Aggravating effect of ergometrine on pyloric antral lesions in indomethacin-treated animals and stimulating effect of this drug on gastric acid secretion.

Induction of distinctive gastric antral ulcer by ergometrine in indomethacin-treated rats was investigated together with the gastric secretagogue property of this drug. Influence of several prophylactic drugs on indomethacin ulcer was examined, and among these drugs, ergometrine and methysergide were found to aggravate the gastric lesions. The aggravating effect was exerted exclusively in the pyloric antrum of rats and mice. Methysergide (20 mg/kg s.c.) and ergometrine (5-40 mg/kg s.c.), but not cyproheptadine (20 mg/kg s.c.), produced aggravation in pyloric antral lesions. This aggravating effect of ergometrine was also found in aspirin-induced gastric lesions in rats. However, in cold and restraint stress ulcers of rats, this effect was not apparent. Both ergometrine (0.5-2.5 mg/kg i.v.) and methysergide (2.5-5.0 mg/kg i.v.) stimulated gastric acid secretion, dose dependently, in anesthetized rats.