NOXIOUS EFFECTS OF OXYGEN REACTIVE SPECIES ON ENERGY-COUPLING PROCESSES IN WHICH ASCITES TUMOR MITOCHONDRIA AND THE PROTECTION BY PANTOTHENIC-ACID

Irradiation of Ehrlich ascites tumor cells with ultraviolet light or e xposure to the Fenton reaction results in lesions in the mitochondrial energy-coupling system. Formation of the membrane potential and its u tilization for ATP synthesis are more affected than the respiratory ch ain. Preincubation of the cells with pantothenic acid or its derivativ es which can serve as precursors of CoA largely protects against the d amage of mitochondrial energetics by oxygen reactive species formed by UV light or the Fenton reaction, Incubation of Ehrlich ascites tumor cells with pantothenic acid increases their content of glutathione (mo st of which is present in the reduced form) by 40%, It is concluded th at the protective effect of precursors of CoA against lesions of the m itochondrial energy-coupling system by oxygen reactive species is main ly due to removal of free radicals and peroxides by glutathione peroxi dase and phospholipid hydroperoxide glutathione peroxidase.