大白鼠心室肌细胞ClC-2型氯通道的特性

The characters of ClC-2 chloride channel in rat ventricular myocytes.

目的研究在生理及病理条件下C lC-2型氯通道(简称C lC-2)的特性。方法以酶解法分离大白鼠心室肌细胞,先后用正常、改变渗透压以及不同的pH值的灌流液灌流,并采用膜片钳全细胞记录法观察心室肌细胞C lC-2通道的活性变化。结果①正常心室肌细胞的C lC-2通道具有电压依赖性。它在细胞膜超极化(-40^-100 mV)时激活,由C l-介导的一种内向整流电流(IC I,ir)。低渗时细胞膨胀会加速激活,增加电流强度。高渗时反之。它可以被9-蒽甲酸(9-AC)所阻断,但对乙拌磷1,2-二苯乙烯衍生物SITS不敏感。②当pH值从7.4升高到8.0时,IC l,ir强度减小;当pH值从7.4下降到6.8时IC l,ir强度明显增加。在pH值为5.5的时候,电流几乎为零。结论C lC-2通道介导的IC l,ir,在超极化、低渗、细胞肿胀及酸性环境下其电流强度明显增加。

Objective To study the characters of ClC-2 channel in rat ventricular myocytes. Methods Single rat ventricular myocytes were isolated with enzyme, the recording of ICI,ir（the inwardly rectifying current） was followed by whole-cell patch-clamp technique . We recorded the current in ventricular myocyte superfused with isotonic, hypertonic and hypotonic solution respectively. ICI,ir was recorded under different pH of extracellular bath solutions. Results ①Hypotonic cell swelling accelerated ICI,ir activation and increased ICI,ir amplitude while hypertonic cell shrinkage inhibited the current. ICI,ir was blocked by 9-anthracene- carboxylicacid but not by stilbene- disulfonates. ②By increasing the pH from 7.4 to 8.0, the magnitude of current decreased. ICI,ir actually increased by application of pH 6.8 to the ClC-2 channel. But when pH reduced from 6.8 to 6.0, the ClC-2 channel almost closed and little ICI,ir was recorded. Conclusion ICI,ir significantly increases in hypotonic, cell swelling, hyperoplarization and acidosis state.