Hypercortisolemia alters muscle protein anabolism following ingestion of essential amino acids.
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.
Paddon-Jones
Douglas
D
Department of Surgery, University of Texas Medical Branch and Metabolism Unit, Shriners Burns Hospital, 815 Market Street, Galveston, TX 77550, USA. djpaddon@utmb.edu
Sheffield-Moore
Melinda
M
Creson
Daniel L
DL
Sanford
Arthur P
AP
Wolf
Steven E
SE
Wolfe
Robert R
RR
Ferrando
Arny A
AA
D000284:Administration, Oral; D000328:Adult; D000601:Amino Acids, Essential / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001786:Blood Glucose / Q000032:analysis; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood* / Q000652:urine; D007328:Insulin / Q000097:blood; D007866:Leg / Q000098:blood supply; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism; D009994:Osmolar Concentration; D010649:Phenylalanine / Q000378:metabolism; D012039:Regional Blood Flow
D000601:Amino Acids, Essential; D001786:Blood Glucose; D007328:Insulin; D009124:Muscle Proteins; D010649:Phenylalanine; D006854:Hydrocortisone