Fig. 4.

Knockdown of NCX1 by siRNA transfection in iCell Cardiomyocytes. A: Western blots illustrating the time course and selectivity of NCX1 knockdown with respect to actin. Densities were related to the density of NCX1 bands in lane 5 with scrambled siRNA for 5 days. B: typical Na/K pump and NCX1 current records in large mock-transfected and siRNA-transfected cardiomyocytes. C: average current densities in large siRNA-transfected cardiomyocytes immediately after transfection and after 1 and 3 days, respectively. D: plots of NCX1 densities from Western blots on days 0, 3, and 5, and of NCX1 current densities on days 0, 1, and 3 after siRNA transfection. Best fits to an exponential function yield time constants of 50 and 45 h for loss of protein and current, respectively.