Is there an Oxyntopyloric Reflex for Release of Gastrin in Man?

Abstract

Plasma gastrin concentrations and gastric acid output were measured during graded balloon distention of the gastric fundus and body in 20 patients with duodenal ulcer. Acid output rose stepwise with increasing distention volumes but plasma gastrin remained unchanged. During intragastric neutralization in 5 of these subjects, fundic distention did not elicit a significant rise in plasma gastrin, whereas the acid response was similar to that observed in the control study when the gastric contents were acid. In 8 of the 20 patients, proximal gastric vagotomy profoundly suppressed the acid response to fundic distention. Basal plasma gastrin concentrations were elevated after vagotomy but were unchanged during graded fundic distention. The results suggest that neural reflex activation of the oxyntic glands is the main mechanism by which fundic distention stimulates acid secretion in man. The failure of fundic distention to release gastrin does not, however, completely rule out the existence of an oxyntopyloric distention reflex for gastrin release in man. Fundic distention in man seems to both stimulate acid secretion and induce an inhibitory mechanism acting on acid secretion. This inhibitory mechanism may, purely speculatively, also mask the effect of an oxyntopyloric reflex for gastrin release. The present study and earlier work suggest that in man distention of the stomach is a poor stimulus for release of gastrin, regardless of whether the pyloric or the oxyntic gland area, or both, are distended.