4. In vitro capsaicin-induced desensitization failed to attenuate the contractile response to poly-L-arginine, suggesting little, if any role for sensory neuropeptides in the functional response in the guinea-pig. 5. Synthetic polypeptides induce an epithelium-independent, charge-dependent contraction of guinea-pig isolated trachea. PMID:8012709

  18. Immunization of mice and guinea-pigs against Salmonella dublin infection with live and inactivated vaccine.

    PubMed

    Cameron, C M; Fuls, W J

    1975-06-01

    The immunogenicity of a number of avirulent rough Salmonella dublin mutants was compared in mice and guinea-pigs. Live vaccine prepared from Strain HB 1/17 at doses of 5 X 10(7) per mouse usually gave an immunity of between 70 and 80% but in certain experiments the results were more variable and always poorer. This strain gave a cross protection of 28,5% to S. typhimurium in mice. In guinea-pigs it evoked an average protection of approximately 46% to homologous challenge and approximately 26% to challenge with S. tryphimurium. Strain 5765 protected up to 80% of mice against S. dublin infection and was generally superior to Strain HB 1/17 in this respect. It was, however, less effective in protecting mice against S. tryphimurium (20%). In guinea-pigs it was also less effective than Strain HB 1/17, giving 34% protection against homologous and 20% against heterologous challenge. Other strains also produced immunity in mice but they were not studied in detail. Formalin-inactivated alum-precipitated vaccine prepared from avirulent smooth strain and containing 0,5% packed cells proved to be extremely effective in protecting mice against S. dublin infection. It produced an average immunity of 75% and was often 100% effective. It also protected 60% of mice against challenge with S. tryphimurium. In guinea-pigs it was, however, totally ineffective against challenge with both S. dublin and S. tryphimurium.

  19. Pathogenesis of endometritis and salpingitis in a guinea pig model of chlamydial genital infection.

    PubMed

    Rank, R G; Sanders, M M

    1992-04-01

    The development of tubal obstruction and subsequent infertility is a major sequelum of upper genital tract infection with Chlamydia trachomatis; however, little is known about the pathogenesis of the infection. In this investigation, the authors present a detailed study of the progression of ascending chlamydial infection in female guinea pigs resulting from intravaginal inoculation of the Chlamydia psittaci agent of guinea pig inclusion conjunctivitis (GPIC). Isolation of chlamydiae from different tissues of the genital tract revealed definitive evidence for ascending infection that was not dose-related. By 7 days after infection, GPIC was isolated from the endometrium and oviducts of 78% of the animals. Pathologic changes analogous to those seen in human chlamydial disease, including polymorphonuclear, mononuclear, and plasma cell infiltration, were seen in the endometrium and oviducts, although not all isolation positive animals developed overt tubal disease. Long-term fibrosis, often in combination with hydrosalpinx, was noted in the mesosalpingeal tissue in 20% of the animals. Thus, the guinea pig:GPIC system represents a model for ascending chlamydial infection resulting from vaginal inoculation of normal guinea pigs that closely approximates the disease as seen in humans and can be used to study the pathogenesis of chlamydial genital infection.

  20. Utility of Oral Swab Sampling for Ebola Virus Detection in Guinea Pig Model.

    PubMed

    Spengler, Jessica R; Chakrabarti, Ayan K; Coleman-McCray, JoAnn D; Martin, Brock E; Nichol, Stuart T; Spiropoulou, Christina F; Bird, Brian H

    2015-10-01

    To determine the utility of oral swabs for diagnosing infection with Ebola virus, we used a guinea pig model and obtained daily antemortem and postmortem swab samples. According to quantitative reverse transcription PCR analysis, the diagnostic value was poor for antemortem swab samples but excellent for postmortem samples.

  1. Use of a Far-Infrared Active Warming Device in Guinea Pigs (Cavia porcellus)

    PubMed Central

    Zarndt, Bethany S; Buchta, Jessica N; Garver, Lindsey S; Davidson, Silas A; Rowton, Edgar D; Despain, Kenneth E

    2015-01-01

    Small mammals have difficulty maintaining body temperature under anesthesia. This hypothermia is a potential detriment not only to the health and comfort of the animal but also to the integrity of any treatment given or data gathered during the anesthetic period. Using an external warming device to assist with temperature regulation can mitigate these effects. In this study, we investigated the ability of an advanced warming device that uses far-infrared (FIR) heating and responds to real-time core temperature monitoring to maintain a normothermic core temperature in guinea pigs. Body temperatures were measured during 30 min of ketamine–xylazine general anesthesia with and without application of the heating device. The loss of core body heat from anesthetized guinea pigs under typical (unwarmed) conditions was significant, and this loss was almost completely mitigated by application of the FIR heating pad. The significant difference between the temperatures of the actively warmed guinea pigs as compared with the control group began as early as 14 min after anesthetic administration, leading to a 2.6 °C difference at 30 min. Loss of core body temperature was not correlated with animals’ body weight; however, weight influences the efficiency of FIR warming slightly. These study results show that the FIR heating device accurately controls core body temperature in guinea pigs, therefore potentially alleviating the effects of body heat loss on animal physiology. PMID:26632788

  2. Oral therapy using nanoparticle-encapsulated antituberculosis drugs in guinea pigs infected with Mycobacterium tuberculosis.

    PubMed

    Johnson, Christine M; Pandey, Rajesh; Sharma, Sadhna; Khuller, G K; Basaraba, Randall J; Orme, Ian M; Lenaerts, Anne J

    2005-10-01

    We evaluated the efficacy of nanoparticle-encapsulated antituberculosis drugs administered every 10 days versus that of daily nonencapsulated drugs against Mycobacterium tuberculosis aerosol infection in guinea pigs. Both treatments significantly reduced the bacterial count and lung histopathology, suggesting that the nanoparticle drug delivery system has potential in intermitted treatment of tuberculosis.

  3. Calcium antagonistic activity of Bacopa monniera in guinea-pig trachea

    PubMed Central

    Channa, Shabana; Dar, Ahsana

    2012-01-01

    Objective: To demonstrate the calcium antagonistic property of ethanol extract of Bacopa monniera in guinea-pig trachea. Materials and Methods: The dose response curves of CaCl2 (1 × 10-5 to 1 × 10-1 M) were constructed in the absence and presence of ethanol extract of Bacopa monniera (100, 500 and 700 μg/ml) or nifedipine (1 × 10-6 M) in guinea-pig trachea in calcium free high K+-MOPS-PSS (3-(N-morpholino)-propanesulphonic acid physiological salt solution). The data was analyzed by ANOVA followed by least significant difference test or by Student's ‘t’ test for unequal variance when appropriate. A probability of at least P < 0.05 was considered statistically significant. Results: The plant extract (500 and 700 μg/ml) significantly (P < 0.05) depressed and shifted the calcium concentration-response curves (1 × 10-3- 1 × 10-1 M) to rightward similar to that of nifedipine. Conclusions: Bacopa monniera extract exhibited calcium channel blocking activity in guinea-pig tracheal smooth muscles that may rationalize its relaxant action on guinea-pig trachea and its traditional use in respiratory disorders. PMID:23087517

  4. The influence of starvation upon hepatic drug metabolism in rats, mice, and guinea pigs.

    NASA Technical Reports Server (NTRS)

    Furner, R. L.; Feller, D. D.

    1971-01-01

    Male rats, mice, and guinea pigs were starved for 1, 2, or 3 days, and the metabolism of ethylmorphine, p-nitroanisole, and aniline was studied. Results suggest that the oxidative enzyme systems studied are not interdependent, and the pathways studied appear to be species dependent.

  5. Effects of ozone and sulfuric acid aerosol on gas trapping in the guinea pig lung

    SciTech Connect

    Silbaugh, S.A.; Mauderly, J.L.

    1986-01-01

    Four groups of 20 guinea pigs were sequentially exposed by inhalation to either air followed by sulfuric acid aerosol, ozone followed by sulfuric acid aerosol, ozone followed by air, or air followed by air to determine whether ozone preexposure sensitizes guinea pigs to the airway constrictive effects of sulfuric acid aerosol. All first exposures to ozone or air were 2 h in duration; all second exposures to sulfuric acid or air were for 1 h. All ozone and sulfuric acid exposures were 0.8 ppm and 12 mg/m3, respectively. Animals were observed for respiratory distress during exposure, and excised lungs were quantitated for trapped gas and wet/dry ratios. None of the guinea pigs developed dyspnea, and wet/dry ratios were not altered. Ozone significantly (p less than 0.05) increased trapped gas volumes, which were 44% (ozone-acid) to 68% (ozone-air) greater than in the air-air group. Trapped gas volume was 23% greater in the ozone-acid group than in the air-acid group, but the difference was not statistically significant (p less than 0.20). Thus, ozone increased gas trapping but did not significantly sensitize guinea pigs to the bronchoconstrictive action of sulfuric acid.

  6. COMPARATIVE GENOTOXIC RESPONSES TO ARSENITE IN GUINEA PIG, MOUSE, RAT AND HUMAN LYMPHOCYTES

    EPA Science Inventory

    Comparative genotoxic responses to arsenite in guinea pig, mouse, rat and human
    lymphocytes.

    Inorganic arsenic is a known human carcinogen causing skin, lung, and bladder cancer following chronic exposures. Yet, long-term laboratory animal carcinogenicity studies have ...

  7. Use of a Far-Infrared Active Warming Device in Guinea Pigs (Cavia porcellus).

    PubMed

    Zarndt, Bethany S; Buchta, Jessica N; Garver, Lindsey S; Davidson, Silas A; Rowton, Edgar D; Despain, Kenneth E

    2015-11-01

    Small mammals have difficulty maintaining body temperature under anesthesia. This hypothermia is a potential detriment not only to the health and comfort of the animal but also to the integrity of any treatment given or data gathered during the anesthetic period. Using an external warming device to assist with temperature regulation can mitigate these effects. In this study, we investigated the ability of an advanced warming device that uses far-infrared (FIR) heating and responds to real-time core temperature monitoring to maintain a normothermic core temperature in guinea pigs. Body temperatures were measured during 30 min of ketamine-xylazine general anesthesia with and without application of the heating device. The loss of core body heat from anesthetized guinea pigs under typical (unwarmed) conditions was significant, and this loss was almost completely mitigated by application of the FIR heating pad. The significant difference between the temperatures of the actively warmed guinea pigs as compared with the control group began as early as 14 min after anesthetic administration, leading to a 2.6 °C difference at 30 min. Loss of core body temperature was not correlated with animals' body weight; however, weight influences the efficiency of FIR warming slightly. These study results show that the FIR heating device accurately controls core body temperature in guinea pigs, therefore potentially alleviating the effects of body heat loss on animal physiology. PMID:26632788

  8. Sensitization studies in the guinea pig with the active ingredients of Euxyl K 400.

    PubMed

    Bruze, M; Gruvberger, B; Agrup, G

    1988-01-01

    The preservative Euxyl K 400 consists of the 2 active ingredients, 2-phenoxyethanol and 1,2-dibromo-2,4-dicyanobutane. Sensitization studies with the guinea pig maximization test were performed with these substances, but no sensitizing capacity was demonstrated in the case of either compound.

  9. Primary structure and functional expression of a guinea pig kappa opioid (dynorphin) receptor.

    PubMed Central

    Xie, G X; Meng, F; Mansour, A; Thompson, R C; Hoversten, M T; Goldstein, A; Watson, S J; Akil, H

    1994-01-01

    A full-length cDNA encoding the guinea pig kappa opioid (dynorphin) receptor has been isolated. The deduced protein contains 380 aa and seven hydrophobic alpha-helices characteristic of the G protein-coupled receptors. This receptor is 90% identical to the mouse and rat kappa receptors, with the greatest level of divergence in the N-terminal region. When expressed in COS-7 cells, the receptor displays high affinity and stereospecificity toward dynorphin peptides and other kappa-selective opioid ligands such as U50, 488. It does not bind the mu- and delta-selective opioid ligands. The expressed receptor is functionally coupled to G protein(s) to inhibit adenylyl cyclase and Ca2+ channels. The guinea pig kappa receptor mRNA is expressed in many brain areas, including the cerebellum, a pattern that agrees well with autoradiographic maps of classical guinea pig kappa binding sites. Species differences in the pharmacology and mRNA distribution between the cloned guinea pig and rat kappa receptors may be worthy of further examination. Images PMID:8170987

  10. THE INFLUENCE OF THE "DIAPLYTE" ANTIGEN OF DREYER ON TUBERCULOSIS OF THE GUINEA PIG.

    PubMed

    Bronfenbrenner, J J; Straub, E L

    1925-01-31

    We have prepared "diaplyte" antigen according to Dreyer's procedure and have studied its therapeutic and prophylactic value in experimental tuberculosis of guinea pigs. In our hands it has failed to yield beneficial effects. The animals treated with the antigen tended in general to develop lesions more quickly and to die earlier than the controls.

  11. Occurrence of parasympathetic vasodilator fibers in the lower lip of the guinea-pig.

    PubMed

    Watanabe, H; Ishii, H; Niioka, T; Yamamuro, M; Izumi, H

    2008-03-01

    The present study was designed to examine whether there are parasympathetic vasodilator fibers in the lower lip of the guinea-pig. Electrical stimulation of the central cut end of the lingual nerve of guinea-pigs evoked intensity- and frequency-dependent decreases in lower lip blood flow and systemic arterial blood pressure (SABP). Pretreatment with guanethidine, a postganglionic sympathetic nerve blocker and antihypertensive drug (30 mg kg(-1), s.c., 24 h prior to experiments), reduced the magnitude of the decrease in SABP while the intensity- and frequency-dependent increases of the lip blood flow occurred by the lingual nerve stimulation only on the side ipsilateral to stimulation. Increases in the lip blood flow evoked by lingual nerve stimulation in guanethidine pretreated guinea-pigs were reduced by hexamethonium (an autonomic ganglion cholinergic blocker) in a dose-dependent manner. When fluoro-gold (a retrograde neural tracer) was injected into the lower lip, labeled neurons were observed in the ipsilateral otic ganglion. The present study indicates the presence of parasympathetic vasodilator fibers originating from the otic parasympathetic ganglion in the guinea-pig lower lip, similar to those reported previously in rats, cats, rabbits and humans. PMID:18030480

  12. [The effection of obstructing OCB with strychnine on the guinea pig's DPOAE].

    PubMed

    Li, K; Wang, Z; Ni, D

    1998-08-01

    The strychnine was used to obstruct the oliver cochlear bundle (OCB) in order to explore the effect of the efferent system on distortion product otoacoustic emission (DPOAE) of guinea pig. The result showed that the DPOAE were not changed after strychnine were administrated. It is concluded that the efferent pulses of the CNS does not affect on DPOAE in silent circumstance. PMID:11263161

  13. Adrenergic lipolysis in guinea pig is not a beta 3-adrenergic response: comparison with human adipocytes.

    PubMed

    Carpéné, C; Castan, I; Collon, P; Galitzky, J; Moratinos, J; Lafontan, M

    1994-03-01

    beta 3-Adrenoceptor agonists are potent lipolytic activators in rats, but they are only weak stimulators in human adipocytes, indicating interspecies differences in the adrenergic regulation of lipid mobilization. Like human but not rat adipocytes, guinea pig fat cells were poorly responsive to the beta 3-agonists BRL-37344, CGP-12177, SR-58611, and ICI-215001, acid metabolite of ICI-D7114. In guinea pigs, the beta 1-agonist dobutamine was more lipolytic than the beta 2-agonist procaterol. Anatomic location of fat deposits was without major influence on the beta-adrenergic responsiveness. Weak responses to beta 3-agonists were found whatever the sex or the age (from 2 days to 16 mo) of the animals. Even in the interscapular brown adipose tissue, which is well known in rats for its beta 3-adrenergic responsiveness, a blunted response to BRL-37344 was observed. The alpha 2-adrenergic antilipolytic effect and receptor number were smaller in guinea pig than in human adipocytes, but the beta-adrenergic receptor number was similar in the two species. Thus guinea pig adipocytes resemble human fat cells when their weak beta 3-adrenergic responsiveness is considered. PMID:7909205

  14. Skin sensitization, false positives and false negatives: experience with guinea pig assays.

    PubMed

    Basketter, David A; Kimber, Ian

    2010-07-01

    The advent of the local lymph node assay (LLNA), and efforts to develop in vitro alternatives for the identification of skin sensitizing chemicals has focused attention on the issue of false positive and false negative results. In essence, the question becomes 'what is the gold standard?' In this context, attention has focused primarily on the LLNA as this is now the preferred assay for skin sensitization testing. However, for many years prior to introduction of the LLNA, the guinea pig maximization test and the occluded patch test of Buehler were the methods of choice. In order to encourage a more informed dialogue about the relative performance, accuracy and applicability of the LLNA and guinea pig tests, we have here considered the extent to which guinea pig methods were themselves subject to false positives and negative results. We describe and discuss here well-characterized examples of instances where both false negatives (including abietic acid and eugenol) or false positives (including vanillin and sulfanilic acid) have been recorded in guinea pig tests. These and other examples are discussed with particular reference to the fabrication of a gold standard dataset that is required for the validation of in vitro alternatives.

  15. Endogenous histamine and promethazine-induced gastric ulcers in the guinea pig

    NASA Technical Reports Server (NTRS)

    Djahanguiri, B.; Hemmati, M.

    1978-01-01

    Experiments performed with an inhibitor of diaminoxydase, aminoguanidine and an inhibitor of histidine decarboxylase, NSD 1055, showed that the frequency of gastric ulcers induced by promethazine was increased with the first inhibitor and decreased with the second. It is suggested that ulcers induced by promethazine in guinea pigs might be due to histamino-liberator effect of the antihistaminio compound.

  16. The sensitizing potential of primary amyl acetate in the guinea pig.

    PubMed

    Ballantyne, B; Tyler, T R; Auletta, C S

    1986-06-01

    Primary amyl acetate is a liquid mixture of the isomeric forms of pentyl acetate, which is used as a volatile organic solvent. Because of the possibility for skin contact, primary amyl acetate was investigated for its potential to cause allergic contact dermatitis. Using a guinea pig maximization procedure, primary amyl acetate was found to be a possible marginal skin sensitizer. PMID:3727350

  17. Utility of Oral Swab Sampling for Ebola Virus Detection in Guinea Pig Model.

    PubMed

    Spengler, Jessica R; Chakrabarti, Ayan K; Coleman-McCray, JoAnn D; Martin, Brock E; Nichol, Stuart T; Spiropoulou, Christina F; Bird, Brian H

    2015-10-01

    To determine the utility of oral swabs for diagnosing infection with Ebola virus, we used a guinea pig model and obtained daily antemortem and postmortem swab samples. According to quantitative reverse transcription PCR analysis, the diagnostic value was poor for antemortem swab samples but excellent for postmortem samples. PMID:26401603

  18. Effect of ozone exposure on antigen-induced airway hyperresponsiveness in guinea pigs

    SciTech Connect

    Vargas, M.H.; Segura, P.; Campos, M.G.; Hong, E.; Montano, L.M.

    1994-12-31

    Airway hyperresponsiveness can be induced by several stimuli including antigen and ozone, both of which may be present in the air of polluted cities. Though the effect of ozone on the bronchoconstrictor response to antigen has been well described, the combined effect of these stimuli on airway hyperresponsiveness has not yet been studied. Sensitized guinea pigs with or without ozone exposure for 1 h at 3 ppm, 18 h prior to study, were challenged with a dose-response curve to histamine (0.01-1.8 {mu}g/kg, iv), and then by a second histamine dose-response curve 1 h later. Airway responses were measured as the increase in pulmonary insufflation pressure. In sensitized guinea pigs, the histamine ED50 significantly decreased after antigen challenge, demonstrating the development of airway hyperresponsiveness. Sensitized guinea pigs exposed to ozone showed airway hyperresponsiveness to histamine when compared with nonexposed animals, and such hyperresponsiveness was further enhanced after antigen challenge. We conclude that in this guinea pig model of acute allergic bronchoconstriction both antigen challenge and ozone induce airway hyperresponsiveness, while ozone exposure does not modify the development of antigen-induced hyperresponsiveness. 25 refs., 1 fig., 1 tab.

  19. Effects of magnesium supplementation on electrophysiological remodeling of cardiac myocytes in L-NAME induced hypertensive rats.

    PubMed

    Ozturk, Nihal; Olgar, Yusuf; Aslan, Mutay; Ozdemir, Semir

    2016-08-01

    Hypertension is one of the major risk factors of cardiac hypertrophy and magnesium deficiency is suggested to be a contributing factor in the progression of this complication. In this study, we aimed to investigate the relationship between intracellular free Mg(2+) levels and electrophysiological changes developed in the myocardium of L-NAME induced hypertensive rats. Hypertension was induced by administration of 40 mg/kg of L-NAME for 6 weeks, while magnesium treated rats fed with a diet supplemented with 1 g/kg of MgO for the same period. L-NAME administration for 6 weeks elicited a significant increase in blood pressure which was corrected with MgO treatment; thereby cardiac hypertrophy developing secondary to hypertension was prevented. Cytosolic free magnesium levels of ventricular myocytes were significantly decreased with hypertension and magnesium administration restored these changes. Hypertension significantly decreased the fractional shortening with slowing of shortening kinetics in left ventricular myocytes whereas magnesium treatment was capable of restoring hypertension-induced contractile dysfunction. Long-term magnesium treatment significantly restored the hypertension-induced prolongation in action potentials of ventricular myocytes and suppressed Ito and Iss currents. In contrast, hypertension dependent decrement in intracellular Mg(2+) level did not cause a significant change in L-type Ca(2+) currents, SR Ca(2+) content and NCX activity. Nevertheless, hypertension mediated increase in superoxide anion, hydrogen peroxide and protein oxidation mitigated with magnesium treatment. In conclusion, magnesium administration improves mechanical abnormalities observed in hypertensive rat ventricular myocytes due to reduced oxidative stress. It is likely that, changes in intracellular magnesium balance may contribute to the pathophysiology of chronic heart diseases.

  20. Effects of magnesium supplementation on electrophysiological remodeling of cardiac myocytes in L-NAME induced hypertensive rats.

    PubMed

    Ozturk, Nihal; Olgar, Yusuf; Aslan, Mutay; Ozdemir, Semir

    2016-08-01

    Hypertension is one of the major risk factors of cardiac hypertrophy and magnesium deficiency is suggested to be a contributing factor in the progression of this complication. In this study, we aimed to investigate the relationship between intracellular free Mg(2+) levels and electrophysiological changes developed in the myocardium of L-NAME induced hypertensive rats. Hypertension was induced by administration of 40 mg/kg of L-NAME for 6 weeks, while magnesium treated rats fed with a diet supplemented with 1 g/kg of MgO for the same period. L-NAME administration for 6 weeks elicited a significant increase in blood pressure which was corrected with MgO treatment; thereby cardiac hypertrophy developing secondary to hypertension was prevented. Cytosolic free magnesium levels of ventricular myocytes were significantly decreased with hypertension and magnesium administration restored these changes. Hypertension significantly decreased the fractional shortening with slowing of shortening kinetics in left ventricular myocytes whereas magnesium treatment was capable of restoring hypertension-induced contractile dysfunction. Long-term magnesium treatment significantly restored the hypertension-induced prolongation in action potentials of ventricular myocytes and suppressed Ito and Iss currents. In contrast, hypertension dependent decrement in intracellular Mg(2+) level did not cause a significant change in L-type Ca(2+) currents, SR Ca(2+) content and NCX activity. Nevertheless, hypertension mediated increase in superoxide anion, hydrogen peroxide and protein oxidation mitigated with magnesium treatment. In conclusion, magnesium administration improves mechanical abnormalities observed in hypertensive rat ventricular myocytes due to reduced oxidative stress. It is likely that, changes in intracellular magnesium balance may contribute to the pathophysiology of chronic heart diseases. PMID:27193439

  1. Computed tomography analysis of guinea pig bone: architecture, bone thickness and dimensions throughout development

    PubMed Central

    Witkowska, Agata; Alibhai, Aziza; Hughes, Chloe; Price, Jennifer; Klisch, Karl; Sturrock, Craig J.

    2014-01-01

    The domestic guinea pig, Cavia aperea f. porcellus, belongs to the Caviidae family of rodents. It is an important species as a pet, a source of food and in medical research. Adult weight is achieved at 8–12 months and life expectancy is ∼5–6 years. Our aim was to map bone local thickness, structure and dimensions across developmental stages in the normal animal. Guinea pigs (n = 23) that had died of natural causes were collected and the bones manually extracted and cleaned. Institutional ethical permission was given under the UK Home Office guidelines and the Veterinary Surgeons Act. X-ray Micro Computed Tomography (microCT) was undertaken on the left and right scapula, humerus and femur from each animal to ascertain bone local thickness. Images were also used to undertake manual and automated bone measurements, volumes and surface areas, identify and describe nutrient, supratrochlear and supracondylar foramina. Statistical analysis between groups was carried out using ANOVA with post-hoc testing. Our data mapped a number of dimensions, and mean and maximum bone thickness of the scapula, humerus and femur in guinea pigs aged 0–1 month, 1–3 months, 3–6 months, 6 months–1 year and 1–4 years. Bone dimensions, growth rates and local bone thicknesses differed between ages and between the scapula, humerus and femur. The microCT and imaging software technology showed very distinct differences between the relative local bone thickness across the structure of the bones. Only one bone showed a singular nutrient foramen, every other bone had between 2 and 5, and every nutrient canal ran in an oblique direction. In contrast to other species, a supratrochlear foramen was observed in every humerus whereas the supracondylar foramen was always absent. Our data showed the bone local thickness, bone structure and measurements of guinea pig bones from birth to 4 years old. Importantly it showed that bone development continued after 1 year, the point at which most

  2. A factor from Trypanosoma cruzi induces repetitive cytosolic free Ca2+ transients in isolated primary canine cardiac myocytes.

    PubMed Central

    Barr, S C; Han, W; Andrews, N W; Lopez, J W; Ball, B A; Pannabecker, T L; Gilmour, R F

    1996-01-01

    An unusual 120-kDa alkaline peptidase contained in a trypomastigote soluble fraction (TSF) of Trypanosoma cruzi is associated with the induction of repetitive Ca2+ transients and subsequent invasion by the parasite of a number of mammalian cell lines, including tissue culture L6E2 myoblasts (B. A. Burleigh and N. W. Andrews, J. Biol. Chem. 270:5172-5180, 1995; S. N. J. Moreno, J. Silva, A. E. Vercesi, and R. Docampo, J. Exp. Med. 180:1535-1540, 1994; A. Rodríguez, M. G. Rioult, A. Ora, and N. W. Andrews, J. Cell Biol. 129:1263-1273, 1995; I. Tardieux, M. H. Nathanson, and N. W. Andrews, J. Exp. Med. 179:1017-1022, 1994). Using single cell spectrofluorometry and whole-cell patch clamping, we show that TSF produces rapid repetitive cytosolic Ca2+ transients (each associated with cell contraction) in primary cardiac myocytes isolated from dogs. The response of myocytes to TSF was dose dependent in that increasing numbers of cells responded to increasing concentrations of TSF. The TSF-induced Ca2+ transients could be obliterated when TSF was heated or treated with trypsin or the protease inhibitor leupeptin. Aprotinin, pepstatin A, and E-64 did not affect TSF activity. The TSF-induced Ca2+ transients and trypomastigote cell invasion could not be inhibited by alpha (prazosin)- or beta (propanolol)-adrenergic blockers or L-type Ca2+ channel blockers (verapamil, nisoldipine, or cadmium) or by removal of extracellular Ca2+. However, inhibition of pertussis toxin-sensitive G proteins and Ca2+ release from the sarcoplasmic reticulum (with thapsigargin or ryanodine) prevented the TSF-induced Ca2+ transients and cell invasion by trypomastigotes. These data suggested that cardiac myocyte pertussis toxin-sensitive G proteins are associated with the regulation of TSF-induced Ca2+ transients and myocyte invasion by trypomastigotes but are independent of Ca2+ entry into the cytosol via L-type Ca2+ channels. The Ca2+ transients are dependent on release of Ca2+ from sarcoplasmic

  3. Direct toxic effects of aqueous extract of cigarette smoke on cardiac myocytes at clinically relevant concentrations

    SciTech Connect

    Yamada, Shigeyuki; Zhang Xiuquan; Kadono, Toshie; Matsuoka, Nobuhiro; Rollins, Douglas; Badger, Troy; Rodesch, Christopher K.; Barry, William H.

    2009-04-01

    Aims: Our goal was to determine if clinically relevant concentrations of aqueous extract of cigarette smoke (CSE) have direct deleterious effects on ventricular myocytes during simulated ischemia, and to investigate the mechanisms involved. Methods: CSE was prepared with a smoking chamber. Ischemia was simulated by metabolic inhibition (MI) with cyanide (CN) and 0 glucose. Adult rabbit and mouse ventricular myocyte [Ca{sup 2+}]{sub i} was measured by flow cytometry using fluo-3. Mitochondrial [Ca{sup 2+}] was measured with confocal microscopy, and Rhod-2 fluorescence. The mitochondrial permeability transition (MPT) was detected by TMRM fluorescence and myocyte contracture. Myocyte oxidative stress was quantified by dichlorofluorescein (DCF) fluorescence with confocal microscopy. Results: CSE 0.1% increased myocyte contracture caused by MI. The nicotine concentration (HPLC) in 0.1% CSE was 15 ng/ml, similar to that in humans after smoking cigarettes. CSE 0.1% increased mitochondrial Ca{sup 2+} uptake, and increased the susceptibility of mitochondria to the MPT. CSE 0.1% increased DCF fluorescence in isolated myocytes, and increased [Ca{sup 2+}]{sub i} in paced myocytes exposed to 2.0 mM CN, 0 glucose (P-MI). These effects were inhibited by the superoxide scavenger Tiron. The effect of CSE on [Ca{sup 2+}]{sub i} during P-MI was also prevented by ranolazine. Conclusions: CSE in clinically relevant concentrations increases myocyte [Ca{sup 2+}]{sub i} during simulated ischemia, and increases myocyte susceptibility to the MPT. These effects appear to be mediated at least in part by oxidative radicals in CSE, and likely contribute to the effects of cigarette smoke to increase myocardial infarct size, and to decrease angina threshold.

  4. Effect of ochratoxin and aflatoxin on serum proteins, complement activity, and antibody production to Brucella abortus in guinea pigs.

    PubMed

    Richard, J L; Thurston, J R; Deyoe, B L; Booth, G D

    1975-01-01

    The effect of ochratoxin alone and in combination with aflatoxin and Brucella abortus antigen on complement activity, serum proteins, and antibody response in guinea pigs was investigated. Ochratoxin did not affect complement activity or antibody response and there was no interaction between ochratoxin and aflatoxin on any of the responses tested. Ochratoxin significantly lowered the level of beta-globulin in serum of guinea pigs. There was no significant interaction between aflatoxin and antigen on lowering of the serum albumin levels of guinea pigs. PMID:45955

  5. Microfluidic systems to examine intercellular coupling of pairs of cardiac myocytes.

    PubMed

    Klauke, Norbert; Smith, Godfrey; Cooper, Jonathan M

    2007-06-01

    In this paper we describe a microfluidic environment that enables us to explore cell-to-cell signalling between longitudinally linked primary heart cells. We have chosen to use pairs (or doublets) of cardiac myocyte as a model system, not only because of the importance of cell-cell signalling in the study of heart disease but also because the single cardiomyocytes are both mechanically and electrically active and their synchronous activation due to the intercellular coupling within the doublet can be readily monitored on optical and electrical recordings. Such doublets have specialised intercellular contact structures in the form of the intercalated discs, comprising the adhesive junction (fascia adherens and macula adherens or desmosome) and the connecting junction (known as gap junction). The latter structure enables adjacent heart cells to share ions, second messengers and small metabolites (<1 kDa) between them and thus provides the structural basis for the synchronous (syncytical) behaviour of connected cardiomyocytes. Using the unique environment provided by the microfluidic system, described in this paper, we explore the local ionic conditions that enable the propagation of Ca(2+) waves between two heart cells. We observe that the ability of intracellular Ca(2+) waves to traverse the intercalated discs is dependent on the relative concentrations of diastolic Ca(2+) in the two adjacent cells. These experiments rely upon our ability to independently control both the electrical stimulation of each of the cells (using integrated microelectrodes) and to rapidly change (or switch) the local concentrations of ions and drugs in the extracellular buffer within the microfluidic channel (using a nanopipetting system). Using this platform, it is also possible to make simultaneous optical recordings (including fluorescence and cell contraction) to explore the effect of drugs on one or both cells, within the doublet.

  6. Velocity-curvature relationship of colliding spherical calcium waves in rat cardiac myocytes.

    PubMed Central

    Wussling, M H; Scheufler, K; Schmerling, S; Drygalla, V

    1997-01-01

    Colliding spherical calcium waves in enzymatically isolated rat cardiac myocytes develop new wavefronts propagating perpendicular to the original direction. When investigated by confocal laser scanning microscopy (CLSM), using the fluorescent Ca2+ indicator fluo-3 AM, "cusp"-like structures become visible that are favorably approximated by double parabolae. The time-dependent position of the vertices is used to determine propagation velocity and negative curvature of the wavefront in the region of collision. It is evident that negatively curved waves propagate faster than positively curved, single waves. Considering two perfectly equal expanding circular waves, we demonstrated that the collision of calcium waves is due to an autocatalytic process (calcium-induced calcium release), and not to a simple phenomenon of interference. Following the spatiotemporal organization in simpler chemical systems maintained under conditions far from the thermodynamic equilibrium (Belousov-Zhabotinskii reaction), the dependence of the normal velocity on the curvature of the spreading wavefront is given by a linear relation. The so-called velocity-curvature relationship makes clear that the velocity is enhanced by curvature toward the direction of forward propagation and decreased by curvature away from the direction of forward propagation (with an influence of the diffusion coefficient). Experimentally obtained velocity data of both negatively and positively curved calcium waves were approximated by orthogonal weighted regression. The negative slope of the straight line resulted in an effective diffusion coefficient of 1.2 x 10(-4) mm2/s. From the so-called critical radius, which must be exceeded to initiate a traveling calcium wave, a critical volume (with enhanced [Ca2+]i) of approximately 12 microm3 was calculated. This is almost identical to the volume that is occupied by a single calcium spark. Images FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 6 PMID:9284291

  7. The effects of an alpha hydroxy acid (glycolic acid) on hairless guinea pig skin permeability.

    PubMed

    Hood, H L; Kraeling, M E; Robl, M G; Bronaugh, R L

    1999-11-01

    The barrier integrity of hairless guinea pig skin after treatment with an alpha hydroxy acid was assessed through in vivo topical application of an oil-in-water emulsion containing 5 or 10% glycolic acid at pH 3.0. The control was a commercial moisturizing lotion, pH 7.8. A dosing regimen for the glycolic acid formulations that was tolerated by the hairless guinea pigs and significantly decreased stratum corneum turnover time was determined using the dansyl chloride staining technique. Once-daily dosing of hairless guinea pig skin for 3 weeks with the glycolic acid formulations resulted in approximately a 36-39% decrease in stratum corneum turnover time compared with the control lotion. After this treatment, hairless guinea pigs were sacrificed for the in vitro measurement of the percutaneous absorption of [14C]hydroquinone and [14C]musk xylol. No significant differences in the 24-hour absorption of either test compound were found for skin treated with the control lotion or the glycolic acid formulations. There were also no significant differences found in the absorption of [3H]water through skin from the different treatment groups. Although no increase in skin penetration occurred after treatment with the glycolic acid formulations, histology revealed approximately a twofold increase in epidermal thickness. Also the number of nucleated cell layers nearly doubled in skin treated with 5% and 10% glycolic acid compared with the control lotion and untreated skin. These studies demonstrate that substantial changes in the structure of hairless guinea pig epidermis can occur without significant effect on skin permeability of two model compounds.

  8. Assessing recruitment of lung diffusing capacity in exercising guinea pigs with a rebreathing technique

    PubMed Central

    Yilmaz, Cuneyt; Dane, D. Merrill; Hsia, Connie C. W.

    2008-01-01

    Noninvasive techniques for assessing cardiopulmonary function in small animals are limited. We previously developed a rebreathing technique for measuring lung volume, pulmonary blood flow, diffusing capacity for carbon monoxide (DlCO) and its components, membrane diffusing capacity (DmCO) and pulmonary capillary blood volume (Vc), and septal volume, in conscious nonsedated guinea pigs at rest. Now we have extended this technique to study guinea pigs during voluntary treadmill exercise with a sealed respiratory mask attached to a body vest and a test gas mixture containing 0.5% SF6 or Ne, 0.3% CO, and 0.8% C2H2 in 40% or 98% O2. From rest to exercise, O2 uptake increased from 12.7 to 25.5 ml·min−1·kg−1 while pulmonary blood flow increased from 123 to 239 ml/kg. The measured DlCO, DmCO, and Vc increased linearly with respect to pulmonary blood flow as expected from alveolar microvascular recruitment; body mass-specific relationships were consistent with those in healthy human subjects and dogs studied with a similar technique. The results show that 1) cardiopulmonary interactions from rest to exercise can be measured noninvasively in guinea pigs, 2) guinea pigs exhibit patterns of exercise response and alveolar microvascular recruitment similar to those of larger species, and 3) the rebreathing technique is widely applicable to human (∼70 kg), dog (20–30 kg), and guinea pig (1–1.5 kg). In theory, this technique can be extended to even smaller animals provided that species-specific technical hurdles can be overcome. PMID:18483171

  9. Pulmonary effects of inhaled zinc oxide in human subjects, guinea pigs, rats, and rabbits

    SciTech Connect

    Gordon, T.; Chen, L.C.; Fine, J.M.; Schlesinger, R.B.; Su, W.Y.; Kimmel, T.A.; Amdur, M.O. )

    1992-08-01

    Occupational exposure to freshly formed zinc oxide (ZnO) particles (less than 1.0 micron aerodynamic diameter) produces a well-characterized response known as metal fume fever. An 8-hr threshold limit value (TLV) of 5 mg/m3 has been established to prevent adverse health effects because of exposure to ZnO fumes. Because animal toxicity studies have demonstrated pulmonary effects near the current TLV, the present study examined the time course and dose-response of the pulmonary injury produced by inhaled ZnO in guinea pigs, rats, rabbits, and human volunteers. The test animals were exposed to 0, 2.5, or 5.0 mg/m3 ZnO for up to 3 hr and their lungs lavaged. Both the lavage fluid and recovered cells were examined for evidence of inflammation or altered cell function. The lavage fluid from guinea pigs and rats exposed to 5 mg/m3 had significant increases in total cells, lactate dehydrogenase, beta-glucuronidase, and protein content. These changes were greatest 24 hr after exposure. Guinea pig alveolar macrophage function was depressed as evidenced by in vitro phagocytosis of opsonized latex beads. Significant changes in lavage fluid parameters were also observed in guinea pigs and rats exposed to 2.5 mg/m3 ZnO. In contrast, rabbits showed no increase in biochemical or cellular parameters following a 2-hr exposure to 5 mg/m3 ZnO. Differences in total lung burden of ZnO, as determined in additional animals by atomic absorption spectroscopy, appeared to account for the observed differences in species responses. Although the lungs of guinea pigs and rats retained approximately 20% and 12% of the inhaled dose, respectively, rabbits retained only 5%.

  10. Effects of 900 MHz electromagnetic field emitted by cellular phones on electrocardiograms of guinea pigs.

    PubMed

    Meral, I; Tekintangac, Y; Demir, H

    2014-02-01

    This study was carried out to determine the effects of electromagnetic field (EMF) emitted by cellular phones (CPs) on electrocardiograms (ECGs) of guinea pigs. A total of 30 healthy guinea pigs weighing 500-800 g were used. After 1 week of adaptation period, animals were randomly divided into two groups: control group (n = 10) and EMF-exposed group (n = 20). Control guinea pigs were housed in a separate room without exposing them to EMFs of CPs. Animals in second group were exposed to 890-915 MHz EMF (217 Hz of pulse rate, 2 W of maximum peak power and 0.95 wt kg(-1) of specific absorption rate) for 12 h day(-1) (11 h 45 min stand-by and 15 min speaking mode) for 30 days. ECGs of guinea pigs in both the groups were recorded by a direct writing electrocardiograph at the beginning and 10th, 20th and 30th days of the experiment. All ECGs were standardized at 1 mV = 10 mm and with a chart speed of 50 mm sec(-1). Leads I, II, III, lead augmented vector right (aVR), lead augmented vector left (aVL) and lead augmented vector foot (aVF) were recorded. The durations and amplitudes of waves on the trace were measured in lead II. The data were expressed as mean with SEM. It was found that 12 h day(-1) EMF exposure for 30 days did not have any significant effects on ECG findings of guinea pigs. However, this issue needed to be further investigated in a variety of perspectives, such as longer duration of exposure to be able to elucidate the effects of mobile phone-induced EMFs on cardiovascular functions.

  11. Uptake and Accumulation of Oxidized Low-Density Lipoprotein during Mycobacterium tuberculosis Infection in Guinea Pigs

    PubMed Central

    Palanisamy, Gopinath S.; Kirk, Natalie M.; Ackart, David F.; Obregón-Henao, Andrés; Shanley, Crystal A.; Orme, Ian M.; Basaraba, Randall J.

    2012-01-01

    The typical host response to infection of humans and some animals by M. tuberculosis is the accumulation of reactive oxygen species generating inflammatory cells into discrete granulomas, which frequently develop central caseous necrosis. In previous studies we showed that infection of immunologically naïve guinea pigs with M. tuberculosis leads to localized and systemic oxidative stress that results in a significant depletion of serum total antioxidant capacity and the accumulation of malondialdehyde, a bi-product of lipid peroxidation. Here we show that in addition, the generation of excessive reactive oxygen species in vivo resulted in the accumulation of oxidized low density lipoproteins (OxLDL) in pulmonary and extrapulmonary granulomas, serum and lung macrophages collected by bronchoalveolar lavage. Macrophages from immunologically naïve guinea pigs infected with M. tuberculosis also had increased surface expression of the type 1 scavenger receptors CD36 and LOX1, which facilitate the uptake of oxidized host macromolecules including OxLDL. Vaccination of guinea pigs with Bacillus Calmette Guerin (BCG) prior to aerosol challenge reduced the bacterial burden as well as the intracellular accumulation of OxLDL and the expression of macrophage CD36 and LOX1. In vitro loading of guinea pig lung macrophages with OxLDL resulted in enhanced replication of bacilli compared to macrophages loaded with non-oxidized LDL. Overall, this study provides additional evidence of oxidative stress in M. tuberculosis infected guinea pigs and the potential role OxLDL laden macrophages have in supporting intracellular bacilli survival and persistence. PMID:22493658

  12. Sp8 expression in putative neural progenitor cells in guinea pig and human cerebrum.

    PubMed

    Zhang, Xue-Mei; Cai, Yan; Wang, Fang; Wu, Jun; Mo, Lin; Zhang, Feng; Patrylo, Peter R; Pan, Aihua; Ma, Chao; Fu, Jin; Yan, Xiao-Xin

    2016-09-01

    Neural stem/progenitor cells have been characterized at neurogenic sites in adult mammalian brain with various molecular markers. Here it has been demonstrated that Sp8, a transcription factor typically expressed among mature GABAergic interneurons, also labels putative neural precursors in adult guinea pig and human cerebrum. In guinea pigs, Sp8 immunoreactive (Sp8+) cells were localized largely in the superficial layers of the cortex including layer I, as well as the subventricular zone (SVZ) and subgranular zone (SGZ). Sp8+ cells at the SGZ showed little colocalization with mature and immature neuronal markers, but co-expressed neural stem cell markers including Sox2. Some layer I Sp8+ cells also co-expressed Sox2. The amount of Sp8+ cells in the dentate gyrus was maintained 2 weeks after X-ray irradiation, while that of doublecortin (DCX+) cells was greatly reduced. Mild ischemic insult caused a transient increase of Sp8+ cells in the SGZ and layer I, with the subgranular Sp8+ cells exhibited an increased colabeling for the mitotic marker Ki67 and pulse-chased bromodeoxyuridine (BrdU). Sp8+ cells in the dentate gyrus showed an age-related decline in guinea pigs, in parallel with the loss of DCX+ cells in the same region. In adult humans, Sp8+ cells exhibited comparable morphological features as seen in guinea pigs, with those at the SGZ and some in cortical layer I co-expressed Sox2. Together, these results suggested that Sp8 may label putative neural progenitors in guinea pig and human cerebrum, with the labeled cells in the SGZ appeared largely not mitotically active under normal conditions. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 939-955, 2016.

  13. In vivo formation of nitrosocarbamates in the stomach of rats and guinea pigs

    SciTech Connect

    Rickard, R.W.; Dorough, H.W.

    1984-01-01

    The N-nitrosocarbamates are potent mutagens and carcinogens and have been synthesized under acid conditions that prevail in the human stomach. However, it has never been documented that nitrosocarbamates are actually formed in vivo in the stomach of any mammalian species. Using /sup 14/C-labeled carbaryl and carbofuran, attempts were made to isolate the nitroso derivatives from the stomach contents of rats and guinea pigs treated orally with the carbamate and sodium nitrite. Only trace quantities of nitrocarbamate were recovered from the rat stomach, whereas 0.5 to 2.0% of the carbamate doses were isolated as the nitroso derivative from the contents of the guinea pig stomach. The rather low apparent yields resulted in part from the instability of the nitrosocarbamates and from absorption of the carbamate and/or nitrosocarbamate from the stomach. Higher rates of synthesis were indicated by incubating the carbamates with sodium nitrite in the presence of the stomach contents at 37/sup 0/C for 15 min. About 30% nitrosation occurred with the guinea pig and about 0.5% with the rat. The difference was attributed to the pH of the gastric contents. For the rat, the pH ranged from 3 to 5; gastric contents of the guinea pig had a pH between 1 and 2. Since the pH of the human stomach is also in the pH 1-2 range, it is likely that nitrosation of carbamates in humans would be very similar to that in the guinea pig. 21 references, 3 figures, 3 tables.

  14. Metabolism and disposition of 2,3,7,8-tetrachlorodibenzo-p-dioxin in guinea pigs

    SciTech Connect

    Olson, J.R.

    1986-09-15

    Marked interspecies variability exists in the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), with the guinea pig being the mammalian species most sensitive to the acute toxicity of TCDD. The metabolism and disposition of TCDD was investigated in guinea pigs for 45 days following a single exposure to purified (/sup 3/H)TCDD (0.56 microgram/kg, ip). Guinea pigs included in the toxicokinetic study gained body weight, maintained a normal relative body composition, and exhibited no gross signs of toxicity during the 45-day study. Approximately 36% of the dose of TCDD-derived /sup 3/H remained in the adipose tissue at 45 days following exposure to (/sup 3/H)TCDD, while the liver, pelt, and skeletal muscle and carcass each contained about 7% of the administered dose. Although most of the TCDD-derived radioactivity in liver, kidney, perirenal adipose tissue, and skeletal muscle represented unchanged TCDD, from 4 to 28% of the /sup 3/H was associated with metabolites of TCDD. This unexpected finding suggests that TCDD metabolites are not efficiently excreted from guinea pigs. The urinary and fecal excretion of TCDD-derived radioactivity followed apparent first-order kinetics, with an elimination half-life of 93.7 +/- 15.5 days (mean +/- SD). HPLC analysis of urine and bile from (/sup 3/H)TCDD-treated guinea pigs showed that all of the radioactivity represented metabolites of TCDD, indicating that these routes of elimination are dependent on prior metabolism of TCDD. However, 70 to 90% of the radioactivity in fecal samples was found to represent unmetabolized TCDD throughout the 45-day excretion study. The presence of TCDD in feces and its absence in bile suggest that the fecal excretion of unchanged TCDD resulted from the direct intestinal elimination of the lipophilic toxin.

  15. Hrd1 and ER-Associated Protein Degradation, ERAD, Are Critical Elements of the Adaptive ER Stress Response in Cardiac Myocytes

    PubMed Central

    Doroudgar, Shirin; Völkers, Mirko; Thuerauf, Donna J; Khan, Mohsin; Mohsin, Sadia; Respress, Jonathan L; Wang, Wei; Gude, Natalie; Müller, Oliver J; Wehrens, Xander HT; Sussman, Mark A; Glembotski, Christopher C

    2015-01-01

    Rationale Hrd1 is an endoplasmic reticulum (ER)-transmembrane E3 ubiquitin ligase that has been studied in yeast, where it contributes to ER protein quality control by ER-associated degradation (ERAD) of misfolded proteins that accumulate during ER stress. Neither Hrd1 nor ERAD have been studied in the heart, or in cardiac myocytes, where protein quality control is critical for proper heart function. Objective The objectives of this study were to elucidate roles for Hrd1 in ER stress, ERAD, and viability in cultured cardiac myocytes and in the mouse heart, in vivo. Methods and Results The effects of siRNA-mediated Hrd1 knockdown were examined in cultured neonatal rat ventricular myocytes. The effects of adeno-associated virus (AAV)-mediated Hrd1 knockdown and overexpression were examined in the hearts of mice subjected to pressure-overload induced pathological cardiac hypertrophy, which challenges protein-folding capacity. In cardiac myocytes, the ER stressors, thapsigargin (TG) and tunicamycin (TM) increased ERAD, as well as adaptive ER stress proteins, and minimally affected cell death. However, when Hrd1 was knocked down, TG and TM dramatically decreased ERAD, while increasing maladaptive ER stress proteins and cell death. In vivo, Hrd1 knockdown exacerbated cardiac dysfunction, and increased apoptosis and cardiac hypertrophy, while Hrd1 overexpression preserved cardiac function, and decreased apoptosis and attenuated cardiac hypertrophy in the hearts of mice subjected to pressure-overload. Conclusions Hrd1 and ERAD are essential components of the adaptive ER stress response in cardiac myocytes. Hrd1 contributes to preserving heart structure and function in a mouse model of pathological cardiac hypertrophy. PMID:26137860

  16. Quantitative determination of adenovirus-mediated gene delivery to rat cardiac myocytes in vitro and in vivo.

    PubMed Central

    Kass-Eisler, A; Falck-Pedersen, E; Alvira, M; Rivera, J; Buttrick, P M; Wittenberg, B A; Cipriani, L; Leinwand, L A

    1993-01-01

    To optimize the use of modified adenoviruses as vectors for gene delivery to the myocardium, we have characterized infection of cultured fetal and adult rat cardiac myocytes in vitro and of adult cardiac myocytes in vivo by using a replication-defective adenovirus carrying the chloramphenicol acetyltransferase (CAT) reporter gene driven by the cytomegalovirus promoter (AdCMVCATgD). In vitro, virtually all fetal or adult cardiocytes express the CAT gene when infected with 1 plaque-forming unit of virus per cell. CAT enzymatic activity can be detected in these cells as early as 4 hr after infection, reaching near-maximal levels at 48 hr. In fetal cells, CAT expression was maintained without a loss in activity for at least 1 week. Using in vitro studies as a guide, we introduced the AdCMVCATgD virus directly into adult rat myocardium and compared the expression results obtained from virus injection with those obtained by direct injection of pAdCMVCATgD plasmid DNA. The amount of CAT activity resulting from adenovirus infection of the myocardium was orders of magnitude higher than that seen from DNA injection and was proportional to the amount of input virus. Immunostaining for CAT protein in cardiac tissue sections following adenovirus injection demonstrated large numbers of positive cells, reaching nearly 100% of the myocytes in many regions of the heart. Expression of genes introduced by adenovirus peaked at 5 days but was still detectable 55 days following infection. Adenoviruses are therefore a very useful tool for high-efficiency gene transfer into the cardiovascular system. Images Fig. 1 Fig. 5 PMID:8265580

  17. Identification and localization of caldesmon in cardiac muscle.

    PubMed Central

    Scott-Woo, G C; Walsh, M P; Ikebe, M; Kargacin, G J

    1998-01-01

    Caldesmon has been detected in smooth muscle and in a number of non-muscle cells. It binds both actin and myosin and may act as a regulator of contraction or a structural element in smooth muscle. The presence of caldesmon in striated muscle has not been well established. To address this issue, polyclonal antibodies and a panel of monoclonal antibodies were raised against chicken gizzard smooth muscle caldesmon and used to demonstrate that caldesmon is present in adult cardiac muscle of a variety of mammalian species. Western-blot analysis revealed the presence of caldesmon in ventricular myocytes isolated from rat heart. The epitopes for the individual monoclonal antibodies were mapped to the caldesmon primary structure using chymotryptic and 2-nitro-5-thiocyanatobenzoic acid fragments. Bovine and rat cardiac caldesmons were recognized only by a subset of these monoclonal antibodies, indicating primary sequence differences from the chicken smooth muscle protein. Immunofluorescence labelling of isolated myocytes from rat, rabbit and guinea pig cardiac muscle revealed a striated pattern of fluorescence labelling. Dual labelling of caldesmon and myosin or caldesmon and alpha-actinin demonstrated that caldesmon was present at the centre of the I-band rather than in the A-band, as might have been expected from the myosin binding properties of the smooth muscle protein. These results suggest a structural role for caldesmon in cardiac muscle cells. PMID:9693116

  18. Animal model studies of genital chlamydial infections. Immunity to re-infection with guinea-pig inclusion conjunctivitis agent in the urethra and eye of male guinea-pigs.

    PubMed

    Howard, L V; O'Leary, M P; Nichols, R L

    1976-08-01

    A previous report demonstrated that male guinea-pigs could be infected in the urethra with guinea-pig inclusion conjunctivitis (GPIC) agent and that the infection was transmitted during mating from infected males to females. In the experiments reported here, inoculation of male guinea-pigs in the urethra with GPIC organisms resulted in infection which subsided spontaneously in about 2 weeks. Males were demonstrated to be completely resistant to urethral challenge with 10(3)ID50 when tested 6 weeks after urethral infection. These guinea-pigs, immune to re-infection of the urethra, remained susceptible to infection of the eye, but this ocular infection was shorter in duration than that in previously uninfected control animals. Infection in the eye resulted in immunity to both ocular and urethral infection when animals were challenged 6 weeks after the ocular infection.

  19. Depletion of Tip60 from In Vivo Cardiomyocytes Increases Myocyte Density, Followed by Cardiac Dysfunction, Myocyte Fallout and Lethality

    PubMed Central

    Fisher, Joseph B.; Horst, Audrey; Wan, Tina; Kim, Min-Su; Auchampach, John; Lough, John

    2016-01-01

    Tat-interactive protein 60 (Tip60), encoded by the Kat5 gene, is a member of the MYST family of acetyltransferases. Cancer biology studies have shown that Tip60 induces the DNA damage response, apoptosis, and cell-cycle inhibition. Although Tip60 is expressed in the myocardium, its role in cardiomyocytes (CMs) is unclear. Earlier studies here showed that application of cardiac stress to globally targeted Kat5+/—haploinsufficient mice resulted in inhibition of apoptosis and activation of the CM cell-cycle, despite only modest reduction of Tip60 protein levels. It was therefore of interest to ascertain the effects of specifically and substantially depleting Tip60 from CMs using Kat5LoxP/-;Myh6-Cre mice in the absence of stress. We report initial findings using this model, in which the effects of specifically depleting Tip60 protein from ventricular CMs, beginning at early neonatal stages, were assessed in 2–12 week-old mice. Although 5’-bromodeoxyuridine immunostaining indicated that CM proliferation was not altered at any of these stages, CM density was increased in 2 week-old ventricles, which persisted in 4 week-old hearts when TUNEL staining revealed inhibition of apoptosis. By week 4, levels of connexin-43 were depleted, and its patterning was dysmorphic, concomitant with an increase in cardiac hypertrophy marker expression and interstitial fibrosis. This was followed by systolic dysfunction at 8 weeks, after which extensive apoptosis and CM fallout occurred, followed by lethality as mice approached 12 weeks of age. In summary, chronic depletion of Tip60 from the ventricular myocardium beginning at early stages of neonatal heart development causes CM death after 8 weeks; hence, Tip60 protein has a crucial function in the heart. PMID:27768769

  20. Second-harmonic microscopy of unstained living cardiac myocytes: measurements of sarcomere length with 20-nm accuracy.

    PubMed

    Boulesteix, Thierry; Beaurepaire, Emmanuel; Sauviat, Martin-Pierre; Schanne-Klein, Marie-Claire

    2004-09-01

    We extend second-harmonic generation (SHG) microscopy to the measurement of sarcomere length in unstained living cardiac myocytes with 20-nm accuracy. We quantify individual sarcomere shortening in the presence of saxitoxin and find that it is in agreement with mechanical measurements of atrial tissue contracture. This functional application of SHG microscopy is generally applicable to quantify the physiological effects of drugs on contractile tissue. Our data also suggest that packed myosin heads in sarcomere thick filaments are responsible for the large second-harmonic endogenous signal in muscle tissue. PMID:15455770

  1. Nesprin-1{alpha} contributes to the targeting of mAKAP to the cardiac myocyte nuclear envelope

    SciTech Connect

    Pare, Genevieve C.; Easlick, Juliet L.; Mislow, John M.; McNally, Elizabeth M.; Kapiloff, Michael S. . E-mail: kapiloff@ohsu.edu

    2005-02-15

    Muscle A-kinase anchoring protein (mAKAP) is a scaffold protein found principally at the nuclear envelope of striated myocytes. mAKAP maintains a complex consisting of multiple signal transduction molecules including the cAMP-dependent protein kinase A, the ryanodine receptor calcium release channel, phosphodiesterase type 4D3, and protein phosphatase 2A. By an unknown mechanism, a domain containing spectrin repeats is responsible for targeting mAKAP to the nuclear envelope. We now demonstrate that the integral membrane protein nesprin-1{alpha} serves as a receptor for mAKAP on the nuclear envelope in cardiac myocytes. Nesprin-1{alpha} is inserted into the nuclear envelope by a conserved, C-terminal, klarsicht-related transmembrane domain and forms homodimers by the binding of an amino-terminal spectrin repeat domain. Through the direct binding of the nesprin-1{alpha} amino-terminal dimerization domain to the third mAKAP spectrin repeat, nesprin-1{alpha} targets mAKAP to the nuclear envelope. In turn, overexpression of these spectrin repeat domains in myocytes can displace mAKAP from nesprin-1{alpha}.

  2. Influence of frequency of stimulation on the toxicity of digoxin on isolated guinea-pig atria in different extracellular Ca2+.

    PubMed

    Wagner, J; Bremhorst, T; Schümann, H J

    1978-12-01

    In isolated guinea-pig left atria driven by rates of 0.5, 1,2, 3 and 4 Hz digoxin was infused continuously until cardiac arrest occurred. The experiments were performed in Tyrode solution with normal and twice the calcium content. Calculated was the toxic concentration of digoxin as that concentration which caused arrest of the preparation. In normal Ca2+-content (1.8 mM) an increase of the driving frequency decreased significantly the toxic concentration of digoxin, i.e. elevated the toxicity of this cardiac glycoside. The elevation of the Ca2+-content of the Tyrode caused a further diminution of the toxic concentrations of digoxin in dependence of the driving rate, thus demonstrating a synergism of Ca2+ and digoxin with regard to its toxicity.

  3. Inhibition of human ether-a-go-go-related gene K+ channel and IKr of guinea pig cardiomyocytes by antipsychotic drug trifluoperazine.

    PubMed

    Choi, Se-Young; Koh, Young-Sang; Jo, Su-Hyun

    2005-05-01

    Trifluoperazine, a commonly used antipsychotic drug, has been known to induce QT prolongation and torsades de pointes, which can cause sudden death. We studied the effects of trifluoperazine on the human ether-a-go-go-related gene (HERG) channel expressed in Xenopus oocytes and on the delayed rectifier K(+) current of guinea pig cardiomyocytes. The application of trifluoperazine showed a dose-dependent decrease in current amplitudes at the end of voltage steps and tail currents of HERG. The IC(50) for a trifluoperazine block of HERG current progressively decreased according to depolarization: IC(50) values at -40, 0, and +40 mV were 21.6, 16.6, and 9.29 microM, respectively. The voltage dependence of the block could be fitted with a monoexponential function, and the fractional electrical distance was estimated to be delta = 0.65. The block of HERG by trifluoperazine was use-dependent, exhibiting more rapid onset and greater steady-state block at higher frequencies of activation; there was partial relief of the block with decreasing frequency. In guinea pig ventricular myocytes, bath applications of 0.5 and 2 microM trifluoperazine at 36 degrees C blocked the rapidly activating delayed rectifier K(+) current by 32.4 and 72.9%, respectively; however, the same concentrations of trifluoperazine failed to significantly block the slowly activating delayed rectifier K(+) current. Our findings suggest the arrhythmogenic side effect of trifluoperazine is caused by a blockade of HERG and the rapid component of the delayed rectifier K(+) current rather than by the blockade of the slow component.

  4. Afterhyperpolarization current in myenteric neurons of the guinea pig duodenum.

    PubMed

    Vogalis, F; Furness, J B; Kunze, W A

    2001-05-01

    Whole cell patch and cell-attached recordings were obtained from neurons in intact ganglia of the myenteric plexus of the guinea pig duodenum. Two classes of neuron were identified electrophysiologically: phasically firing AH neurons that had a pronounced slow afterhyperpolarization (AHP) and tonically firing S neurons that lacked a slow AHP. We investigated the properties of the slow AHP and the underlying current (I(AHP)) to address the roles of Ca(2+) entry and Ca(2+) release in the AHP and the characteristics of the K(+) channels that are activated. AH neurons had a resting potential of -54 mV and the AHP, which followed a volley of three suprathreshold depolarizing current pulses delivered at 50 Hz through the pipette, averaged 11 mV at its peak, which occurred 0.5-1 s following the stimulus. The duration of these AHPs averaged 7 s. Under voltage-clamp conditions, I(AHP)'s were recorded at holding potentials of -50 to -65 mV, following brief depolarization of AH neurons (20-100 ms) to positive potentials (+35 to +50 mV). The null potential of the I(AHP) at its peak was -89 mV. The AHP and I(AHP) were largely blocked by omega-conotoxin GVIA (0.6-1 microM). Both events were markedly decreased by caffeine (2-5 mM) and by ryanodine (10-20 microM) added to the bathing solution. Pharmacological suppression of the I(AHP) with TEA (20 mM) or charybdotoxin (50-100 nM) unmasked an early transient inward current at -55 mV following step depolarization that reversed at -34 mV and was inhibited by niflumic acid (50-100 microM). Mean-variance analysis performed on the decay of the I(AHP) revealed that the AHP K(+) channels have a mean chord conductance of ~10 pS, and there are ~4,000 per AH neuron. Spectral analysis showed that the AHP channels have a mean open dwell time of 2.8 ms. Cell-attached patch recordings from AH neurons confirmed that the channels that open following action currents have a small unitary conductance (10-17 pS) and open with a high probability (

  5. Inhibition of the effects of thrombin on guinea pig platelets by the diacylglycerol lipase inhibitor RHC 80267

    SciTech Connect

    Amin, D.; Sutherland, C.A.; Khandwala, A.S.; Jamall, I.S.; Kapoor, A.L.

    1986-10-01

    Phospholipase C (PLC) and diacylglycerol lipase (DGL) activities were found in guinea pig platelet microsome preparations. No phospholipase A2 (PLA2) activity was detected. RHC 80267 (1,6-di (0-(carbamoyl) cyclohexanone oxime)hexane) inhibited DGL activity (IC50 = 4 uM) from guinea pig platelet microsomes but had no effect on PLC. RHC 80267 inhibited platelet aggregation (IC50 = 11 uM), release of arachidonic acid (AA), its metabolites, and ATP (IC50 = 4.5 uM) when guinea pig platelets were challenged with a low concentration of thrombin. We propose that PLC-DGL is an important enzymatic pathway for the release of AA in guinea pig platelets.

  6. [Effect produced by the alkaloid fraction of Mimosa tenuiflora (tepescohuite) on the peristaltic reflex of the guinea pig ileum].

    PubMed

    Meckes-Lozoya, M; Lozoya, X; González, J L; Martínez, M

    1990-01-01

    An alkaloidal fraction was obtained from Mimosa tenuiflora (Willd.) Poir (tepescohuite) trunk bark. The product contained mainly an indolealkylamine and three minor alkaloids. This fraction inhibited the peristaltic reflex in the guinea-pig isolated ileum in vitro.

  7. NOS1AP modulates intracellular Ca2+ in cardiac myocytes and is up-regulated in dystrophic cardiomyopathy

    PubMed Central

    Treuer, Adriana V; Gonzalez, Daniel R

    2014-01-01

    NOS1AP gene (nitric oxide synthase 1-adaptor protein) is strongly associated with abnormalities in the QT interval of the electrocardiogram and with sudden cardiac death. To determine the role of NOS1AP in the physiology of the cardiac myocyte, we assessed the impact of silencing NOS1AP, using siRNA, on [Ca2+]i transients in neonatal cardiomyocytes. In addition, we examined the co-localization of NOS1AP with cardiac ion channels, and finally, evaluated the expression of NOS1AP in a mouse model of dystrophic cardiomyopathy. Using siRNA, NOS1AP levels were reduced to ~30% of the control levels (p<0.05). NOS1AP silencing in cardiac myocytes reduced significantly the amplitude of electrically evoked calcium transients (p<0.05) and the degree of S-nitrosylation of the cells (p<0.05). Using confocal microscopy, we evaluated NOS1AP subcellular location and interactions with other proteins by co-localization analysis. NOS1AP showed a high degree of co-localization with the L-type calcium channel and the inwardly rectifying potassium channel Kir3.1, a low degree of co-localization with the ryanodine receptor (RyR2) and alfa-sarcomeric actin and no co-localization with connexin 43, suggesting functionally relevant interactions with the ion channels that regulate the action potential duration. Finally, using immunofluorescence and Western blotting, we observed that in mice with dystrophic cardiomyopathy, NOS1AP was significantly up-regulated (p<0.05). These results suggest for a role of NOS1AP on cardiac arrhythmias, acting on the L-type calcium channel, and potassium channels, probably through S-nitrosylation. PMID:24665357

  8. Improved facility and sensitivity in the use of guinea pigs for the isolation of Legionella pneumophila from cooling tower water

    SciTech Connect

    Leinbach, E.D.; Winkler, H.H.; Wood, D.O.; Coggin, J.H. Jr.

    1983-03-01

    The established criteria for the determination of the optimum time for the sacrifice of guinea pigs inoculated with samples of cooling tower water were found to be inadequate for the detection of low levels of Legionella pneumophila. By ignoring the requirement for fever and by sequentially sacrificing the infected guinea pigs on days 3 through 5 postinoculation, we simplified the procedure, and the sensitivity of detection was improved a great deal.

  9. An enzyme-linked immunosorbent assay (ELISA) for anti-chlamydial secretory immunoglobulin A in guinea pig tears.

    PubMed

    Finney, P M; Bushell, A C

    1986-01-22

    A method is described which permits the assay of specific secretory immunoglobulin A (sIgA) antibodies produced by guinea pigs in response to ocular infection with the guinea pig inclusion conjunctivitis strain of Chlamydia psittaci (GPIC agent). The enzyme-linked immunosorbent assay (ELISA) developed was shown to be more sensitive and less subjective than the micro-immunofluorescence assay as a means of assaying specific antibody.

  10. Nickel allergy: tolerance to metallic surface-plated samples in nickel-sensitive humans and guinea pigs.

    PubMed

    Cavelier, C; Foussereau, J; Gille, P; Zissu, D

    1988-11-01

    The purpose of this work is to evaluate in nickel-sensitive patients and guinea pigs the tolerance to nickel samples, surface-plated with one or several metals of varying structures and thicknesses. All the metal samples elicited allergic reactions in the guinea pig. In humans, absolute tolerance was not observed for any sample. In humans, the interposing of a layer of bright copper between nickel and surface chrome greatly increased the tolerance.

  11. Activation of the alternative complement pathway by natural antibody to glycolipids in guinea-pig serum.

    PubMed Central

    Okada, N; Yasuda, T; Tsumita, T; Okada, H

    1983-01-01

    Liposomes containing paragloboside (PG) on their membrane were readily lysed by C4-deficient guinea-pig serum (C4D-GPS) through activation of the alternative complement pathway (ACP). Therefore we examined the reactivity of several types of guinea-pig serum (GPS) on PG-liposomes and determined that all GPS except that from specific pathogen-free (SPF) Hartley guinea-pigs had lytic capacity in Mg-EGTA-GVB (gelatin veronal-buffered saline containing Mg++ and ethyleneglycol-bis(beta-aminoethyl ether)N,N'-tetraacetate). This lytic capacity of GPS corresponded with the amount of natural antibody to PG in those sera. Although GPS of SPF guinea-pigs (SPF-GPS) could not lyse PG-liposomes in Mg-EGTA-GVB, it could lyse the liposomes when heated C4D-GPS or Hartley GPS was added. Natural antibody to PG in the heated sera was regarded to have sensitized PG-liposomes to lysis by SPF-GPS via ACP activation. Since the antibody to PG-liposomes was removed by lacto-N-nor-hexaosylceramide which has the same chemical structure in the terminal oligosaccharide, the antibody to PG in GPS was suggested to have a specificity to the terminal structure of oligosaccharide shared by lacto-N-nor-hexaosylceramide. Furthermore, the IgM fraction, which had been prepared by gel filtration of heated C4D-GPS on a Sephadex G200 column, could also sensitize PG-liposomes to lytic reaction of SPF-GPS in Mg-EGTA-GVB. This sensitizing capacity of heated C4D-GPS was suppressed by absorption of the serum or its IgM fraction with anti-guinea-pig mu-chain antibody coupled to Sepharose. Therefore, it was concluded that the lysis of PG-liposomes by GPS in Mg-EGTA-GVB was a result of ACP activation mediated by natural antibodies to PG of the IgM type which are present in usual GPS. This conclusion indicated that natural antibodies of the IgM type might play a role with ACP in host defence, especially in C4-deficient guinea-pigs where the classical complement pathway is impaired. PMID:6193057

  12. Bicarbonate effects, electromotive forces and potassium effluxes in rabbit and guinea-pig gall-bladder.

    PubMed

    Cremaschi, D; Meyer, G; Rossetti, C

    1983-02-01

    The stimulating effect of external HCO3- on Na+ salt transport has been examined in rabbit and guinea-pig gall-bladder by electrophysiological methods, as a sequel to a previous study carried out by radiochemical techniques. At steady state, cell K+ activity was found to be significantly reduced in the presence of HCO3-, whereas cell Na+ activity significantly increased; in parallel the apical membrane p.d. was depolarized; K+ equilibrium potential was higher than membrane p.d. in every case. The apical p.d. dependence on K+ was unaffected by HCO3-, but in the guinea-pig it was affected by Cl-. Rapid increases in HCO3- concentration on the luminal side caused a depolarization of the apical p.d. of the guinea-pig within about 30 sec, an effect that did not occur if the tissue was pre-treated with 10(-4) M-acetazolamide; the epithelial resistance and apical/basolateral resistance ratio were unchanged in all cases. The primary action of HCO3- is confirmed to be on the apical membrane; an HCO3- conductance does not seem to be present at this level, either in the rabbit or guinea-pig, nor does HCO3- affect Na+ influx through the apical conductive pathway, so that all the stimulating effects of the anion are confirmed to be on the neutral transports of Na+ salts; in spite of this, the apical electromotive force is modified due to the changed cell K+ activity. The rapid depolarization caused by the anion in the guinea-pig is in agreement with an HCO3- electrogenic secretion and/or a basolateral conductance for the anion. Polyelectrolyte dissociation from protons increases in the absence of external HCO3-: the negative charges are mainly counterbalanced by bound Na+ in the rabbit and by free K+ in the guinea-pig. K+ leakage from the cell into the lumen is calculated to be minimal in the rabbit and all K+ lost could be reabsorbed through the paracellular pathways; K+ efflux to the subepithelial layer via conductive routes is insufficient to account for the over-all K

  13. Opioid binding sites in the guinea pig and rat kidney: Radioligand homogenate binding and autoradiography

    SciTech Connect

    Dissanayake, V.U.; Hughes, J.; Hunter, J.C. )

    1991-07-01

    The specific binding of the selective {mu}-, {delta}-, and {kappa}-opioid ligands (3H)(D-Ala2,MePhe4,Gly-ol5)enkephalin ((3H) DAGOL), (3H)(D-Pen2,D-Pen5)enkephalin ((3H)DPDPE), and (3H)U69593, respectively, to crude membranes of the guinea pig and rat whole kidney, kidney cortex, and kidney medulla was investigated. In addition, the distribution of specific 3H-opioid binding sites in the guinea pig and rat kidney was visualized by autoradiography. Homogenate binding and autoradiography demonstrated the absence of {mu}- and {kappa}-opioid binding sites in the guinea pig kidney. No opioid binding sites were demonstrable in the rat kidney. In the guinea pig whole kidney, cortex, and medulla, saturation studies demonstrated that (3H)DPDPE bound with high affinity (KD = 2.6-3.5 nM) to an apparently homogeneous population of binding sites (Bmax = 8.4-30 fmol/mg of protein). Competition studies using several opioid compounds confirmed the nature of the {delta}-opioid binding site. Autoradiography experiments demonstrated that specific (3H)DPDPE binding sites were distributed radially in regions of the inner and outer medulla and at the corticomedullary junction of the guinea pig kidney. Computer-assisted image analysis of saturation data yielded KD values (4.5-5.0 nM) that were in good agreement with those obtained from the homogenate binding studies. Further investigation of the {delta}-opioid binding site in medulla homogenates, using agonist ((3H)DPDPE) and antagonist ((3H)diprenorphine) binding in the presence of Na+, Mg2+, and nucleotides, suggested that the {delta}-opioid site is linked to a second messenger system via a GTP-binding protein. Further studies are required to establish the precise localization of the {delta} binding site in the guinea pig kidney and to determine the nature of the second messenger linked to the GTP-binding protein in the medulla.

  14. Coagulation and fibrinolysis in capybara (Hydrochaeris hydrochaeris), a close relative of the guinea-pig (Cavia porcellus).

    PubMed

    Leitão, D P; Polizello, A C; Rothschild, Z

    2000-01-01

    Fibrinolytic and coagulation properties of capybara (Hydrochaeris hydrochaeris, LINNAEUS, 1766) plasma were analysed and the results compared to the guinea-pig (Cavia porcellus), a close relative. Capybara fibrinogen was isolated and fibrinolysis of its plasma was carried out in a homologous system and with bovine fibrin. Undiluted plasma did not have fibrinolytic activity on fibrin plates; euglobulins gave a dose-related response. Zymography of capybara and guinea-pig plasma gave the same patterns of activity as human or bovine plasma. Human urokinase (UK) and tissue plasminogen activator (t-PA) produced lysis in capybara fibrin plates. Streptokinase (SK) (500 IU/ml) did not activate capybara or guinea-pig plasma. In this system, human plasma was extensively activated. Coagulation tests for both species of rodent were prolonged. The capybara showed values for prothrombin time (PT) shorter than activated thromboplastin time (APTT). The guinea-pig, as already shown, had longer PT values. Factors X and VII were very low for capybara and guinea-pig when tested using reference curves and diagnostic kits for human plasma. It is suggested that the capybara could be a valuable laboratory animal considering its size and closeness to the guinea-pig, and this could allow for the provision of materials from one single animal when convenient or necessary.

  15. Identification, evolution, and regulation of expression of Guinea pig trappin with an unusually long transglutaminase substrate domain.

    PubMed

    Furutani, Yutaka; Kato, Akira; Fibriani, Azzania; Hirata, Taku; Kawai, Ryoji; Jeon, Ju-Hong; Fujii, Yasuhisa; Kim, In-Gyu; Kojima, Soichi; Hirose, Shigehisa

    2005-05-27

    Trappins are found in human, bovine, hippopotamus, and members of the pig family, but not in rat and mouse. To clarify the evolution of the trappin genes and the functional significance of their products, we isolated the trappin gene in guinea pig, a species belonging to a rodent family distinct from rat and mouse. Guinea pig trappin was confirmed to encode the same domain structure as trappin, consisting of a signal sequence, an extra large transglutaminase substrate domain, and a whey acidic protein motif. Northern blot analysis and in situ hybridization histochemistry as well as immunohistochemistry demonstrated that guinea pig trappin is expressed solely in the secretory epithelium of the seminal vesicle and that its expression is androgen-dependent. We confirmed that guinea pig trappin is cross-linked by prostate transglutaminase and that the whey acidic protein motif derived from guinea pig trappin has an inhibitory activity against leukocyte elastase. Genome sequence analysis showed that guinea pig trappin belongs to the family of REST (rapidly evolving seminal vesicle transcribed) genes. PMID:15778505

  16. Capillarity and oxygen diffusion distances of the soleus muscle of guinea pigs and rats. Effects of hyperthyroidism.

    PubMed

    Sillau, A H

    1985-01-01

    The relationship between capillarity and oxidative capacity in the soleus muscle of rats and guinea pigs injected with triiodothyronine (T3) or with saline for up to 4 weeks was studied. The rats' soleus weight and FCSA were not affected by T3, but the guinea pigs that received T3 had smaller muscle weight and FCSA than the controls. The activities of cytochrome c oxidase and citrate synthase were significantly (41 and 65%) higher in the T3 than in the control rats. T3 administration did not affect the activities of these enzymes in the soleus of the guinea pigs. Capillary density (CD) was higher in T3 rats (892 +/- 80 vs 622 +/- 54 caps/mm2), and in T3 guinea pigs (1219 +/- 95 vs 739 +/- 142 caps/mm2). The higher CD in T3 rats was due to growth of new microvessels, while in the T3 guinea pigs it was due to a reduction in FCSA. Mean and maximal diffusion distances evaluated by the closest individual method were reduced by 2.02 and 3.37 microns in rats, and by 3.73 and 6.16 microns in guinea pigs. The magnitude of the reduction in diffusion distances brought about by the increased capillary density was partially offset by a concomitant change in the capillary arrangement from an ordered (hexagonal), towards a random distribution. These results seem to indicate that skeletal muscle capillarity is not necessarily determined by the oxidative capacity of the fibers.

  17. Effects of sulfuric acid mist inhalation on mucous clearance and on airway fluids of rats and guinea pigs

    SciTech Connect

    Wolff, R.K.; Henderson, R.F.; Gray, R.H.; Carpenter, R.L.; Hahn, F.F.

    1986-01-01

    The responses of guinea pigs and rats to inhaled sulfuric acid aerosols were compared to define species differences and to determine the small-animal model most relevant to human exposures. Rats were exposed for 6 hr to 1, 10, and 100 mg H/sub 2/SO/sub 4//m/sup 3/. Guinea pigs were exposed for 6 h to 1, 10, and 27 mg H/sub 2/SO/sub 4//m/sup 3/. Tracheal mucous clearance of guinea pigs was slowed 1 d after exposures to 1 mg H/sub 2/SO/sub 4//m/sup 3/. A tendency toward faster clearance was observed at high concentrations of H/sub 2/SO/sub 4/ for both guinea pigs and rats (statistically significant only for the rats). The speeding of mucous clearance was correlated with increases in airway sialic acid and also with the appearance of excess tracheal secretions, detected using scanning electron microscopy in both rats and guinea pigs. The responses of guinea pigs to sulfuric acid exposures were more similar to those reported for humans than were those of rats.

  18. Increased severity of tuberculosis in Guinea pigs with type 2 diabetes: a model of diabetes-tuberculosis comorbidity.

    PubMed

    Podell, Brendan K; Ackart, David F; Obregon-Henao, Andres; Eck, Sarah P; Henao-Tamayo, Marcela; Richardson, Michael; Orme, Ian M; Ordway, Diane J; Basaraba, Randall J

    2014-04-01

    Impaired glucose tolerance and type 2 diabetes were induced in guinea pigs to model the emerging comorbidity of Mycobacterium tuberculosis infection in diabetic patients. Type 2 diabetes mellitus was induced by low-dose streptozotocin in guinea pigs rendered glucose intolerant by first feeding a high-fat, high-carbohydrate diet before M. tuberculosis exposure. M. tuberculosis infection of diabetic guinea pigs resulted in severe and rapidly progressive tuberculosis (TB) with a shortened survival interval, more severe pulmonary and extrapulmonary pathology, and a higher bacterial burden compared with glucose-intolerant and nondiabetic controls. Compared with nondiabetics, diabetic guinea pigs with TB had an exacerbated proinflammatory response with more severe granulocytic inflammation and higher gene expression for the cytokines/chemokines interferon-γ, IL-17A, IL-8, and IL-10 in the lung and for interferon-γ, tumor necrosis factor-α, IL-8, and monocyte chemoattractant protein-1 in the spleen. TB disease progression in guinea pigs with impaired glucose tolerance was similar to that of nondiabetic controls in the early stages of infection but was more severe by day 90. The guinea pig model of type 2 diabetes-TB comorbidity mimics important features of the naturally occurring disease in humans. This model will be beneficial in understanding the complex pathogenesis of TB in diabetic patients and to test new strategies to improve TB and diabetes control when the two diseases occur together.

  19. Conventional anticonvulsant drugs in the guinea-pig kindling model of partial seizures: effects of acute phenytoin.

    PubMed

    Gilbert, T H; Bharadia, V; Teskey, G C

    2001-10-01

    This study addressed some of the controversial issues surrounding the anticonvulsant effect of phenytoin, and the predictive validity of the guinea-pig kindling model for the screening of anticonvulsant drugs. Following an intraperitoneal injection of either 50 or 75 mg/kg phenytoin, we analysed plasma concentrations of phenytoin at various time intervals. Behavioural toxicity was assessed at 0.5 h postinjection using quantitative locomotor tests, as well as scores on a sedation/muscle relaxation rating index. The anticonvulsant efficacy of phenytoin was evaluated from measurements of afterdischarge threshold (ADT), afterdischarge duration (ADD) and behavioural seizure severity at three phases of kindling: non-kindled, kindling acquisition (early and late) and kindled (50+ ADs). ADD and seizure severity were also measured in response to both threshold and suprathreshold kindling stimulation. Plasma levels of phenytoin corresponded to the human therapeutic range at the time of behavioural testing and kindling. Phenytoin did not exert significant adverse effects in guinea-pigs on both the behavioural tests and rating index. Phenytoin increased ADT in non-kindled and kindled guinea-pigs and effectively reduced ADD and seizure severity, indicating that the guinea-pig model correctly predicted phenytoin's anticonvulsant effect. Phenytoin produced reliable anticonvulsant activity in the guinea-pig at threshold stimulation but a somewhat reduced efficacy on seizure severity at suprathreshold stimulation intensities. Kindling in the guinea-pig is a valid model of human partial seizures.

  20. Calcium and IP3 dynamics in cardiac myocytes: experimental and computational perspectives and approaches.

    PubMed

    Hohendanner, Felix; McCulloch, Andrew D; Blatter, Lothar A; Michailova, Anushka P

    2014-01-01

    lays in quantitative differences of local [Ca(2+)] in the nuclear and cytosolic compartment. In this review, we discuss the state of knowledge regarding the origin and the physiological implications of nuclear Ca(2+) transients in different cardiac cell types (adult atrial and ventricular myocytes) as well as experimental and mathematical approaches to study Ca(2+) and IP3 signaling in the cytosol and nucleus. In particular, we focus on the concept that highly localized Ca(2+) signals are required to translocate and activate Ca(2+)-dependent transcription factors (e.g., nuclear factor of activated T-cells, NFAT; histone deacetylase, HDAC) through phosphorylation/dephosphorylation processes. PMID:24639654

  1. Partial protection against genital reinfection by immunization of guinea-pigs with isolated outer-membrane proteins of the chlamydial agent of guinea-pig inclusion conjunctivitis.

    PubMed

    Batteiger, B E; Rank, R G; Bavoil, P M; Soderberg, L S

    1993-12-01

    Because partial protection against reinfection is induced by experimental infection in the guinea-pig model of genital chlamydial infection, we sought to induce immunity by immunization. Female guinea-pigs were immunized subcutaneously with the major outer-membrane protein (MOMP) and the 61 kDa cysteine-rich outer-membrane protein (61 kDa) of the agent of guinea-pig inclusion conjunctivitis (GPIC) eluted from SDS-polyacrylamide gels (SDS-MOMP, SDS-61 kDa). Post-immunization sera and secretions contained antibodies to the SDS-purified proteins at high titre as measured by immunoblotting, whereas enzyme immunoassays (EIA) using whole elementary bodies as antigen showed significantly lower titres (P < 0.001). Likewise, blastogenic responses of peripheral mononuclear cells to GPIC elementary bodies were weak. Animals immunized with SDS-MOMP and SDS-61 kDa were fully susceptible to intravaginal challenge, as were control animals immunized with buffer without protein. Another group of animals were immunized with material prepared by extraction of chlamydial outer-membrane complexes with octyl beta-D-glucopyranoside (OGP) and dithiothreitol, which consisted largely of MOMP (OGP-MOMP). In contrast to the SDS-MOMP group, sera and secretions in the OGP-MOMP group showed high titres in EIA, and high titre antibodies to MOMP by immunoblot; however, most animals also had antibodies to 61 kDa, 72 kDa and ca. 84 kDa outer-membrane proteins. OGP-MOMP animals were partially protected against genital challenge as evidenced by low inclusion scores compared to control animals, although duration of infection measured by culture isolation was similar to controls.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Profound regulation of Na/K pump activity by transient elevations of cytoplasmic calcium in murine cardiac myocytes

    PubMed Central

    Lu, Fang-Min; Deisl, Christine; Hilgemann, Donald W

    2016-01-01

    Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activation of Ca influx by reverse Na/Ca exchange enhances pump currents and attenuates current decay, while repeated Ca elevations suppress pump currents. Pump current enhancement reverses over 3 min, and results are similar in myocytes lacking the regulatory protein, phospholemman. Classical signaling mechanisms, including Ca-activated protein kinases and reactive oxygen, are evidently not involved. Electrogenic signals mediated by intramembrane movement of hydrophobic ions, such as hexyltriphenylphosphonium (C6TPP), increase and decrease in parallel with pump currents. Thus, transient Ca elevation and Na/K pump inactivation cause opposing sarcolemma changes that may affect diverse membrane processes. DOI: http://dx.doi.org/10.7554/eLife.19267.001 PMID:27627745

  3. Minocycline protects cardiac myocytes against simulated ischemia-reperfusion injury by inhibiting poly(ADP-ribose) polymerase-1

    PubMed Central

    Tao, Rong; Kim, Sun Hee; Honbo, Norman; Karliner, Joel S.; Alano, Conrad C.

    2010-01-01

    There is an increase in reactive oxygen and nitrogen species in cardiomyocytes during myocardial ischemia/reperfusion injury. This leads to oxidative DNA damage and activation of nuclear repair enzymes such as poly(ADP-ribose) polymerase-1 (PARP-1). PARP-1 activation promotes DNA repair under normal conditions. However, excessive activation of PARP-1 leads to cell death. Here we report that PARP-1 enzymatic activity is directly inhibited by minocycline, and we propose that one mechanism of minocycline cardioprotection is due to PARP-1 inhibition. Using cultured adult rat cardiac myocytes, we evaluated the mechanism of minocycline protection in which PARP-1 activation was induced by simulated ischemia/reperfusion (sI/R) injury using oxygen-glucose deprivation. We found an increase in reactive oxygen species production, PARP-1 activation, and PARP-1-mediated cell death after sI/R. Cell death was significantly reduced by the PARP inhibitors DPQ (10 μM) and PJ-34 (500 nM), or by minocycline (500 nM). Cellular NAD+ depletion and poly(ADP-ribose) formation, which are biochemical markers of PARP-1 activation, were also blocked by minocycline. Finally, sI/R led to induction of the mitochondrial permeability transition (MPT), which was prevented by minocycline. Therefore, we propose that the protective effect of minocycline on cardiac myocyte survival is due to inhibition of PARP-1 activity. PMID:20881608

  4. Reduction of biliverdin and placental transfer of bilirubin and biliverdin in the pregnant guinea pig.

    PubMed Central

    McDonagh, A F; Palma, L A; Schmid, R

    1981-01-01

    Biliverdin was reduced to bilirubin in pregnant and foetal guinea pigs, and the 100000 g supernatant from homogenates of foetal liver, placenta and maternal liver showed high biliverdin reductase activity. The placental transport of unconjugated bilirubin and biliverdin was compared by injecting unlabelled and radiolabelled pigments into the foetal or maternal circulation and analysing blood collected from the opposite side of the placenta. Injected bilirubin crossed the placenta from foetus to mother and vice versa, but injected biliverdin did not appear to cross without prior reduction to bilirubin. The guinea-pig placenta is apparently more permeable to bilirubin than biliverdin. Reduction of biliverdin to bilirubin in the foetus may, therefore, be essential for efficient elimination of haem catabolites from the foetus in placental mammals. PMID:7305981

  5. Protein A suppresses immune responses during Staphylococcus aureus bloodstream infection in guinea pigs

    DOE PAGES

    Kim, Hwan Keun; Falugi, Fabiana; Thomer, Lena; Missiakas, Dominique M.; Schneewind, Olaf

    2015-01-06

    Staphylococcus aureus infection is not associated with the development of protective immunity, and disease relapses occur frequently. We hypothesize that protein A, a factor that binds immunoglobulin Fcγ and cross-links VH3 clan B cell receptors (IgM), is the staphylococcal determinant for host immune suppression. To test this, vertebrate IgM was examined for protein A cross-linking. High VH3 binding activity occurred with human and guinea immunoglobulin, whereas mouse and rabbit immunoglobulins displayed little and no binding, respectively. Establishing a guinea pig model of S. aureus bloodstream infection, we show that protein A functions as a virulence determinant and suppresses host Bmore » cell responses. Immunization with SpAKKAA, which cannot bind immunoglobulin, elicits neutralizing antibodies that enable guinea pigs to develop protective immunity.« less

  6. Induction of contact drematitis in guinea pigs by quaternary ammonium compounds: the mechanisms of antigen formation

    SciTech Connect

    Schallreuter, K.R.; Schulz, K.H.; Wood, J.M.

    1986-12-01

    Eight quaternary ammonium compounds were tested for their ability to induce contact dermatitis in guinea pigs by using a modified Freund's complete adjuvant test together with the guinea pig maximization test. Only two quaternary ammonium salts of eight tested could be designated as strong allergens. These two active substances were shown to be capable of stable association with membrane lipids in forming immunogenic complexes. This surface complexation phenomenon was confirmed by using a spin-labeled quaternary ammonium salt which competed for binding sites to the surface of epidermal cells in vivo. Electron spin resonance was used to demonstrate that stable ion-pairs are formed between binding sites and the two allergenic preservatives. Furthermore, information was obtained on the kinetics of immunogenic complex formation as well as on the position and orientation of the quaternary ammonium ion at the cell surface.

  7. Semicarbazide-sensitive amine oxidase activity of guinea pig dorsal skin.

    PubMed

    Buffoni, F; Cambi, S; Banchelli, G; Ignesti, G; Pirisino, R; Raimondi, L

    1994-01-01

    A semicarbazide-sensitive amine oxidase activity with a high affinity for benzylamine (Bz.SSAO) (E.C. 1.4.3.6) is present in guinea pig dorsal skin. This enzymic activity oxidized benzylamine, histamine, 1,4-methylhistamine and acetylputrescine and was inhibited by semicarbazide and by B24 (3,5-diethoxy-4-aminomethylpyridine), a selective inhibitor of Bz.SSAO enzymes. It cross reacted with the antibodies raised against pure pig plasma benzylamine oxidase. Immunohistochemistry showed that it was localized in fibroblasts. Bz.SSAO activity of guinea pig dorsal skin increased during the process of skin healing. A treatment of the wounds with 3 micrograms of b-FGF significantly accelerated the process of skin healing and the increase of Bz.SSAO activity. PMID:7931260

  8. Further characterization of presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries.

    PubMed

    Misu, Y; Kuwahara, M; Kaiho, M; Kubo, T

    1983-07-22

    Presynaptic beta-adrenoceptors were further characterized in spiral strips of guinea-pig pulmonary arteries preloaded with [3H]norepinephrine. l-Metoprolol (3 X 10(-6) M) inhibited isoproterenol (3 X 10(-7) M)-induced increases in 3H efflux by transmural field stimulation, whereas the d-isomer produced no inhibition. However, IPS 339, H 35/25, butoxamine and metoprolol (3 X 10(-6) M) antagonized salbutamol (3 X 10(-7) M)-induced increases in the parameter, whereas acebutolol, bevantolol and practolol (3 X 10(-6) M) produced no antagonism. Presynaptic beta-adrenoceptors in guinea-pig pulmonary arteries appear to have characteristics similar to those postsynaptic classical beta-adrenoceptors.

  9. Scanning electron microscopy of experimental Trichophyton mentagrophytes infections in guinea pig skin.