Endothelium-derived prostanoids reduce 5-hydroxytryptamine-induced contraction in the human uterine artery.

The contribution of endothelium-linked mechanisms to the contraction induced by 5-hydroxytryptamine (5-HT) was investigated in the isolated human uterine artery. 5-HT contracted the uterine artery concentration-dependently. Removal of the endothelium or treatment with the cyclooxygenase inhibitor indomethacin potentiated the contractile response to 5-HT. The nitric oxide synthase inhibitor L-N(G)-monomethyl-arginine (L-NMMA) did not influence the contraction induced by 5-HT. Indomethacin did not affect the response to 5-HT in endothelium-denuded vessels. The 5-HT1 receptor agonist 5-carboxyamidotryptamine (5-CT) did not relax precontracted arteries. Removal of the endothelium did not change the response to 5-HT in the presence of the 5-HT(1B/D) receptor antagonist GR127935 and the 5-HT1A and 5-HT1B receptor antagonist -pindolol. The 5-HT1B receptor antagonist SB224289 did not affect the contraction induced by 5-HT. The results indicate that the 5-HT-induced contraction in the human uterine artery is accompanied by the release of an endothelium-derived relaxing factor (EDRF). This EDRF seems to be a prostanoid, probably prostacyclin (PGI2). The endothelium-linked mechanism seems to be mediated via a 5-HT1 receptor, but it is not possible to further classify the receptor subtype by the information obtained in this study.