Effect of Dopamine on Pentagastrin-Stimulated Gastric Acid Secretion and Mucosal Blood Flow in Dogs with Gastric Fistula

Abstract

The purpose of this study was to elucidate the effect of intravenously administered dopamine on dopamine receptors and adrenergic receptors in terms of its effect on gastric acid secretion, the kinetic mechanism, blood flow, and antral motility. Dopamine was used alone and in conjunction with selective blockade of α-, β-, and dopaminergic receptors. A significant inhibition of gastric acid secretion was found with the highest dose of dopamine used (40 μg/kg/min). The kinetic study showed characteristics of a non-competitive type. The anti-secretory effect of dopamine was significantly blocked by non-selective β-blockade or by selective β₁-blockade but not by α- or dopaminergic receptor blockade. This suggests that the inhibitory effect of dopamine on gastric secretion is mediated by β₁-receptors. There was no significant effect on gastric mucosal blood flow, but the ratio between blood flow and acid secretion was significantly elevated during dopamine infusion, indicating that the acid inhibition was not secondary to changes in blood flow. It is concluded that the dopamine inhibition of acid secretion is mediated by β₁-receptors, unlike the effect on antral gastric motility, which is mediated by dopamine receptors.