Effects of whole-body irradiation on the microsomal enzyme system and on cytochrome P-450 of rat liver.
The rate of oxidative demethylation of ethylmorphine by preparations of microsomes from livers of male rats decreased following whole-body gamma-irradiation, reaching a minimum of 50% of the control value on the 5th or 6th day. The value of apparent Vmax changed markedly after irradiation when the Km value was unaltered. At the same time, the amount of cytochrome P-450 also decreased. For cytochrome P-450, the spectral change induced by ethylmorphine and the Ks value were not altered significantly. The reduced rate of oxidative demethylation may be explained partially by the reduction of cytochrome P-450 concentration. The radiation-induced peroxidation of microsomal lipids was also measured in this study.
D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000528:radiation effects*; D005037:Ethylmorphine-N-Demethylase / Q000528:radiation effects; D005720:Gamma Rays; D008054:Lipid Peroxides / Q000096:biosynthesis; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism / Q000528:radiation effects*; D051381:Rats; D011919:Rats, Inbred Strains
D008054:Lipid Peroxides; D008315:Malondialdehyde; D003577:Cytochrome P-450 Enzyme System; D005037:Ethylmorphine-N-Demethylase