The present study examined the effects of oral
reduced glutathione (GSH) supplementation in conjunction with
endurance training on contractile function,
antioxidant defense, and oxidative damage in response to
ischemia-reperfusion (I/R) in rat hearts. Female Sprague-Dawley rats (age 4 mo, n = 72) were randomly assigned to a treadmill-trained (T; 25 m/min, 15% grade, for 75 min/day, 5 days/wk, for 10 wk) or untrained (U) group. Each group was further divided into rats receiving 5 g GSH/kg diet during the final 17 days of training (GSH-S) and control (C) groups. One-half of each group of rats was subjected to I/R by surgical occlusion of the main coronary artery for 45 min, followed by 30-min reperfusion or
sham operation. Left ventriclar (LV) peak systolic pressure (LVSP) and contractility (+dP/dt), measured with a
catheter inserted into the LV via the carotid artery, decreased with I/R in all groups (P < 0.05). However, LVSP with I/R in the T/GSH-S group was 9.5%, 17%, and 18% higher (P < 0.05) than that in the U/GSH-S, T/C, and U/C groups, respectively. +dP/dt with I/R was 19%, 27%, and 29% (P < 0.05) greater in the T/GSH-S group versus the T/C, U/GSH-S, and U/C groups, respectively. I/R decreased heart GSH content by 12-17% (P < 0.05) and increased
oxidized glutathione (
GSSG) by 20-27% (P < 0.05). T/GSH-S hearts showed 15% higher GSH (P < 0.05) and a 32% higher GSH-to-
GSSG ratio (P < 0.05) than the U/C group at the end of I/R. Myocardial
superoxide dismutase, GSH
peroxidase, glutathione reductase, and
gamma-glutamyl transpeptidase activities were increased with treadmill training in both GSH-S and C rats. I/R induced myocardial lipid peroxidation and
lactate dehydrogenase release were attenuated with T/GSH-S treatment. The present data indicate that training in conjunction with dietary GSH supplementation can increase myocardial GSH content and
antioxidant defense capacity, thereby protecting the intact heart against oxidative damage and functional retardation caused by I/R.