Pancreastatin and its 33-49 C-terminal fragment inhibit glucagon-stimulated insulin in vivo.

1. Pancreastatin, a 49 amino acid peptide derived from chromogranin A, has been shown to have an inhibitory effect on insulin secretion in the perfused pancreas and isolated islets. 2. We have studied the effect of pancreastatin on glucagon-stimulated insulin release and the hyperglycemic of glucagon effect in vivo. 3. When administered in the mesenteric vein, pancreastatin inhibited the increase in insulin levels induced by glucagon stimulation, thereby potentiating the hyperglycemic effect of glucagon. 4. This study describes a regulatory role of pancreastatin on glucagon-induced insulin release in vivo.