Microsomal monooxygenase system in frog livers

Liver microsomes prepared from four species of frog, Rana catesbeiana, Rana nigromaculata , Bufo bufo japonicus, and Xenopus laevis, contained cytochrome P-450 and showed NAD(P)H-dependent monooxygenase activities to several foreign chemical compounds tested. The oxidations of the chemical compounds by frog liver microsomes showed significant variations among frog species. The oxidation of 7-ethoxycoumarin was much faster than that by rat liver microsomes. The oxidation of benzo(a)pyrene was significantly induced by 3-methylcholanthrene administration. The monooxygenase activities of frog liver microsomes were more sensitive to cyanide inhibition than those of rat liver microsomes.