Effect of a β-Sympathomimetic on Pentagastrin-and Histamine-Stimulated Gastric Acid Secretion in Vagotomized Gastric Fistula Dogs

The effect of a β-adrenoceptor agonist on pentagastrin- and histamine-stimulated gastric acid secretion was studied in conscious vagotomized gastric fistula dogs. A dose-dependent inhibition was found after pentagastrin stimulation, whereas minor differences were found after histamine stimulation. No major differences between truncal, selective, and parietal cell vagotomy were found after pentagastrin stimulation, whereas one truncal vagotomy dog showed a high inhibition after histamine stimulation. Dose-response experiments with five doses of pentagastrin or histamine (single-dose studies) and two doses of β-agonist suggested a change after vagotomy in the mechanisms of inhibition of gastric acid secretion: for pentagastrin, from a non-competitive type to an uncompetitive type, and for histamine, from a competitive type to a non-significant inhibition. Furthermore, the dose-response curves for the vagotomized dogs were very similar to the curve from intact innervated dogs inhibited by a β-agonist, from a...