FIGURE 2.

A, post-MI 14-day survival was significantly lower in the MT1-MMPexp mice following MI when compared with WT mice (χ² = 7. 6, p = 0.006). B, a relative index of total in vivo MMP activity was determined using an MMP radiotracer ^99mTc-RP805 (22). Inset, total myocardial MMP radiotracer retention was significantly higher in referent control MT1-MMPexp when compared with WT mice (n = 5/group). At 14 days post-MI (n = 6/group), increased MMP radiotracer uptake occurred within both the remote and MI regions, but was nearly 2-fold higher within the MI region in the MT1-MMPexp group (n = 6) (*, p < 0.05 versus WT non-MI; ⁺, p < 0.05 versus WT remote). C, long axis LV sections were stained with picro-sirius and viewed under bright field (left panels) as well as polarized light (right panels) taken from WT and MT1-MMPexp mice. Increased collagen staining was observed in the MT1-MMPexp mice. At 14 days post-MI, significant LV enlargement was observed in both groups, but substantially higher myocardial collagen was observed within remote viable myocardium in the MT1-MMPexp mice. (Scale = 1 mm.)