Boross M, Kinsella J, Cheng L, Sacktor B
Am J Physiol. 1986 May;250(5 Pt 2):F827-33. doi: 10.1152/ajprenal.1986.250.5.F827.
The initial rate (5 s) of Na+-dependent inorganic phosphate (Pi) uptake in brush-border membrane vesicles isolated from rat proximal tubule was decreased in metabolic acidosis, 0.42 +/- 0.02 vs. 0.59 +/- 0.05 nmol/mg protein, in vesicles from control animals. Phosphate, ammonium, and Ca2+ excretions were increased 100, 600, and 56%, respectively. These changes in brush-border Pi transport and urinary excretion of ions were largely dependent on intact adrenal glands. After adrenalectomy there were no significant changes in brush-border Pi transport, Pi, and Ca2+ excretion, whereas ammonium excretion increased only 300% compared with controls. When the glucocorticoid dexamethasone was administered to adrenalectomized animals, it mimicked the effects of metabolic acidosis both in the presence and the absence of metabolic acidosis. The initial rate of brush-border Pi transport was decreased by dexamethasone administration to 0.37 +/- 0.04 nmol/mg protein in adrenalectomized acidotic animals and 0.39 +/- 0.03 nmol/mg protein in adrenalectomized animals. Dexamethasone administered to adrenalectomized acidotic animals increased Pi, ammonium, and Ca2+ excretion 190, 690, and 23%, respectively. Dexamethasone administered to nonacidotic adrenalectomized animals increased Pi ammonium and Ca2+ excretion 165, 240, and 31%, respectively. We conclude that changes in Pi, ammonium, and Ca2+ excretion observed during metabolic acidosis were dependent on intact adrenal glands and that glucocorticoids administered to adrenalectomized acidotic or nonacidotic animals mimicked the changes observed in acidotic animals with intact adrenal glands.
从大鼠近端肾小管分离的刷状缘膜囊泡中，依赖钠离子的无机磷酸盐（Pi）摄取的初始速率（5秒）在代谢性酸中毒时降低，对照组动物囊泡的摄取速率为0.59±0.05nmol/mg蛋白质，而代谢性酸中毒动物囊泡的摄取速率为0.42±0.02nmol/mg蛋白质。磷酸盐、铵和钙离子的排泄分别增加了100%、600%和56%。刷状缘Pi转运和离子尿排泄的这些变化在很大程度上依赖于完整的肾上腺。肾上腺切除术后，刷状缘Pi转运、Pi和钙离子排泄没有显著变化，而铵排泄仅比对照组增加300%。当给肾上腺切除的动物注射糖皮质激素地塞米松时，无论是否存在代谢性酸中毒，它都能模拟代谢性酸中毒的作用。给肾上腺切除的酸中毒动物注射地塞米松后，刷状缘Pi转运的初始速率降至0.37±0.04nmol/mg蛋白质，给肾上腺切除的动物注射地塞米松后，刷状缘Pi转运的初始速率降至0.39±0.03nmol/mg蛋白质。给肾上腺切除的酸中毒动物注射地塞米松后，Pi、铵和钙离子排泄分别增加190%、690%和23%。给非酸中毒的肾上腺切除动物注射地塞米松后，Pi、铵和钙离子排泄分别增加165%、240%和31%。我们得出结论，代谢性酸中毒期间观察到的Pi、铵和钙离子排泄变化依赖于完整的肾上腺，给肾上腺切除的酸中毒或非酸中毒动物注射糖皮质激素能模拟在肾上腺完整的酸中毒动物中观察到的变化。
