RESUMO
Heme-nonapeptide, derived from cytochrome c, inhibited both the NADPH- and NADH-dependent lipid peroxidation of brain microsomes but, in the case of liver microsomes, this inhibitory effect manifested itself in the presence of SKF-525A (a specific blocker of cytochrome P-450) only. Heme-nonapeptide prevented the transient accumulation of lipid peroxides in microsomes during lipid peroxidation. The oxygen consumption of microsomes in the presence of NADPH or NADH was stimulated by heme-nonapeptide. From these results we concluded that, in vitro, there are two independent mechanisms of lipid peroxidation in liver microsomes. It is suggested that, in vivo, the heme-peptide-sensitive mechanism, observed in brain microsomes, is more important.
Assuntos
Encéfalo/metabolismo , Grupo dos Citocromos c/metabolismo , Citocromos c , Heme/metabolismo , Peróxidos Lipídicos/metabolismo , Microssomos Hepáticos/metabolismo , Microssomos/metabolismo , Fragmentos de Peptídeos/metabolismo , Animais , Grupo dos Citocromos c/farmacologia , Heme/farmacologia , Cinética , NAD/metabolismo , NADP/metabolismo , Consumo de Oxigênio , Fragmentos de Peptídeos/farmacologia , Ratos , Ratos EndogâmicosRESUMO
Heme-nonapeptide inhibits NADH and NADPH dependent lipid peroxidation of brain microsomes in the presence or absence of ADP-Fe complex. The transient accumulation of lipid peroxides during NADH or NADPH dependent, ADP-Fe stimulated lipid peroxidation, is inhibited by heme-nonapeptide. Oxygen consumption of brain microsomes in the presence of NADH or NADPH is stimulated by heme-nonapeptide. Reduction of cytochrome-c and nitro-tetrazolium-blue by O2- generated by xanthine oxidase is inhibited by heme-nonapeptide.