title: Effect of MDL 646, a new synthetic prostaglandin, on gastroesophageal motility of the rat.
abstract: Compound marked MDL 646, a synthetic prostaglandin belonging to the 16-methyl-16-methoxy PGE1 series was tested for its motor effects on some in vitro and in vivo preparations from the rat. The lower esophageal sphincter (LES) was contracted at threshold doses ranging from 10 to 20 ng/ml; the fundus was even more sensitive whereas the pyloric sphincter showed remarkable differences according to the in vitro or in vivo preparation. In all the different tests MDL 646 showed a high degree of tachyphylaxis. PGE1 tested for comparison, exerted a constant relaxant effect in all the preparations excepting the gastric fundus. The present data emphasize the importance of the substitutions in positions 15 and 16 in the synthetic prostaglandin for determining the peculiar biological activity: in fact both MDL 646 and the parent PGE1 inhibit gastric secretion but they have almost opposite effects on gastroesophageal motility.
mesh_terms: D000527:Alprostadil / Q000031:analogs & derivatives; D000818:Animals; D004943:Esophagogastric Junction / Q000187:drug effects; D004947:Esophagus / Q000187:drug effects*; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D011458:Prostaglandins E / Q000494:pharmacology; D011459:Prostaglandins E, Synthetic / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013270:Stomach / Q000187:drug effects
chemical_list: D011458:Prostaglandins E; D011459:Prostaglandins E, Synthetic; D000527:Alprostadil; C036058:mexiprostil