Absence of insulinotropic glucagon‐like peptide‐I(7–37) receptors on isolated rat liver hepatocytes

The effects of glucagon and the glucagon-like peptide GLP-1(7-37) were compared in rat liver hepatocytes. Glucagon elevated cAMP, elevated intracellular free calcium ([Ca2+]i), activated phosphorylase and stimulated gluconeogenesis, whereas GLP-1(7-37) was without effect on any of these parameters. GLP-1(7-37) did not block any of the actions of glucagon. The glucagon analog, des His1[Glu9] glucagon amide, was a partial agonist in liver, but also was an effective antagonist of glucagon actions in liver but not those of GLP-1(7-37) in islet B cells. It was concluded that in the rat, GLP-1(7-37) is a potent insulin secretagogue [1] but is without effect on liver.