FIGURE 4.

A, LV myocardial membrane extracts from wild type (WT), WT at 14 days post-MI, MT1-MMP overexpression (MT1-MMPexp), and at 14 days post-MI were subjected to MT1-MMP immunoblotting (n = 10/group). Total MT1-MMP myocardial levels, which includes the full-length and truncated active forms (51–55 kDa) significantly increased following MI. As expected, MT1-MMP total levels were increased in the MT1-MMPexp groups, and were increased by ∼2-fold following MI. B, crude LV myocardial extracts were subjected to gelatin zymography, which provides a measure of relative MMP-9 and MMP-2 levels. Relative MMP-9 levels were increased in the post-MI groups, as were total MMP-2 levels. Molecular weight fractionation of the MMP-2 zymographic bands revealed a pronounced increase in the active form of MMP-2 (64 kDa) in the MT1-MMPexp groups, which was further increased post-MI. (*, p < 0.05 versus WT non-MI; ^#, versus MT1-MMPexp non-MI; ⁺, p < 0.05 versus WT MI.)