Mechanisms of anoxia-induced activation of ATP-sensitive K channels in isolated ventricular myocytes

缺氧诱导离体心室肌细胞 ATP 敏感 K 通道激活的机制

基本信息

批准号：
06670064
负责人：
ARITA Makoto
金额：
$ 1.28万
依托单位：
Oita Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06670064/
关键词：
isolated ventricular cells anoxia ATP sensitive K channel patch clamp action potential duration oxidative phosphrylation anaerobic glycolysis glucose 活動電位

项目摘要

Objective. Exposure to anoxia has been reported to activate ATP-sensitive potassium (K^+_<ATP>) channels in isolated ventricular myocytes. We aim to investigate the mechanisms underlying the anoxia-induced activation of K^+_<ATP> channels, using specially designed "air-tight perfusion chamber".Methods. Guinea pig ventricular myocytes were isolated using collagenase digestion. Action potentials and membrane currents were recorded in the whole-cell mode of patch clamp. Exposure to anoxia was performed in a semi-closed airtight chamber, which prevented the diffusion of atmospheric oxygen into anoxic perfusate.Results. Exposure to glucose-free anoxia shortened the action potential duration (APD) to less than 20% of control in 13 (]SY.+-。[) 3 min. Subsequent reoxygenation rapidly and completely restored the APD.The time-independent large outward current developed during anoxia, and was completely suppressed by reoxygenation or by the application of glibenclamide, a K<@D1+@>D1<@D2ATP@>D2 channel blocker. The presence of extracellular glucose did not prevent the APD from shortening during anoxia, although it significantly decreased the rate of shortening. Application of glucose during anoxia could not restore the action potential that was shortened by glucose-free anoxia. Reoxygenation-induced restoration of the APD was inhibited after a long-lasting anoxia. In addition, repeated exposure to anoxia/reoxygenation progressively impaired the recovery of APD during reoxygenation.Conclusions. Activation of K^+_<ATP> channels occurs during anoxia. The primary source of ATP that regulates the channel activity seems to be oxidative phosphorylation. ATP derived from anaerobic glycolysis (attained by the increase of extracellular glucose) was observed to partially suppress the channel activity only when oxidative phosphorylation was severely impaired during anoxia.

客观的。据报道，暴露于缺氧会激活孤立心肌细胞中的ATP敏感钾（K^+_ <ATP>）通道。我们旨在使用专门设计的“气密灌注室”。方法来研究缺氧诱导的K^+_ <ATP>通道激活的机制。使用胶原酶消化分离豚鼠心室心肌细胞。动作电位和膜电流记录在斑块夹的整个细胞模式下。暴露于半密封的气密室中进行了缺氧，这阻止了大气中的氧气扩散到缺氧的灌注液中。暴露于无葡萄糖缺氧的情况下，在13（]SY。+ - 。[）3分钟中，动作电位持续时间（APD）缩短到少于20％的对照。随后的重合迅速并完全恢复了APD。目前在缺氧期间开发的时间无关的大外向，并被Rexygyganation或Glibenclamide施加了k <@d1+@> d1+@> d1 <@d2atp@> d2通道阻滞剂。细胞外葡萄糖的存在并不能阻止APD在缺氧过程中缩短，尽管它大大降低了缩短速度。缺氧期间葡萄糖的应用无法恢复无葡萄糖缺氧缩短的作用电位。长期缺氧后，抑制了重氧诱导的APD的恢复。此外，反复暴露于缺氧/重氧逐渐损害了Rexygygy.Conconconions期间APD的恢复。 K^+_ <ATP>通道的激活发生在缺氧期间。调节通道活性的ATP的主要来源似乎是氧化磷酸化。观察到源自厌氧糖酵解（通过增加细胞外葡萄糖实现的ATP）仅在缺氧期间严重损害氧化磷酸化时，才能部分抑制通道活性。