Abstract

SIACHOQUE, Nadezda et al. Ischemic Preconditioning Preserves Dystrophin Through Matrix Metalloproteinase-2 Inhibition. Rev. argent. cardiol. [online]. 2013, vol.81, n.1, pp.7-14. ISSN 1850-3748.

Background Ischemia/reperfusion injury produces cell death through different pathways, some of which induce plasma membrane rupture. In cardiomyocytes, dystrophin and spectrin provide stability to cell membrane and associate the intracellular environment with the extracellular environment. Dystrophin breakdown causes membrane fragility. Ischemic preconditioning has been suggested to attenuate this injury, yet, the mechanism is unknown. Objective To determine whether ischemic preconditioning prevents dystrophin breakdown through matrix metalloproteinase-2 (MMP-2) inhibition. Methods Isolated rabbit hearts were treated as follows: G1 (n=5): 30-min perfusion (Nx); G2 (n=6): 30-min global ischemia (GI) without reperfusion; G3: same as G2, except for 180-min reperfusion (I/R); G4 (n=5): doxycycline (MMP inhibitor) before GI; G5 (n=6): normoxic hearts treated with SIN-1 (which stimulates ONOO^- production) with monitoring of ventricular function during 30 min; G6 (n=5): doxycycline during 5 min, before SIN-1 administration; G7 and G8 (n=5): ischemic preconditioning (n=5) before 30-min GI with/ without reperfusion, respectively. Dystrophin expression decreased during ischemia, reaching 21% of control values (p <0.05); spectrin expression remained unchanged. MMP-2 activity increased 71% during ischemia compared to control values (p <0.05). The administration of doxycycline before ischemia prevented dystrophin breakdown. In normoxic hearts, SIN-1 increased thiobarbituric acid reactive substances (TBARS) by 33% (p <0.05) and MMP-2 activity by 36% (p <0.05), and significantly reduced dystrophin expression to 23% of control values (p <0.05). Ischemic preconditioning significantly attenuated dystrophin breakdown by inhibiting MMP-2 activity. Conclusions Activation of MMP-2 due to increased oxidative stress is responsible for dystrophin breakdown. Ischemic preconditioning attenuates dystrophin breakdown by inhibiting MMP-2 activity.

Keywords : Ischemic Preconditioning; Dystrophin; Matrix Metalloproteinase 2.

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