Molecular characterization of endothelin receptors and the effect of insulin on their expression in retinal...

Microvascular pericytes contain predominantly endothelin A (ET(A))-like binding sites and also a smaller number of ETB binding sites. In this study we verified the expression of both receptors in these cells. We then examined the effect of insulin, a potent mediator of vasodilatation, on the expression of these receptors in pericytes by Northern hybridization. Northern hybridization studies showed that ET(A) mRNA levels were not influenced by exposure to insulin (1 x 10(-7) M). By contrast, ETB receptor mRNA, which was minimal under basal conditions, was significantly increased by 4 h after exposure to insulin.