Cardioprotection by ischemic postconditioning: role of MMP-2

VERÓNICA D'ANNUNZIO; MARTÍN DONATO; VERÓNICA MIKSZTOWICZ; BRUNO BUCHHOLZ; CRISTINA LORENZO CARRIÓN; LAURA SCHREIER; REGINA WIKINSKI; GABRIELA BERG; RICARDO GELPI

Buenos Aires

Congreso; XVI World Congress of Cardiology; 2008

World Heart Federation

Experimental evidence demonstrates that the metaloproteinases (MMP), a group of endopeptidases, are involved in the ischemia/reperfusion injury. Also, it has showed that the activation of MMP-2 is attenuated by ischemic preconditioning. Nevertheless, there has not been studied the effect of the ischemic postconditioning (Post-con) on the activity of the MMP-2. The main objective was to evaluate if the Post-con reduced infarct size trough the inhibition of MMP-2 activity.To test this hypothesis we used isolated and isovolumic rabbits hearts, perfused according to Langendorff technique. In G1 (n=7) after a 20 min of stabilization, we performed 30 min global ischemia and 2 hours of reperfusion. In G2 (n=7), after 30 min of global ischemia we performed two cycles of reperfusión/ischemia of 30 sec each one (Post-con), followed by 2 hours of reperfusion. In G3 (n=4), the protocol of G1 was repeated but during the first two minutes of reperfusion doxyciclyne (10µM; an antibiotic that has been demonstrated that inhibits the activity of the MMP) was administered. Samples of the coronary effluent were collected in basal (before ischemia), 5 and 30 min of the reperfusion period and the activity of MMP-2 measured by quantitative zimography, and there were quantified the gelatinolytic areas as relative areas (AR). The AR was expressed as percentage of basal value. After 2 hours of reperfusion, the hearts were frozen, and cut into slices from the apex to the base. Sections were incubated for 20 minutes in 1% triphenyltetrazolium chloride, (pH 7.4, 37° C) and then immersed in 10% formalin. The infarct size was expressed as a percentage of the left ventricular area. X±ESM.* p<0.05 vs. Basal; #: p>0.05 vs. G1. R: Reperfusion. ND: no detectable.                            MMP-2       MMP-2        MMP-2         Infarto (%)                     Basal         5 min R       30 min R                     G1 (%)       100±0.0    77.1±9.4       40.8±10.1*    15.8±1.5G2 (%)       100±0.0    38.2±8.1*#     1.1±1.2*#       5.4±1.3#G3 (%)       100±0.0          ND                ND               4.9±0.9#    Ischemic postconditioning reduces infarct size and attenuated MMP-2 activity during reperfusion. The results obtained with doxycicline administration suggest that MMP-2 could be involved in the cardioprotection afforded by ischemic postconditioning.