Alzamora Rodrigo, Marusic Elisa T, Gonzalez Magdalena, Michea Luis
Laboratory of Cellular and Molecular Physiology, Faculty of Medicine, University of Los Andes, Las Condes 6782468, Santiago, Chile.
Endocrinology. 2003 Apr;144(4):1266-72. doi: 10.1210/en.2002-220950.
Aldosterone increases Na(+),K(+)-adenosine triphophatase (Na(+),K(+)-ATPase) pump activity and abundance under chronic conditions in several tissues, including rat arterial vessels. The present study was undertaken to evaluate whether aldosterone has also short-term effects on the Na(+),K(+)-ATPase of rat aorta. The pump function was measured as ouabain-sensitive (86)Rb/K uptake in aortic rings. Addition of aldosterone induced a rapid inhibition of the Na(+),K(+)-ATPase (57.0 +/- 2.3% of control values; P < 0.05; n = 8), followed by a return to control values after 120 min. The aldosterone-induced decrease in ouabain-sensitive (86)Rb/K uptake was prevented by the new mineralocorticoid receptor antagonist eplerenone. The inhibition of gene transcription (actinomycin D) or protein synthesis (cycloheximide) had no effect on short-term aldosterone action on Na(+),K(+)-ATPase. The rapid aldosterone inhibition was also observed in the presence of monensin, a sodium-specific ionophore. Rapamycin, an immunosuppressive drug that stabilizes the heat shock protein-steroid receptor complex, blocked the rapid aldosterone effect. Bisindole I, an inhibitor of protein kinase C, also blocked nongenomic action of aldosterone on the Na pump. The nongenomic effect of aldosterone was inhibited by disrupters of microtubule (colchicine). Plasma membrane protein biotinylation of aortic segments and Western blot indicated a diminished presence of catalytic isoforms of Na(+),K(+)-ATPase on the cell surface. Our findings indicate that aldosterone has a nongenomic effect on the Na(+),K(+)-ATPase of vascular tissue. This effect is mediated through protein kinase C activation and implies reduced cell surface abundance of catalytic subunits. These observations together with our previous report on chronic hormone replacement suggest that aldosterone is directly involved in ionic cellular homeostasis of the vascular system through Na pump regulation.
在包括大鼠动脉血管在内的多种组织中，醛固酮在慢性条件下会增加钠钾 - 三磷酸腺苷酶（Na⁺,K⁺ - ATPase）的泵活性和丰度。本研究旨在评估醛固酮对大鼠主动脉的钠钾 - 三磷酸腺苷酶是否也有短期影响。泵功能通过主动脉环中哇巴因敏感的⁸⁶Rb/K摄取来测量。添加醛固酮可迅速抑制钠钾 - 三磷酸腺苷酶（为对照值的57.0±2.3%；P<0.05；n = 8），随后在120分钟后恢复到对照值。新型盐皮质激素受体拮抗剂依普利酮可阻止醛固酮诱导的哇巴因敏感的⁸⁶Rb/K摄取减少。基因转录抑制（放线菌素D）或蛋白质合成抑制（环己酰亚胺）对醛固酮对钠钾 - 三磷酸腺苷酶的短期作用没有影响。在存在莫能菌素（一种钠特异性离子载体）的情况下也观察到了醛固酮的快速抑制作用。雷帕霉素是一种稳定热休克蛋白-类固醇受体复合物的免疫抑制药物，可阻断醛固酮的快速作用。双吲哚I是一种蛋白激酶C抑制剂，也可阻断醛固酮对钠泵的非基因组作用。醛固酮的非基因组作用被微管破坏剂（秋水仙碱）抑制。主动脉段的质膜蛋白生物素化和蛋白质印迹表明，钠钾 - 三磷酸腺苷酶催化同工型在细胞表面出现减少。我们的研究结果表明，醛固酮对血管组织的钠钾 - 三磷酸腺苷酶有非基因组作用。这种作用是通过蛋白激酶C激活介导的，意味着催化亚基在细胞表面的丰度降低。这些观察结果与我们之前关于慢性激素替代的报告一起表明，醛固酮通过钠泵调节直接参与血管系统的离子细胞内稳态。
