The kinetics of electrical activity of beta cells in response to a "square wave" stimulation with glucose or glibenclamide.

The effect of a "square wave" stimulation with glucose or glibenclamide on the electrical activity of beta-cells has been studied with microelectrode techniques in isolated perifused mouse islets. While glucose evoked a burst activity with periodic oscillations of the membrane potential between two levels, glibenclamide produced a constant depolarization with a continuous spike activity. In both cases the time course of activity was biphasic and resembled closely the corresponding patterns of insulin release. The effect of glibenclamide on the membrane was irreversible. The results provide further evidence for a direct correlation between insulin release and electrical activity. Furthermore, it is suggested that the membrane potential is, at least in part, involved in the mechanism of biphasic insulin release.