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Effect of 5‐hydroxytryptamine on neurogenic vasoconstriction in the isolated, autoperfused hindquarters of the rat
Author(s) -
Calama E,
Ortíz de Urbina AV,
Morán A,
Martín ML,
San Román L
Publication year - 2005
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2010.04281.x
Subject(s) - agonist , ritanserin , endocrinology , medicine , receptor antagonist , 5 ht receptor , receptor , chemistry , stimulation , pharmacology , competitive antagonist , antagonist , serotonin , biology
SUMMARY 1. In the present study, we analysed the effect of different doses of 5‐hydroxytryptamine (5‐HT; intravenous infusions of 0.001–40 µg/kg per min) in the autoperfused hindquarters of the rat subjected to electrical stimulation (frequencies of 0.5–20 Hz) of the lumbar chains, investigating the relationship between the adrenergic and serotonergic systems in this vascular bed. 2. Because we observed that 5‐HT inhibited the increases in perfusion pressure induced by electrical stimulation of the lumbar chains, we used different agonists and antagonists to analyse the mechanism of action of 5‐HT. 3. The effect of 5‐HT was inhibited by methiothepin (a non‐specific 5‐HT receptor antagonist), but not by ritanserin (a selective 5‐HT 2 receptor antagonist). The effects of 5‐HT were mimicked by 5‐carboxamidotryptamine (a 5‐HT 1 receptor agonist) and L‐694 247 (a selective 5‐HT 1D receptor agonist), but not by 8‐hydroxy‐2‐dipropylaminotetralin (a 5‐HT 1A receptor agonist), CGS‐12066B (a 5‐HT 1B receptor agonist), α‐methyl‐5‐HT (a 5‐HT 2 receptor agonist), 1‐(3‐chlorophenyl) piperazine (a 5‐HT 2C receptor agonist) or 1‐phenylbiguanide (a 5‐HT 3 receptor agonist). The selective 5‐HT 1D/1B receptor antagonist BRL 15572 inhibited the effect of the agonist L‐694 247. 4. Our data suggest that 5‐HT inhibits the increases in perfusion pressure induced by the electrical stimulation of the lumbar chains, acting on presynaptic 5‐HT 1D receptors and decreasing the release of noradrenaline from the sympathetic nerves in the hindquarter vascular bed of the rat.