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Adenosine produces nitric oxide and prevents mitochondrial oxidant damage in rat cardiomyocytes.

Abstract：

OBJECTIVE:To examine if adenosine prevents oxidant-induced mitochondrial dysfunction by producing nitric oxide (NO) in cardiomyocytes. METHODS AND RESULTS:Adenosine significantly enhanced the fluorescence of DAF-FM, a dye specific for NO, implying that adenosine induces synthesis of NO. Adenosine-induced NO production was blocked by both the nonspecific NOS inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME) and N(5)-(1-Iminoethyl)-l-ornithine dihydrochloride (l-NIO), an inhibitor of endothelial NOS (eNOS), but not by N(6)-(1-Iminoethyl)-l-lysine hydrochloride (l-NIL), an inhibitor of inducible NOS (iNOS), indicating that adenosine activates eNOS. Adenosine also enhances eNOS phosphorylation and its activity. The adenosine A(2) receptor antagonist 8-(3-chlorostyryl)caffeine but not the A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine prevented the increase in NO production. CGS21680, an adenosine A(2) receptor agonist, markedly increased NO, further supporting the involvement of A(2) receptors. Adenosine-induced NO production was blocked by 4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo(3,4-d)pyrimidine (PP2), a selective Src tyrosine kinase inhibitor, suggesting that Src tyrosine kinase is crucial for adenosine-induced NO production. Adenosine-induced NO production was partially reversed by both wortmannin and Akt inhibitor indicating an involvement of PI3-kinase/Akt. Pretreatment of cells with adenosine prevented H(2)O(2)-induced depolarization of mitochondrial membrane potential (DeltaPsi(m)). The protective effect was blocked by l-NAME and l-NIO but not by l-NIL, indicating that eNOS plays a role in the action of adenosine. The protective effect of adenosine was further suppressed by KT5823, a specific inhibitor of protein kinase G (PKG), indicating the PKG may serve as a downstream target of adenosine. CONCLUSION:Adenosine protects mitochondria from oxidant damage through a pathway involving A(2) receptors, eNOS, NO, PI3-kinase/Akt, and Src tyrosine kinase.

journal_name

Cardiovasc Res

journal_title

Cardiovascular research

authors

Xu Z,Park SS,Mueller RA,Bagnell RC,Patterson C,Boysen PG

doi

10.1016/j.cardiores.2004.12.004

subject

Has Abstract

pub_date

2005-03-01 00:00:00

pages

803-12

issue

eissn

0008-6363

issn

1755-3245

pii

S0008-6363(04)00551-6

journal_volume

pub_type

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Adenosine produces nitric oxide and prevents mitochondrial oxidant damage in rat cardiomyocytes.