In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 302, No. 4 ( 2012-02-15), p. R400-R408
Abstract:
Previously, we have shown that A 2A adenosine receptor (A 2A AR) knockout mice (KO) have increased contraction to adenosine. The signaling mechanism(s) for A 2A AR is still not fully understood. In this study, we hypothesize that, in the absence of A 2A AR, ω-hydroxylase (Cyp4a) induces vasoconstriction through mitogen-activated protein kinase (MAPK) via upregulation of adenosine A 1 receptor (A 1 AR) and protein kinase C (PKC). Organ bath and Western blot experiments were done using isolated aorta from A 2A KO and corresponding wild-type (WT) mice. Isolated aortic rings from WT and A 2A KO mice were precontracted with submaximal dose of phenylephrine (10 −6 M), and concentration responses for selective A 1 AR, A 2A AR 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 2A AR 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 2A KO 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 2A KO 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 2A KO 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 2A KO aorta was inhibited by PD-98059 and Gö-6976. Western blot analysis indicated the upregulation of A 1 AR, Cyp4a, PKC-α, and phosphorylated-ERK1/2 in A 2A KO 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 2A AR, Cyp4a induces vasoconstriction through MAPK via upregulation of A 1 AR and PKC-α.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.00481.2011
Language:
English
Publisher:
American Physiological Society
Publication Date:
2012
detail.hit.zdb_id:
1477297-8
SSG:
12
Bookmarklink