Activation of
adenosine A(3) receptor (A(3)AR) protects against
ischemia/reperfusion injury in the heart. However, the downstream signaling mechanisms leading to its delayed anti-ischemic effects remain unclear. We hypothesized that A(3)AR stimulation protects the heart via activation of nuclear
transcription factor kappa B (
NF-kappa B) and synthesis of
inducible nitric oxide synthase (iNOS). Mice were treated with selective A(3)AR agonist, N(6)-(3-iodobenzyl)
adenosine-5;-N-methyluronamide (
IB-MECA). Twenty-four h later, hearts were perfused in Langendorff mode and subjected to 30 min of global
ischemia and 30 min of reperfusion.
IB-MECA caused post-ischemic reduction in
necrosis and improvement in myocardial performance which was abolished by A(3)AR antagonist, MRS1191. Electrophoretic mobility shift assay demonstrated increased
NF-kappa B binding in nuclear extracts following A(3)AR stimulation, which was diminished by MRS1191 and
NF-kappa B inhibitor, pyrrolidinediethyldithiocarbamate (
PDTC). The cardioprotection was abrogated by
PDTC and targeted ablation of p50 subunit of
NF-kappa B in mice. The inhibition of iNOS with
S-methylisothiourea and targeted disruption of the iNOS gene also abolished the protective effect of A(3)AR stimulation. Expression of iNOS
mRNA and NO production were enhanced after 6 and 24 h respectively of
IB-MECA treatment. MRS1191 and
PDTC blocked
IB-MECA induced NO production after A(3)AR stimulation.
MitoK(ATP) channel blocker,
5-hydroxydecanoate abolished the protective effect of A(3)AR. For the first time, we have provided direct evidence of an essential role of
NF- kappa B activation and iNOS in A(3)AR-induced late preconditioning. Selective activation of A(3)AR with
IB-MECA can be used to trigger long-lasting ischemic protection in the heart.