Propranolol-induced Insulin Release in Isolated Rat Islets of Langerhans

Immunoreactive insulin was measured in the medium following incubation of isolated rat islets of Langerhans in different concentrations of propranolol and propranolol plus glucose. Pretreatment with propranolol (20 μg./ml.) prevented glucose (3 mg./ml.)-mediated insulin release. Propranolol alone in concentrations up to 25 μg./ml. did not cause insulin release; however, at 50 μg./ml. this drug had strong beta-cytotrophic activity.