Tolbutamide and diazoxide influence insulin secretion by changing the concentration but not the action of cytoplasmic Ca2+ in beta-cells

Sulfonylureas stimulate insulin secretion by blocking ATP-sensitive [K.sup.+] channels ([K.sup.+]-ATP channels) of the Β-cell membrane, thereby causing depolarization, [Ca.sup.2+] influx, and rise in cytoplasmic [Ca.sup.2+] concentration ([[[Ca.sup.2+]].sub.i]), whereas diazoxide inhibits [...]