Zhou Y Y, Liu T F
Laboratory of Biological Membrane and Membrane Engineering, College of Life Science, Peking University, Beijing, China.
Zhongguo Yao Li Xue Bao. 1995 May;16(3):261-5.
To study the similarities and the differences in the induction of early afterdepolarization (EAD) by CsCl, a blocker of potassium channels, between mouse atrial and ventricular fibers.
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 microelectrode method.
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 (CL)-dependence while the EAD occurred in ventricle mainly belonged to the second plateau type (14/17) which showed no definite relation with the CL.
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.
研究钾通道阻滞剂氯化铯（CsCl）在诱导小鼠心房和心室肌纤维早期后去极化（EAD）方面的异同。
分离瑞士白化小鼠左心室乳头肌或一小块右心房。采用传统微电极方法记录跨膜动作电位（AP）和EAD。
基于动作电位时程（APD）延长，CsCl可直接在小鼠心房和心室肌纤维中诱导EAD。在两种标本中，暴露于CsCl 5 - 15分钟后均出现EAD，其起始电位（TOP）在相同范围内（-30至-60 mV）。但心室肌纤维的诱导浓度（3 mmol.L-1）低于心房肌纤维（5 mmol.L-1），心房中诱导出的大多数EAD属于触发爆发型（6/9），表现出周期长度（CL）依赖性，而心室中出现的EAD主要属于第二平台型（14/17），与CL无明确关系。
低浓度CsCl在小鼠心室肌纤维中比在心房肌纤维中更容易诱导EAD，且EAD的类型也彼此不同。这表明小鼠心房和心室肌纤维的钾通道可能存在一些差异。
