Serotonin is a potent vasoconstrictor in human umbilical arteries in vitro, and its effect is specifically blocked by methysergide.
A method was developed for the assessment of in vitro perfusion of the umbilical cord arteries. A perfusion pressure of 60-80 mmHg gave flow rates ranging from 30 to 40 ml/min per artery. Serotonin, PGF2 alpha and PGE2 were added to the perfusate and tested for vasoactivity. All substances induced a dose-dependent vasoconstriction. Serotonin proved to be the most potent vasoconstrictor. The minimum dose required to induce visible pressure responses was 10(-9) - 10(-8) M of serotonin and 10(-7) M of PGF2 alpha and PGE2. When adding methysergide to the perfusate, the serotonin response was abolished, while the effects of the prostanoids remained unaltered.
Bjøro et al. (1986) studied this question.