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- Title
5- HT modulates the rat mesenteric vasopressor outflow by 5-HT<sub>1D</sub> sympatholytic receptors.
- Authors
García‐Pedraza, José‐Ángel; García‐Domingo, Mónica; Gómez‐Roso, Miriam; Rodríguez‐Barbero, Alicia; Martín, María‐Luisa; Morán, Asunción
- Abstract
5-hydroxytryptamine (5- HT) modulates noradrenergic activity in different cardiovascular territories, but its effect on the mesenteric vasopressor outflow has not yet been clarified. This study investigated the in vivo serotonergic influence, characterizing 5- HT receptors implicated, in sympathetic innervation of mesenteric vasculature. Wistar rats were anaesthetised and prepared for the in situ autoperfused rat mesentery, monitoring systemic blood pressure ( SBP), heart rate ( HR) and mesenteric perfusion pressure ( MPP). Electrical stimulation of mesenteric sympathetic nerves resulted in frequency-dependent increases in MPP (9 ± 1.6, 25.7 ± 3.9 and 60.2 ± 5 mmHg for 2, 4 and 8 Hz, respectively), without altering SBP or HR. 5- HT (1-25 μg/kg), 5-carboxamidotryptamine (5- HT1/7 agonist; 25 μg/kg) or L-694,247 (5-HT1D agonist; 1-25 μg/kg) i.a. bolus inhibited vasopressor responses by mesenteric nerves electrical stimulation, unlike i.a. bolus of agonists 8- OH- DPAT (5- HT1A), CGS-12066B (5- HT1B), BRL 54443 (5- HT1e/1F), α-methyl-5- HT (5- HT2), 1- PBG (5- HT3), cisapride (5- HT4) or AS-19 (5- HT7) (25 μg/kg each). Interestingly, i.a. L-694,247 (25 μg/kg) also reduced the exogenous norepinephrine-induced vasoconstrictions. Pretreatment with selective 5- HT1D receptor antagonist, LY310762 (1 mg/kg, i.v.), completely abolished L-694,247- and 5- HT-induced mesenteric sympathoinhibition. Furthermore, ELISA analysis confirmed 5- HT1D receptors expression in mesenteric artery. These findings suggest that serotonergic mechanisms-induced sympathoinhibition of mesenteric noradrenergic outflow is mediated by pre and/or postjunctional 5- HT1D receptors.
- Subjects
MESENTERIC blood vessels; SEROTONIN receptors; VASOCONSTRICTION; MESENTERIC artery; SYMPATHETIC nervous system
- Publication
Clinical & Experimental Pharmacology & Physiology, 2017, Vol 44, Issue 12, p1224
- ISSN
0305-1870
- Publication type
Article
- DOI
10.1111/1440-1681.12841