Action Potentials ; drug effects ; physiology ; Animals ; Female ; Guinea Pigs ; Heart Ventricles ; drug effects ; Papillary Muscles ; drug effects ; physiology ; Progesterone ; pharmacology

The effects of vanadate on cellular Ca2+ movements across the sarcolemma of cardiac muscle cells were investigated by measuring the intracellular and extracellular Ca2+ activities of guinea pig papillary muscle with Ca2+-selective electrodes. During the rest period following a steady-state of 2 contractions per second the extracellular Ca2+ concentration was increased over the basal level within a minute. During the rest period Ca2+ was transported across the sarcolemma into the extracellular space. Vanadate decreased the change in extracellular Ca2+ concentration during the rest period implying that the Ca2+ efflux across the sarcolemma was decreased by vanadate. Vanadate increased intracellular Ca2+ activities significantly (from 1.9 X 10(-7) M to 10(-6)M) resulting in an increase in resting tension. These results suggest that vanadate decreases Ca2+ efflux from the cells into the extracellular space by blocking Ca2+ transport across the sarcolemma, possibly blocking the Na+-Ca2+ exchange transport.
Animal ; Calcium/metabolism* ; Female ; Guinea Pigs ; Ion Channels/drug effects* ; Male ; Membrane Potentials/drug effects ; Papillary Muscles/drug effects* ; Vanadates ; Vanadium/pharmacology*

Action Potentials ; drug effects ; Animals ; Estradiol ; pharmacology ; Female ; Guinea Pigs ; Heart Ventricles ; cytology ; Myocardial Contraction ; drug effects ; Papillary Muscles ; drug effects ; physiology ; Progesterone ; pharmacology

Common amino acid nutrients mainly contain glutamine, arginine, leucine, methionine and cysteine, which are not only the components participating in body protein synthesis, but also regulate the patients' immune system and metabolism. Glutamine can improve the intestinal barrier, reduce inflammatory reaction, and promote immunity recovery, but the clinical effects of different patients with different diseases are still lack of clear conclusions. The catabolism of arginine can produce NO, promoting the inflammatory reaction, and can also generate ornithine, alleviating inflammatory reaction and promoting wound healing. Two competing ways coexist, but the specific effects on different diseases have no clear conclusions yet. Leucine promotes muscle protein synthesis mainly through mTOR pathway, however, the influence on metabolism is still debating. Sulfur-containing amino acids methionine and cysteine can promote the synthesis of connective tissue and collagen conducive to wound healing, and their beneficial effects on lipid metabolism are of value. The purpose of this review is to cover potential beneficial physiological mechanisms of amino acid nutrients, to describe their results of clinical applications and to evaluate the interactions among individual nutrients or between individual nutrients and body.
Amino Acids ; pharmacology ; Humans ; Muscle Proteins ; Muscles ; Signal Transduction ; drug effects ; TOR Serine-Threonine Kinases

This study is to evaluate the effects of Shenmai injection on the temporal alterations of action potential (AP), early afterdepolarization (EAD) and delayed afterdepolarization (DAD) in papillary muscles. The action potentials were recorded by a glass electrode. APD at 90% repolarization (APD9 ) was measured, and spontaneous EAD and DAD were observed. The results show APD90 was significantly prolonged in model group compared with sham-operated group, whereas it was remained unchanged in Shenmai injec- tion treatment group and amiodarone group. The spontaneous EADs and DADs were frequently visible in model group. In conclusion, EAD, DAD and trigger activities increase gradually during pathological progression of rat cardiac hypertrophy, and Shenmai injection could improve the action potential change in rat cardiac hypertrophy.
Action Potentials ; drug effects ; Animals ; Blood Pressure ; drug effects ; Cardiomegaly ; physiopathology ; Drug Combinations ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Heart Ventricles ; drug effects ; physiopathology ; Injections ; Male ; Papillary Muscles ; drug effects ; physiopathology ; Rats ; Rats, Sprague-Dawley

AIMTo investigate the effects of interleukin-2 (IL-2) on the transmembrane potential and contractile force in ventricular papillary muscle of rat and the underlying mechanism.

METHODSThe transmembrane potentials and contractile force were recorded by intracellular glass microelectrode and tension transducer in the isolated rat papillary muscles.

RESULTS(1) IL-2 shortened the action potential duration (APD50 and APD80), while had no effects on resting potential, action potential amplitude and depolarization rate. (2) IL-2 depressed the contractile force of the muscle in dose-dependent manner. IL-2 at concentrations of 0.5, 2.5, 10, 50 and 200 u/ml decreased the developed tension to 94.8% (P < 0.05), 85.8%, 76.3%, 69.3% and 52.5% (P < 0.01), respectively. (3) Pretreatment with L-NAME (10(-4) mol/L) attenuated the negative inotropic effect of IL-2, in which effect of IL-2 at concentrations from 0.5 to 10 u/ml was completely abolished, and the effect of IL-2 at high dose (50 and 200 u/ml) was partly attenuated by L-NAME.

CONCLUSIONIL-2 had inhibitory effects on action potential duration and contractile force of papillary muscle, and its negative inotropic effect was mediated by nitric oxide.

Action Potentials ; drug effects ; Animals ; Heart Ventricles ; drug effects ; Interleukin-2 ; pharmacology ; Male ; Myocardial Contraction ; drug effects ; physiology ; Nitric Oxide ; metabolism ; Papillary Muscles ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley

PURPOSE: The purpose of this study was to investigate the myotoxicity of bevacizumab on extraocular muscles in a rabbit model. METHODS: Thirty New Zealand white rabbits were used for this study. The animals were evenly divided into two groups. In the first group, 15 rabbits were treated with intramuscular injections of bevacizumab (1.25 mg/0.05 mL) in the right superior rectus muscle and normal saline solution (0.05 mL) in the left superior rectus muscle. In the second group, 15 rabbits were treated with subconjunctival injections of bevacizumab (2.5 mg/0.1 mL) in the right superior subconjunctival area and normal saline solution (0.1 mL) in the left superior subconjunctival area. Five rabbits in each group were sacrificed at one day, two weeks and four weeks after the injections. Extraocular muscle samples were prepared for light microscopic (LM) and electron microscopic (EM) examination. Degrees of acute inflammation were evaluated via CD-11b immunohistochemistry, and global muscle change was investigated using hematoxylin and eosin stains. Intensity of fibrosis was evaluated using Masson trichrome stains, and ultrastructural changes were observed on EM. RESULTS: We observed no significant inflammatory cell infiltration, muscle necrosis or fibrotic change in treated and control eyes. EM findings revealed no significant damage to muscle or vascular tissue after bevacizumab injection. CONCLUSIONS: We found no signs of extraocular muscle toxicity after LM and EM intramuscular and subconjunctival bevacizumab injections in a rabbit model.
Angiogenesis Inhibitors/*administration & dosage/toxicity ; Animals ; Antibodies, Monoclonal, Humanized/*administration & dosage/toxicity ; Conjunctiva/drug effects ; Injections ; Oculomotor Muscles/*drug effects ; Rabbits

The purpose of this study was to investigate the electrophysiological effects of resveratrol on guinea pig papillary muscles and the underlying mechanism. Action potentials were recorded by using intracellular microelectrode technique. The results obtained are as follows: (1) In normal papillary muscles, resveratrol (30, 60, and 120 micromol/L) shortened the duration of action potential (APD) in a concentration-dependent manner. (2) In partially depolarized papillary muscles, resveratrol (60 micromol/L ) not only shortened APD, but also decreased the amplitude of action potential (APA), overshoot (OS) and maximal rate of depolarization in phase 0 (Vmax). (3) Perfusion with Ca2+-free K-H solution, completely abolished the effects of resveratrol (60 micromol/L) on papillary muscles. (4) Application of potassium channel blocker tetraethylammonium chloride (TEA, 20 mmol/L) did not prevent the effect of resveratrol (60 micromol/L) on action potential. (5) Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), a nitric oxide (NO) synthase inhibitor, failed to abolish the effect of resveratrol (60 micromol/L). All these results indicate that the electrophysiological effects of resveratrol on guinea pig papillary muscles are likely due to the reduction of calcium influx, which might not be mediated by NO.
Action Potentials ; drug effects ; Animals ; Calcium Channel Blockers ; pharmacology ; Guinea Pigs ; In Vitro Techniques ; Male ; Microelectrodes ; Papillary Muscles ; drug effects ; physiology ; Stilbenes ; pharmacology

The purpose of this study was to investigate the effects of phytoestrogen genistein (GST) on delayed after depolarization (DAD) and triggered activity (TA) induced by ouabain in guinea pig papillary muscles. Action potentials (APs) were recorded from the guinea pig papillary muscles with standard glass microelectrode technique. The results are as follows: (1) DAD and TA induced by ouabain (1 micromol/L) were markedly inhibited by pretreatment with GST (10, 50, 100 micromol/L) in a concentration-dependent manner. (2) NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), an NO synthase inhibitor, failed to affect the above effects of GST. (3) 5 micromol/L 17beta-estradiol (E2) or 10 micromol/L GST alone showed no effects on DAD and TA, whereas GST combined with E(2) at the same doses exerted significant inhibitory effects on DAD and TA. Since GST is known to reduce the calcium influx, it is suggested that GST might have antiarrhythmic effects, possibly by reducing calcium influx. The antiarrhythmic effects of GST may contribute to its cardioprotective action.
Action Potentials ; drug effects ; Animals ; Genistein ; pharmacology ; Guinea Pigs ; Male ; Neuromuscular Depolarizing Agents ; pharmacology ; Ouabain ; pharmacology ; Papillary Muscles ; drug effects ; physiology ; Phytoestrogens ; pharmacology

No abstract available.
Anesthesia, Local/*adverse effects ; Anesthetics, Local/administration & dosage/*adverse effects ; Eye Movements/*drug effects ; Female ; Humans ; Middle Aged ; Ocular Motility Disorders/*chemically induced/diagnosis/physiopathology ; Oculomotor Muscles/drug effects/*physiopathology ; Phacoemulsification/*adverse effects ; *Postoperative Complications