The Relationship between Delta-Aminolaevulinate Synthetase Induction and the Concentrations of Cytochrome P-450 and Catalase in Rat Liver

Abstract

The porphyrinogenic drug 2-allyl-2-isopropylacetamide causes the degradation of microsomal cytochrome P-450 and inhibits the synthesis of catalase in rat liver. The inhibition of catalase synthesis follows the induction of δ-aminolaevulinate synthetase and the consequent overproduction of haem. The allylisopropylacetamide-mediated breakdown of cytochrome P-450 is a rapid event and has a reciprocal relationship to the pattern of δ-aminolaevulinate synthetase induction. Breakdown of cytochrome P-450 appears to be one of the conditions leading to the `derepression' of δ-aminolaevulinate synthetase.