Continuous MT1-MMP activity computed as a function of baseline in the CIRC (targeted for MI) region (top) and LAD (targeted for I/R) region (bottom) in pigs with and without previous MI undergoing I/R. MT1-MMP activity was elevated in the CIRC (MI) region in the +MI,+I/R group but unchanged in the LAD (I/R) region. In contrast, no changes in MT1-MMP activity occurred in the CIRC region in the −MI,+I/R group, but activity increased in the LAD (I/R) region at 60 min of reperfusion. Values are means ± SE; sample size was n = 8 in the −MI,+I/R group and +MI,+I/R group. *P < 0.05 vs. the respective baseline.