Non-protein thiols (NP-SH) and the activities of the glutathione statu
s-regulating enzymes gamma-glutamylcysteine synthetase (G-GCS), gamma-
glutamyl transpeptidase (G-GT) and glutathione reductase (GR) were ass
essed in perfused rabbit hearts subjected to severe (60 min) or mild (
7 min) total ischemia and 30 min reperfusion, Severe ischemia signific
antly decreased NP-SH, which were further depressed on reperfusion tog
ether with a significant decline in G-GCS activity; G-GT and GR activi
ties were unchanged, Specific analytes were unaffected by mild ischemi
a-reperfusion. Thus, impaired enzymatic biosynthesis of GSH is operati
ve in the reperfused rabbit myocardium after 60 min ischemia, This phe
nomenon may favour myocardial GSH depression and oxidative reperfusion
injury after severe ischemia.