Payet M D, Durroux T, Bilodeau L, Guillon G, Gallo-Payet N
Département de Physiologie et Biophysique, Faculté de Médecine, Université de Sherbrooke, Quebec, Canada.
Endocrinology. 1994 Jun;134(6):2589-98. doi: 10.1210/endo.134.6.7515004.
Ionic currents of primary cultured glomerulosa cells from human adrenal glands were studied with the patch-clamp technique. Two types of outward K+ currents and two types of inward Ca2+ currents were described. The transient outward K+ current activated at potential positive to -40 mV and demonstrated a marked time-dependent inactivation. It was blocked by 4-aminopyridine but not tetraethylammonium. A second type of outward current activated rapidly at the depolarization onset and then increased slowly with no time-dependent inactivation. The transient inward T-type Ca2+ current was activated for potential positive to -60 mV with a maximal current amplitude at -30 mV and zero current voltage at +40 mV; it was completely inactivated for membrane potential positive to -40 mV. The pharmacological studies of the T-type channel showed that Ni2+ was a potent blocker but that the channel was not sensitive to dihydropyridine. The long-lasting inward Ca2+ current was activated for potentials positive to -20 mV with a maximum current amplitude at +70 mV. This current was increased by the agonist Bay K 8644 and blocked by the antagonist nifedipine; in addition, it was blocked by Cd2+ but less sensitive to Ni2+. This study revealed that glomerulosa cells from human adrenal demonstrated the presence of K+ and Ca2+ currents similar to those found in rat and bovine cells. Moreover, the main stimuli of aldosterone secretion, ACTH and angiotensin II, induce an increase in aldosterone secretion which is inhibited in a Ca(2+)-free external medium.
采用膜片钳技术研究了人肾上腺原代培养的球状带细胞的离子电流。描述了两种外向钾电流和两种内向钙电流。瞬时外向钾电流在电位正于 -40 mV 时激活，并表现出明显的时间依赖性失活。它被 4-氨基吡啶阻断，但不被四乙铵阻断。第二种外向电流在去极化开始时迅速激活，然后缓慢增加，无时间依赖性失活。瞬时内向 T 型钙电流在电位正于 -60 mV 时激活，在 -30 mV 时具有最大电流幅度，在 +40 mV 时电流为零；对于膜电位正于 -40 mV 时，它完全失活。T 型通道的药理学研究表明，Ni2+ 是一种有效的阻滞剂，但该通道对二氢吡啶不敏感。持久内向钙电流在电位正于 -20 mV 时激活，在 +70 mV 时具有最大电流幅度。该电流被激动剂 Bay K 8644 增强，被拮抗剂硝苯地平阻断；此外，它被 Cd2+ 阻断，但对 Ni2+ 不太敏感。这项研究表明，人肾上腺球状带细胞表现出与大鼠和牛细胞中发现的钾电流和钙电流相似。此外，醛固酮分泌的主要刺激物促肾上腺皮质激素和血管紧张素 II 可诱导醛固酮分泌增加，而在无钙的细胞外培养基中这种增加受到抑制。
