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This Article Full Text Full Text (PDF) All Versions of this Article: 292/3/E812    most recent 00300.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Cade, W. T. Articles by Yarasheski, K. E. Search for Related Content PubMed PubMed Citation Articles by Cade, W. T. Articles by Yarasheski, K. E.

Blunted lipolysis and fatty acid oxidation during moderate exercise in HIV-infected subjects taking HAART

¹Department of Medicine, Divisions of Endocrinology, Metabolism, and Lipid Research, ²Geriatrics and Nutritional Science, ³Infectious Disease, and ⁴Program in Physical Therapy, Washington University School of Medicine, St. Louis, Missouri

Submitted 22 June 2006 ; accepted in final form 10 November 2006

The protease inhibitor (PI) ritonavir (RTV) has been associated with elevated resting lipolytic rate, hyperlipidemia, and insulin resistance/glucose intolerance. The purpose of this study was to examine relationships between lipolysis and fatty acid (FA) oxidation during rest, moderate exercise and recovery, and measures of insulin sensitivity/glucose tolerance and fat redistribution in HIV-positive subjects taking RTV (n = 12), HAART but no PI (n = 10), and HIV-seronegative controls (n = 10). Stable isotope tracers [1-¹³C]palmitate and [1,1,2,3,3-²H₅]glycerol were continuously infused with blood and breath collection during 1-h rest, 70-min submaximal exercise (50% O_{2 peak}), and 1-h recovery. Body composition was evaluated using DEXA, MRI, and MRS, and 2-h oral glucose tolerance tests with insulin monitoring were used to evaluate glucose tolerance and insulin resistance. Lipolytic and FA oxidation rates were similar during rest and recovery in all groups; however, they were lower during moderate exercise in both HIV-infected groups [glycerol R_a: HIV + RTV 5.1 ± 1.2 vs. HIV + no PI 5.9 ± 2.8 vs. Control 7.4 ± 2.2 µmol·kg fat-free mass (FFM)^–1·min^–1; palmitate oxidation: HIV + RTV 1.6 ± 0.8 vs. HIV + no PI 1.6 ± 0.8 vs. Control 2.5 ± 1.7 µmol·kg FFM·min, P < 0.01]. Fasting and orally-challenged glucose and insulin values were similar among groups. Lipolytic and FA oxidation rates were blunted during moderate exercise in HIV-positive subjects taking HAART. Lower FA oxidation during exercise was primarily due to impaired plasma FA oxidation, with a minor contribution from lower nonplasma FA oxidation. Regional differences in adipose tissue lipolysis during rest and moderate exercise may be important in HIV and warrant further study.

human immunodeficiency virus; highly active antiretroviral therapy; ritonavir; lipodystrophy; insulin resistance; metabolic syndrome; mass spectrometry