Anionic dependence of secretion and secretory potentials in the perfused sublingual gland.

Abstract

Summary.The sublingual gland of the cat has been found to give normal amounts of saliva in response to acetylcholine or stimulation of the chorda when perfused at 20° C with a saline containing physiological amounts of sodium and potassium and chloride and with chloride as the only anion. On intracellular recording normal secretory potentials are found over the outer membrane with activation.After replacement of chloride by nitrate in the perfusion fluid the amount of saliva in response to acetylcholine drops to 10–25 per cent of normal and the secretory potential over the outer gland cell membrane is greatly reduced. On readmission of chloride, secretion and the secretory potentials recover promptly. With partial substitution of chloride by nitrate, secretion is about 50 per cent at 10 per cent chloride and virtually normal at 50 per cent chloride.It is concluded i) that the decrease of secretion and secretory potential in the nitrate‐perfused gland is due to the lack of chloride ion in the external medium of the cells; ii) that normal secretion of salt and water is largely caused by an active transport of chloride over the outer gland cell membrane.Of other anions tested with regard to their capacity to maintain secretion bromide was found to substitute fully for chloride and iodide and thiocyanate in about the same degree as nitrate. The possibility is discussed that the activated outer membrane has a limited ability for transport of these latter ions.On perfusion with potassium‐free saline, secretion is greatly reduced. This finding is discussed in the light of the fact that in other tissues the transport of sodium and potassium is linked.