The effect of salbutamol and propranolol on pentagastrin, histamine and meal-stimulated acid and pepsin secretion in the dog.

The beta 2 adrenergic agonist Salbutamol was infused intravenously in doses of 0.05, 0.1 and 0.2 microgram/kg-min in conscious dogs with gastric fistulae. Salbutamol inhibited meal-stimulated acid (measured with intragastric titration) by up to 82%. Salbutamol produced dose-related inhibition of acid stimulated by pentagastrin (up to 88%) and by histamine (up to 52%). Pepsin secretion in response to histamine (but not pentagastrin) was also inhibited by salbutamol. The salbutamol infusion caused a marked tachycardia, an increase in pulse pressure, slight hyperkalaemia and hyperglycaemia. The beta-adrenergic antagonist propranolol augmented pentagastrin-stimulated acid and inhibited meal-stimulated secretion. Propranolol abolished salbutamol - induced tachycardia, and blocked the inhibition by salbutamol of pentagastrin-stimulated acid. Salbutamol inhibition of acid in the dog provides further support for the hypothesis that there are beta 2-adrenergic receptors in the stomach.