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Pharmacological studies on prostanoid receptors in the rabbit isolated saphenous vein: a comparison with the rabbit isolated ear artery
Author(s) -
Lydford S.J.,
McKechnie K.C.W.,
Dougall I.G.
Publication year - 1996
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.1476-5381.1996.tb15148.x
Subject(s) - prostanoid , agonist , prostaglandin e2 receptor , endocrinology , medicine , receptor , prostaglandin , phenylephrine , thromboxane a2 , chemistry , receptor antagonist , pharmacology , antagonist , biology , blood pressure
1 In isolated ring preparations of the rabbit saphenous vein, prostaglandin E 2 (PGE 2 ) caused well‐defined, stable and concentration‐dependent relaxations of KC1 contracted tissues with a mean potency (p[A 50 ]) of 9.39. 2 The prostanoid EP‐receptor agonists, PGE 1 , 11‐deoxy PGE 1 , 16,16‐dimethyl PGE 2 and misoprostol were all full agonists in this preparation. The EP 2 ‐receptor selective agonists, butaprost and AH13205, and the EP 1 /EP 3 ‐receptor selective agonist, sulprostone, also relaxed this tissue but were at least 300 times less potent than PGE 2 . 3 Prostaglandin D 2 (PGD 2 ), the DP‐receptor agonist, BW245C, and the IP‐receptor agonist, cicaprost, caused concentration‐dependent relaxations of the rabbit saphenous vein but were at least 60 times less potent than PGE 2 . 4 The selective EP 4 ‐receptor antagonist, AH23848B (30 μ m ), antagonized the PGE 2 concentration‐effect (E/[A]) curves yielding a pA 2 estimate of 4.96. The EP 1 /DP‐receptor antagonist, AH6809 (10 μ m ), had no effect on the location of PGE 2 E/[A] curves. 5 The stable thromboxane A 2 ‐mimetic, U46619, elicited concentration‐dependent contractions of the rabbit saphenous vein (p[A 50 ] = 8.01) however, PGE 2 and prostaglandin F 2α (PGF 2α ) were unable to produce a contractile response. The response to U46619 was competitively antagonized by the TP‐receptor antagonist, GR32191B, yielding a p K B estimate of 7.08. 6 In the rabbit isolated ear artery, PGE 2 , misoprostol and AH13205 relaxed tissues pre‐contracted with phenylephrine. PGE 2 (p[A 50 ] = 7.04) and misoprostol were equipotent, whereas AH13205 was some 40 fold less potent. AH23848B (30 μ m ) and AH6809 (1 and 10 μ m ) caused no significant shift in the location of PGE 2 E/[A] curves. 7 These data suggest that the rabbit isolated saphenous vein contains prostanoid, EP‐, DP‐, IP‐ and TP‐receptors. Based on antagonist affinity information and agonist potency orders, the rabbit saphenous vein contains an inhibitory prostanoid EP‐receptor different from that in the rabbit ear artery, but comparable to the recently described EP 4 ‐receptor.