KATP Channel-Independent Glucose Action: An Elusive Pathway in Stimulus-Secretion Coupling of Pancreatic .BETA.-cell.

ALMOST 40 years have passed since Douglas and Rubin coined a term, stimulus-secretion coupling, for endocrine cells [1]. In the pancreatic n-cell, glucose is undoubtedly the most important stimulus for insulin secretion, and the coupling had long been explained mostly, if not solely, by an elevation of cytosolic free Ca2+ concentration ([Ca2+]i) in response to glucose. The story was straightforward and rather simple [2, Glucose metabolism increases ATP or ATP/ADP ratio in the jl-cell, which closes KATP channels and causes membrane depolarization.