Abstract
Serotonin (5-hydroxytryptamine; 5-HT) is released during platelet aggregation, a phenomenon commonly observed in blood clot formation and venous diseases. Once released, 5-HT can interact with its receptors in the peripheral vasculature to modify vascular tone. The goal of this study was to perform a detailed pharmacological characterization of the 5-HT receptors involved in the contractile response of the rat jugular vein (RJV) using recently developed drugs with greater selectivity toward 5-HT receptor subtypes. We hypothesized that, as for other blood vessels, the 5-HT1B/1D and 5-HT2B receptor subtypes mediate contraction in RJV alongside the 5-HT2A receptor subtype. Endothelium-intact RJV rings were set up in an isolated organ bath for isometric tension recordings, and contractile concentration-effect curves were obtained for 13 distinct serotonergic receptor agonists. Surprisingly, the 5-HT1A and the mixed 5-HT1A/1B receptor agonists (±)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene (8-OH-DPAT) and 5-methoxy-3 (1,2,3,6-tetrahydropyridin-4-yl) (1H indole) (RU24969) caused contractions that were antagonized by the 5-HT1A receptor antagonist [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide (WAY100135). The contractile curve to 5-HT was shifted to the right by WAY100135, 3-[2-[4-(4-fluoro benzoyl)-piperidin-1-yl]ethyl]-1H-quinazoline-2,4-dione (ketanserin; 5-HT2A/C receptor antagonist), and 1-(2-chloro-3,4-dimethoxybenzyl)-6-methyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole hydrochloride (LY266097; 5-HT2B receptor antagonist). Ketanserin also caused rightward shifts of the contractile curves to 8-OH-DPAT, RU24969, and the 5-HT2B receptor agonist (α-methyl-5-(2-thienylmethoxy)-1H-indole-3-ethanamine) (BW723C86). Agonists for 5-HT1B/1D/1F, 5-HT3, 5-HT6, and 5-HT7 receptors were inactive. In real-time polymerase chain reaction experiments that have never been performed in this tissue previously, we observed mRNA expression for the 5-HT2A, 5-HT2B, and 5-HT7 receptors, whereas no significant mRNA expression was found for 5-HT1A, 5-HT1B, and 5-HT1D receptors. These results support the 5-HT2A receptor as the main subtype targeted by 5-HT to contract the RJV.
Footnotes
This work was supported in part by the National Institutes of Health National Heart, Lung, and Blood Institute [Grant 81115] (to S.W.W.) and Fundação de Apoio à Pesquisa Científica e Tecnológica do Estado de Santa Catarina and Conselho Nacional de Desenvolvimento Científico e Tecnológico [Grant 2371/090] (to A.E.L.). A.E.L. was a recipient of an American Heart Association Postdoctoral Fellowship [Grant 0725729Z].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.109.163014.
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ABBREVIATIONS:
- 5-HT
- 5-hydroxytryptamine (serotonin)
- DOI
- (±)-2,5-dimethoxy-(−)4-iodo-2,5-dimethoxyphenylisopropylamine
- PCR
- polymerase chain reaction
- PGF2α
- prostaglandin F2α
- 8-OH-DPAT
- (±)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene
- RU24696
- 5-methoxy-3 (1,2,3,6-tetrahydropyridin-4-yl) (1H indole)
- 5-CT
- 5-carboxamidotryptamine
- BRL54443
- 5-hydroxy-3-(1-methylpiperidin-4-yl)-1H-indole
- BW723C86
- α-methyl-5-(2-thienylmethoxy)-1H-indole-3-ethanamine
- EMD386088
- 5-chloro-2-methyl-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole hydrochloride
- LP44
- 4-[2-(methylthio)phenyl]-N-(1,2,3,4-tetrahydro-1-naphthalenyl)-1-piperazinehexanamide hydrochloride
- WAY100135
- [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide
- GR127935
- 2-methyl-4-(5-methyl-[1,2,4]oxadiazol-3-yl)-biphenyl-4-carboxylic-acid[4-methoxy-3-(4-methyl-piperazin-1-yl)-phenyl]amide
- LY266097
- (1-(2-chloro-3,4-dimethoxybenzyl)-6-methyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole hydrochloride)
- SB269970
- (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-mentyl-1-piperidinyl)ethyl] pyrrolidine hydrochloride
- β2m
- β-2-microglobulin
- Ct
- cycle threshold.
- Received October 26, 2009.
- Accepted April 7, 2010.
- Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics
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