On the Induction of the Hepatic Tyrosine Aminotransferase by Quinolinic Acid

Abstract

The induction of tyrosine aminotransferase by quinolinic acid is inhibited completely by cycloheximide and by α-araanitin, but only partially during the first 3 hours by 5-azacytidine and 8-azaguanine; longer treatment with 8-azaguanine, however, also prevents the major increase in enzyme activity. The hepatic concentration of cyclic AMP does not change after administration of quinolinic acid. Insulin, like hydrocortisone, acts additively to quinolinic acid. The isoenzyme pattern of tyrosine aminotransferase is not changed considerably during induction by quinolinic acid. Most likely, quinolinic acid acts through its own mechanism of induction.