[Effects of 16,16-dimethyl-trans-delta 2-PGE1 methyl ester (ONO-802) on uterine motility (author's transl)].

In rats on day 20 of pregnancy, ONO-802 exerted a uterine contractile effect when 0.2 microgram/kg was given i.v. and also with an intrauterine administration of 0.5 ng, s.c. administration of 1 microgram/kg and vaginal administration of 10 microgram/kg. The contractile activity of ONO-802 was 100-1000 times more potent than that of PGE2 alpha and was long-acting. Intravenous PGE1 or PGE2 induced a transient contraction followed by inhibition of spontaneous uterine motility in nonpregnant rats and in those with an early pregnancy. In nonpregnant hamsters, a relaxation was seen. ONO-802, similar to PGF2 alpha, showed a contractile effect regardless of states of nonpregnancy and pregnancy, both rats and hamsters. IN rats, a contractile threshold dose of ONO-802 was similar from day 15 to day 21 of pregnancy. Oxytocin produced an acute decrease in this threshold dose on phentolamine or methysergide, but was inhibited by papaverine, dibutyryl cAMP, salbutamol and verapamil. These results suggest that uterine contraction induced by ONO-802 differs from the contractions induced by PGE1, PGE2, and oxytocin, that ONO-802 does not induce endogenous PGs, and that the effect of ONO-802 is not mediated by the autonomic nervous system.