Figure 1.

Western blot analysis of sodium pump expression in heterologous cells and myocardium.A, untransfected HEK cell microsomal fractions (UTF) showed endogenous NKA with an apparent MW of 100 kDa. Microsomes from cells transfected with human mCer-α₁ NKA (TF) showed bands representing endogenous NKA and exogenous fluorescent NKA, which showed a decreased mobility due to the 30 kDa tag. NKA was highly expressed in microsomal fractions isolated from human myocardium. We observed decreased expression of NKA in failing human heart (HF1-3) compared to nonfailing hearts (NF1-3). B, total protein staining (Revert). C, quantification of NKA expression in HEK cells and human nonfailing and failing hearts, normalized to total protein. TF and UTF data represent three independent transfections. NF and HF data represent tissue samples from eight nonfailing donor hearts and eight explanted hearts with dilated cardiomyopathy. NKA, Na/K-ATPase.