Jakobsson B, Larsson S H, Wieslander A, Aperia A
Department of Pediatrics, Huddinge Hospital, Sweden.
Acta Physiol Scand. 1990 May;139(1):9-13. doi: 10.1111/j.1748-1716.1990.tb08891.x.
Ouabain-sensitive (OS) O2 consumption was determined in proximal tubular cells from weanling rats fed 21% (normal-protein, NP) or 50% (high-protein, HP) protein diet for 4 days. Butyric acid 10(-3)M was added as a substrate for mitochondrial respiration and the ionophore amphotericin B (10 micrograms ml-1) was used to sodium-load the cells. OS respiration was higher in HP than in NP cells in both DME and amino acid-free electrolyte solution (ES). Amphotericin B significantly increased OS respiration in both NP and HP cells, implying that the Na-K pump was activated by increased intracellular Na. In cells incubated in ES, addition of amino acids stimulated OS respiration significantly in HP cells (16.9 +/- 1.4 vs 21.2 +/- 1.1 nmol min-1 mg-1 protein) and in NP cells (13.9 +/- 0.3 vs 14.9 +/- 0.6 nmol min-1 mg-1 protein). Stimulation was significantly higher in HP cells (26 +/- 4%) than in NP cells (7 +/- 4%) (P less than 0.001). The amino acids did not stimulate ouabain-insensitive respiration. The results indicate that an HP diet to weanling rats will increase proximal tubule cell Na, K-ATPase-dependent respiration by enhancing Na entry via the Na-amino acid symports.
对喂食21%（正常蛋白，NP）或50%（高蛋白，HP）蛋白饮食4天的断奶大鼠近端肾小管细胞中的哇巴因敏感（OS）耗氧量进行了测定。添加10⁻³M丁酸作为线粒体呼吸的底物，并使用离子载体两性霉素B（10微克/毫升）使细胞钠负荷增加。在DME和无氨基酸电解质溶液（ES）中，HP细胞中的OS呼吸均高于NP细胞。两性霉素B显著增加了NP和HP细胞中的OS呼吸，这意味着Na-K泵被细胞内钠增加所激活。在ES中孵育的细胞中，添加氨基酸可显著刺激HP细胞（16.9±1.4对21.2±1.1纳摩尔/分钟·毫克⁻¹蛋白）和NP细胞（13.9±0.3对14.9±0.6纳摩尔/分钟·毫克⁻¹蛋白）中的OS呼吸。HP细胞中的刺激作用（26±4%）显著高于NP细胞（7±4%）（P<0.001）。氨基酸不会刺激哇巴因不敏感的呼吸。结果表明，给断奶大鼠喂食高蛋白饮食将通过增强经由钠-氨基酸同向转运体的钠内流来增加近端小管细胞中依赖钠、钾-ATP酶的呼吸。
