Effects of administration of cobalt chloride and cobalt protoporphyrin on delta-aminolevulinate synthase in rat liver.

Cobalt protoporphyrin inhibited the drug-induced increase of delta-aminolevulinate synthase as well as its transfer from the cytosol fraction to the mitochondria in rat liver in a similar way to protoheme. Cobalt chloride given to animals in a large dose exhibited similar effects. Cobalt protoporphyrin was isolated from the liver of rats treated with cobalt chloride. The observed regulatory effects of cobalt chloride with respect to the induction and the intracellular translocation of delta-aminolevulinate synthase may be mediated by cobalt protoporphyrin synthesized in vivo.