The Effect of Cobalt Chloride Administration on the Synthesis of Hepatic Micr.osomal Cytochrome

Cobalt chloride administration to rats stimulates erythropoesis but inhibits the synthesis of hepatic microsomal P-450 and ethylmorphine N-dealkylase activity by hepatic microsomes. No effect on NADPHcytochrome c reductase activity was observed. Phenobarbital induction of P-450 and ethylmorphine N-demethylation are prevented by simultaneous administration of cobalt chloride but phenobarbital induction of NADPHcytochrome c reductase activity is not affected. Hexobarbital oxidation by the perfused rat liver is also inhibited by prior administration of cobalt chloride. Since cobalt treatment of rats has no effect on hepatic protein synthesis over the course of these experiments, cobalt administration may be valuable as a tool for studying the role(s) of P-450 in various biological reactions.