Kinetische Analyse von Enzym-Aktivitätssteigerungen durch Barbital und Aminophenazon

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Abstract
The primary effect of barbital is a significant decrease in the activity of liver-UDPG [uridine diphosphate glucose] dehydrogenase, which returns to normal levels within 48 hr. The specific activity never exceeds the normal value. After the 3rd hour, the urinary ascorbic acid excretion and the enzyme activity show parallel behavior. After 24 hr. the liver weight is 21% higher, and after 48 hr. the liver protein content is 26% higher than in the controls. An analogous behavior, with a primary decrease in activity, is shown by liver-UDP-glucuronyltransferase after the administration of aminophenazone. The overall change of enzyme activity and the return to the starting level is about 3 times more rapid than after the administration of barbital. The level of urinary ascorbic acid excretion is independent of the UDP-glucuronyl-transferase activity. The weight and protein content of the liver are not changed. The increase in enzyme activities caused by these "inducer" pharmaceuticals is assumed to be due to a primary, transient inhibition of protein synthesis. The subsequent regulatory reactions are determined by the length of this inhibitory phase and by differences in the half lives of the enzyme proteins.