TY - JOUR T1 - Identification of Contractile P2Y<sub>1</sub>, P2Y<sub>6</sub>, and P2Y<sub>12</sub> Receptors in Rat Intrapulmonary Artery Using Selective Ligands JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 755 LP - 762 DO - 10.1124/jpet.112.198051 VL - 343 IS - 3 AU - Callum Mitchell AU - Nawazish-i-Husain Syed AU - Asrin Tengah AU - Alison M. Gurney AU - Charles Kennedy Y1 - 2012/12/01 UR - http://jpet.aspetjournals.org/content/343/3/755.abstract N2 - ATP and UDP constrict rat intrapulmonary arteries, but which receptors mediate these actions is unclear. Here, we used selective agonists and antagonists, along with measurements of P2Y receptor expression, to characterize the receptor subtypes involved. Isometric tension was recorded from endothelium-denuded rat intrapulmonary artery rings (i.d. 200–500 μm) mounted on a wire myograph. Expression of P2Y receptor subtype expression was determined by using reverse transcription-polymerase chain reaction with receptor-specific oligonucleotide primers. The selective P2Y1 agonist (N)-methanocarba-2-methylthioadenosine-5′-O-diphosphate (MRS2365) induced small, concentration-dependent contractions that were inhibited by the P2Y1 antagonist N6-methyl-2′-deoxyadenosine-3′,5′-bisphosphate (MRS2179). Contractions evoked by ATP were unaffected by MRS2179, but inhibited by approximately one-third by the P2Y12 antagonist N6-(2-methylthiomethyl)-2-(3,3,3-trifluoropropylthio)dichloro-methylene ATP (AR-C69931MX). Combined blockade of P2X1 and P2Y12 receptors virtually abolished the response to ATP. ADP also evoked contractions that were abolished by AR-C69931MX. The selective P2Y6 receptor agonist 3-(2-oxo-2-phenylethyl)-UDP (PSB 0474) evoked concentration-dependent contractions and was approximately three times more potent than UDP, but the P2Y14 agonist UDP-glucose had no effect. Contractions evoked by UDP were inhibited by the P2Y6 receptor antagonist N,N′-1,4-butanediylbis-N′-(3-isothiocyanatophenyl)thiourea (MRS2578), but not the cysteinyl leukotriene 1 (CysL1) antagonist 3-(3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)((3-dimethylamino-3-oxopropyl)thio)methyl)thiopropanoic acid (MK571). Higher concentrations of MRS2578 inhibited contractions to KCl, so they were not studied further. mRNA for P2Y1, P2Y6, and P2Y12 receptors was identified. Our working model is that P2Y12 and P2X1 receptors are present in rat intrapulmonary arteries and together mediate ATP-induced vasoconstriction. Contractile P2Y6, but not P2Y14 or CysLT1, receptors are also present and are a major site through which UDP evokes constriction. ER -