镉对心肌细胞动作电位的影响及硒的保护作用

Effect of cadmium on action potentials of cultured myocardiocytes and protective effects of selenium

目的探讨镉（Ｃｄ）对心肌的毒性作用机制及硒的保护效应。方法在培养的Ｗｉｓｔａｒ大鼠乳鼠心肌细胞上观察了镉对膜电位活动的影响及亚硒酸钠和硒代蛋氨酸的保护作用。结果镉使心肌细胞动作电位幅值（ＡＰＡ）、超射（ＯＳ）、阈电位（ＴＰ）、最大舒张电位（ＭＤＰ）及最大除极速率（Ｖｍａｘ）显著降低；复极化时程（ＡＰＤ）明显缩短；动作电位发放频率（ＡＰＦ）明显加快。硒与镉按等摩尔浓度加入（１０μｍｏｌ／Ｌ），亚硒酸钠和硒代蛋氨酸均可减轻镉对心肌细胞动作电位参数ＡＰＡ、ＴＰ、ＭＤＰ、Ｖｍａｘ等的影响，但两种硒化合物对动作电位复极化时程的影响表现不一致，前者延长ＡＰＤ，后者未能改变镉对ＡＰＤ的影响。结论镉能抑制心肌细胞的跨膜电位；亚硒酸钠和硒代蛋氨酸均可不同程度地减轻镉对心肌细胞动作电位的影响。

The effect of sodium selenite and selenomethionine on cadmiuminduced inhibition of the action potentials was investigated by using ventricular myocardiocytes of Wistar rats in a culture system.It was revealed that cadmium could decrease the action potential parameters such as action potential amplitude(APA),overshoot(OS),threshold potential(TP),maximum diastolic potential(MDP) and maximum rate of depolarization(Vmax),shorten the action potential duration of repolarization(APD) and accelerate the action potential frequency(APF).When Se and Cd were added in equal molarity(10 mol/L) simultaneously,both of them significantly decreased APA,TP,MDP,Vmax.However,the effects of these two selenium compounds on APD were different.Sodium selenite prolonged APD whereas selenomethionine failed to prevent the change of APD by cadmium.