[Biological activity of prostaglandin E1 derivative, ONO-802 on smooth muscle (author's transl)]

The effects of prostaglandin (PG) E1 derivative, 16,16-dimethyl-trans-delta-2PGE1 methyl ester (ONO-802) on the rat stomach fundal strip, uterus and ileum were studied. Its substrate specificity for 15-hydroxy prostaglandin dehydrogenase (PGDH) was also examined. Contractions were recorded isometrically by superfusion method. PGE1, E2, and F2 alpha caused maximal contraction of the fundal strip immediately after application and relaxation to the original state within 10 min. Contractile pattern of the fundal strip produced by ONO-802 was quite specific and different from those by classic PGs. Contraction was increased slowly to its maximum in 10 to 20 min after application of ONO-802 and thereafter returned to the original state in 20 to 40 min. Contractive response of the rat ileum to ONO-802 was a gradual increase of the tonus and restoration in more than 120 min after reaching its maximal tonus. The rat uterus responded to 1 microgram of ONO-802 with double maximal contraction amplitude of spontaneous activity, with increased contraction amplitude restored in 90 min. In a combination of ONO-802 with PGE1, E2 and F2 alpha, the contractile response of the fundal strip to ONO-802 was masked by the actions of classic PGs and additional potentiation was not observed. Contractive activity of ONO-802 was not reduced by placental PGDH.