STIMULATION OF INSULIN SECRETION IN RAT BY GLUCAGON SECRETIN AND PANCREOZYMIN - EFFECT OF AMINOPHYLLINE

Male, 150 gram rats were injected i.p. twice; first with either saline or aminophylline and second, after 10 or 14 minutes with saline or one of the following hormones: glucagon, secretin or pancreozymin. The animals were bled by cardiac puncture after a short time. Serum immunoreactive insulin and serum glucose were measured. All three hormones exerted a serum insulin elevating effect which was apparently potentiated by the phosphodiesterase inhibitor, aminophylline. This potentiation produced indirect evidence that glucagon, secretin and pancreozymin stimulate the release of insulin from the pancreatic beta cell through the mediation of 3′, 5′ cyclic AMP. It was further shown that secretin and pancreozymin do not stimulate insulin release indirectly by increasing the blood glucose concentration. © 1969.