慢性低氧对豚鼠右室心肌细胞钙、钾电流的影响

EFFECT OF CHRONIC HYPOXIA ON THE CALCIUM AND POTASSIUM CURRENT OF MYOCYTES OF THE RIGHT VENTRICLE IN GUINEA PIG

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。

To explore the effect of chiDnic hypoala on calcium and potassium crmnts of therigh ventricle myocytes in the guinea pig, the cell mernbrane caPacihes, calcium anddelayed rectifier potassium current were recorded using the whole-cell patch clamptecboque from single right ventricle myocpes in guinea pigs under cbonic hypokia. Theresult demonstraed tha the cell meInbran capacities of the hypokic gnup were loprthan those of the conbol; between test potenhal of - 20 mV to＋20 mV, the calciumcnnt density of the myocytes of the cbonic hypokic group was less than tha of thecontrol; the amplitude of IK of the Inyocytes of the cbonic hypokia group were less thantha of the control pop between test POtenhal of ＋20 mV to＋60 mV, and the IKdensity of the hypokic groUp was also less than that of the control mp between - 20 mVto ＋ 60 mV. Conseopenily, it is suggested that cbonic hypokia Inay cause an increase ofthe membrane capacity, a decrease of the calciurn crmnt density of ventricle myocytesand a delay of the rectifier potassiurn crmnt amplitude and density. All theseobservations provide infonnation for the ionic basis of the attenuated contraction of cedacmuscles and prolonged achon potential forion of hypokic gUinea pigs.