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- Title
Characterization of 5-HT receptor subtypes mediating contraction in human umbilical vein. 2. Evidence of involvement of 5-HT<sub>1B</sub> receptors using functional studies.
- Authors
Rogines-Velo, María Pía; Pelorosso, Facundo Germán; Zold, Camila Lidia; Brodsky, Paula Tamara; Rothlin, Rodolfo Pedro
- Abstract
Previous studies have shown that a heterogeneous 5-HT receptor population may be involved in vasoconstrictor actions of 5-HT in human umbilical vein (HUV). The aim of the present study was to evaluate whether the 5-HT1B/1D receptor subtype mediates contraction in this tissue. 5-HT1B/1D-mediated responses can be enhanced or unmasked after exposure to threshold or sub-threshold KCl concentrations. In HUV rings, when 5-HT, α-Me-5HT or bradykinin concentration-response curves (CRC) were generated in the presence or absence of sub-threshold concentrations of KCl, there were not significant differences between the control and the treated rings. On the other hand, sumatriptan, the classic selective 5-HT1B/1D receptor agonist, produced a concentration-related contraction that was potentiated in the presence of sub-threshold KCl concentration. In addition, L-694,247, the novel selective 5-HT1B/1D receptor agonist, displayed a concentration-dependent contraction with high potency in HUV. The presence of sub-threshold concentrations of KCl produced a marked leftward shift of its CRCs. GR-55562, a 5-HT1B/1D-selective antagonist, competitively blocked sumatriptan CRCs with an estimated pA2 of 8.00 and a slope not different from unity. Likewise, SB-216641, a selective 5-HT1B antagonist, produced a parallel rightward shift of sumatriptan CRCs in HUV. The Schild analysis yielded a pA2 of 9.29, with a slope not different from unity. In addition, L-694,247 contractile responses were competitively blocked by SB-216641 with an estimated pA2 value of 9.12 and a Schild slope not different from unity. On the other hand, ketanserin behaved as a weak antagonist of L-694,247-induced responses, yielding a calculated pA2 value of 6.40. In summary, the results obtained in this study support that the 5-HT1B receptor subtype is involved in vasoconstrictor responses in HUV.
- Subjects
KETANSERIN; RECEPTOR antibodies; SEROTONIN agonists; VASOCONSTRICTORS; PHARMACOLOGY; BLOOD vessels
- Publication
Naunyn-Schmiedeberg's Archives of Pharmacology, 2002, Vol 366, Issue 6, p596
- ISSN
0028-1298
- Publication type
Article
- DOI
10.1007/s00210-002-0637-8