Beaufrere B, Horber F F, Schwenk W F, Marsh H M, Matthews D, Gerich J E, Haymond M W
Department of Pediatrics, Mayo Clinic, Rochester, Minnesota 55905.
Am J Physiol. 1989 Nov;257(5 Pt 1):E712-21. doi: 10.1152/ajpendo.1989.257.5.E712.
High-dose glucocorticoid treatment results in protein wasting. To determine whether such therapy affects leucine oxidation in the postabsorptive state and the disposal of dietary amino acids, eight normal subjects were studied twice in random order, once after 5 days of prednisone (20 mg three times daily) and on a second occasion without prednisone as a control. In the postabsorptive state prednisone therapy increased (P less than 0.05) plasma concentrations of leucine, alpha-ketoisocaproate, glucose, insulin, and C-peptide, as well as leucine carbon flux and oxidation calculated by means of isotope dilution techniques and [1-13C]leucine. During infusion of a chemically defined meal, total leucine carbon flux and oxidation increased similarly on both study days, but leucine oxidation was greater (P less than 0.01) during prednisone treatment; net leucine balance became positive on the control day but remained negative or zero on the prednisone study day despite higher (P less than 0.05) plasma insulin concentrations. These studies demonstrate that high-dose glucocorticoid treatment impairs the balance of the essential amino acid leucine in both the postabsorptive and absorptive states in humans.
大剂量糖皮质激素治疗会导致蛋白质消耗。为了确定这种治疗是否会影响空腹状态下的亮氨酸氧化以及膳食氨基酸的代谢，八名正常受试者按随机顺序进行了两次研究，一次是在服用泼尼松（每日三次，每次20毫克）5天后，另一次是在不服泼尼松作为对照的情况下。在空腹状态下，泼尼松治疗使亮氨酸、α-酮异己酸、葡萄糖、胰岛素和C肽的血浆浓度升高（P<0.05），同时亮氨酸碳通量和通过同位素稀释技术及[1-13C]亮氨酸计算得出的氧化量也升高。在输注特定化学组成的餐食期间，两天的研究中总亮氨酸碳通量和氧化量均以类似方式增加，但在泼尼松治疗期间亮氨酸氧化量更大（P<0.01）；尽管泼尼松研究日血浆胰岛素浓度较高（P<0.05），但在对照日亮氨酸净平衡变为正值，而在泼尼松研究日亮氨酸净平衡仍为负值或零值。这些研究表明，大剂量糖皮质激素治疗会损害人体在空腹和进食状态下必需氨基酸亮氨酸的平衡。
