Mediation by 5-HT2 receptors of 5-hydroxytryptamine-induced contractions of human placental vein

• Published in: General pharmacology 1998-04, Vol.30 (4), p.483-488
• Main Authors: CRUZ, M. A, GALLARDO, V, MIGUEL, P, CARRASCO, G, GONZALEZ, C
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cardiovascular system; Dose-Response Relationship, Drug; Female; Humans; Medical sciences; Pharmacology. Drug treatments; Placenta - blood supply; Receptors, Serotonin - metabolism; Serotonin - analogs & derivatives; Serotonin - pharmacology; Serotonin Antagonists - pharmacology; Serotonin Receptor Agonists - pharmacology; Umbilical Veins - drug effects; Umbilical Veins - physiology; Vascular wall; Vasoconstriction - drug effects
• ISSN: 0306-3623; 1879-0011
• DOI: 10.1016/S0306-3623(97)00107-9

1. In isolated human placental chorionic vein segments, 5-hydroxytryptamine (5-HT; 10(-8) to 5 x 10(-5) M) elicited concentration-dependent contractions with EC50 = 5.5 (5.2-5.7) x 10(-8) M) and Emax = 93.1 +/- 7.3% of 75 mM KCl-induced contraction. 2. The agonist of 5-HT2 receptors, alpha-methyl-5-hydroxytryptamine, and the selective agonist of 5-HT1 receptors, N,N-dipropyl-5-carboxamidotryptamine and 5-carboxamidotryptamine, induced pronounced concentration-related contractions, which reached 71.1 +/- 6.0%, 53.0 +/- 5.0% and 75.0 +/- 7.8% at the highest dose tested, respectively. The agonist of 5-HT3 receptor, 2-methyl-5-hydroxytryptamine, reached a maximum averaging 36.7 +/- 5.1% of the maximal response to KCl. 3. The 5-HT1 and 5-HT3 receptor antagonists, methiothepin and metoclopramide (10(-7) to 10(-6) M) did not alter the response to 5-HT. However, ketanserin (10(-7) to 10(-6) M), a 5-HT2 receptor antagonist, induced significant inhibition of the concentration-response curve to 5-HT. 4. Contractile responses to 5-carboxamidotryptamine and 2-methyl-5-hydroxytryptamine were not affected by methiothepin and metoclopramide, respectively, whereas ketanserin significantly attenuated the contractile response to these agonists. 5. In conclusions, our study shows that 5-HT2 receptors mediate contraction of the human placental vein with no obvious role for 5-HT1-like, or 5-HT3 receptors.