Protein kinase C-mediated inhibition of renal Ca2+ ATPase by physiological concentrations of angiotensin II is reversed by AT1- and AT2-receptor antagonists
Protein kinase C-mediated inhibition of renal Ca2+ ATPase by physiological concentrations of angiotensin II is reversed by AT1- and AT2-receptor antagonists
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DOI：
10.1016/j.regpep.2004.11.004
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发表时间：
2005-04-15
影响因子：
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通讯作者：
Vieyra, A
中科院分区：
文献类型：
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作者：
Assunçao-Miranda, I;Guilherme, AL;Vieyra, A
血管紧张素II（AngII）增加不同细胞类型中的胞浆Ca 2+浓度。本研究探讨了血管紧张素Ⅱ对纯化的肾近曲小管基底外侧膜Ca ~（2+）ATP酶的影响。这种酶在与ATP水解偶联的反应中将Ca 2+泵出胞质溶胶，并且它负责细胞质Ca 2+活性的精细定时调节。皮摩尔浓度的Ang Ⅱ可抑制Ca ~（2+）-ATP酶的活性，最大抑制作用约为对照值的50%。升高氯沙坦（一种AT（1）受体拮抗剂）或PD 123319（一种AT（2）受体拮抗剂）的浓度（10（-11）至10（-7）M）可逐渐逆转Ang H的抑制作用。磷脂酶C（PLC）抑制剂U-73122（10 - 6 M）和蛋白激酶C（PKC）抑制剂staurosporine（10-7 M）都能阻止Ang H对Ca 2+泵的抑制。用PKC激活剂佛波醇酯12-O-十四烷酰基佛波醇-13-乙酸酯（10（-8）M）孵育先前分离的膜，模拟用Ang H发现的抑制作用，并且化合物的作用不是累加的。总的来说，这些结果表明，Ang H通过在激素与偶联到PLC的氯沙坦和PD 123319敏感性受体结合后激活这些膜中以引发状态存在的PKC系统来抑制Ca 2 +-ATP酶。因此，激酶介导的磷酸化抑制基底外侧膜Ca 2 +-ATP酶似乎是Ang II促进近曲小管细胞胞浆Ca 2+浓度增加的途径之一。(C)2004年由Elsevier B. V.出版
Angiotensin II (Ang II) increases the cytosolic Ca2+ concentration in different cell types. In this study, we investigate the effect of Ang II on the Ca2+ ATPase of purified basolateral membranes of kidney proximal tubules. This enzyme pumps Ca2+ out of the cytosol in a reaction coupled to ATP hydrolysis, and it is responsible for the fine-timed regulation of cytosolic Ca2+ activity. Ca2+-ATPase activity is inhibited by picomolar concentrations of Ang II, with maximal inhibition being attained at approximate to 50% of the control values. The presence of raising concentrations (10(-11) to 10(-7) M) of losartan (an AT(1)-receptor antagonist) or PD123319 (an AT(2)-receptor antagonist) gradually reverts inhibition by Ang H. Both the phospholipase C (PLC) inhibitor U-73122 (10(-6) M) and the inhibitor of protein kinase C (PKC) staurosporine (10-7 M) prevent inhibition of the Ca2+ pump by Ang H. Incubation of the previously isolated membranes with a PKC activator-the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (10(-8) M)-mimics the inhibition found with Ang H, and the effects of the compounds are not additive. Taken as a whole, these results indicate the Ang H inhibits Ca2+-ATPase by activation of a PKC system present in primed state in these membranes after binding of the hormone to losartan- and PD123319-sensitive receptors coupled to a PLC. Therefore, inhibition of the basolateral membrane Ca2+-ATPase by kinase-mediated phosphorylation appears to be one of the pathways by which Ang II promotes an increase in the cytosolic Ca2+ concentration of proximal tubule cells. (C) 2004 Published by Elsevier B.V.