Regulation of methionine adenosyltransferase activity by the glutathione level in rat liver during ischemia-reperfusion

Hepatic ischemia was induced by clamping the hepatic artery, portal vein, a nd bile duct, After 15 min of ischemia, the hepatic glutathione (GSH) conte nt rapidly decreased. On the other hand, after the start of reperfusion, th e hepatic GSH levels promptly increased and reached a peak at about 1 h, an d thereafter decreased to a minimum level by 2 h. Under such conditions, we examined the changes in the methionine adenosyltransferase (MAT) activity in the liver. Though the time course of MAT activity was somewhat delayed c ompared with that of the hepatic GSH levels, both patterns were substantial ly similar during ischemia-reperfusion, In contrast to the changes in the M AT activity during ischemia-reperfusion, the levels of MAT protein were unc hanged during these periods, When endogenous antioxidant coenzyme Q(10) (Co Q(10)) was administered to rats prior to ischemia, both the reduction in th e MAT activity and hepatic GSH levels induced by ischemia-reperfusion were protected. Our findings suggest that CoQ(10) may post-translationally regul ate the MAT activity via the changes in the GSH level in the liver.