[The effect of pyridine and pyridine-N-oxide on the monooxygenase system of rat liver microsomes].

Effects of pyridine and pyridine-N-oxide on the monooxygenase system of rat liver microsomes have been studied. Pyridine (200 mg/kg) increased total cytochrome P-450 content and activated metabolism of some specific substrates 24 hours after injection. There was an increase in the degree of p-nitrophenol and chlorzoxazone hydroxylation due to increasing ethanol-induced cytochrome P-450IIE1 content. Pyridine was also able to induce cytochrome P-450IIB1 in rat microsomes; this reaction was accompanied by acceleration of 7-pentoxyresorufin 0-dealkylation. Cytochrome P-450IA1 appearance in liver microsomes was associated with increasing content of cytochrome P-450IA2. Dealkylation rates for specific substrates (7-ethoxyresorufin and 7-methoxyresorufin) were also increased. Similar to pyridine, pyridine-7-oxide induced cytochromes P-450IIE1, P-450IIB1/B2, and P-450IA1/A2, resulting in activation of specific substrate metabolism. Hence, pyridine and its derivative pyridine-N-oxide can be regarded as effective inducers of cytochrome P-450.