REGULATION OF URINARY ACIDIFICATION

尿液酸化的调节

• 批准号: 2139751
• 负责人: NEIL A KURTZMAN
• 金额: $ 21.07万
• 依托单位: TEXAS TECH UNIVERSITY HEALTH SCIS CENTER
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-01-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2139751
• 关键词: acidity /alkalinity; adrenalectomy; aldosterone; alkalosis; amphotericin B; drug delivery systems; enzyme activity; hormone regulation /control mechanism; hypokalemia; kidney pharmacology; laboratory rabbit; laboratory rat; maleimides; phosphatase inhibitor; potassium; renal tubular transport; renal tubule acidosis; sodium potassium exchanging ATPase; toluene; urine acidity

The research proposed in this application deals with the control of urinary acidification in the collecting tubule (CT). We propose that this process is controlled by two pumps, an H-ATPase and an H-K-ATPase. We will characterize these pumps, both functionally and biochemically. Two hypotheses will be tested. Hypothesis I - Acidification in the CT is mediated by two proton pumps, an H-ATPase and an H-K-ATPase. The experiments testing this hypothesis will be performed in rat and rabbit nephron fragments. Considerable data concerning the H-ATPase is already available, much less is known about the H-K-ATPase. To show that these enzymes mediate distal acidification it is necessary to show that their activities change appropriately with acid-base perturbations and that their inhibition reduces acidification. We will study inhibition of the H-ATPase with bafilomycin A and N-ethylmaleimide; H-K-ATPase activity will be studied using vanadate, SCH28080, or K removal. The roles of aldosterone, K, and Cl in modulating enzyme activity will be examined. Hypothesis II - Inhibition of the H-K-ATPase results in hypokalemic distal renal tubular acidosis. These studies will be performed in rats and will employ clearance techniques, measurement of enzyme activities along the nephron, and functional studies in isolated tubules. We will study the effects of inhibiting the H-K-ATPase with vanadate and SCH28080. New data show, as predicted, that vanadate induces hypokalemic distal renal tubular acidosis. Other models of distal renal tubular acidosis will also be studied. By studying alterations in whole animal acid-base status and acid excretion, enzyme activities, net acidification in isolated tubules, and cell pH recovery when basolateral proton extension is blocked, we hope to elucidate the relationship between ATPase activity and tubular function.

本申请提出的研究涉及控制 集合管（CT）中的尿液酸化。 我们建议 该过程由两个泵控制，即 H-ATP 酶和 H-K-ATP 酶。 我们将从功能和生化两个方面对这些泵进行表征。 将测试两个假设。 假设 I - CT 中的酸化 由两个质子泵介导，即 H-ATP 酶和 H-K-ATP 酶。 这 测试这一假设的实验将在大鼠和兔子中进行 肾单位碎片。 关于 H-ATP 酶的大量数据已经 但对于 H-K-ATP 酶的了解却少之又少。 为了表明这些 酶介导远端酸化，有必要表明它们的作用 活性随酸碱扰动而适当变化，并且 它们的抑制作用减少了酸化。 我们将研究抑制 H-ATP酶与巴弗洛霉素A和N-乙基马来酰亚胺； H-K-ATP酶活性 将使用钒酸盐、SCH28080 或 K 去除进行研究。 的角色 将检查醛固酮、K 和 Cl 在调节酶活性方面的作用。 假设 II - 抑制 H-K-ATP 酶导致低钾血症 远端肾小管酸中毒。 这些研究将在大鼠中进行 并将采用清除技术、酶活性测量 沿着肾单位，以及分离肾小管的功能研究。 我们将 研究用钒酸盐抑制 H-K-ATPase 的效果 SCH28080。 新数据显示，正如预测的那样，钒酸盐会导致低钾血症 远端肾小管酸中毒。其他远端肾小管模型 还将研究酸中毒。 通过研究整个动物酸碱状态和酸的变化 排泄、酶活性、离体小管中的净酸化，以及 当基底外侧质子延伸受阻时，细胞 pH 值恢复，我们希望 阐明 ATPase 活性与肾小管之间的关系 功能。