Short communication: Time effect of mode of delivery on contractile function of placental arteries in vitro

This study was designed to determine the effect of the node of delivery on the in vitro assessment of placental blood vessel function. Twenty-two subjects with uncomplicated pregnancies, normal antenatal Doppler flow, velocity, waveforms and normal birth weights were recruited for the study. The 11 subjects who were delivered by elective caesarean section mere matched with 11 controls, who had uncomplicated labours and spontaneous vaginal delivery. Two tertiary chorionic plate arteries mere dissected free 1 h after delivery and mounted in a myograph. Cumulative concentration response curves mere constructed to the thromboxane A(2) analogue U46619, prostaglandin F-2 alpha and angiotensin II. After a period of 12 h a further two vessels mere mounted and a concentration response curve to U46619 was repeated to determine whether a delay, of several hours after delivery mould have an effect on the responses of these vessels. These placental arteries constrict to U46619, prostaglandin F-2 alpha and angiotensin II in a dose-dependent manner. There was no statistical difference in the maximum contractile responses or pD(2) values between the different modes of delivery. A delay in dissection of up to 12 h had no effect on the maximum response or pD(2) with U46619. Therefore, contractile function of placental arteries is unaffected by mode of delivery or a delay in dissection.