Functional insulin receptors are known to occur in pancreatic beta cells; however, except for
a positive feedback on insulin synthesis, their physiological effects are unknown.
Amperometric measurements at single, primary pancreatic beta cells reveal that application
of exogenous insulin in the presence or absence of nonstimulatory concentrations of
glucose evokes exocytosis mediated by the beta cell insulin receptor. Insulin also elicits
increases in intracellular Ca 2+ concentration in beta cells but has minimal effects on …