Gastric acid response to modified sham feeding in patients with duodenal ulcer: is increased vagal tone the cause of basal acid hypersecretion?

In order to test the hypothesis that increased basal vagal tone causes basal acid hypersecretion in duodenal ulcer (DU), the effect of sham feeding on gastric acid secretion was studied in 26 patients with DU and 20 healthy controls. Basal acid output (BAO), sham feeding-stimulated acid output (SAO) and peak histamine-stimulated acid output (PAO) were significantly higher in DU patients compared with healthy controls (P less than 0.01). The BAO/PAO ratio in DU patients (0.28 +/- 0.03) was not significantly different from that of healthy subjects (0.19 +/- 0.03), indicating that the higher BAO in DU patients group, as a whole, was due to a higher parietal cell mass. The basal subtracted response to sham feeding expressed as a fraction of secretory capacity [(SAO-BAO)/PAO], which correlates inversely with the basal vagal tone, was not significantly different in the patients and control subjects (0.27 +/- 0.03 versus 0.3 +/- 0.03; P greater than 0.05). Based on the data from the healthy controls, a ratio of BAO/PAO greater than 0.44 was defined as abnormal (using 95% confidence limits) and it indicated marked basal acid hypersecretion. Four of 26 DU patients had basal acid hypersecretion (that is, BAO/PAO greater than 0.44), but only two of them did not show an increase over their basal rate of secretion in response to sham feeding. All other DU patients, including two with marked basal acid hypersecretion, and all healthy controls showed an appreciable increase in their acid secretion in response to sham feeding.(ABSTRACT TRUNCATED AT 250 WORDS)