The Amino Acid-Induced Secretion of Glucagon

An increase in the amino acid concentration in contact with pancreatic A-cells is followed by a stimulation of glucagon release. This phenomenon is observed not only in vitro at some pharmacologic concentrations of amino acid, but also in vivo, during the rise in blood amino acid which follows a protein meal. The magnitude of the A-cell secretory response is modulated by the concomitant physiologic status, i.e., mainly the plasma glucose and insulin concentrations, and by the nutritional status in the preceding days: short-term and long-term influences can modify amino acid-induced glucagon release. As a clinical consequence of this phenomenon, the administration of an amino acid, or a mixture of amino acids has become a standard functional test for exploration of A-cells in vivo as well as in vitro.