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This Article Full Text Full Text (PDF) All Versions of this Article: 93/10/1139    most recent expphysiol.2008.042465v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Dutta, A. Articles by Singh, S. B. PubMed PubMed Citation Articles by Dutta, A. Articles by Singh, S. B. Related Collections Muscle

¹ Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi-110 054, India

The concept of L-carnitine (L-CAR) supplementation to improve muscular performance is based on the role of L-CAR in regulating aerobic metabolism. L-CAR has also been found to attenuate free radical-induced oxidative stress in various pathological conditions. Thus, it was hypothesized that L-CAR may reduce intermittent hypoxia (IH)-induced oxidative stress and thereby benefit skeletal muscle performance. Thirty-six adult male Sprague–Dawley rats were divided into three groups: unexposed control; IH exposed (6 h day^–1 for 7 consecutive days), IH exposed with L-CAR supplementation (100 mg (kg body weight)^–1 day^–1). Electrical stimulation was used to induce six tetanic muscular contractions in the gastrocnemius muscle after completion of exposure. Percentage mean performed work (PW), time of decay to 50% peak force of contraction (T₅₀), and peak force of contraction (F_Peak) were measured during tetanic contractions. Mean frequency (MF) was measured using electromyography between tetanic contractions. Muscle damage was indirectly measured from plasma creatine kinase (CK) and lipid hydroperoxide (LHP) levels. The levels of thiobarbituric acid reactive substances (TBARS), protein carbonyl (PC) and LHP were estimated in the muscle tissue to investigate the efficacy of L-CAR in attenuating oxidative stress. Significant reduction in TBARS, PC and LHP levels and CK activity in the L-CAR-supplemented IH group as compared to the IH placebo group suggests that L-CAR reduces oxidative damage and thereby delays muscular fatigue, which was evident from MF, T₅₀, PW and F_Peak. From these studies, we conclude that L-CAR delays muscle fatigue by the reducing free radical-induced oxidative damage of IH exposure.

(Received 26 February 2008; accepted after revision 9 June 2008; first published online 20 June 2008)
Corresponding author Arkadeb Dutta: Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi-110 054, India. Email: arka_07dutta{at}rediffmail.com