慢性低氧对豚鼠右室心肌细胞钙、钾电流的影响

采用全细胞膜片箝技术,分别记录并比较正常对照组与慢性低氧组豚鼠单个右室心肌细胞的膜电容、L型钙电流和延迟整流钾电流峰值和电流-电压关系曲线,以探讨慢性低氧对豚鼠右室心肌细胞L型钙电流和延迟整流钾电流的影响。结果表明,上述两组细胞膜电容分别为（155±13．2）pF、（179±14,8）pF,低氧组显著大于正常对照组（P＜0．01）;L型钙电流峰值分别为（1．07±0．21）nA和（0．99±0．17）nA,两组之间无显著差异;在-20mV至＋20mV,慢性低氧组L型钙电流密度较正常对照组显著下降（P＜0．05）。在＋月mV至＋60mV之间,慢性低氧组豚鼠右室心肌细胞延迟整流钾电流幅度均小于正常对照组;在-20mV至＋60mV之间,慢性低氧组豚鼠右室心肌细胞延迟整流钾电流密度明显低于正常对照组。可见慢性低氧能使豚鼠右室心肌细胞膜电容增加,L型钙电流幅度不变,但L型钙电流密度下降;同时慢性低氧降低豚鼠右室心肌细胞延迟整流钾电流幅度和密度。

Effect of chronic hypoxia on the calcium and potassium current of myocytes of the right ventricle in guinea pig

To explore the effect of chronic hypoxia on calcium and potassium currents of the right ventricle myocytes in the guinea pig, the cell membrane capacities, calcium and delayed rectifier potassium current were recorded using the whole-cell patch clamp technique from single right ventricle myocytes in guinea pigs under chronic hypoxia. The result demonstrated that the cell membrane capacities of the hypoxic group were larger than those of the control; between test potential of -20 mV to +20 mV, the calcium current density of the myocytes of the chronic hypoxic group was less than that of the control; the amplitude of IK of the myocytes of the chronic hypoxia group were less than that of the control group between test potential of +20 mV to +60 mV, and the IK density of the hypoxic group was also less than that of the control group between -20 mV to +60 mV. Consequently, it is suggested that chronic hypoxia may cause an increase of the membrane capacity, a decrease of the calcium current density of ventricle myocytes and a delay of the rectifier potassium current amplitude and density. All these observations provide information for the ionic basis of the attenuated contraction of cardiac muscles and prolonged action potential duration of hypoxic guinea pigs.