The effects of calcium and calcium antagonist, nifedipine on the adrenergic receptor-stimulated glycogenolysis were investigated in isolated rat hepatocytes. The hepatic glycogenolysis induced by alpha-adrenergic receptor stimulation depended on calcium ions, and beta-adrenergic activation was unrelated to calcium ions. Nifedipine decreased the alpha-adrenergic agonist-induced glucose release significantly and the decrease was depended on calcium ions. The glucose release induced by beta-adrenergic agonist was not inhibited by nifedipine.