Hypercortisolemia alters muscle protein anabolism following ingestion of essential amino acids

• Published in: American journal of physiology: endocrinology and metabolism Vol. 284; no. 5; p. E946
• Main Authors: Paddon-Jones, Douglas, Sheffield-Moore, Melinda, Creson, Daniel L, Sanford, Arthur P, Wolf, Steven E, Wolfe, Robert R, Ferrando, Arny A
• Format: Journal Article
• Language: English
• Published: United States 01-05-2003
• Subjects: Administration, Oral; Adult; Amino Acids, Essential - administration & dosage; Amino Acids, Essential - pharmacokinetics; Blood Glucose - analysis; Female; Humans; Hydrocortisone - blood; Hydrocortisone - urine; Insulin - blood; Leg - blood supply; Male; Muscle Proteins - metabolism; Muscle, Skeletal - metabolism; Osmolar Concentration; Phenylalanine - metabolism; Regional Blood Flow; NASA Discipline Musculoskeletal; NASA Discipline Regulatory Physiology; Non-NASA Center
• ISSN: 0193-1849
• DOI: 10.1152/ajpendo.00397.2002

Debilitating injury is accompanied by hypercortisolemia, muscle wasting, and disruption of the normal anabolic response to food. We sought to determine whether acute hypercortisolemia alters muscle protein metabolism following ingestion of a potent anabolic stimulus: essential amino acids (EAA). A 27-h infusion (80 microg. kg(-1). h(-1)) of hydrocortisone sodium succinate mimicked cortisol (C) levels accompanying severe injury (>30 microg/dl), (C + AA; n = 6). The control group (AA) received intravenous saline (n = 6). Femoral arteriovenous blood samples and muscle biopsies were obtained during a primed (2.0 micromol/kg) constant infusion (0.05 micromol. kg(-1). min(-1)) of l-[ring-(2)H(5)]phenylalanine before and after ingestion of 15 g of EAA. Hypercortisolemia [36.5 +/- 2.1 (C + AA) vs. 9.0 +/- 1.0 microg/dl (AA)] increased postabsorptive arterial, venous, and muscle intracellular phenylalanine concentrations. Hypercortisolemia also increased postabsorptive and post-EAA insulin concentrations. Net protein balance was blunted (40% lower) following EAA ingestion but remained positive for a greater period of time (60 vs. 180 min) in the C + AA group. Thus, although differences in protein metabolism were evident, EAA ingestion improved muscle protein anabolism during acute hypercortisolemia and may help minimize muscle loss following debilitating injury.