Adaptable glucokinase activity of human liver

Abstract

The possible existence of an insulin-dependent dietary adaptation of human hepatic glucokinase was investigated. The feeding of normal voluntary human subjects with a carbohydrate-poor diet for several days caused a considerable decrease in glucokinase activity measured with pieces of liver tissue obtained by needle biopsy. When this diet was substituted with a carbohydrate-rich type, glucokinase activity was restored in the course of 2 days. No consistent variation in hexokinase activity was observed. In correlation with the difference in hepatic glucokinase activity, blood glucose values during intravenous glucose infusion were higher in subjects fed a carbohydrate-poor diet than in those fed a normal mixed diet. No correlation between the activity of glucokinase and the glycogen synthesizing capability of the liver was found. The low activities of hepatic glucokinase of untreated diabetic patients were restored to normal values by treatment with insulin or tolbutamide.