Elliott M E, Siegel F L, Hadjokas N E, Goodfriend T L
Endocrinology. 1985 Mar;116(3):1051-9. doi: 10.1210/endo-116-3-1051.
We investigated the role of cellular calcium pools in angiotensin II-stimulated aldosterone synthesis in bovine adrenal glomerulosa cells. Angiotensin II decreased the size of the exchangeable cell calcium pool by 34%, consistent with previous observations that angiotensin II causes decreased uptake of 45Ca+2 into cells and increased efflux of 45Ca+2 from preloaded cells. Atomic absorption spectroscopy showed that angiotension II caused a decrease of 21% in total cellular calcium. Angiotensin II caused efflux of 45Ca+2 in the presence of EGTA and retarded uptake of 45Ca+2 when choline was substituted for sodium, suggesting that hormone effects on calcium pools do not involve influx of trigger calcium or sodium. Cells incubated in calcium-free buffer and 0.1 mM or 0.5 mM EGTA synthesized reduced (but still significant) amounts of the steroid in response to hormone. Cells incubated in increasing concentrations of extracellular calcium contained increasing amounts of intracellular calcium and synthesized increasing amounts of aldosterone in response to angiotensin II. These results point to the participation of intracellular calcium pools in angiotensin II-stimulated steroidogenesis and the importance of extracellular calcium in maintaining these pools.
我们研究了细胞钙库在牛肾上腺球状带细胞中血管紧张素II刺激醛固酮合成过程中的作用。血管紧张素II使可交换细胞钙库的大小减少了34%，这与之前的观察结果一致，即血管紧张素II导致细胞对45Ca+2的摄取减少以及预加载细胞中45Ca+2的外流增加。原子吸收光谱显示血管紧张素II使细胞总钙含量降低了21%。在存在乙二醇双四乙酸（EGTA）的情况下，血管紧张素II导致45Ca+2外流，并且当用胆碱替代钠时，45Ca+2的摄取受到抑制，这表明激素对钙库的影响不涉及触发钙或钠的内流。在无钙缓冲液以及0.1 mM或0.5 mM EGTA中孵育的细胞，对激素的反应是合成的类固醇量减少（但仍显著）。在细胞外钙浓度不断增加的环境中孵育的细胞，细胞内钙含量增加，并且对血管紧张素II的反应是合成的醛固酮量增加。这些结果表明细胞内钙库参与了血管紧张素II刺激的类固醇生成过程，以及细胞外钙在维持这些钙库中的重要性。
