ALTERATION OF GLUTATHIONE TRANSFERASE SUBUNITS COMPOSITION IN THE LIVER OF YOUNG AND AGED RATS SUBMITTED TO HYPOXIC AND HYPEROXIC CONDITIONS

In the present work, we have studied glutathione transferase (GST) act ivity and GST subunits distribution in the liver of young and aged rat s kept under hypoxic or hyperoxic normobaric conditions as model of ox idative stress. A significant decrease of GST activity was detected in young hypoxic rat liver, whereas a significant increase occurred in a ged hypoxic liver. No significant alteration of activity was obtained in both young and aged rat livers subjected to hyperoxic treatment. Su bstrate specificity measurements, SDS/PAGE analysis and reverse-phase HPLC, of GSH-affinity purified fractions were used to study the change s in the GST subunits pattern occurring in the liver of rat as a conse quence of hypoxic and hyperoxic treatment. The results demonstrate tha t young and aged rat liver has a different constitutive GST subunit pa ttern which are markedly and differentially altered in hypoxia or hype roxia. The hyperoxic treatment caused an increase of GST subunit 3 in aged, but not in young liver. In aged liver, both the hypoxic and hype roxic treatment produced a decrease of GST subunit 4. After hypoxic tr eatment GST subunit 3 significantly increased in both young and aged l iver. GST subunit la increased in both young and adult liver after hyp eroxia. Following hypoxia a decrease of subunit la was seen in both yo ung and aged liver. After hypoxic treatment, subunit 6 doubled in youn g, but not in aged, livers. It was concluded that the alterations in G ST subunit expression occurring in the liver as a consequence of hypox ic or hyperoxic treatment respond to the necessity of a better protect ion of liver against the products of oxidative metabolism.