Effect of proximal gastric vagotomy on basal and vagally stimulated gastric bicarbonate secretion in duodenal ulcer patients

Basal gastric bicarbonate secretion and the response to vagal stimulation accomplished by sham feeding were investigated in duodenal ulcer patients before and after proximal gastric vagotomy. Gastric bicarbonate secretion was measured with a computer-based system, which continuously recorded the pH and PCO2 of the gastric perfusate. Preoperatively, basal bicarbonate secretion was 414 +/- 57 mumol/h (mean +/- SEM, n = 9), and the secretory response to vagal stimulation 691 +/- 83 mumol/h (p less than 0.01). About 2 months after proximal gastric vagotomy the basal gastric bicarbonate secretion was 539 +/- 74 mumol/h, and the response to vagal stimulation 693 +/- 72 mumol/h (p less than 0.01). The basal bicarbonate secretion thus increased by 30% after vagotomy (p less than 0.01) but about 1 year later was not significantly different from the basal preoperative value. In the early postoperative period anticholinergics significantly reduced the enhanced basal bicarbonate secretion to a preoperative level. When tested 1 year after the operation anticholinergics did not affect basal bicarbonate secretion but abolished the response to sham feeding. The findings of the study suggest the existence of cholinergic vagal nerve fibres stimulating human gastric bicarbonate secretion and indicate that inhibitory nerve fibres may modulate gastric bicarbonate secretion.