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Distinction between relaxations induced via prostanoid EP4 and IP1 receptors in pig and rabbit blood vessels

Jones, R.L. and Chan, K.M. (2001) Distinction between relaxations induced via prostanoid EP4 and IP1 receptors in pig and rabbit blood vessels. British Journal of Pharmacology, 134. pp. 313-324. ISSN 0007-1188

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Our study shows that the prostacyclin analogues AFP-07 and cicaprost are moderately potent agonists for prostanoid EP4 receptors, in addition to being highly potent IP1 receptor agonists. Both activities were demonstrated on piglet and rabbit saphenous veins, which are established EP4 preparations. On piglet saphenous vein, PGE2 was 6.1, 24, 96, 138, 168 and 285 times respectively more potent than AFP-07, cicaprost, PGI2, iloprost, carbacyclin and TEI-9063 in causing relaxation. Another prostacyclin analogue taprostene did not induce maximum relaxation (21 – 74%), and did not oppose the action of PGE2. The EP4 receptor antagonist AH 23848 (30 μm) blocked relaxant responses to PGE2 (dose ratio=8.6±1.3, s.e.mean) to a greater extent than cicaprost (4.9±0.7) and AFP-07 (3.8±0.8), had variable effects on TEI-9063-induced relaxation (3.7±1.5), and had no effect on taprostene responses (<2.0). On rabbit saphenous vein, AH 23848 blocked the relaxant actions of PGE2, AFP-07, cicaprost, iloprost and carbacyclin to similar extents. AFP-07, cicaprost and TEI-9063 showed high IP1 relaxant potency on piglet carotid artery, rabbit mesenteric artery and guinea-pig aorta, with AFP-07 confirmed as the most potent IP1 agonist reported to date. AH 23848 did not block cicaprost-induced relaxation of piglet carotid artery. EP3 contractile systems in these preparations can confound IP1 agonist potency estimations. Caution is urged when using AFP-07 and cicaprost to characterize IP1 receptors in the presence of EP4 receptors. Taprostene may be a lead to a highly selective IP1 receptor agonist.

Item type: Article
ID code: 38401
Keywords: vascular smooth muscle, AH 23848 , iloprost, cicaprost , prostanoid EP receptors, prostanoid IP receptors, prostacyclin, prostaglandin E2 , sulprostone, Pharmacy and materia medica, Therapeutics. Pharmacology, Pharmacology
Subjects: Medicine > Pharmacy and materia medica
Medicine > Therapeutics. Pharmacology
Department: Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical Sciences
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    Depositing user: Pure Administrator
    Date Deposited: 12 Mar 2012 14:57
    Last modified: 04 Sep 2014 18:55

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