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5‐HYDROXYTRYPTAMINE‐INDUCED CONTRACTION OF THE MARMOSET AORTA IS MEDIATED BY A 5‐HT 1 ‐LIKE RECEPTOR
Author(s) -
Frewin SM Dyer, IS de la Lande, DB,
Head RJ
Publication year - 1998
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.1440-1681.1998.t01-13-.x
Subject(s) - ketanserin , methysergide , medicine , endocrinology , agonist , receptor antagonist , chemistry , receptor , antagonist , 5 ht receptor , pharmacology , serotonin , biology
1. 5‐Hydroxytryptamine (5‐HT) exerts both contractile and relaxant effects in the marmoset isolated aorta, actions that are unaffected by the 5‐HT 2 antagonist ketanserin. The aim of the present study was to define the receptors mediating the contractile activity of 5‐HT in the marmoset aorta. 2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A 2 agonist U44069 in order to amplify the responses; or (ii) exposed to N ω ‐nitro‐ L ‐arginine (100 μmol/L) plus LY 53857 (0.1 μmol/L; a 5‐HT 2 receptor antagonist shown previously to inhibit relaxation). The effect of 5‐HT on adenosine 3′,5′‐cyclic monophosphate (cAMP) formation was also investigated. 3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5‐carboxamidotryptamine > 5‐HT > sumatriptan > 8‐hydroxy‐2‐(di‐ n ‐propylamino)tetralin; (ii) inhibition of contractile action of 5‐HT by the 5‐HT 1D antagonist GR 127935; (iii) a contractile response to methysergide; (iv) a lack of effect of tropisetron, an antagonist of 5‐HT 3 and 5‐HT 4 receptors; and (v) inhibition of forskolin‐stimulated cAMP formation by 5‐HT (in the presence of LY 53857), indicative of negative coupling to adenylate cyclase. 4. The above effects fulfil the criteria for a 5‐HT 1 ‐like receptor. In view of the previous finding that this contractile response is insensitive to ketanserin, it is concluded that the contractile effects of 5‐HT in the marmoset aorta are mediated exclusively by a 5‐HT 1 ‐like receptor.