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Advisor(s)
Abstract(s)
We studied the role of several serotonin (5-HT) and histamine receptors in the regulation of human umbilical artery (HUA) contractility. Among the 5-HT agonists used, only the 5-HT2A and 5HT1B/D agonists contracts HUA. The 5-HT-induced contractions were fully inhibited by ketanserin (5-HT2A antagonist). The 5-HT7-activation also relaxes and increases intracellular cyclic adenosine monophosphate (cAMP). Among the histamine receptor agonists, only betahistine (H1 agonist) induced significant contractile effect. Histamine-induced contraction was partially relaxed by pyrilamine (H1 antagonist). Betahistine-induced contraction was partially blocked by dimaprit (H2 agonist) and by the H3 agonist when a low concentration of forskolin is present. Both, H2 and H3 agonists increased the cAMP intracellular levels in HUA smooth muscle. These findings show that in HUA, 5-HT2A- and 5-HT1B/1D-activation lead to vasoconstriction and 5-HT7-activation induces vasorelaxation. Concerning histamine receptors, H1-activation induces contraction and H2- and H 3-activation lead to vasorelaxation.