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The Catabolic Effects of Prolonged Inactivity and Acute Hypercortisolemia Are Offset by Dietary Supplementation

2005; Oxford University Press; Volume: 90; Issue: 3 Linguagem: Inglês

10.1210/jc.2004-1702

1945-7197

Douglas Paddon‐Jones, Melinda Sheffield‐Moore, Randall J. Urban, Asle Aarsland, Robert R. Wolfe, Arny A. Ferrando,

Clinical Nutrition and Gastroenterology

We compared the anabolic stimulus provided by an essential amino acid and carbohydrate (AA/CHO) supplement to a mixed clinical meal during bed rest (BR) and episodic hypercortisolemia (∼24 μg·dl−1). In the experimental (EXP; n = 7) and control (CON; n = 6) groups, femoral arteriovenous blood samples and vastus lateralis biopsy samples were obtained during a primed constant infusion of l-[ring-2H5]phenylalanine and a 14-h infusion of hydrocortisone sodium succinate (60 μg·kg·h−1) before (pre-BR) and after (post-BR) 28 d of BR. Muscle protein kinetics were calculated during the postabsorptive state, for 2.5 h after ingestion of a meal and for 2.5 h after ingestion of an AA/CHO supplement (EXP) or placebo (CON). Postabsorptive net phenylalanine balance values were as follows: EXP, −35.14 ± 2.93, and CON, −32.60 ± 6.65 (pre-BR); and EXP, −32.91 ± 5.67, and CON, −30.43 ± 6.28 nmol phe·ml−1·100 ml leg volume−1 (post-BR). After AA/CHO supplementation, net phenylalanine balance improved to 33.51 ± 8.06 (pre-BR) and 24.15 ± 11.4 nmol phe·ml−1·100 ml leg volume−1 (post-BR), but remained negative after the meal. Cumulative 5.5-h mixed muscle fractional synthetic rate was greater in the EXP group pre-BR (EXP, 0.108 ± 0.01, and CON, 0.073 ± 0.04%·h−1) and post-BR (EXP, 0.111 ± 0.015, and CON, 0.05 ± 0.002%·h−1). Unlike a typical clinical meal, AA/CHO supplementation stimulated net muscle protein synthesis despite acute hypercortisolemia and prolonged inactivity.