Effect of atropine on esophageal motor function in humans

Abstract

In this study, a high-fidelity manometric recording system was used to quantitate the effects of atropine on lower esophageal sphincter (LES) pressure and primary peristalsis (1.degree. P). A sleeve sensor recorded LES pressure, and 7 recording orifices spaced at 3 cm intervals registered motor activity in the esophageal body. Five randomized manometric studies were done in each of 5 normal subjects. LES pressure and 1.degree. P with wet swallows were recorded for 30 min before and 70 min after i.v. injection of saline or atropine, 3, 6, 12, and 24 .mu.g/kg. The effect of atropine on LES pressure was studied in 5 additional subjects, 4 dogs, 4 opossums and 6 monkeys. In humans, saline and 3 .mu.g/kg atropine caused no significant change in pulse rate, LES pressure, or the incidence of complete peristaltic sequences. The 6, 12 and 24 .mu.g/kg atropine doses caused significant inhibition of LES pressure and the incidence of intact 1.degree. P. Only the 12 and 24 .mu.g/kg doses increased pulse rate. When 1.degree. P occurred in the smooth muscle portion of the esophagus, its appearance in the proximal portion of the smooth muscle segment was delayed for several seconds. The amplitude of 1.degree. P was decreased 30-60% in the smooth muscle segment, bt 1.degree. P was not affected in the proximal striated muscle esophageal segment. Atropine reduced canine LES pressure substantially but caused no change in opossums or monkeys. Basal LES tone in humans and dogs, unlike that of the opossums and monkey, is partially generated by cholinergic neural input. Cholinergic nerves elicit 1.degree. P in human esophageal smooth muscle. Species variation exists in esophageal responses to atropine.