Increase of liver heme concentration after the administration of insulin, glucagon and dibutyryl cyclic AMP to rats and its relevance to regulation of δ-aminolevulinate synthase

The administration of either insulin, glucagon or dibutyryl cyclic AMP to rats significantly decreases the activity of δ-aminolevulinate synthase in liver mitochondria. The administration of those substances was found to also cause a considerable increase in the degree of heme saturation of tryptophan pyrrolase, suggesting the increase in liver heme concentration. The regulatory effects of those substances on δ-aminolevulinate synthase may be well accounted for by the increase in liver heme concentration.