Deoxyglucose and reduced glutathione mimic effects of hypoxia on K+ and Ca2+ conductances in pulmonary artery cells.
Deoxyglucose and reduced glutathione mimic effects of hypoxia on K+ and Ca2+ conductances in pulmonary artery cells.
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脱氧葡萄糖和还原型谷胱甘肽模拟缺氧对肺动脉细胞 K 和 Ca2 电导的影响。
DOI：
10.1152/ajplung.1994.267.1.l52
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Blaustein,MP
中科院分区：
文献类型：
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作者：
Yuan,XJ;Tod,ML;Rubin,LJ;Blaustein,MP
缺氧诱导的肺血管收缩（HPV）是由细胞内Ca 2+浓度（[Ca 2 +]i）升高触发的，而细胞内Ca 2+浓度（[Ca 2 +]i）升高部分受电压门控Ca 2+通道控制。缺氧抑制肺动脉（PA）心肌细胞的电压门控性K+（KV）通道。这使细胞去极化，打开电压门控Ca 2+通道，从而增加[Ca 2 +]i，并启动HPV。在完整动物和离体灌注肺中，代谢抑制剂和还原剂增加HPV。我们比较了缺氧与糖酵解抑制剂，2-脱氧-D-葡萄糖（2-DOG），还原剂，还原型谷胱甘肽（GSH），对电压门控稳态K+电流（IK，SS）和膜电位（Em）在培养的大鼠肺动脉和肠系膜动脉（MA）平滑肌细胞。浴应用10 mM 2-DOG（无葡萄糖）或5-10 mM GSH可逆地减少PA肌细胞中IK，ss 25-35%，5 mM ATP存在于移液管溶液中。缺氧和2-DOG对MA心肌细胞IK，ss均无明显影响，但GSH可降低MA心肌细胞IK，ss。此外，缺氧，2-DOG，和GSH去极化PA细胞的情况下，以及在存在外部Ca 2+。缺氧，2-DOG，和GSH也诱发动作电位的顶部的稳定去极化在36-50%的PA心肌细胞，但不是在任何MA心肌细胞;去除外部Ca 2+废除的动作电位，而不影响稳定的去极化。这些作用与KV通道阻滞剂4-氨基吡啶（5-10 mM）产生的作用相当。这意味着动作电位可归因于通过KV通道抑制引起的稳定去极化打开的电压门控性Ca 2+通道的Ca 2+内流。在2-DOG或GSH存在下，缺氧对PA细胞中的IK、ss或Em没有进一步的影响;这意味着缺氧、2-DOG和GSH都阻断相同的K+通道。结果提示：（1）缺氧引起的PA心肌细胞IK，ss降低及由此引起的去极化可能与局部细胞内ATP水平降低和/或细胞膜或胞浆氧化还原状态改变有关;（2）细胞外Ca（2+）依赖性动作电位可能是HPV过程中[Ca（2+）]i升高的部分原因。缺氧、2-DOG和GSH对PA肌细胞IK、SS和Em的影响相似，沿着PA和MA肌细胞的不同反应，表明PA细胞对这些处理的反应可能有共同的机制。
Hypoxia-induced pulmonary vasoconstriction (HPV) is triggered by a rise in cytosolic Ca2+ concentration ([Ca2+]i) that is partially controlled by voltage-gated Ca2+ channels. Hypoxia inhibits voltage-gated K+ (KV) channels in pulmonary artery (PA) myocytes. This depolarizes the cells, opens voltage-gated Ca2+ channels, thereby increases [Ca2+]i, and initiates HPV. In intact animals and isolated perfused lungs, metabolic inhibitors and reducing agents augment HPV. We compared the effects of hypoxia with the glycolysis inhibitor, 2-deoxy-D-glucose (2-DOG), and the reducing agent, reduced glutathione (GSH), on voltage-gated steady-state K+ currents (IK,ss) and membrane potential (Em) in cultured rat pulmonary and mesenteric arterial (MA) smooth muscle cells. Bath application of 10 mM 2-DOG (glucose-free) or 5-10 mM GSH reversibly reduced IK,ss by 25-35% in PA myocytes, with 5 mM ATP present in the pipette solution. Neither hypoxia nor 2-DOG significantly affected IK,ss in MA myocytes, but GSH did reduce IK,ss in these cells. Furthermore, hypoxia, 2-DOG, and GSH depolarized PA cells in the absence as well as in the presence of external Ca2+. Hypoxia, 2-DOG, and GSH also evoked action potentials on the top of the steady depolarization in 36-50% of PA myocytes but not in any MA myocytes; removal of external Ca2+ abolished the action potentials without affecting the steady depolarization. These effects were comparable to those produced by 4-aminopyridine (5-10 mM), a blocker of KV channels. This implies that the action potentials are attributable to Ca2+ influx through voltage-gated Ca2+ channels opened by the steady depolarization due to KV channel inhibition. In the presence of 2-DOG or GSH, hypoxia had no further effect on IK,ss or Em in PA cells; this implies that hypoxia, 2-DOG, and GSH all block the same K+ channels. The data suggest that 1) the hypoxia-induced decrease of IK,ss and the resultant depolarization in PA myocytes may be related to a local decrease of intracellular ATP level and/or a change in redox status of the membrane or cytosol and 2) extracellular Ca(2+)-dependent action potentials may be responsible for at least part of the increase in [Ca2+]i during HPV. Similarities between the effects of hypoxia, 2-DOG, and GSH on IK,ss and Em in PA myocytes, along with the dissimilar responses of PA and MA myocytes, suggest that a common mechanism may underlie the responses of PA cells to these treatments.