The effects of temperature and 2,4-dinitrophenol on transmembrane potentials of submandibular acinar cells.

1. Micro-electrodes were used to investigate the effect of different temperatures and of DNP on salivary secretory potentials of the cat and the possum produced in response to parasympathetic nerve stimulation. 2. The mean resting potential was unchanged between temperatures of 15 and 40 degrees C in both species. 3. The amplitude of the secretory potential decreased as the temperature was lowered. Below 25 degrees C there was often no response to 1 Hz stimulation but a poorly maintained response to higher frequencies could still be obtained at 20 degrees C. 4. Decrease in temperature prolonged both the latency and time course of the secretory potential. In both species and at all frequencies the latency was increased with a Q10 of about 2-0; the increase in hyperpolarization time had a Q10 of about 1-6. 5. Close arterial injection of DNP (1 times 10- minus 4 M) decreased the amplitude of the parasympathetic secretory potential without affecting its latency and time course or the resting potential. The electrical response to close arterial injection of acetylcholine was also abolished. 6. It was concluded that metabolic energy is required to activate the hyperpolarization mechanism, and this may involve the formation of high-energy phosphate bonds.