Glucose‐induced electrical activity in pancreatic islet cells

Abstract

1. Intracellular recording of the transmembrane potential in mouse pancreatic cells revealed a membrane potential of −20·1 ± 0·8 mV for islet cells and −41·2 ± 1·4 mV for acinar cells. 2. The membrane potential of islet cells was glucose dependent and in the absence of glucose the cells hyperpolarized to −32·7 mV; with glucose 27·7 m M they depolarized to −16·1 mV. 3. Above a threshold concentration of glucose (4 m M) small action potentials of amplitude 1-4 mV were induced in islet cells. The percentage of cells impaled exhibiting action potentials reached a maximum of 80% at 27·7 m M glucose. 4. Mannose 16·6 m M was similar to glucose in its ability to induce action potential discharge in islet cells. 5. 2,4-Dinitrophenol (0·25 m M) hyperpolarized islet cells and blocked electrical activity induced by glucose 11·1 m M. 6. Adrenaline (1 μ M) completely blocked glucose-induced electrical activity but without altering the membrane potential. 7. The origin and functional significance of glucose-induced electrical activity in islet cells is discussed in relation to insulin secretion.