The Vasoactive Effects of Serotonin in Normal and Single Umbilical Artery Cords in Normotensive and Hypertensive Pregnancies

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Abstract
Objective: To investigate the vasoactive effects of serotonin in umbilical cord arteries from pregnancies complicated with severe or moderate pre-eclampsia or hypertension without proteinuria as compared to normotensive pregnancies matched for gestational age. Methods: Umbilical cord arteries from severe preterm preeclamptic (n = 9) and moderate term preeclamptic (n = 10) pregnancies, hypertensive term pregnancies without 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 artery (SUA) were included in the study. Results: Serotonin induced a monophasic pressure increase or a biphasic pressure response with a transient vasodilatation succeeded by a constrictory response. Two preparations 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 significantly smaller in preterm as compared to term normotensive pregnancies (2/8 vs. 9/10, P < 0.02). This proportion was nonsignificantly different in severe preeclampsia (3/9) as compared to the preterm normotensive group as well as between the moderate preeclamptic (8/10), hypertensive (without proteinuria) (6/7), and term normotensive groups. No significant differences were observed in the maximum constrictory responses 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 seems to be dependent on gestational stage but seems not to be altered by hypertension or preeclampsia.