Effect of Glucagon on Gluconeogenesis by the Isolated Perfused Rat Liver

Glucagon stimulated both carbohydrate and urea production by isolated perfused glycogen-depleted rat livers. This effect was demonstrable at concentrations of the hormone of about 1 μg/I of plasma and was maximal at concentrations of 4–5 μg/1- This range is similar to that which was previously shown to induce modest to maximal glycogenolysis in this experimental system, and is of the same order of magnitude as the glucagon concentrations which result from endogenous secretion of the hormone. It is concluded that glucagon plays a dual physiologic role, stimulating hepatic gluconeogenesis as well as glycogenolysis. In contrast to its glycogenolytic effect, which is of brief duration, stimulation of gluconeogenesis persists for at least 60–90 min after all the glucagon in the system has presumably been inactivated. (Endocrinology 78: 538, 1966)