Some effects of methyl linoleate hydroperoxide on oxidative phosphorylation in rat liver mitochondria

Dysbaric osteonecrosis (caisson disease of bone): are active oxygen species and the endocrine system responsible, and can control of the production of free radicals and their reaction products confer protection?

The development of osteonecrosis after exposure to altered air pressures is consistent with cellular injury brought about by active oxygen species. The syndrome is considered to arise as a result of an unusual combination of circumstances in which hyperoxia itself, together with the additive responses of the endocrine system to hyperoxia, hypothermia and exertion, each appear to play a part; the net result is thought to increase the mitochondrial generation of superoxide. It is suggested that effective prophylaxis may be possible primarily by establishing a nutritional status that is adequate to ensure that the functional activities of radical-scavenging systems are not hampered by deficiencies either of essential trace elements or of vitamin E. Pharmacological pretreatments designed both to decrease excessive levels of superoxide through increased catalysis of anionic dismutation and to attenuate enzyme-dependent peroxidation may provide an additional line of defence.

Subcellular distribution of the cytochrome P-450 complex and glutathione peroxidase activity in vitamin E and essential fatty acid deficiency

Glutathione peroxidase (EC 1.11.1.9.) (GSHPx) and P-450 activity were measured in hepatic mitochondrial and microsomal fractions from rats deficient in vitamin E and/or essential fatty acids (EFA). The data were compared to corresponding normal values. GSHPx was significantly decreased in the mitochondrial matrix from animals in all 3 deficiency states. In vitamin E deficiency, a non-significant decreased GSHPx activity was found in mitochondrial membranes. Opposite to these findings, GSHPx was significantly increased in mitochondrial membranes of EFA-deficient animals. In combined EFA and vitamin E deficiency, the mitochondrial membrane GSHPx activity was only insignificantly increased. The P-450 complex activity was not detectable in the mitochondrial matrix. In mitochondrial membranes and microsomes, the P-450 complex activity changed parallel to the GSHPx activity.