Na,K-ATPase expression in normal and failing human left ventricle

The expression of the Na,K-ATPase was studied in both normal and failing human myocardium which was collected within 5 min of cardiac explantation in preparation for orthotopic transplantation or at the time of organ harvest. Abundance of mRNA for all three catalytic alpha subunits of the Na,K-ATPase was analyzed in samples from patients with end-stage heart failure due to either ischemic or dilated cardiomyopathy, as well as from normal controls. Vanadate facilitated 3H-ouabain binding before and after a Digibind wash was analyzed on tissue from a subset of these patients. mRNA analysis demonstrated that all three catalytic Na,K-ATPase alpha subunits were expressed in human heart and that there was no evidence for change in relative expression or abundance induced by disease. The specific digitalis receptor concentration was 760 +/- 58 and 614 +/- 47 pmol/g wet weight in the samples from normal and failing hearts, respectively (p = NS). From these studies it can be concluded that, whereas there is a tendency for a decrease in the number of ouabain receptors in heart failure, there is no significant alteration in the expression of Na,K-ATPase message or protein caused by chronic heart failure.