A specific β3-adrenoceptor agonist induces increased pancreatic islet blood flow and insulin secretion in rats

In order to study the role of β3-adrenoceptor stimulation on insulin secretion in rats, plasma insulin level and islet blood flow were measured during treatment with CL 316243 which is chemically named disodium (R,R)-5-[2-[[2,3-(3-chlorophenyl)-2-hydroxyethyl]-amino]propyl]-1,3-benzodioxole-2,2-dicarboxylate, a specific β3-adrenoceptor agonist. CL 316243 induced a marked increase in both islet blood flow and plasma insulin concentration without changes in whole pancreatic blood flow. This increase was totally prevented when the rats were pretreated with bupranolol, a β1,β2,β3-adrenoceptor antagonist, but not with nadolol, a β1,β2-adrenoceptor antagonist. We conclude that β3-adrenoceptor stimulation provokes a marked vasodilatation of microvessels in the islets of Langerhans, which in turn could contribute to the increase in insulin secretion.