Membrane potentials of salivary gland cells of rat.

Abstract

Transmembrane electrical potentials were recorded from cells of rat salivary glands in vivo, using microelectrodes. The mean (±se) from 61 impalements of unstimulated submaxillary cells was 28 ± 1.4 mv. In submaxillary gland, acinar cells and cells of granular tubules account for approximately 70 and 30%, respectively, of all secretory elements. Dividing the range of submaxillary potentials at 35 mv gave two groups with new means of 23 ± 1.0 and 41 ± 0.6 mv, in which were contained 70 and 30%, respectively, of all values. Potentials in submaxillary gland from which granular tubules had been caused virtually to disappear (by isoproterenol) were always below 35 mv (mean ± se = 25 ± 0.6 mv). Similarly, potentials from normal parotid gland (in which granular tubules do not appear) never exceeded 34 mv (mean ± se = 20 ± 2.4). In submaxillary, stimulation, at least over relatively long durtion, produced no change in average potential. It was concluded that membrane potentials from rat salivary glands are generally below the potassium equilibrium potential, with acinar cells showing lower values than cells of granular tubules.