The importance of Ca2+ for glucose-induced priming in pancreatic islets.

Experiments have been performed to determine the importance of Ca2+ in the induction of priming by high, stimulatory concentrations of glucose in pancreatic islets. It is shown, in paired islets, that as little as 15 min exposure to 16.7 mM glucose in the presence of Ca2+ induced priming and an enhanced response to a subsequent glucose challenge. In contrast, exposure to 16.7 mM glucose for 15-60 min in the absence of extracellular Ca2+ failed to induce priming. From this and other data, it appears that Ca2+ is essential for the induction of priming and that Ca2+ synergizes with some aspect of glucose metabolism beyond the triose stage in stimulus-secretion coupling, to produce the primed state.