Influence of beta blockade on gastric acid secretion and changes in gastric mucosal blood flow before and after parietal cell vagotomy in dogs and man

Gastric mucosal integrity: gastric mucosal blood flow and microcirculation. An overview

The stomach is in a state of continuous exposure to potentially hazardous agents. Hydrochloric acid together with pepsin constitutes a major and serious threat to the gastric mucosa. Reflux of alkaline duodenal contents containing bile and pancreatic enzymes are additional important injurious factors of endogenous origin. Alcohol, cigarette smoking, drugs and particularly aspirin and aspirin-like drugs, and steroids are among exogenous mucosal irritants that can inflict mucosal injury. The ability of the stomach to defend itself against these noxious agents has been ascribed to a number of factors constituting the gastric mucosal defense. These include mucus and bicarbonate secreted by surface epithelial cells, prostaglandins, sulfhydryl compounds and gastric mucosal blood flow. The latter is considered by several researchers to be of paramount importance in maintaining gastric mucosal integrity. The aim of this paper is to review the experimental and clinical data dealing with the role of mucosal blood flow and in particular the microcirculation in both damage and protection of the gastric mucosa.

Beta-adrenergic agonists inhibit gastric acid and pepsin secretion through somatostatin release in dogs

The purpose of the present study was to evaluate whether the inhibitory effects of beta-adrenergic agonists on gastric secretory activity in vivo could be mediated through a local release of somatostatin. The gastric secretion was measured during continuous stimulation with pentagastrin (1 microgram/kg/h). The infusion of isoprenaline (beta 1 + beta 2), salmefamol (beta 2), and somatostatin produced inhibitory effects on both acid and pepsin secretion. The reaction patterns were similar for isoprenaline and somatostatin, whereas salmefamol induced an inhibition of longer duration and with dissimilar dose-response kinetics. The gastric somatostatin release was significantly increased after infusion of both beta-adrenergic agonists and somatostatin, with patterns similar to those obtained for the secretory inhibition. There was a significant correlation between the somatostatin release and the acid and pepsin secretion during infusion of the secretory inhibitors but not in the control state. This study shows that beta-adrenergic agonists have inhibitory effects on gastric secretion in vivo similar to those of somatostatin. Both somatostatin and the beta-adrenergic agonists stimulated the release of somatostatin from the gastric mucosa. beta-Adrenergic antagonists were without effects. Somatostatin thereby fulfils the requirements for an endogenous mediator of the beta-adrenergic inhibition.