Influence of Na+ intake on dopamine-induced inhibition of renal cortical Na(+)-K(+)-ATPase.
Influence of Na+ intake on dopamine-induced inhibition of renal cortical Na(+)-K(+)-ATPase.
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DOI：
10.1152/ajprenal.1990.258.1.f52
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
I. Seri;B. Kone;S. Gullans;A. Aperia;B. Brenner;B. Ballermann
中科院分区：
文献类型：
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作者：
I. Seri;B. Kone;S. Gullans;A. Aperia;B. Brenner;B. Ballermann
在大鼠近曲小管细胞胞质溶胶中大量发现的酶L-氨基酸脱羧酶（L-AADC）将L-多巴转化为多巴胺。多巴胺反过来通过抑制Na（+）-K（+）-ATP酶活性抑制近端小管钠转运。我们试图确定大鼠饮食中钠摄入量的变化是否导致多巴胺形成的适应和多巴胺诱导的Na（+）-K（+）-ATP酶抑制。在高盐（HS）饮食的大鼠中，肾皮质L-AADC的最大速度（Vmax）比低盐（LS）饮食的大鼠高78 +/- 19%。酶的米氏常数（Km）保持不变。在肾皮质小管细胞悬液中，L-多巴诱导的哇巴因敏感性耗氧量（QO 2）的抑制作用在HS饮食的大鼠中显著大于LS饮食的大鼠。此外，L-多巴完全抑制了制霉菌素诱导的HS中QO 2的升高，但在LS组中没有。卡比多巴，一种L-AADC的抑制剂，取消了L-多巴诱导的抑制制霉菌素刺激的QO 2在HS大鼠的细胞中，并没有显着的效果在LS大鼠的细胞。与LS大鼠细胞中7 +/- 6 nmol.min-1.mg蛋白-1相比nmol.min-1.ng蛋白-1的L-多巴刺激的K+外流更大。相比之下，哇巴因刺激的K+流出没有组间差异。（250字处删节）
The enzyme L-amino acid decarboxylase (L-AADC), found in abundance in rat proximal tubule cell cytosol, converts L-dopa to dopamine. Dopamine, in turn, suppresses proximal tubule sodium transport by inhibiting Na(+)-K(+)-ATPase activity. We sought to determine whether changes in dietary sodium intake in rats lead to adaptation of dopamine formation and dopamine-induced Na(+)-K(+)-ATPase inhibition. In rats on a high-salt (HS) diet, the maximal velocity (Vmax) of renal cortical L-AADC was 78 +/- 19% higher than that in rats on a low-salt (LS) diet. The Michaelis constant (Km) of the enzyme remained unchanged. In renal cortical tubule cell suspensions the L-dopa-induced inhibition of ouabain-sensitive oxygen consumption (QO2) was significantly greater in rats on HS diet than in rats on LS diet. Furthermore, L-dopa completely inhibited the nystatin-induced rise in QO2 in the HS but not in the LS group. Carbidopa, an inhibitor of L-AADC, abolished the L-dopa-induced inhibition of nystatin-stimulated QO2 in cells from HS rats and was without significant effect in cells from LS rats. L-Dopa-stimulated K+ efflux was greater in cells from HS rats at 28 +/- 1 nmol.min-1.mg protein-1, compared with 7 +/- 6 nmol.min-1.ng protein-1 in cells from LS rats. By contrast, ouabain-stimulated K+ efflux did not differ between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)