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

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.