Cell surface measurements of ATP release from single pancreatic beta cells using a novel biosensor technique

To examine the possibility that ATP modulates insulin secretion by an autocrine mechanism, we measured the local concentration of released ATP at the surface of a single pancreatic beta cell by a new biosensor technique, using PC12 cells expressing ligand-gated cation channels, P2X2 receptors. Upon application of glucose or glibenclamide, a series of current spikes, whose amplitude equates to an ATP concentration of over 25 microM, were recorded from a PC12 cell using the whole-cell patch-clamp technique, when placed near a rat pancreatic beta cell at 37 degrees C. The current response was inhibited by cooling (below 30 degrees C) or by applying an ATP-hydrolysing enzyme (apyrase) or a P2 receptor blocker (suramin). Thus, it is concluded that pancreatic beta cells secrete ATP in response to glucose stimulation, thereby increasing the ATP concentration close to the cell surface sufficiently high enough to enhance insulin secretion from the pancreatic beta cells.