Secretory response of dispersed rat submandibular cells. I. Potassium release

Abstract

The secretory response of dispersed rat submandibular cells as it relates to the net efflux of K+ following sympathomimetic and parasympathomimetic stimulation was evaluated. The cholinergic agonists acetylcholine and carbamylcholine had equal efficacy but dissimilar receptor affinity. Median effective concentrations (EC50''s) were 1.7 .times. 10-7 M and 7.1 .times. 10-7 M, respectively. Pilocarpine was acting as a partial agonist and had an EC50 at 5.6 .times. 10-7 M. (-)-Norepinephrine and (-)-epinephrine had similar efficacy and potency with EC50''s at 5.6 .times. 10-7 M and 3.8 .times. 10-7 M, respectively. (-)-Phenylphrine acts as a partial agonist with an EC50 at 3.8 .times. 10-6 M, whereas (-)-isoproterenol stimulation resulted in no net K+ efflux within the concentrations tested (10-8 M-10-3 M). Extracellular Ca2+, but not Mg2+, was required to elicit a net K efflux following either cholinergic or .alpha.-adrenergic stimulation.