DUAL ACTIONS OF PROSTACYCLIN (PGI2) ON THE RAT PREGNANT UTERUS

Using strips of rat pregnant uterus, treated with indomethacin to suppress spontaneous contractility, the oxytocic activity of prostacyclin was compared with other prostaglandins. A prostacyclin concentration of 32 ng/ml elicited uterine contractions in all experiments. In this respect prostacyclin was 80 times more active than 6-oxo-PGF1α but less active than PGE2 or PGF2α. Apart from a direct stimulant effect, prostacyclin also exhibited an indirect potentiating action. In threshould concentrations prostacyclin caused a 3-fold potentiation of threshold doses of oxytocin. A lesser 1.5-fold potentiation of PGF2α was also observed. The implications of these findings in relation to prostacyclin playing a role in parturition are discussed. © 1979.