CHANGES IN THE MALE-RAT HEPATIC CYTOCHROME-P-450 LEVEL, HEME OXYGENASE AND DELTA-AMINOLEVULINIC-ACID SYNTHASE ACTIVITIES AT VARIOUS STAGES OF LIFE

delta-Aminolevulinic acid synthase and heme oxygenase are closely func tionally connected with the hepatic microsomal mixed function oxydase system. There is a wide range of changes in microsomal heme oxygenase activity, cytochrome P-450 level and mitochondrial delta-aminolevulini c acid synthase activity in rat livers at various stages of life. We t ried to investigate the spontaneous phases of these enzymatic protein activities and the levels of cytochrome P-450 as a function of age. We noted that each of these proteins change their activity and level ver y characteristically during the rats' lifetime. However, correlations between heme oxygenase activity, delta-aminolevulinic acid synthase ac tivity and cytochrome P-450 levels still need to be investigated to el ucidate the mechanism of these connections.