Effect of tolbutamide on fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase in rat liver.
The effects of tolbutamide on the activities of fructose-6-phosphate,2-kinase and fructose-2,6-bisphosphatase were examined using rat hepatocytes. Tolbutamide stimulated fructose-6-phosphate,2-kinase activity and inhibited fructose-2,6-bisphosphatase activity, resulting in an increase of fructose-2,6-bisphosphate level. Changes in the activities of the enzyme by tolbutamide were due to variation in the Km value, but not dependent on alteration of Vmax. Glucagon inhibition of fructose-2,6-bisphosphate formation resulting from an inactivation of fructose-6-phosphate,2-kinase and an activation of fructose-2,6-bisphosphatase was released by tolbutamide. Tolbutamide stimulation of fructose-2,6-bisphosphate formation through regulation of fructose-6-phosphate,2-kinase/fructose-2,6-bisphosphatase may produce enhancement of glycolysis and inhibition of gluconeogenesis in the liver.
D000818:Animals; D005635:Fructosediphosphates / Q000378:metabolism; D005934:Glucagon / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014044:Tolbutamide / Q000494:pharmacology*
D005635:Fructosediphosphates; C027652:fructose 2,6-diphosphate; D005934:Glucagon; D014044:Tolbutamide; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D010744:Phosphoric Monoester Hydrolases