Some factors influencing stimulation‐induced release of potassium from the cat submandibular gland to fluid perfused through the gland

Abstract

1. The release of K from the cat submandibular gland to the extracellular fluid (ECF) after stimulation with acetylcholine (ACh) and the subsequent uptake of K from the ECF was studied in glands perfused artificially with Locke solutions.2. The first injection of ACh after shift of the perfusion fluid from control to K‐free Locke solution evoked a normal loss of K and a normal secretion of saliva. The second injection only evoked a small release of K and a reduced secretion.3. Perfusion with dinitrophenol (DNP) (10⁻⁴ M) containing solutions, Na‐free Li Locke solutions and chloride‐free nitrate Locke solutions inhibited salivary secretion and the uptake of K. The first injection of ACh after shift of the perfusion fluid from control to test solution gave a normal K loss, but thereafter the ACh‐induced K‐loss declined.4. Perfusion with g‐strophanthin (10⁻⁵‐10⁻⁴ M) always inhibited K uptake whereas K release was not affected primarily. The sensitivity of the secretory mechanism of different glands to strophanthin varied considerably.5. Perfusion with tetraethylammonium Locke solution inhibited secretion, K uptake and release of K.6. It is suggested that the release of K from salivary glands to the ECF after stimulation with ACh can be explained by diffusion as a consequence of an enhanced permeability of the cell membranes to K. Concomitantly with the release of K, Na is taken up. It is suggested that the subsequent uptake of K and extrusion of Na is due to active transport processes probably involving a Na—K activated ATP‐ase.