Cholinergic control of smooth muscle peristalsis in the cat esophagus

The aim of this study was to examine in detail the effects of selective cholinergic and other pharmacological antagonists on primary and secondary peristalsis in the smooth muscle of the cat esophagus in order to fully characterize the cholinergic contribution to peristalsis in this species. Primary and secondary peristalsis in the smooth muscle part of the feline esophagus was completely abolished by atropine, 4-dephenylacetoxy-N-methylpiperidine methiodide (4-DAMP) (a selective M2 muscarinic antagonist), hexamethonium, and high doses of nicotine. Pirenzepine (a selective M1 muscarinic antagonist), propranolol, and phentolamine were without effect, as were naloxone, methysergide, and pyrilamine. From these findings we conclude that primary and secondary peristalsis in feline esophageal smooth muscle involves nicotinic ganglionic neurotransmission as well as postganglionic release of acetylcholine that acts directly on muscarinic receptors located on the smooth muscle. Peristalsis in esophageal striated muscle does not involve either synaptic transmission or muscarinic receptors.