The effects of beta-adrenergic receptor blockade on the inhibition of gastric acid secretion, and the release of pancreatic polypeptide by antral distension in healthy subjects.

In a randomized double-blind study of seven healthy subjects an intravenous injection of metoprolol and propranolol did not change the submaximal gastric acid response to pentagastrin. The inhibition of pentagastrin-stimulated acid secretion by balloon distension of the antrum was unchanged by a preceding intravenous injection of metoprolol or propranolol. The plasma level of pancreatic polypeptide in peripheral venous blood showed a significant rise during antral distension. This rise was unaltered by a preceding injection of metoprolol and slightly depressed by propranolol. We conclude that the inhibitory effect of antral distension on gastric acid secretion in healthy subjects is not mediated by beta 1 or beta 2-adrenergic mechanisms. The reflex release of pancreatic polypeptide by antral distension may possibly involve a weak beta 2-adrenergic component.