ISSN:
1432-0738
Schlagwort(e):
N-Nitrosamine
;
Cytochrome P-450
;
Rat
;
Phenobarbital
;
β-Naphthoflavone
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Medizin
Notizen:
Abstract Five cytochrome P-450 forms were purified from livers of rats pretreated with phenobarbital (PB) or β-naphthoflavone (BNF), and the oxidative dealkylation of N-nitrosodialkylamines by the reconstituted cytochrome P-450 systems was measured. PB-II (P450IIB1) showed very high N-nitrosomethybutylamine (NMBA) debutylase activity, high NMBA demethylase activity and high N-nitrosomethyl-benzylamine (NMBeA) debenzylase activity, suggesting that the increase following PB treatment in hepatic microsomal NMBA debutylation and NMBeA debenzylation was due to the induction of PB-II. BNF-H (P450IA2) showed very high NMBA debutylase and high NMBeA debenzylase activities, and BNF-L (P450IA1) showed NMBA debutylase and high NMBeA debenzylase activities. These results suggested that the increase by BNF pretreatment in hepatic microsomal NMBA debutylation was due mainly to the induction of BNF-H and in some part to that of BNF-L. PB-II also showed very high dealkylation activity of lipophilic N-nitrosodialkylamines with long alkyl moieties. On the other hand, BNF-H dealkylated N-nitrosodipropylamine (NDPA), N-nitrosomethylbutylamine (NMBA) and N-nitrosoethylbutylamine (NEBA) at higher rates than N-nitrosodibutylamine (NDBA). BNF-L dealkylated NEBA at higher rates than NMBeA and NDBA. These results reveal that substrate specificity of each cytochrome P-450 form in N-nitrosodialkylamine metabolism is different from each other and several forms of cytochrome P-450 support each N-nitrosamine dealkylase activity in mammalians.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02342508
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