铬对大鼠心电图及心肌细胞的电生理影响

THE ELECTROPHYSIOLOGICAL EFFECTS OF CHROMIUM ON ECG AND ACTION POTENTIAL OF CARDIOCYTES IN RATS

应用心电图及细胞内微电极技术观察铬对心肌电生理的影响。大鼠腹腔内注射铬，９周后心电图显示各剂量组ＱＴ间期均缩短，细胞内微电极检查显示动作电位时程（ＡＰＤ５０、ＡＰＤ９０）于２周后随剂量增加而逐渐缩短，０．４ｍｇ组显著缩短，９周后各剂量组ＡＰＤ５０、ＡＰＤ９０均缩短。心率、静息电位（ＲＰ）与动作电位（ＡＰＡ）幅度及动作电位最大上升速率（Ｖｍａｘ）无变化。铬影响了心肌复极引起ＱＴ间期缩短，而ＡＰＤ５０、ＡＰＤ９０缩短可能是铬影响了钙内流及钾外流的结果。

Effects of chromium on the electrophysiological properties of rat heart were observed with electrocardiogram (ECG) and the technique of intracelluar microelectrode recording. Wistar rats were given intraabdominal injection of chromium. (0.1mg/kg, 0.2mg/kg, 0.4mg/kg) once daily for 2 weeks and every other day for 7 weeks. After injection for 9 weeks, Q T interval in ECG was shortened in all dose groups. Intracellular recording indicated that the action potential duration (APD 50 and APD 90 ) of the ventricular papillary muscle gradually shortened in a dose dependent manner.After injection for two weeks, APD 50 and APD 90 shortened only in the 0.4mg group, while after injection for 9 weeks, they were shortened in all dose groups. Chromium had no effects on the heart rate, resting potential(RP), amplitude of action potential (APA) and the maximum depolarization rate of the action potential (Vmax). The results showed that chromium could influence the repolarization process of myocardium and induce the shortening of Q T interval, and the shortening of APD 50 , APD 90 might be due to its influence on the inward calcium current or/and the outward potassium current.