Mucosal blood flow and gastric protection--effect of neurohormonal and pharmacological agents.

The role of mucosal blood flow in the protection of gastric mucosa is now well recognized. While impairment of local blood supply promotes mucosal injury, an increase in mucosal blood flow protects against experimental damage. In fact gastric microcirculation supplies both nutrients and bicarbonate to the gastric mucosa and provides removal of back-diffused hydrogen ions. In order to protect the mucosa against acid excess, blood flow normally increases when acid secretion is stimulated by gastric secretagogues. In contrast, most antisecretory agents induce local vasoconstriction secondary to gastric acid inhibition. The effect of various substances (neural transmitters, gastrointestinal hormones, anti-ulcer drugs, prostaglandins) on mucosal blood flow is reviewed and discussed.