[Action of a new synthetic prostaglandin on gastroesophageal motility of the rat].

A new synthetic prostaglandin, namely the 15 alpha, 16 (R), 16-methyl-16-methoxy PGE1 (compound marked MDL 646), endowed with a potent antiulcer activity, was studied for its effects on gastroesophageal motility of the rat in comparison with natural PGE1. Surprisingly enough, the two compounds were found to differ not only from a quantitative but also from a qualitative point of view. In fact, the natural PGE1 had, as expected, a relaxant effect on all the preparations examined except the rat fundus which is known to be contracted by all the different types of prostaglandins; conversely its synthetic analogue (MDL 646) showed a remarkable stimulatory effect on both "in vitro" and "in vivo" preparations. It is obvious that if these observations will be confirmed in other animal species, they could have a remarkable practical interest.