REC-2615

We have recently shown that the postjunctional alpha(2)-adrenoceptor mediating contraction of porcine pulmonary veins is of the alpha(2C)-subtype. We could also demonstrate that alpha(1)-adrenoceptors might contribute to the contraction in that blood vessel. In the present study, we aimed at characterising the alpha(1)-adrenoceptor subtype(s) involved using pharmacological and molecular biological methods. In isolated rings of porcine pulmonary veins the typical alpha(1)-adrenoceptor agonist phenylephrine caused a concentration-dependent contraction that was inhibited by the alpha(1B)-adrenoceptor selective antagonists 1-[4-(4-amino-6,7-dimethoxyquinazolin-2-yl)piperazin-1-yl]-2-[2-(isopropyl)-6-methoxyphenoxy]ethan-1-one (Rec15/2615; pA(2) 8.96+/-0.13) and 4-amino-2-[4-[1-(benzyloxycarbonyl)-2(S)-[[(1,1-dimethylethyl)amino]carbonyl]-piperazinyl]-6,7-dimethoxyquinazoline (L-765,314; pA(2) 7.22+/-0.05), as well as the alpha(1D)-adrenoceptor selective antagonist 8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]decane-7,9-dione (BMY7378; pA(2) 8.29+/-0.15, slope of the Schild plot 0.75+/-0.09, significantly different from unity, P<0.05), but not by the alpha(1A)-adrenoceptor selective antagonists (+/-)-1,3,5-trimethyl-6-[[3-[4-((2,3-dihydro-2-hydroxymethyl)-1,4-benzodioxin-5-yl)-1-piperazinyl]propyl]amino]-2,4(1H,3H)-pyrimidinedione (B8805-033) and N-[2-(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha,alpha-dimethyl-1H-indole-3-ethanamine (RS-17053). These findings suggest that phenylephrine activates both alpha(1B)- and alpha(1D)-adrenoceptors. The observation was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR) in porcine pulmonary veins, where mRNA signals for alpha(1B)- and alpha(1D)-adrenoceptors could be detected. However, the antagonist properties of rauwolscine and yohimbine (non-subtype selective alpha(2)-adrenoceptor antagonists) against phenylephrine showed that this agonist also activates alpha(2)-adrenoceptors in pulmonary veins. This was strengthened in experiments using tissues that were stimulated with forskolin (cell permeable activator of adenylyl cyclase). Phenylephrine mimicked the effect of the selective alpha(2)-adrenoceptor agonist UK14304 by causing an inhibition of forskolin-stimulated cAMP accumulation that was blocked by rauwolscine. It is concluded that, in addition to alpha(1B)- and alpha(1D)-adrenoceptors, phenylephrine can stimulate alpha(2)-adrenoceptors in porcine pulmonary veins.

1-Octanol, 9vPnC-MnCc; Abiraterone acetate, Adalimumab, Adefovir dipivoxil, Alemtuzumab, Aliskiren fumarate, Aminolevulinic acid hexyl ester, Amlodipine besylate/atorvastatin calcium, Amrubicin hydrochloride, Anakinra, Aripiprazole, ARRY-520, AS-1404, Asimadoline, Atazanavir sulfate, AVE-0277, Azelnidipine; Bevacizumab, Bimatoprost, Boceprevir, Bortezomib, Bosentan, Botulinum toxin type B; Certolizumab pegol, Cetuximab, Clevudine, Contusugene ladenovec, CP-751871, Crofelemer, Cypher, CYT006-AngQb; Darbepoetin alfa, Desmopressin, Dexlansoprazole, DG-041; E-5555, Ecogramostim, Entecavir, Erlotinib hydrochloride, Escitalopram oxalate, Eszopiclone, Everolimus, Ezetimibe, Ezetimibe/simvastatin; Falecalcitriol, Fampridine, Fesoterodine fumarate, Fingolimod hydrochloride; Gefitinib, Ghrelin (human), GS-7904L, GV-1001; HT-1001; Insulin detemir, ISIS-112989, Istradefylline; Laquinimod sodium, Latanoprost/timolol maleate, Lenalidomide, Levobetaxolol hydrochloride, Liposomal doxorubicin, Liposomal morphine sulfate, Lubiprostone, Lumiracoxib, LY-518674; MEM-1003, Mesna disulfide, Mipomersen sodium, MM-093, Mycophenolic acid sodium salt; Naptumomab estafenatox, Natalizumab; Olmesartan medoxomil, Olmesartan medoxomil/hydrochlorothiazide; Paclitaxel nanoparticles, Paclitaxel poliglumex, Pasireotide, Pazufloxacin mesilate, Pegfilgrastim, Peginterferon alfa-2a, Peginterferon alfa-2b, Peginterferon alfa-2b/ribavirin, Pegvisomant, Pemetrexed disodium, Pimagedine, Pimecrolimus, Pramlintide acetate, Prasterone, Pregabalin, Prulifloxacin; QAE-397; Rec-15/2615, RFB4(dsFv)-PE38, rhGAD65, Roflumilast, Romiplostim, Rosuvastatin calcium, Rotigotine, Rupatadine fumarate; Safinamide mesilate, SIR-Spheres, Sitagliptin phosphate, Sodium phenylacetate, Sodium phenylacetate/Sodium benzoate, Sorafenib, SSR-244738; Taribavirin hydrochloride, Taxus, Teduglutide, Tegaserod maleate, Telaprevir, Telbivudine, Tenofovir disoproxil fumarate, Tigecycline, Tiotropium bromide, Trabectedin, Travoprost, Treprostinil sodium; Ustekinumab; Valsartan/amlodipine besylate, Varenicline tartrate, Vildagliptin; Zofenopril calcium.