title: Electrophysiological effects of capsaicin on guinea pig papillary muscles.
abstract: The cardiac electrophysiological effects of capsaicin (CAP) were examined in guinea pig papillary muscles using intracellular microelectrode technique. The results obtained are as follows: (1) the duration of action potential (APD) in normal papillary muscles was decreased by CAP (30, 60, 120 micromol/L) in a concentration-dependent manner; (2) in partially depolarized papillary muscles, 60 micromol/L CAP not only reduced APD, but also decreased the amplitude of action potential, overshoot and maximal velocity of phase 0 depolarization; (3) pretreatment with L-type Ca(2+) channel agonist Bay K8644 (0.5 micromol/L) could completely block the effects of CAP (60 micromol/L); (4) pretreatment with ruthenium red (20 micromol/L), a vanilloid receptor (VR) blocker, did not affect the actions of capsaicin on papillary muscles. All these results suggest that the effects of CAP on papillary muscles are likely due to a decrease in calcium influx which is not mediated by VR.
authors.affiliation: Department of Physiology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang 050017.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Cheng
authors.forename: Rui-Rong
authors.initials: RR
authors.lastname: He
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001693:Biological Transport, Active; D002120:Calcium Channel Agonists / Q000494:pharmacology; D020746:Calcium Channels, L-Type; D002211:Capsaicin / Q000494:pharmacology*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008839:Microelectrodes; D010210:Papillary Muscles / Q000502:physiology*; D011955:Receptors, Drug / Q000037:antagonists & inhibitors; D012430:Ruthenium Red / Q000494:pharmacology
chemical_list: D002120:Calcium Channel Agonists; D020746:Calcium Channels, L-Type; D011955:Receptors, Drug; D012430:Ruthenium Red; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002211:Capsaicin