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Influence of Gestational Age on the Vasodilatory Response of Serotonin in Human Umbilical Arteries Perfused in vitro

Background: Serotonin (5-hydroxytryptamine) is a potent vasoactive substance in human umbilical arteries (HUA). Aim: To investigate the vasodilatory response pattern of serotonin in HUA from pregnancies complicated by preterm deliveries as compared to uncomplicated term pregnancies. Methods and Subjects: Umbilical cord segments were perfused in vitro. These were taken from pregnancies complicated by preterm delivery before 34 weeks’ gestation (group 1, n = 8), between 34 and 37 weeks’ gestation (group 2, n = 7), and uncomplicated term pregnancies (group 3, n = 17). All women were normotensive and without proteinuria, and showed no signs of infection. Results: Serotonin induced monophasic vasoconstrictory responses or biphasic responses with a transient vasodilation succeeded by a vasoconstriction. The frequency of preparations displaying a biphasic response increased with gestational age. The frequencies were 1/8, 3/7 and 12/17 in groups 1, 2 and 3, respectively (p = 0.023). The correlation between the maximum dilatory response obtained in each preparation and gestational age was positive and significant (r = 0.49, p = 0.004). No significant differences were observed in the constrictory responses between the groups. Conclusion: In in vitro perfused HUA, the vasodilatory response is dependent on gestational age.