TNNI3 and myocardial infarction: Using ELISA kit, 2, 3, 5-triphenyltetrazolium chloride (TTC) staining and ultrasonography, we found that MICU1 deficiency markedly enhanced MI/R-induced cardiac troponin-I (cTnI) leak, MI and contractile dysfunction (Figures 2a and b and Supplementary Figure 2).