Over-expression of calpastatin protects hearts against MI in mice. (A) Calpain activity was upregulated in the infarcted myocardium in WT mice and restrained by over-expression of calpastatin in Tg-CAST mice. (B,C) Ejection fraction (EF%) and fractional shortening (FS%) were determined by echocardiography 7 days after MI. (D) Measurement of LV cavity size was performed at the papillary muscle level 7 days after MI. (E) Representative photomicrographs of Picrosirius red staining captured at the papillary muscle level 7 days after MI are shown. (F) Quantifications of scar size at the papillary muscle level were performed 7 days after MI. Data are represented as mean ± SD. n=5–6 per group. *, P<0.05 versus sham group; †, P<0.05 versus WT-MI. MI, myocardial infarction; WT, wild type.