EphA2 receptor has emerged as a novel cardioprotective target against
myocardial infarction by preserving cardiac function, limiting
infarct size and
inflammation and enhancing cell survival via elevating phosphorylated Akt
protein levels. However, the role of
Eph receptors in postconditioning remains to be elucidated. Thus, the present study was designed to explore the role of EphA2 receptors in cardioprotective mechanism of postconditioning by employing
Doxazosin as
EphA2 receptor agonist,
Lithocholic acid as antagonist and
Wortmannin as specific
phosphoinositide 3-kinase (PI3K) inhibitor. In Langendorff perfused isolated rat hearts, exposure of
ischemia for 30 min succeeded by reperfusion for 2 h produced cardiac damage as determined by increase in size of
infarct, LVDP, liberation of LDH and CK in effluent from coronary arteries. The reperfused hearts were homogenized and tissue concentrations of
TBARs, reduced GSH and
Catalase were determined. A marked rise in
infarct size, liberation of LDH and CK in effluent and
TBARs in myocardial tissue was observed in ischemic and reperfused hearts.
Ischemic postconditioning comprising of 6 alternate episodes of 10 s
ischemia and 10 s reperfusion and pharmacological post-conditioning by
Doxazosin infusion for 5 min Before reperfusion confers significant protection against myocardial injury as manifested by remarkably decreased
infarct size, levels of LDH, CK and tissue
TBARs along with increase in GSH and
Catalase activity. Pre-treatment of EphA2 antagonist,
Lithocholic acid and PI3K inhibitor,
Wortmannin attenuated the cardioprotective effect of postconditioning. Our results suggest that EphA2 receptors may be involved in postconditioning mediated cardioprotection probably through PI3K/Akt pathway.