N-acetylglucosamine-insensitive glucose phosphorylation in isolated hepatocytes from rats fasted for 48 h.

Glucose phosphorylation in isolated hepatocytes was studied by the release of 3H from D-[2-3H]glucose. Glucokinase activity was decreased by fasting rats for 48 h and was further reduced in cells by adding 30 mM GlcNAc, a potent competitive inhibitor. Although this treatment resulted in the loss of more than 97% of glucokinase activity in hepatocytes, glucose phosphorylation proceeded at an appreciable rate. These observations demonstrate the involvement of a high -K0.5 enzyme system in addition to glucokinase in hepatocyte glucose phosphorylation.