Pharmacological modulation of endothelial function by insulin in the rat aorta

Nitric oxide (NO)-mediated vasodilation induced by hyperinsulinaemia might involve an indirect action which promotes agonist-stimulated endothelial fu nction. Our aim was to attempt to demonstrate such modulation of endotheliu m-dependent vasodilation by insulin in the rat isolated aorta. We found that vasodilation in response to acetylcholine, but not to adenosi ne diphosphate (ADP), histamine or the calcium ionophore A23187, was modest ly enhanced after 20-min pretreatment with human insulin (100 nM) whereas e ndothelium-independent responses to the NO donor sodium nitroprusside were not significantly affected. Human insulin thus has the acute pharmacological action of selectively enha ncing muscarinic receptor-mediated endothelial function in rat aortic vascu lar smooth muscle in-vitro.