Effect of bethanechol on gastric acid secretion and serum gastrin concentration after proximal gastric vagotomy.

It has been suggested that maximal acid output decreases after vagotomy as a result of reduced cholinergic activity and that maximal acid secretion can be restored to prevagotomy levels with cholinergic agonists. To test this, a maximally tolerated dose of bethanechol (50 micrograms/kg/hr) or saline was infused intravenously in nine duodenal ulcer patients who had been treated by proximal gastric vagotomy. Bethanechol infusion significantly (p less than 0.05) increased basal acid secretion without affecting basal serum gastrin concentrations. Despite stimulation of basal acid secretion, bethanechol had no significant effect on maximal acid output in response to subcutaneous pentagastrin. Although bethanechol significantly increased maximal acid output in response to subcutaneous histamine, maximal acid secretion in response to histamine (or to pentagastrin) was not restored to the prevagotomy level in any patient. Thus, factors other than loss of cholinergic activity appear to be responsible for the large reduction in maximal secretory capacity after vagotomy.