Guiet-Bara Andrée, Bara Michel
Physiology and Physiopathology Laboratory, University Pierre et Marie Curie, Paris, France.
Cell Mol Biol (Noisy-le-grand). 2002;48 Online Pub:OL317-22.
Presence of ionic channels was evaluated in human endothelial cells (ECs) from allantochorial placental vessels by the measure of the membrane potential, the main factor of the excitation-contraction coupling. To characterize endothelial cell channels, vasoactive and vasorelaxant agents and channels blockers were used. In predepolarized cells by high-K+ concentration, the voltage-dependent K+ channels (Kdf) were blocked. Acetylcholine, sodium nitroprusside and isoproterenol hyperpolarized the predepolarized-high K+ ECs. This hyperpolarization was inibited by charybdotoxin (a blocker of big Ca(2+)-activated K+ channels) or/and by tetraethylammonium and was insensitive to glibenclamide (a blocker of ATP-sensitive K+ channels). Serotonin depolarized ECs and the depolarization was inibited by nifedipine, a blocker of voltage-gated Ca2+ channels. These results indicated that membrane potential of human placental allantochorial ECs was regulated by voltage-gated, C(2+)-sensitive K+ channels and by voltage-gated Ca2+ channels.
通过测量膜电位（兴奋 - 收缩偶联的主要因素）来评估人绒毛膜胎盘血管中内皮细胞（ECs）离子通道的存在情况。为了表征内皮细胞通道，使用了血管活性和血管舒张剂以及通道阻滞剂。在高钾浓度预去极化的细胞中，电压依赖性钾通道（Kdf）被阻断。乙酰胆碱、硝普钠和异丙肾上腺素使预去极化的高钾内皮细胞超极化。这种超极化被蝎毒素（一种大电导钙激活钾通道阻滞剂）或/和四乙铵抑制，且对格列本脲（一种ATP敏感性钾通道阻滞剂）不敏感。5-羟色胺使内皮细胞去极化，而去极化被硝苯地平（一种电压门控钙通道阻滞剂）抑制。这些结果表明，人胎盘绒毛膜内皮细胞的膜电位受电压门控、钙敏感钾通道和电压门控钙通道调节。
