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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 characteristics of C lC-2 chloride channel (C lC-2) under physiological and pathological conditions. Methods Rat ventricular myocytes were separated by enzymatic method and perfused by perfusion fluid with normal, varying osmotic pressure and different pH values. The changes of C lC-2 channel activity in ventricular myocytes were observed by patch clamp whole cell recording. Results ① The C lC-2 channels of normal ventricular myocytes were voltage-dependent. It activates at hyperpolarization (-40 ~ -100 mV) of the cell membrane, a C l -mediated inward rectification current (IC I, ir). Hypotonic cell swelling will accelerate the activation, increasing the current intensity. On the contrary when hypertonic. It can be blocked by 9-anthracenecarboxylic acid (9-AC) but insensitive to SITS, the phosphinothricin stilbene derivative. ② When the pH value increased from 7.4 to 8.0, IC l, ir intensity decreased; when the pH value decreased from 7.4 to 6.8 IC l, ir intensity increased significantly. At a pH of 5.5, the current is almost zero. CONCLUSION C lc-2 channel-mediated IC 1, IR shows a significant increase in current intensity in hyperpolarised, hypotonic, cell-swollen and acidic environments.