Effects of amidated rat islet amyloid polypeptide on glucose-stimulated insulin secretion in vivo and in vitro in rats.

Amidated rat islet amyloid polypeptide (IAPP) is a constituent of secretory granules in islet B-cells. We examined its influence on glucose-stimulated insulin secretion in rats. In vivo, intravenous infusion of IAPP (68 pmol/min) did not affect glucose-stimulated insulin secretion. In vitro, IAPP slightly inhibited glucose (8.3 mM)-stimulated insulin secretion from isolated rat islets at the high dose level of 10(-5) M but not at the lower dose levels. We conclude that the IAPP is not involved in the normal regulation of insulin secretion.