DYNAMICS OF INTRACELLULAR FREE MG2+ CHANGES IN A VASCULAR SMOOTH-MUSCLE CELL-LINE
DYNAMICS OF INTRACELLULAR FREE MG2+ CHANGES IN A VASCULAR SMOOTH-MUSCLE CELL-LINE
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DOI：
10.1152/ajpheart.1993.265.1.h281
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发表时间：
1993-07-01
影响因子：
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通讯作者：
RABKIN, SW
中科院分区：
文献类型：
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作者：
QUAMME, GA;DAI, LJ;RABKIN, SW
细胞内游离Mg ~（2+）浓度（[Mg ~（2+）]i）与高血压的发病机制有关。Mg 2+可能通过拮抗细胞内Ca 2+浓度而影响血管平滑肌细胞的张力和收缩力。建立大鼠胸主动脉细胞（A10）的细胞系培养在玻璃盖片上，并通过荧光技术与使用mag-fura-2的单细胞上测定[Mg 2 +]i。基础[Mg 2 +]i为0.52 +/- 0.02 mM（n = 15）。血管平滑肌细胞用A23187加5 mM MgCl 2激发以快速升高[Mg 2 +]i。[Mg2+]，在1-2 s内增加到1.03 +/- 0.09 mM的峰值，然后在45-60 s内快速下降到低于基础水平0.30 +/- 0.03 mM，尽管A23187和外部Mg 2+持续存在。Mg 2+挑战快速去除至低于基础水平表明存在细胞内转运机制，可能存在于细胞内区室或细胞器中。空间成像研究表明，Mg 2+是不均匀分布在细胞内的最大变化在核周区，大多数胞质细胞器的面积。钒酸盐是一种P型腺苷三磷酸酶的抑制剂，其抑制去除速率从10.2 +/- 0.9 μ M/s到6.8 +/- 1.0 μ M/s。细胞内Ca 2+动员的抑制剂，毒胡萝卜素，丹曲林，和3，4，5-三甲氧基苯甲酸8（二乙基氨基）辛酯，抑制Mg 2+螯合。Ryanodine和咖啡因对Mg 2+的去除没有影响。钌红不抑制Mg 2+的螯合，但寡霉素B减缓其去除。这些研究表明，血管平滑肌细胞中的[Mg 2 +]i受到涉及细胞内和质膜转运蛋白的活性机制的仔细控制。这种控制的改变可能在异常血管收缩中起作用。
Intracellular free Mg2+ concentration ([Mg2+]i) has been implicated in the pathogenesis of hypertension. It has been postulated that Mg2+ through its antagonistic effects on intracellular Ca2+ concentration may affect tension and contractility of vascular smooth muscle cells. An established cell line of rat thoracic aorta cells (A10) was cultured on glass cover slips, and [Mg2+]i was determined by fluorescent techniques on single cells with the use of mag-fura-2. Basal [Mg2+]i was 0.52 +/- 0.02 mM (n = 15). Vascular smooth muscle cells were challenged with A23187 plus 5 mM MgCl2 to rapidly elevate [Mg2+]i. [Mg2+], increased to a peak of 1.03 +/- 0.09 mM within 1-2 s and then quickly declined to below basal levels, 0.30 +/- 0.03 mM, within 45-60 s despite the continued presence of A23187 and external Mg2+. The rapid removal of the Mg2+ challenge to below basal levels suggests the presence of intracellular transport mechanisms, likely in intracellular compartments or organelles. Spatial imaging studies indicated that Mg2+ is heterogeneously distributed within the cell with the greatest variations in the perinuclear region, the area of most cytosolic organelles. Vanadate, an inhibitor of P-type adenosinetriphosphatases, inhibited the removal rate from 10.2 +/- 0.9 to 6.8 +/- 1.0 muM/s. Inhibitors of intracellular Ca2+ mobilization, thapsigargin, dantrolene, and 3,4,5-trimethoxybenzoic acid 8(diethylamino)octyl ester, inhibited Mg2+ sequestration. Ryanodine and caffeine had no effect on Mg2+ removal. Ruthenium red did not inhibit Mg2+ sequestration, but oligomycin B slowed its removal. These studies demonstrated that [Mg2+]i in vascular smooth muscle cells is carefully controlled by active mechanisms involving intracellular and plasma membrane transporters. Alteration of this control may play a role in aberrant vasoconstriction.