Adaptations of glutathione antioxidant system to endurance training
are tissue and muscle fiber specific.
Leeuwenburgh, Christiaan, John Hollander, Steve Leichtweis, Margaret
Griffiths, Mitch Gore, and Li Li Ji.
Department of Kinesiology, University of Wisconsin-Madison,
Madison, WI 53706
APStracts 3:0316R, 1996.
The effect of endurance training on glutathione (GSH) status and
antioxidant enzyme system was investigated in skeletal muscle, heart,
and liver of female Sprague-Dawley rats pair-fed an isocaloric diet.
Ten weeks of treadmill training (25 m/min, 10% grade for 2 h/day, 5
days/wk) increased citrate synthase activity in the deep vastus
lateralis (DVL) and soleus muscles by 79 and 39 %, respectively
(P<0.01), but not in the heart or liver. In DVL, GSH content was
increased 33% (P<0.05) with training, accompanied by a 64%
(P<0.05) increase in glutamate content but no change in
cysteine. Trained rats showed a 62 and 27% higher GSH peroxidase
(GPX) and superoxide dismutase (SOD) activity, respectively
(P<0.05), in DVL compared to control rats. In contrast, GSH
content and glutathione reductase (GR) activity in soleus declined
with training (P<0.05), whereas activities of GPX and SOD
remained unchanged. Training did not alter GSH status in the liver or
plasma, but significantly decreased the GSH: glutathione disulfide
ratio in the heart. In addition, GR activity in the liver and GSH
sulfur-transferase activity in the heart and DVL were significantly
lower in the trained vs. control rats. DVL muscle had three-fold
higher [tau]-glutamyltranspeptidase activity compared to other
tissues, however, no significant alteration was observed in the
activity of [tau]-glutamyltranspeptidase and [tau]-glutamylcysteine
synthetase in the liver, heart, or skeletal muscle. These data
indicate that endurance training can cause tissue and muscle fiber
specific adaptation of antioxidant systems and that GSH homeostasis
in extrahepatic tissues may be determined by utilization and uptake
of GSH via the [tau]-glutamyl cycle.
Received 24 January 1996; accepted in final form 24 July 1996.
APS Manuscript Number R38-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996