A new diagnostic test for incomplete vagotomy: experimental study in dogs

Despite the decline in the number of operations for intractable duodenal ulcer disease, there are still many patients who suffer from the side effects of vagotomy. Incomplete vagotomy may be a significant cause of surgical treatment failure. Diagnosis of incomplete vagotomy is not easy since there is no reliable, safe, single test available for this purpose. We hypothesized that incomplete vagotomy can be made temporarily complete in response to a muscarinic blocking agent. A gastric cannula was inserted and vagotomy performed in 12 female dogs, which was incomplete in 6 and complete in 6 dogs. Gastric acid secretion was stimulated for 2 h with i.v. pentagastrin at a rate of 6 micrograms/kg per h. After the first hour 6 mg/kg pirenzepine (M1 muscarinic receptor antagonist which may block the effect of intact vagal fibers on postganglionic submucosal neurons) was added i.v. In the complete vagotomy dogs there was no significant decrease in gastric output rate: 12.28 +/- 4.06 mEq/h in the first hour, and 12.00 +/- 3.80 mEq/h in the second hour (mean +/- SE, P = 0.963, t = 0.048). In the incomplete vagotomy dogs a significant decrease in gastric acid output rate was observed: 10.19 +/- 1.10 mEq/h in the first hour, and 4.33 +/- 0.95 mEq/h in the second hour (mean +/- SE, P = 0.002, t = 4.029). We conclude that a pentagastrin/pirenzepine test may differentiate between complete and incomplete vagotomy in the dog.