Ecto-5′-nucleotidase plays a role in the cardioprotective effects of heat shock protein 72 in ischemia–reperfusion injury in rat hearts

Abstract

Objective: Heat shock protein 72 (HSP72) is involved in the myocardial self-preservation system under several conditions such as ischemia–reperfusion injury or late preconditioning. However, its mechanism is not fully understood. Ecto-5′-nucleotidase is a key enzyme for synthesizing adenosine and plays an important role in ischemic preconditioning. In this study, we tested the hypothesis that ecto-5′-nucleotidase plays a role in the cardioprotection of HSP72. Methods: Rat hearts (H group, n=6) were transfected with HSP72 gene by an intracoronary infusion of hemagglutinating virus of Japan (HVJ)–liposome complex. Control hearts (C group, n=6) were transfected with the β-galactosidase gene. Following 30 min of normothermic ischemia, grafts were reperfused using Langendorff apparatus. Results: The activity of ecto-5′-nucleotidase was significantly higher in H group than C group both before and after ischemia–reperfusion (H vs. C; 0.51±0.05 vs. 0.29±0.06, and 1.41±0.15 vs. 0.85±0.11 nmol/mg protein/min, P<0.05). H group also showed significant better functional recoveries than C group (P<0.05), as well as less creatine phosphokinase leakage (4.4±2.8 vs. 14.2±3.4 mU/min, P<0.05) and higher adenosine release (247.5±35.1 vs. 54.3±1.7 pmol/min, P<0.05). Administration of α,β-methylene adenosine diphosphate (AMP-CP), an inhibitor of ecto-5′-nucleotidase, significantly diminished the tolerance to ischemia–reperfusion injury in H group (P<0.05). Conclusion: These results demonstrated that ecto-5′-nucleotidase activated by an overexpression of HSP72 attenuated ischemia–reperfusion injury in the rat myocardium. They suggest that ecto-5′-nucleotidase plays a role in the cardioprotective effects of HSP72 in rat hearts.

Adenosine, Gene therapy, Hypoxia/anoxia, Preconditioning, Ventricular function