Age-dependent ultrastructural alterations and biochemical response of rat skeletal muscle after hypoxic or hyperoxic treatments

This work deals with the antioxidant enzymatic response and the ultrastruct ural aspects of the skeletal muscle of young and aged rats kept under hypox ic or hyperoxic normobaric conditions. It is in fact well known that the su pply of oxygen at concentrations higher or lower than those occurring under normal conditions can promote oxidative processes that can cause tissue da mage. The enzymes investigated were both those directly involved in reactiv e oxygen species (ROS) scavenging (superoxide dismutase, catalase and selen ium-dependent glutathione peroxidase), and those challenged with the detoxi cation of cytotoxic compounds produced by the action of ROS on biological m olecules (glutathione transferase, glyoxalase I, glutathione reductase), in order to obtain a comparative view of the defence strategies used with res pect to aging. Our results support the hypothesis that one of the major con tributors to the aging process is the oxidative damage produced at least in part by an impairment of the antioxidant enzymatic system. This makes the aged organism particularly susceptible to oxidative stress injury and to th e related degenerative diseases, especially in those tissues with high dema nd for oxidative metabolism. (C) 1999 Elsevier Science B.V. All rights rese rved.