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Electrophysiological effects of capsaicin on guinea pig papillary muscles

Li Qian, Cheng Yanping, He Ruirong

Department of Physiology，Institute of Basic Medicine, Hebei Medical University. Shijiazhuang 050017,China

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 μmol/L) in a concentration-dependent manner; (2) in partially depolarized papillary muscles, 60 μmol/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 Ca2 + channel agonist Bay K8644 (0. 5μmol/L) could completely block the effects of CAP (60 μmol/L); (4) pretreatment with ruthenium red (20μmol/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.

Key words: Physiology;Capsaicin;Action potential;Papillary muscles

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Citing This Article：

Li Qian, Cheng Yanping, He Ruirong. Electrophysiological effects of capsaicin on guinea pig papillary muscles. Acta Physiol Sin 2003; 55 (5): (in Chinese with English abstract).