Potent glycogenic effect of GLP-1(7-36)amide in rat skeletal muscle.

GLP-1(7-36)amide is an intestinal post-translational proglucagon product released mainly after carbohydrate ingestion, the glucose dependent insulinotropic and antidiabetogenic actions of which have been documented. In this work, by exploring whether GLP-1(7-36)amide has any effect on the glucose metabolism of the muscle, we have observed that this peptide, at physiological concentrations, exerts in this tissue an increment of the D-[U-14C]glucose incorporated into glycogen, which is accompanied by an increase in the glycogen synthase a activity; also, it stimulates both glucose oxidation and lactate formation. These data indicate that the skeletal muscle is one of the target tissues for GLP-1(7-36)amide, where its insulin-like effect explains, at least in part, its plasma glucose lowering action; thus, GLP-1(7-36)amide may well be implicated in the physiological control of glucose homeostasis after meals, not only by acting as an incretin, but also by directly promoting glucose disposal.