High-K+-induced inhibition of cAMP accumulation in smooth muscle.

This study examines a possibility that high-K+ depolarization induced inhibition of cAMP accumulation by beta-adrenoceptor stimulation (observed in our previous studies) is mediated by depolarization induced release of acetylcholine. Rat uterine strips were depolarized by high-K+ solution with or without atropine. Isoproterenol produced similar degrees of relaxation and increases in cAMP levels in depolarized smooth muscle with or without atropine. It is suggested that the release, if any, of acetylcholine from smooth muscle depolarization is not the primary cause of the observed inhibition of cAMP accumulation.