Whole-body protein turnover from leucine kinetics and the response to nutrition in human immunodeficiency virus infection.
Whole-body protein metabolism was investigated in human immunodeficiency virus (HIV) infection by primed constant infusion of L-[1-13C]leucine in 8 control and 22 HIV-infected subjects (8 stage II; 14 stage IV disease), in postabsorptive and fed states. Postabsorptive leucine flux was increased 25% in subjects with stage IV HiV infection vs that in control subjects (130 +/- 13 vs 103 +/- 10 mumol leucine.kg-1.h-1, P < 0.001); both leucine disposal by protein synthesis (111.6 +/- 12.1 vs 82.3 +/- 9.2, P < 0.001) and release by protein degradation (129.7 +/- 13.1 vs 103.4 +/- 10.2, P < 0.001) were increased. No difference in leucine balance or oxidation was found but fat oxidation was greater in subjects with HIV infection (61.1 +/- 13.0% of energy) than in control subjects (47.6 +/- 13.7% of energy, P < 0.025). Stage II subjects had intermediate values of leucine flux, not significantly different from those of control subjects. Provision of parenteral nutrition for 4 h increased leucine flux with a switch in leucine balance from net loss to net gain; this response was quantitatively similar in all groups. HIV infection increases whole-body protein turnover but does not quantitatively impair the acute anabolic response to intravenous nutrition.
Macallan
D C
DC
Department of Cellular and Molecular Sciences, St George's Hospital Medical School, London, UK.
McNurlan
M A
MA
Milne
E
E
Calder
A G
AG
Garlick
P J
PJ
Griffin
G E
GE
D000328:Adult; D002247:Carbon Isotopes; D004734:Energy Metabolism; D015658:HIV Infections / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D007930:Leucine / Q000378:metabolism* / Q000493:pharmacokinetics*; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D009747:Nutritional Physiological Phenomena; D010084:Oxidation-Reduction; D010288:Parenteral Nutrition; D011506:Proteins / Q000378:metabolism*; D011863:Radioimmunoassay; D015431:Weight Loss / Q000502:physiology
D002247:Carbon Isotopes; D011506:Proteins; D007930:Leucine