The influence of temperature on the effects of acetylcholine and adrenaline on the membrane potential and 86Rb efflux in mouse pancreatic B-cells.

Pancreatic mouse islets were used to evaluate the influence of temperature on the B-cell response to acetylcholine and adrenaline. At 20 degrees C, the rate of 86Rb efflux from islet cells was lower, the membrane potential of B-cells was slightly less negative, and glucose-induced electrical activity was characterized by longer slow waves than at 37 degrees C. At 20 degrees C, the acceleration of 86Rb efflux produced by 1 microM-ACh was only reduced by 25%, but its reversibility was slower. Acetylcholine rapidly depolarized the B-cell membrane and increased electrical activity regardless of the temperature. However, this increase was characterized by the appearance of short slow waves of high frequency at 37 degrees C and by continuous spiking at 20 degrees C. Adrenaline (1 microM) inhibited 86Rb efflux at 37 and 20 degrees C, but the amplitude of the inhibition was decreased and its time course and reversibility were altered at the lower temperature. Adrenaline repolarized the B-cell membrane and abolished glucose-induced electrical activity for a longer period at 20 degrees C than at 37 degrees C. In conclusion, no marked decrease in signal transduction occurs at 20 degrees C. This suggests that the difficulty of identifying the currents induced by acetylcholine and adrenaline in patch-clamp experiments performed at room temperature is probably due to the small magnitude of these currents