Compared with a TAT-tagged, scrambled control peptide, NOPT-TAT increased the activity of NCX1, as measured as the NCX1 rate constant, in adult cardiomyocytes that were isolated from both SHAM-operated (Figure 4C, approximately 40%) and aorta banded HF mice (Figure 4D, approximately 60%). The gene discussed is SLC8A1; the disease is hydrops fetalis.