May R C, Bailey J L, Mitch W E, Masud T, England B K
Renal Division, Emory University School of Medicine, Atlanta, Georgia, USA.
Kidney Int. 1996 Mar;49(3):679-83. doi: 10.1038/ki.1996.96.
We have shown that chronic metabolic acidosis in awake rats accelerates whole body protein turnover using stochastic modeling and a continuous infusion of L-[1-13C] leucine. To delineate the role that glucocorticoids play in mediating these catabolic responses, we measured protein turnover in awake, chronically catheterized, adrenalectomized rats in the presence or absence of glucocorticoids and/or a NH4Cl feeding regimen which induced chronic metabolic acidosis. In adrenalectomized rats receiving no glucocorticoids there was no statistical difference in amino acid oxidation, protein degradation or synthesis whether or not the rats had acidosis. In contrast, chronically acidotic, adrenalectomized rats receiving glucocorticoids demonstrated accelerated whole body protein turnover with a 84% increase in amino acid oxidation and a 26% increase in protein degradation, compared to rats not receiving glucocorticoids or those given the same dose of glucocorticoids but without acidosis. We conclude that metabolic acidosis accelerates amino acid oxidation and protein degradation in vivo, and that glucocorticoids are necessary but not sufficient to mediate the catabolic effects of metabolic acidosis.
我们已经表明，利用随机建模和持续输注L-[1-13C]亮氨酸，清醒大鼠中的慢性代谢性酸中毒会加速全身蛋白质周转。为了阐明糖皮质激素在介导这些分解代谢反应中所起的作用，我们在存在或不存在糖皮质激素和/或诱导慢性代谢性酸中毒的氯化铵喂养方案的情况下，测量了清醒的、长期插管的肾上腺切除大鼠的蛋白质周转。在未接受糖皮质激素的肾上腺切除大鼠中，无论大鼠是否患有酸中毒，氨基酸氧化、蛋白质降解或合成均无统计学差异。相比之下，与未接受糖皮质激素的大鼠或接受相同剂量糖皮质激素但无酸中毒的大鼠相比，接受糖皮质激素的慢性酸中毒肾上腺切除大鼠表现出全身蛋白质周转加速，氨基酸氧化增加84%，蛋白质降解增加26%。我们得出结论，代谢性酸中毒会加速体内氨基酸氧化和蛋白质降解，并且糖皮质激素是介导代谢性酸中毒分解代谢作用所必需的，但并不充分。
