Failure of atropine to inhibit gastrin-17 stimulation of the lower esophageal sphincter in man.

Heptadecapeptide gastrin I (G-17) contrast the lower esophageal sphincter (LES) in man and animals. Previous studies in man found that atropine infusion (12 microgram kg-1hr-1) inhibited the effect of gastrin on the LES, suggesting that this effect of gastrin is mediated by a cholinergic mechanism. Studies in the opossum have not shown similar inhibition. To reevaluate the interaction of atropine and G-17 on the LES, 5 normal males were studied. Submaximal and maximal effective doses of G-17 were used with both atropine infusion (12 microgram kg-1hr-1) and rapid intravenous injection (1 mg). There was a small decrease in basal LES pressure with atropine infusion. However, neither atropine infusion nor rapid intravenous injection inhibited LES stimulation by submaximal and maximal doses of G-17. The results do not support the hypothesis that LES responses to gastrin are mediated by an atropine-sensitive cholinergic mechanism.