Genetic control of responsiveness of rat liver supernatant aldehyde dehydrogenase to phenobarbital and 3-methylcholanthrene.

The responsiveness of the hepatic supernatant NAD+-dependent aldehyde dehydrogenase with a high Km value (high Km-AldDH) to phenobarbital (PB) and 3-methylcholanthrene (3-MC) treatment was studied in male rats of three strains; Wistar, Long-Evans, and Sprague-Dawley. A remarkable strain difference in the response of the enzyme to PB or 3-MC was observed. In rats of the Wistar strain the enzyme activity remained unchanged ("non-responsive") in all rats after treatment with PB while it increased ("responsive") 5- to 19-fo-d in all rats after treatment with 3-MC. The enzyme activity increased 8- to 20-fold and 2- to 8-fold respectively after treatment with PB and 3-MC in all rats of the Long-Evans strain. In rats of the Sprague-Dawley strain the enzyme activity remained unchanged in half of all the rats treated with PB or 3-MC and increased 2- to 7-fold over the basal level in half of the treated rats. The non-responsive rats to PB were all responsive to 3-MC treatment while the responsive rats to PB were responsive in 65% and non-responsive in 35% to 3-MC treatment.