The capability for regulation of insulin secretion by somatostatin in purified pancreatic islet B cells during aging.

Pancreatic islet B cells from Sprague-Dawley and Fisher 344 rats aged 3-27 months were separated from A and D cells by centrifugation over a linear percoll density gradient, and incubated in vitro with various concentrations of glucose and somatostatin. Elevation of glucose concentration in the incubation medium from 2.6 to 16.7 mM provokes an insulin secretory response that is independent of rat donor age. Inhibition of the insulin secretory response by somatostatin is independent of rat donor age beyond 12 months. These data indicate that the impaired regulation of insulin secretion during aging observed previously in vivo and in vitro in intact islets may not be intrinsic to the B cells, but instead reflect changes in islet paracrine regulatory mechanisms that relate to the quality and/or quantity of endogenous somatostatin and/or glucagon.