Comparision of Stimulus-Secretion Coupling in Normal and ob/ob (Norwich Colony) Mouse Islets of Langerhans
The Norwich colony of ob/ob mice has been compared with albino mice. The electrical response of the islet membrane to high glucose stimulation is different in the 2 types of mice, 22.2 mM glucose generating continuous spike activity in normal but producing bursts of activity in ob/ob mouse islets. The magnitude and dynamics of the insulin and lactate response to high glucose are similar in the 2 types of mice, although the absolute amounts released are higher in the ob/ob mice. Potassium permeability in islets from normal mice is inhibited by quinine, which potentiates glucose-induced insulin release. Quinine does not potentiate glucose-induced insulin release in ob/ob islets but in the absence of glucose, 100 μm quinine induces electrical activity in such islets.