Figure 1.

Gcgr^−/− mice lack functional glucagon receptors. [¹²⁵I]Glucagon-binding (a) and glucagon-stimulated cAMP production (b) in liver membranes from male Gcgr^+/+, Gcgr^+/−, and Gcgr^−/− mice. Control (open bars), Gcgr^+/− (hatched bars), and Gcgr^−/− (filled bars) mice are indicated. Gluc, glucagon; Forsk, forskolin. Data represent mean ± SEM (n = 3) from three independent preparations. (c) Intraperitoneal glucagon challenge of male Gcgr^−/− (●), Gcgr^+/− (▴), and Gcgr^+/+ (□) mice. Data represent mean ± SEM, n = 5–7. *, P < 0.05; **, P < 0.01; ***, P < 0.001.