Acetylcholine exerts inhibitory and excitatory actions on mouse ileal pacemaker activity: role of muscarinic versus nicotinic receptors

Abstract

The study discovered an acute action of acetylcholine on pacemaker potentials that is mediated by muscarinic receptors on the mouse ileum. Bethanechol, but not nicotine, mimicked the inhibitory actions of acetylcholine on pacemaker potentials. Atropine, but not hexamethonium, reversed the inhibitory actions of acetylcholine. When introduced after acetylcholine, atropine exhibited excitatory actions that increased the pacemaker frequency. Acetylcholine and bethanechol distorted the propagation activity and pattern, and this was also reversed by atropine. These actions of acetylcholine on pacemaker potentials may contribute to pathophysiology in bowel diseases.