Purinergic signalling in pancreatic islet endothelial cells

Abstract

Both the microvascular endothelium and the endocrine cells in the pancreatic islet can release and react upon ATP. In support for the idea that intermittently released ATP, related to exocytosis of insulin secretory granules, affects the secretory activity of the capillary endothelium, we have demonstrated that isolated endothelial cells respond to activation of P2Y 2 receptors with pronounced and extended rises of [Ca 2+]i. The presence of such ATP effect is consistent with reports that β-cells regulate the blood flow within islets, where adenosine is a key mediator, and that the endothelial cell produce pro-angiogenic and angiostatic factors. In β-cells down-regulation of P2Y1 receptors results in disappearance of the transients of [Ca2+] i supposed to entrain these cells into a common rhythm. Since the islet endothelial cells respond to activation of P2Y2 receptors with extended elevation of [Ca2+]i, it is likely that the accompanying release of ATP is prolonged. Accordingly, the endothelial cells may have a tonic inhibitory action on the coordination of islet release pulses. © Springer Science+Business Media B.V. 2010.