Effects of Vanadate on Glucose Production in Rat Hepatocytes Cultured in Vitro

The aim of the study was to determine the effect of vanadate on glucose production in hepatocytes cultured in vitro. Hepatocytes were isolated by the collagenase perfusion technique and cultured for 24 h in M 199 serum-free medium. The glucose production was measured by incubating the cultures in glucose-free HanksHepes medium with the addition of 10 mmol/l pyruvate. The glucose released into the medium was determined enzymatically with glucose oxidase. Glycogenolysis was determined as net decrease in glycogen content during the incubation period. Vanadate alone in a concentration of 1 mmol/l caused a significant (p<0.01) 57% increase of glucose production during the first hour, whereafter complete cessation of glucose production occurred and hepatocytes started to consume glucose, shown as a steady and slow glucose decrease in the medium. Although insulin alone did not change glucose production, vanadate in the presence of insulin induced an even stronger (80%) increase in glucose production during the first hour, followed by a very strong (60%) glucose decrease in the medium during the second hour. The results obtained indicated that vanadate decreased glucose production by inhibiting gluconeogenesis. INTRODUCTION