par Ponnoth, Dovenia D.S.;Nayeem, Mohammed M.A.;Kunduri, Swati S.S.;Jamal Mustafa, S;Tilley, Stephen S.L.;Zeldin, Darryl D.C.;Ledent, Catherine 
Référence American journal of physiology. Regulatory, integrative and comparative physiology, 302, 4, page (R400-R408)
Publication Publié, 2012-02
Référence American journal of physiology. Regulatory, integrative and comparative physiology, 302, 4, page (R400-R408)
Publication Publié, 2012-02
Article révisé par les pairs
| Résumé : | Previously, we have shown that A 2A adenosine receptor (A 2AAR) knockout mice (KO) have increased contraction to adenosine. The signaling mechanism(s) for A 2AAR is still not fully understood. In this study, we hypothesize that, in the absence of A 2AAR, ω-hydroxylase (Cyp4a) induces vasoconstriction through mitogen-activated protein kinase (MAPK) via upregulation of adenosine A1 receptor (A 1AR) and protein kinase C (PKC). Organ bath and Western blot experiments were done using isolated aorta from A 2AKO and corresponding wild-type (WT) mice. Isolated aortic rings from WT and A2AKO mice were precontracted with submaximal dose of phenylephrine (10 -6 M), and concentration responses for selective A 1AR, A 2AAR agonists, angiotensin II and cytochrome P-450-epoxygenase, 20-hydroxyeicosatrienoic acid (20- HETE) PKC, PKC-α, and ERK1/2 inhibitors were obtained. 2-p-(2- Carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680, A 2AAR agonist) induced concentration-dependent relaxation in WT, which was blocked by methylsulfonyl-propargyloxyphenylhexanamide (cytochrome P-450-epoxygenase inhibitor; 10 -5 M) and also with removal of endothelium. A 1 agonist, 2-chloro-N 6- cyclopentyladenosine (CCPA) produced higher contraction in A 2AKO aorta than WT (49.2 ± 8.5 vs. 27 ± 5.9% at 10 -6 M, P < 0.05). 20-HETE produced higher contraction in A 2AKO than WT (50.6 ± 8.8 vs. 21.1 ± 3.3% at 10 -7 M, P < 0.05). Contraction to CCPA in WT and A 2AKO aorta was inhibited by PD-98059 (p42/p44 MAPK inhibitor; 10 -6 M), chelerythrine chloride (nonselective PKC blocker; 10 -6 M), Gö-6976 (selective PKC-α inhibitor; 10 -7 M), and HET0016 (20-HETE inhibitor; 10 -5 M). Also, contraction to 20- HETE in WT and A 2AKO aorta was inhibited by PD-98059 and Gö-6976. Western blot analysis indicated the upregulation of A 1AR, Cyp4a, PKC-α, and phosphorylated-ERK1/2 in A 2AKO compared with WT (P < 0.05), while expression of Cyp2c29 was significantly higher in WT. CCPA (10 -6 M) increased the protein expression of PKC-α and phosphorylated-ERK1/2, while HET0016 significantly reduced the CCPA-induced increase in expression of these proteins. These data suggest that, in the absence of A 2AAR, Cyp4a induces vasoconstriction through MAPK via upregulation of A 1AR and PKC-α. © 2012 the American Physiological Society. |
