| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 School of Human Movement, Recreation & Performance; Centre for Aging, Rehabilitation, Exercise and Sport Science, Victoria University of Technology, Melbourne, Victoria, Australia
2 Department of Anaesthesia, Austin and Repatriation Medical Centre, Melbourne, Victoria, Australia
3 Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Melbourne, Victoria, Australia
* To whom correspondence should be addressed. E-mail: michael.mckenna{at}vu.edu.au.
The production of reactive oxygen species in skeletal muscle is linked with muscle fatigue. This study investigated the effects of the antioxidant compound N-acetylcysteine (NAC) on muscle cysteine, cystine and glutathione, and on time to fatigue during prolonged, submaximal exercise in endurance athletes. Eight males completed a double-blind, crossover study, receiving NAC or placebo before and during cycling for 45 min at 71%VO2peak, then to fatigue at 92%VO2peak. NAC was intravenously infused at 125 mg.kg-1.h-1 for 15 min, then 25 mg.kg-1.h-1 for 20 min prior to and throughout exercise. Arterialized venous blood was analyzed for NAC, glutathione status and cysteine concentration. A vastus lateralis biopsy was taken pre-infusion, at 45 min exercise and fatigue and analysed for NAC, total glutathione (TGSH), reduced glutathione (GSH) cysteine and cystine. Time to fatigue at 92%VO2peak was reproducible in preliminary trials (CV 5.6±0.6%) and with NAC was enhanced by 26.3±9.1% (NAC 6.4±0.6 vs CON 5.3±0.7 min, P<0.05). NAC increased muscle total and reduced NAC at both 45 min and fatigue (P<0.005). Muscle cysteine and cystine were unchanged during CON, but were elevated above pre-infusion levels with NAC (P<0.001). Muscle TGSH declined (P<0.05) and muscle GSH tended to decline (P=0.06) during exercise. Both were greater with NAC (P<0.05). Neither exercise nor NAC affected whole blood TGSH. Whilst blood GSH was decreased and calculated oxidised glutathione (cGSSG) increased with exercise (P<0.05), both were unaffected by NAC. In conclusion, NAC improved performance in well-trained individuals, with enhanced muscle cysteine and GSH availability a likely mechanism.
This article has been cited by other articles:
|
|
 |
|
  H.-J. Wang, Y.-X. Pan, W.-Z. Wang, I. H. Zucker, and W. Wang NADPH oxidase-derived reactive oxygen species in skeletal muscle modulates the exercise pressor reflex J Appl Physiol, August 1, 2009; 107(2): 450 - 459. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Stav and M. Raz Effect of N-Acetylcysteine on Air Trapping in COPD: A Randomized Placebo-Controlled Study Chest, August 1, 2009; 136(2): 381 - 386. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. F. Ferreira, L. A. A. Gilliam, and M. B. Reid L-2-Oxothiazolidine-4-carboxylate reverses glutathione oxidation and delays fatigue of skeletal muscle in vitro J Appl Physiol, July 1, 2009; 107(1): 211 - 216. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. T. Murphy, I. Medved, M. J. Brown, D. Cameron-Smith, and M. J. McKenna Antioxidant treatment with N-acetylcysteine regulates mammalian skeletal muscle Na+-K+-ATPase {alpha} gene expression during repeated contractions Exp Physiol, December 1, 2008; 93(12): 1239 - 1248. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. K. Powers and M. J. Jackson Exercise-Induced Oxidative Stress: Cellular Mechanisms and Impact on Muscle Force Production Physiol Rev, October 1, 2008; 88(4): 1243 - 1276. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. E. R. Philipp, M. Schmidt, C. Gsottbauer, A. M. Sanger, and D. Abele Size- and age-dependent changes in adductor muscle swimming physiology of the scallop Aequipecten opercularis J. Exp. Biol., August 1, 2008; 211(15): 2492 - 2501. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. F. Ferreira and M. B. Reid Muscle-derived ROS and thiol regulation in muscle fatigue J Appl Physiol, March 1, 2008; 104(3): 853 - 860. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. J. McKenna, I. Medved, C. A. Goodman, M. J. Brown, A. R. Bjorksten, K. T. Murphy, A. C. Petersen, S. Sostaric, and X. Gong N-acetylcysteine attenuates the decline in muscle Na+,K+-pump activity and delays fatigue during prolonged exercise in humans J. Physiol., October 1, 2006; 576(1): 279 - 288. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Sahlin, J. S. Nielsen, M. Mogensen, and M. Tonkonogi Repeated static contractions increase mitochondrial vulnerability toward oxidative stress in human skeletal muscle J Appl Physiol, September 1, 2006; 101(3): 833 - 839. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
