von der Weid P Y, Bény J L
Department of Zoology and Animal Biology, University of Geneva, Switzerland.
Am J Physiol. 1992 Jun;262(6 Pt 2):H1823-31. doi: 10.1152/ajpheart.1992.262.6.H1823.
Ca2+ ionophores (A23187 and ionomycin) were used to determine whether an increase in cytosolic Ca2+ plays a direct role in pig coronary endothelial cell hyperpolarization. Ionophores induced concentration-dependent hyperpolarizations that were not altered by the presence of N omega-nitro-L-argnine (L-NNA), and inhibitor of nitric oxide synthesis. d-Tubocurarine decreased by 65-89% the A23187- and substance P (SP)-generated hyperpolarization of endothelial cells. To study the role of endothelial cell hyperpolarization in the endothelium-dependent relaxation of precontracted coronary artery strips, A23187 and SP concentration-response curves were built up in the presence of d-tubocurarine and/or L-NNA. A decrease in the maximal response was observed only when both d-tubocurarine and L-NNA were present. Our direct in situ approach gives results in agreement with a gating of Ca(2+)-activated K+ channels during A23187- and SP-induced hyperpolarizations of endothelial cells. We suggest that these hyperpolarizations play a role in the endothelial cell-dependent relaxation induced by A23187 and SP in the pig coronary artery.
使用钙离子载体（A23187和离子霉素）来确定胞质钙离子增加是否在猪冠状动脉内皮细胞超极化中起直接作用。离子载体诱导浓度依赖性超极化，一氧化氮合成抑制剂Nω-硝基-L-精氨酸（L-NNA）的存在不会改变这种超极化。筒箭毒碱使A23187和P物质（SP）引起的内皮细胞超极化降低65% - 89%。为了研究内皮细胞超极化在预收缩冠状动脉条内皮依赖性舒张中的作用，在筒箭毒碱和/或L-NNA存在的情况下建立了A23187和SP的浓度 - 反应曲线。仅当同时存在筒箭毒碱和L-NNA时，才观察到最大反应降低。我们的直接原位方法得出的结果与A23187和SP诱导内皮细胞超极化期间钙激活钾通道的门控一致。我们认为这些超极化在A23187和SP诱导的猪冠状动脉内皮细胞依赖性舒张中起作用。
