STUDIES ON THE SECRETORY POTENTIAL OF ACINAL CELL OF DOG'S SUBMAXILLARY GLAND AND THE IONIC DEPENDENCY OF IT

Abstract

The intra-cellular potentials were very sensitive to changes of K+ concentration in the perfusate. The secretory potential completely disappeared while the secretion was still observed when K+ was over 13 mM/1. Even when Cl- In the perfusate was replaced completely by suHate, the secretory potential remained practically normal 15 min. after starting the perfuslon; but the rate of salivary flow decreased. The secretory potential seems to originate from some factor other than the Cl" pump along the cell membrane of the gland acinus. The gland lost K+ into the blood and saliva during the secretion at about 14[mu]Eq/g gland/min. It was restored into the gland from the blood after cessation of stimu- lation; the restoration was completed in 15 min. The Na+ and Cl- were retained in the gland tissue en route from the blood to saliva by stimulation, while they were completely driven out into the blood during the restoration of 15 min. A similar ionic movement was observed by analysis of the ionic concentration in the gland tissue. The K+ in the gland decreased during the salivary secretion, whereas the Na+ concentration Increased. The rate of K permeability to that of the other ions increased more markedly in the secreting than in the resting state. The equilibrium potential manifested by the increase of K permeability during the stimulation of the gland seems to account for the hyper-polarization of the intracellular potential of the gland acinus. The secretion of saliva not necessarily concomitant with the hyperpolariza-tion of the cell membrane potential is probably due to some factor other than the secretory potential. A possible mechanism of salivary secretion is suggested.