Glucose-activated beta-cell insulin secretion depends upon elevation of intracellular calcium
concentration,[Ca2+] i, which is thought to arise from Ca2+ influx through voltage-dependent
calcium channels. Using fura-2-loaded mouse islets, we demonstrate, in fact, that the major
component of the glucose-activated [Ca2+] i rise represents voltage-dependent intracellular
Ca2+ release. Furthermore, the Ca2+ release pool possesses a novel pharmacology in that
it is caffeine-sensitive but ryanodine-insensitive. In the absence of external Ca2+, glucose …