Effects of prostaglandins on the isolated uterine artery of nonpregnant women.

Specimens from the ascending branch of the human uterine artery were obtained from 35 nonpregnant fertile women undergoing hysterectomy. The specimens were cut either longitudinally or helically and mounted in organ chambers for isometric recording of the contractile activity. Spontaneous phasic activity occurred in 30% of the specimens. Both PGE2 and PGF2 alpha caused an increase in basal tonus of the strips while PGI2 relaxed spontaneously active as well as PG- and norepinephrine (NE2)-stimulated preparations. PGI2 had no effect on nonactive specimens, NE and transmural nerve stimulation (TNS) induced contractile activity that could be blocked by phenoxybenzamine. PGI2 counteracted the NE-induced response but not that of TNS. It is concluded that PGI2, which is synthesized both within the vessel wall and the myometrium, has a potent relaxing effect on uterine arteries and that the compound may balance the effect of vasocontricting substances.