Inhibition of cytochrome P-450 reduces voltage-gated K+ currents in pulmonary arterial myocytes.
Inhibition of cytochrome P-450 reduces voltage-gated K+ currents in pulmonary arterial myocytes.
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DOI：
10.1152/ajpcell.1995.268.1.c259
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
X. Yuan;M. Tod;L. Rubin;M. Blaustein
中科院分区：
文献类型：
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作者：
X. Yuan;M. Tod;L. Rubin;M. Blaustein
细胞色素P-450（P-450）是一个需要NADPH和O2依赖的单加氧酶系统。它存在于肺中，并被假定在缺氧性肺血管收缩中充当O2传感器。为探讨P-450是否参与肺动脉（PA）心肌细胞电压门控性K+（KV）通道活动的调节，我们采用全细胞膜片钳技术研究了P-450抑制剂对KV通道电流（IKV）和膜电位（Em）的影响。P-450抑制剂克霉唑、咪康唑和1-氨基苯并三唑（1-ABT）的浴应用显著且可逆地抑制了稳态IKV（IKss）和去极化PA细胞，这些细胞浸泡在含Ca（2+）（1.8 mM）或无Ca（2+）[存在0.5-1 mM乙二醇-双（β-氨基乙基醚）-N，N，N 'N'-四乙酸]浴溶液中。克霉唑（1 μ M）、咪康唑（10 μ M）和1-ABT（1 mM）分别可逆性降低+80 mV测试电位诱发的IKss 40%、70%和31%。用10 mM 4-氨基吡啶（4-AP）预处理PA平滑肌细胞可阻止克霉唑对IKV的后续抑制作用。然而，用1 mM四乙基铵预处理细胞可忽略不计地改变咪康唑对IKV和Em的影响。在电流钳（I = 0）测量中，克霉唑在含Ca（2+）和不含Ca（2+）的浴液灌注期间分别使PA肌细胞去极化9和11 mV。1-ABT也使无Ca（2+）溶液中的PA心肌细胞产生9 mV的去极化。这些作用与缺氧、还原型谷胱甘肽和4-AP诱导的作用相似。克霉唑还降低IKV并使肠系膜动脉肌细胞去极化。这些数据提高了P-450系统的可能性，由于其对IKV的影响以及对O2张力和NADPH的敏感性，可能通过KV通道活性的共同途径在将肺血管张力的调节与细胞氧化还原状态的改变联系起来方面发挥作用。
Cytochrome P-450 (P-450) is a NADPH-requiring and O2-dependent monooxygenase system. It is present in lung and has been postulated to act as an O2 sensor in hypoxic pulmonary vasoconstriction. To determine whether P-450 is involved in the regulation of voltage-gated K+ (KV) channel activity in pulmonary artery (PA) myocytes, we used the whole cell patch-clamp technique to evaluate the effects of P-450 inhibitors on KV channel currents (IKV) and membrane potential (Em). Bath application of the P-450 inhibitors clotrimazole, miconazole, and 1-aminobenzotriazole (1-ABT) significantly and reversibly inhibited steady-state IKV (IKss) and depolarized PA cells bathed in either Ca(2+)-containing (1.8 mM) or Ca(2+)-free [0.5-1 mM ethylene glycol-bis(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid present] bath solution. Clotrimazole (1 microM), miconazole (10 microM), and 1-ABT (1 mM) reversibly reduced IKss, elicited by a test potential of +80 mV, by 40, 70, and 31%, respectively. Pretreatment of PA smooth muscle cells with 10 mM 4-aminopyridine (4-AP) prevented the subsequent inhibitory effect of clotrimazole on IKV. However, pretreatment of the cells with 1 mM tetraethylammonium negligibly altered the effects of miconazole on IKV and Em. In current-clamp (I = 0) measurements, clotrimazole depolarized PA myocytes by 9 and 11 mV during perfusion with Ca(2+)-containing and Ca(2+)-free bath solution, respectively. 1-ABT also caused a 9-mV depolarization in PA myocytes bathed in Ca(2+)-free solution. These effects are similar to those induced by hypoxia, reduced glutathione, and 4-AP. Clotrimazole also decreased IKV and depolarized mesenteric arterial myocytes. These data raise the possibility that the P-450 system, due to its influence on IKV and sensitivity to O2 tension and NADPH, may play a role in linking the regulation of pulmonary vascular tone to the alteration of cellular redox status through a common pathway of KV channel activity.