不同牵张刺激对豚鼠胃窦环行肌细胞电压依赖性钙电流的影响

利用全细胞膜片钳技术,在胃窦环行肌细胞上观察了不同方式的牵张刺激对电压依赖性钙电流的影响,探讨牵张刺激对胃窦平滑肌细胞电压依赖性钙电流的作用。用低渗性溶液灌流细胞引起的牵张刺激首先增加电压依赖性钙电流,接着激活一种内向性钳制电流。钙电流的增加发生在灌流后１ｍｉｎ内,而内向性钳制电流在细胞明显膨胀之后缓慢激活。低渗和正压引起的细胞膨胀明显增加电压依赖性钙离子电流,而利用两个电极直接牵细胞则不出现钙电

Effects of different kinds of stretch on voltage-dependent calcium current in antrial circular smooth muscle cells of the guinea-pig

In order to elucidate the effect of membrane stretch on ionic currents, we employed the whole-cell patch-clamp technique to investigate the effects of different kinds of stretch on voltage-dependent calcium currents in antrial circular smooth muscle cells of the guinea-pig. The membrane stretch induced by superfusing the smooth muscle cells with hyposmotic bath solution enhanced voltage-operated calcium current and activated inward holding current. The increase in calcium current occurred within 1 minute of superfusion and the sustained inward holding current was slowly activated after prominent cell swelling. Voltage-dependent calcium currents (Ica) were significantly increased by membrane stretch which was induced by cell swelling and cell inflation, but was not affected by direct longitudinal stretch (110 130%) using two electrodes.The results suggest that the cell membrane stretch can increase voltage-dependent calcium channel activity and the effect of stretch on calcium channels was related to the membrane tension and/or the direction of membrane stretch.