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Mediation by 5‐hydroxytryptamine 2B receptors of endothelium‐dependent relaxation in rat jugular vein
Author(s) -
Ellis Elizabeth S.,
Byrne Clare,
Murphy Olive E.,
Tilford Nicholas S.,
Baxter Gordon S.
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb13240.x
Subject(s) - ketanserin , yohimbine , receptor , agonist , endocrinology , medicine , antagonist , receptor antagonist , endothelium , chemistry , pharmacology , biology , 5 ht receptor , serotonin
1 An ‘atypical’ 5‐HT 2 receptor which is located on the endothelium of rat jugular vein has been described. In the present study we have further defined the nature of the 5‐HT 2 receptor subtype present in this preparation. 2 In experiments conducted in the presence of ketanserin to preclude involvement of 5‐HT 2 receptors, the mixed 5‐HT 2B/2C antagonist, SB 200646, acted as an antagonist of 5‐HT at the endothelial 5‐HT receptor (pA 2 = 7.2). Yohimbine, which exhibits negligible affinity for rat 5‐HT 2C receptors but has high 5‐HT 2B receptor affinity, acted as a potent but non‐surmountable antagonist (pA 2 ≥ 7.3) in rat jugular vein. Neither yohimbine nor SB 200646 affected endothelium‐dependent relaxations induced by carbachol. 3 Mianserin also acted as a surmountable antagonist (pA 2 = 7.3) and the 5‐HT 2B agonist, BW 723C86, acted as a potent partial agonist (pEC 50 [95% C L], intrinsic activity ± s.e.mean = 7.9 [7.6–8.3], 0.84 ± 0.04). Responses to BW 723C86 were antagonized by SB 200646 (0.3 μ m ) yielding an ‘apparent’ pA 2 [95% CL] of 7.03 [6.76–7.32]. 4 These data are consistent with the presence of 5‐HT 2B receptors mediating endothelium‐dependent relaxation of rat jugular vein.