Figure 1.

MMP-9 expression and activity are induced at early time points in hindlimb muscle tissues exposed to ischemia. MMP-9 protein expression was assayed in the nonischemic (day 0) or ischemic (1, 3, 7, and 14 days) WT adductor muscle tissue lysates using SDS-PAGE gelatin zymography (top) and Western blotting (middle). Both indicate early induction of MMP-9 (day 1), with levels peaking at 3 days and returning to baseline by 7 days after ischemia (latent “Pro” MMP-9 and activated MMP-9). Quantification of total gelatinolytic activity associated with MMP-9 or MMP-2 (both pro- and activated bands) in WT and MMP-9^−/− tissue lysates, normalized using standards (“MMP Stds”) (n=4 animal for each time point), illustrates the significant early induction of MMP-9 in response to ischemia in the WT, and similar induction of MMP-2 in the WT and MMP-9^−/−. *P<0.05 vs 0 day time point. For a detailed separate analysis of MMP-2 and MMP-9, see online Figure 1.