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急性低温/再复温对大鼠心室肌膜电位和钾电流的影响

李龙天, 张利彬, 司艳丽, 肖付诚, 李达, 高姗, 李东亮, 周士胜

辽宁省高校生物物理学重点实验室,大连大学医学研究中心.辽宁,大连 116622；新乡医学院生理学教研室.河南,新乡 453003

摘要

该文旨在研究急性低温/再复温对大鼠心室肌膜电位和钾电流的影响。膜电位和膜电流分别在全细胞膜片钳的电压钳和电流钳模式下记录。当细胞外灌流液从25℃降低到4℃后，一过性外向电流(transient outward current, I_(to))完全消失，膜电位为+60 mV时的稳态外向K~(+)电流(sustained outward K~(+) current, I_(ss))和膜电位为--120 mV时的内向整流K~(+)电流(inward rectifier K~(+) current, I_(K1))分别降低(48.5±14.1)% 和 (35.7±18.2)%，同时，膜电位绝对值降低。当细胞外灌流液从4℃再升高到36℃后，膜电位出现一过性超级化，然后恢复到静息电位水平；在58个细胞中，有36个细胞伴随复温出现ATP--敏感性K~(+)(ATP--sensitive K~(+) channels, K_(ATP))通道的激活。再复温引起的上述变化可以被Na~(+)/K~(+)--ATP酶抑制剂哇巴因(100#mu#mol/L)所抑制。再复温引起的K_(ATP)通道激活也能被蛋白激酶A抑制剂H--89(100#mu#mol/L)所抑制。在细胞膜电位被钳制在0 mV时，当灌流液温度从25℃降低到4℃后，细胞的体积不发生明显改变，但当复温引起K_(ATP)通道激活后，细胞很快发生皱缩，同时细胞内部出现许多折光较强的斑点。上述结果表明急性低温/再复温对大鼠心室肌膜电位和K~(+)电流有明显影响, 并提示K_(ATP)通道激活可能与心肌低温/再复温损伤有关。

关键词： 低温; 再复温; 钾通道; 膜电位; 心肌

Effects of acute cooling/rewarming on membrane potential and K~(+) currents in rat ventricular myocytes

Li Longtian, Zhang Libin, Si Yanli, Xiao Fucheng, Li Da, Gao Shan, Li Dongliang, Zhou Shisheng

Liaoning Key Laboratory of Biophysics,Institute of Basic Medical Sciences,Medical College,Dalian University.Dalian 116622,Liaoning；China

Abstract

The effects of acute cooling/rewarming on cardiac K~(+) currents and membrane potential were investigated. Membrane potential and current were assessed with whole-cell patch-clamp technique in current- and voltage-clamp modes. When the temperature of bath solution was decreased from 25℃ to 4℃, the transient outward current (I_(to)) was completely abolished, the sustained outward K~(+) current (I_(ss)) and the inward rectifier K~(+) current (I_(K1)) were depressed by (48.5±14.1)% at +60 mV and (35.7±18.2)% at -120 mV, respectively, and the membrane potential became more positive. After the temperature of bath solution was raised from 4℃ to 36℃, the membrane potential exhibited a transient hyperpolarization and then was maintained at a stable level. In some myocytes (36 out of 58), activation of the ATP-sensitive K~(+) (K_(ATP)) channel after rewarming was observed. The rewarming-induced change in the membrane potential was inhibited by the Na~(+)/K~(+)-ATPase inhibitor ouabain, and the rewarming-elicited activation of K_(ATP) channel was inhibited by the protein kinase A inhibitor H-89. Moreover, decrease of the temperature from 25℃ to 4℃ did not induce any significant change in cell volume when the cell membrane potential was clamped at 0 mV. However, significant cell shrinkage with spots was observed soon after rewarming-induced activation of K_(ATP) channel. These data demonstrate that acute cooling/rewarming have a profound influence on the membrane potential and K~(+) currents of ventricular myocytes, and suggest that activation of K_(ATP) channel may play a role in cardiac cooling/rewarming injury.

Key words: hypothermia;rewarming;Potassium channels;membrane potentials;myocardium

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引用本文：

李龙天, 张利彬, 司艳丽, 肖付诚, 李达, 高姗, 李东亮, 周士胜. 急性低温/再复温对大鼠心室肌膜电位和钾电流的影响[J]. 生理学报 2008; 60 (3): 311-319.

Li Longtian, Zhang Libin, Si Yanli, Xiao Fucheng, Li Da, Gao Shan, Li Dongliang, Zhou Shisheng. Effects of acute cooling/rewarming on membrane potential and K~(+) currents in rat ventricular myocytes. Acta Physiol Sin 2008; 60 (3): 311-319 (in Chinese with English abstract).