Effect of inorganic mercury on drug metabolizing enzymes of promethazine-pretreated and phenobarbitone-pretreated male rabbit

Effects of inorganic mercury have been studied on the drug metabolizing enzymes (dme) of phenobarbitone-(pb-) and promethazine-(pm-) pretreated male new zealand white rabbit,oryctolagus cunciculus. after pb treatment,the activities of cytochrome p-450 (cp),aniline hydroxylase (ah),acetanilide hydroxylase (aah),benzphatamine demethylase (bd),aminopyrine demethylase (apd) and n.n dimethyl aniline demethylase (dad) increased 214,266,207,108,81 and 83%,respectively. cytochrome-c-reductase (ccr) also increased 109%. however,the activities of cytochrome b5 (cb) and n.n dimethyl aniline n-oxide (dao) decreased 76% and 38%,respectively. pm administration had no effect on any of the dmes except for ah,aah and bd,which showed 60,5 and 16% increase,respectively. hgcl2 administered at a dose of 1mg/kg body wt per day for 5 days did not affect the cp,cb,apd and ccr. the activities of ah and aah increased 32 and 33%,respectively,whereas those of bd,dad,and dao decreased 35%,30% and 32%,respectively. when administered to pb-pretreated animals cp,ah,aah,bd,apd,dad,ccr,and dao were inhibited 57,58,42,31,56,55,76 and 59%,respectively. activity of cb increased 351%. hgcl2 had no effect on cp and ccr when administered to pm-pretreated animals. ah,aah and cb increased 17,135 and 30%,respectively. bd,apd and dad were reduced 47,10 and 19,respectively. formation of dao was also inhibited 52%. to conclude,mercury drastically interferes with the dme. the metabolism of pb is inhibited,whereas that of pm is variably affected-hydroxylases are up-regulated and demethylases are down-regulated. cb is however,induced 351% after mercury treatment. © copyright 2016 zoological society of pakistan.