Effect of dietary protein on bed-rest-related changes in whole-body-protein synthesis.
To determine whether increasing dietary protein could exert a beneficial effect on bed-rest-related protein catabolism, two groups of normal subjects were subjected to 7 d of bed rest while taking isocaloric diets containing either 0.6 or 1.0 g protein.kg body wt-1.d-1. Whole-body-leucine turnover, leucine oxidation, and nonoxidative leucine disappearance were measured by use of a constant infusion of 1-13C-leucine. Before bed rest, the higher-protein diet resulted in a 14% decrease in whole-body-leucine turnover and a 28% decrease in leucine oxidation, but net nonoxidative leucine disappearance was not different on the two diets. A 24% decrease in nonoxidative leucine disappearance was seen in subjects assigned to the lower-protein diet, who had been on bed rest, but on the higher-protein diet, leucine kinetics were unchanged by bed rest. Bed rest does not cause an increase in whole-body-protein breakdown, but decreased whole-body-protein synthesis is demonstrable when dietary protein is low. This decrease is prevented by a higher dietary amount of protein.
Stuart
C A
CA
Metabolism Unit, Shriners Burns Institute, Galveston, TX.
Shangraw
R E
RE
Peters
E J
EJ
Wolfe
R R
RR
D000328:Adult; D001510:Bed Rest; D004044:Dietary Proteins / Q000494:pharmacology*; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D007930:Leucine / Q000378:metabolism; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D014176:Protein Biosynthesis; D011488:Protein Deficiency / Q000378:metabolism
D004044:Dietary Proteins; D007328:Insulin; D007930:Leucine; D009584:Nitrogen