Dissociated effects of misoprostol on gastric acid secretion and mucosal blood flow

Misoprostol, a synthetic prostaglandin analog, has been reported to inhibit gastric acid secretion and to protect the gastric mucosa from the effects of aspirin and aspirin plus hemorrhagic shock. This study examined the effect of misoprostol on basal gastric corpus mucosal blood flow (MBF), and on pentagastrin-stimulated gastric acid output and MBF. Gastric corpus MBF in ml/min/100 g was measured by hydrogen gas clearance in fasted, anesthetized rats. Acid output in mueq/min was determined by a continuous gastric perfusion technique. For the basal study, vehicle or misoprostol in doses of 50 and 1000 micrograms/kg was administered intragastrically in separate groups of rats. For the pentagastrin-stimulation study, vehicle or misoprostol, 1000 micrograms/kg, was infused intravenously after gastric acid output was stimulated to plateau by intravenous pentagastrin, 20 micrograms/kg/hr. The results showed that misoprostol had no effect on basal gastric corpus MBF. During pentagastrin stimulation, misoprostol decreased acid secretion but did not decrease gastric corpus MBF. We speculate that this dissociated effect of misoprostol on stimulated gastric acid secretion and corpus MBF may be of therapeutic importance if it can be confirmed in human studies.