Higashihara E, Carter N W, Pucacco L, Kokko J P
Am J Physiol. 1984 May;246(5 Pt 2):F725-31. doi: 10.1152/ajprenal.1984.246.5.F725.
A number of recent studies have suggested that the medullary and papillary collecting ducts possess a high capacity for bicarbonate reabsorption. Because 3H binding studies have suggested the presence of mineralocorticoid receptors along the papillary collecting duct and because clearance studies have suggested that aldosterone affects urinary acidification, we designed a series of clearance and micropuncture studies to examine the role of the papillary collecting duct in final urinary acidification. The studies were conducted in intact and adrenalectomized rats receiving either replacement glucocorticoids alone or glucocorticoids with acute infusion of physiological doses of aldosterone. The results show that under normal acid-base status all rats had a pH profile along the papillary collecting duct with more terminal portions being more acidic than the proximal portions. This decreasing pH profile was diminished in acidotic adrenalectomized rats but returned to normal with acute administration of aldosterone. In all cases the luminal potential difference was slightly positive and did not change with adrenalectomy or administration of aldosterone. These results demonstrate that the papillary collecting duct participates in the generation of maximal urinary pH gradient and that this process is partly influenced by aldosterone.
最近的一些研究表明，髓质和乳头集合管对碳酸氢盐的重吸收能力很强。由于³H结合研究提示乳头集合管存在盐皮质激素受体，且清除率研究表明醛固酮会影响尿液酸化，我们设计了一系列清除率和微穿刺研究，以探讨乳头集合管在最终尿液酸化中的作用。这些研究在完整大鼠和肾上腺切除大鼠中进行，这些大鼠单独接受替代糖皮质激素或接受糖皮质激素并急性输注生理剂量的醛固酮。结果表明，在正常酸碱状态下，所有大鼠沿乳头集合管的pH分布情况是，更靠近末端的部分比近端部分更偏酸性。这种pH降低的分布情况在酸中毒的肾上腺切除大鼠中减弱，但在急性给予醛固酮后恢复正常。在所有情况下，管腔电位差均略为正值，且不因肾上腺切除术或给予醛固酮而改变。这些结果表明，乳头集合管参与了最大尿液pH梯度的形成，且这一过程部分受醛固酮影响。
