title: Mixed-function oxidation in tumors.
abstract: Liver microsomes of the rat contain a group of hydroxylating enzymes which are coupled to a greater or lesser degree to the electron flow system. In our studies, enzymes believed to be directly associated with the electron flow chain of NADPH, ferricyanide reduction, cytochrome c, cytochrome P-450 and substrate hydroxylation have been observed in livers obtained from normal, tumor-bearing and whole body irradiated rats as well as in Morris hepatoma 7777 and dimethyl-amino-biphenyl induced breast tumors.A significant difference appeared to exist in the activity of NADPH oxidase, NADP-ferricyanide reductase and benzopyrene hydroxylase when normal liver was compared with the liver obtained from a breast-tumor-bearing animal. Both cytochrome P-450 and cytochrome b(5) were decreased in the tumor-bearing animal.Tissue distribution of benzopyrene hydroxylase in normal, lactating and tumor-bearing Wistar rats has been studied.With the exception of NADPH oxidase, the activities of NADP-cytochrome c reductase, NADPH-ferricyanide reductase, benzopyrene hydroxylase and P-450 were markedly different in liver from Morris hepatoma 7777-bearing Buffalo rat when this was compared with homologous tissue obtained from normal Buffalo rat.Whole-body irradiated animals showed increased P-450 and NADPH oxidase activity in liver as a function of irradiation and there further appeared to be a correlation with decreased ferricyanide reductase activity.
mesh_terms: D000818:Animals; D001580:Benzopyrenes; D001713:Biphenyl Compounds; D006528:Carcinoma, Hepatocellular / Q000201:enzymology*; D003106:Colon / Q000201:enzymology; D003580:Cytochromes / Q000378:metabolism; D004579:Electron Transport; D005260:Female; D005292:Ferricyanides / Q000378:metabolism; D007668:Kidney / Q000201:enzymology; D007774:Lactation; D008113:Liver Neoplasms / Q000201:enzymology*; D008168:Lung / Q000201:enzymology; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology / Q000528:radiation effects; D006899:Mixed Function Oxygenases / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D009374:Neoplasms, Experimental; D010088:Oxidoreductases / Q000378:metabolism*; D011247:Pregnancy; D011830:Radiation Effects; D051381:Rats
chemical_list: D001580:Benzopyrenes; D001713:Biphenyl Compounds; D003580:Cytochromes; D005292:Ferricyanides; D009249:NADP; D006899:Mixed Function Oxygenases; D010088:Oxidoreductases