氯化铯诱发小鼠心房肌和心室肌早后去极化的比较(英文)

Comparison of early afterdepolarization induced by cesium chloride in mouse atrial and ventricular fibers

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.

AIM: To study the similarities and the differences in the induction of early afterdepolar-ization (EAD) by CsCl, a blocker of potassium channels, between mouse atrial and ventricular fibers. METHODS: Papillary muscle from left ventricle or a small piece of right atrium of Swiss Albino mouse was isolated. Transmembrane action potential (AP) and EAD were recorded using the conventional mi-croelectrode method. RESULTS: CsCl induced EAD directly in the mouse atrial and ventricular fibers on the basis of elongation of action potential duration (APD). In both preparations EAD appeared after 5-15 min exposure to CsCl and the take-off potentials (TOP) were in the same range ( - 30 to -60 mV). But the inducing concentration in ventricular fibers (3 mmol·L-1) was lower than that in atrial fibers ( 5 mmol·L-1) , and most of the EAD induced in atrium belonged to the triggered burst type (6/9) which demonstrated the property of cycle length (CD-dependence while the EAD occurred in ventricle mainly belonged to the second plateau type (14/17) which showed no definite relation with the CL. CONCLUSION: Low concentration of CsCl induced EAD more easily in mouse ventricular fibers than in atrial fibers, and the types of EAD were also different from each other. These suggested that there might be some differences in potassium channels between mouse atrial and ventricular fibers.