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| Research article summary (published 27 Feb 2009): |
Effects of acute and chronic exercise on disulfide-linked growth hormone variants.
Full Abstract
PURPOSE: To test the hypothesis that the appearance of disulfide-linked growth hormone (GH) aggregates during and after an acute resistance exercise test (ARET) in men could be influenced by chronic physical training. METHODS: Fourteen men (28 +/- 1 yr) underwent two different 8-wk physical training programs designed to improve military performance. Before and after chronic training, subjects performed an ARET (six sets of 10 repetition-maximum squat) and had venous blood drawn pre-, mid-, and post-ARET (0, 15, and 30 min postexercise). To determine whether GH molecules were disulfide-linked, serum samples were chemically reduced via glutathione (GSH). Serum immunoreactive GH (IRGH) and immunofunctional GH (IFGH) concentrations were determined using two specific immunoassays, in nonreduced (-GSH) and reduced (+GSH) states. Data were analyzed using repeated-measures ANOVA. RESULTS: No differences were observed in the GH responses of the two training programs; therefore, training group data were combined for analysis. GSH reduction increased the mean GH signal (-GSH: 1.4 +/- 0.3 microg x L(-1) vs +GSH: 1.7 +/- 0.3 microg x L(-1); P < 0.01) only when quantifying IRGH. Post hoc testing indicated that serum contained IRGH disulfide-linked GH aggregates at the mid, 0-, 15-, and 30-min posttime points of the ARET (P < 0.01), whereas GSH reduction did not affect IFGH concentrations. Chronic physical training had no effect on the ARET-induced GH response. CONCLUSION: Acute resistance exercise leads to the appearance of disulfide-linked IRGH aggregates, and this response does not appear to be affected by 8 wk of chronic physical training. The physiological significance of increased proportions of disulfide-linked GH aggregates postexercise remains uncertain; however, structural alterations in GH moieties after acute exercise may represent important regulatory steps in mediating GH biological activity at selected target tissues.
Author information
Author/s: Pierce, Joseph R (JR); Tuckow, Alexander P (AP); Alemany, Joseph A (JA); Rarick, Kevin R (KR); Staab, Jeffery S (JS); Harman, Everett A (EA); Nindl, Bradley C (BC);
Affiliation: Military Performance Division, US Army Research Institute of Environmental Medicine, Natick, MA, USA.
Journal and publication information
Publication Type: Journal Article; Randomized Controlled Trial
Journal: Medicine and science in sports and exercise (Med Sci Sports Exerc), published in United States. (Language: eng)
Reference: 2009-Mar; vol 41 (issue 3) : pp 581-7
Dates: Created 2009/02/19; Completed 2009/05/28;
PMID: 19204593, status: MEDLINE (last retrieval date: 5/28/2009, IMS Date: 28 May 2009 00:00:00)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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