Interaction of vasopressin and prostaglandins in the nonpregnant human uterus.

The interaction of vasopressin (VP) and prostaglandins (PG) on the nonpregnant human uterus was studied in vitro and in vivo. In organ baths arginine (A)- and lysine (L)-VP in concentrations of 0.6 to 100 ng/ml stimulated small human myometrial strips and uterine artery preparations to a similar degree. When these VPs were given in the presence of indomethacin or naproxen in concentrations of 1 microgram/ml and 5 micrograms/ml, respectively, the myometrial and arterial responses were not significantly influenced. PGF2 alpha in concentrations of 0.01-100 ng/ml stimulated the myometrial preparations but caused a slight relaxation of the arteries, with PGE2 the myometrial effects were insignificant and the relaxation of the arteries greater. When AVP was given together with either of the PGs to the bath the result was generally a summation of the individual effects of both types of substances.--In vivo during intrauterine pressure recordings in nonpregnant women 1-2 days before onset of menstruation LVP in single intravenous injection of 1.2 micrograms markedly stimulated uterine contractions. The response remained practically unaltered after pretreatment with 500 micrograms of naproxen given orally. The responses to LVP were also closely similar before, during and after intravenous infusion of PGF2 alpha at a rate of 5 micrograms/min.--It is concluded that the effect of VP on myometrium and uterine arteries is not to any great extent mediated by local synthesis of PG and that PGs do not cause potentiation or inhibition of the VP effects on the nonpregnant uterus.