辣椒素对人心房肌的电生理效应(英文)

目的　研究辣椒素对人心房肌的电生理效应及其作用机制。方法　应用经典玻璃微电极方法记录人心房肌特殊细胞的动作电位。结果　辣椒素(1～ 30 μmol·L- 1)浓度依赖性地抑制人心房肌纤维的动作电位幅值 ,0期最大除极速率 ,舒张期 (4相 )除极化速率和起搏细胞放电频率 ,此外还缩短 90 %动作电位时程。应用L 型钙通道开放剂BayK86 44(0 .5 μmol·L- 1)可拮抗辣椒素对人心房肌纤维的上述电生理效应 ,但辣椒素受体竞争性抑制剂cap sazepine(10 μmol·L- 1)对辣椒素的效应并无影响。结论　辣椒素对人心房肌具有负性变时作用 ,并可缩短复极化时程。这些效应可能与其抑制钙离子内流有关。

Electrophysiological effects of capsaicin on human atrial fibers

AIM To study the electrophysiological effects of capsaicin on human atrial fibers. METHODS Parameters of action potential in human atrial specialized fibers were recorded using standard intracellular microelectrode technique. RESULTS Capsaicin (1-30 μmol·L-1) decreased the amplitude of action potential, maximal rate of depolarization, velocity of diastolic (phase 4) depolarization and rate of pacemaker firing, and shortened the 90% action potential duration in a concentration-dependent manner. L-type Ca2+ channel agonist Bay K8644 (0.5 μmol·L-1) antagonized the inhibitory effects of capsaicin on human atrial fibers. Pretreatment of the fibers with capsazepine (10 μmol·L-1), a competitive capsaicin antagonist, failed to influence the electrophysiological effects of capsaicin. CONCLUSIONCapsaicin exerted a negative chronotropic action and accelerated the repolarization of human atrial specialized fibers which may be due to reduction in calcium influx and not mediated by capsaicin receptors.