Effect of topical acid on duodenal pepsinogen secretion in the rat

The effect of topical acid on duodenal pepsinogen secretion was studied in the anesthetized rat. Perfusion of a 5-cm segment of the proximal duodenum with normal saline or buffered saline (pH 7.2 or 6.0) elicited no detectable pepsinogen response. Perfusion with 10, 25, and 100 mN HCl resulted in a graded increase in pepsinogen output. Acetylcholine bromide, 500 microgram/ml, in buffered saline, pH 7.2, also stimulated pepsinogen secretion. The pepsinogen response to 100 mN HCl and to acetylcholine was completely abolished by atropine. Secretin, 2 units/kg, did not alter pepsinogen output during perfusion with buffered saline or acid, while secretin, 75 units/kg, increased pepsinogen output. These observations suggest that topical acid stimulates duodenal pepsinogen secretion through a cholinergic reflex and that secretin is not a significant stimulant of duodenal pepsinogen secretion in the rat within the dose range employed (1--2 units/kg).