THE VASOACTIVE EFFECTS OF SEROTONIN IN NORMAL AND SINGLE UMBILICAL ARTERY CORDS IN NORMOTENSIVE AND HYPERTENSIVE PREGNANCIES

Objective: To investigate the vasoactive effects of serotonin in umbil ical cord arteries from pregnancies complicated with severe or moderat e preeclampsia or hypertension without proteinuria as compared to norm otensive pregnancies matched for gestational age. Methods: Umbilical c ord arteries from severe preterm preeclamptic (n = 9) and moderate ter m preeclamptic (n = 10) pregnancies, hypertensive term pregnancies wit hout proteinuria (n = 7), and normotensive preterm (n = 8) and term (n = 12) pregnancies were perfused in vitro. Serotonin was administrated through a side infusion. Five umbilical cords with single umbilical a rtery (SUA) were included in the study. Results: Serotonin induced a m onophasic pressure increase or a biphasic pressure response with a tra nsient vasodilatation succeeded by a constrictory response. Two prepar ations from normotensive term pregnancies were serotonin insensitive. These were excluded from the calculations, At a serotonin dose of 10(- 7) M, the proportion of preparations giving a biphasic response was si gnificantly smaller in preterm as compared to term normotensive pregna ncies (2/8 vs. 9/10, P < 0.02). This proportion was nonsignificantly d ifferent in severe preeclampsia (3/9) as compared to the preterm normo tensive group as well as between the moderate preeclamptic (8/10), hyp ertensive (without proteinuria) (6/7), and term normotensive groups. N o significant differences were observed in the maximum constrictory re sponses between the groups. The vascular resistance was significantly reduced in the SUA cords as compared to the normal cords. Conclusions: In the human umbilical cord artery the serotonin response pattern see ms to be dependent on gestational stage but seems not to be altered by hypertension or preeclampsia.