ELEVATED CONCENTRATIONS OF ENDOGENOUS OUABAIN IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Background. An endogenous digitalis-like compound in mammals has long been postulated, but only recently has a substance indistinguishable from ouabain been identified in human plasma. Because of the potential significance of such a substance in patients with congestive heart failure, we sought to evaluate the pathophysiology of endogenous ouabain in these individuals. Methods and Results. Using an immunoassay, we determined plasma ouabain concentrations in 51 patients with heart failure and in 19 control subjects. Plasma ouabain concentrations in control subjects ranged from 0.16 to 0.77 nM (mean, 0.44+/-0.20 nM). In 19 matched heart failure patients receiving digoxin, the mean ouabain was significantly elevated at 1.59+/-2.2 nM (range, 0.17-8.76 nM, p