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目的:研究钾通道阻断剂氯化铯(CsCl)诱发小鼠心房肌和心室肌早后去极化(EAD)的异同.方法:以游离的小鼠左室乳头状肌和右房组织条为标本,细胞内微电极记录跨膜动作电位(AP)和EAD.结果:CsCl可显著延长小鼠心房肌和心室肌的动作电位时程并诱发出EAD.EAD的起始电位均在-30至-60 mV 之间,但CsCI作用的有效浓度不同(心室肌为3 mmol·L~(-1);心房肌为5 mmol·L~(-1)),且心房肌的EAD多表现为触发发放型(6/9)并具频率依赖性,心室肌的EAD多表现为平台突起型(14/17)而无频率依赖性.结论:低浓度CsCl在小鼠心室肌较心房肌更易诱发EAD且二者表现形式不同,提示小鼠心房肌和心室肌的钾通道可能不同.
Aims: To investigate the similarities and differences of the early post-depolarization (EAD) in atrium and ventricular myocytes induced by CsCl, a potassium channel blocker.Methods: The left ventricular papillary muscles and right atrial tissues (AP) and EAD were recorded in intracellular microelectrodes.RESULTS: CsCl significantly prolonged the action potential duration and induced EAD in atrial and ventricular myocardium of mice.The onset potentials of EAD were all at -30 To-60 mV, but the effective concentrations of CsCI were different (3 mmol·L -1 in ventricular muscle and 5 mmol·L -1 in atrial myocardium) (6/9) and frequency-dependent (P <0.05). The EAD of ventricular muscle showed more platelet type (14/17) without frequency dependence.Conclusion: CsCl is more easily induced in ventricular muscle than in atrial myocardium in mice EAD and the performance of the two different forms, suggesting that mouse atrial and ventricular muscle potassium channels may be different.