Acid inhibition of sham feeding-stimulated gastrin release and gastric acid secretion: effect of atropine.

The effect of intraluminal pH on the gastrin response to sham feeding was studied in healthy subjects. Before, during, and after sham feeding, an acidified solution of saline (at either pH 5.0 or 2.5) was infused into the stomach continuously and intragastric pH was maintained at either 5.0 or 2.5 by in vivo intragastric titration. When intragastric pH was maintained at 5.0, vagal stimulation induced by sham feeding released statistically significant amounts of gastrin. Acidification to pH 2.5 abolished the gastrin response and also inhibited by approximately 50% the acid secretory response to sham feeding. A small dose of atropine (2.3 micrograms/kg) prevented the inhibition of gastrin release which had occurred at pH 2.5. Moreover, in the presence of atropine, acidification to pH 2.5 did not inhibit acid secretion stimulated by sham feeding. These findings suggest that acid inhibition of sham feeding-stimulated gastrin release and gastric acid secretion is mediated by an atropine-sensitive pathway.