Purification of endogenous digitalis-like factors from normal human urine

We detected two candidates for endogenous digitalis-like factors in human urine based on the inhibition of H-3-ouabain binding to human erythrocytes. Two ouabain-displacing compound(ODC)s were consistently eluted off the C-18 reverse phase HPLC column with 18% and 31% acetonitrile. The more-polar ODC-1 was ubiquitously found in mammals, markedly increased after acute and chronic salt loading in humans, and was thought to be a natriuretic factor with vasoactive property. ODC-l mostly resembled ouabain in biological, physicochemical, and chromatographic properties and may correspond to ouabainlike compound purified by other investigators. The less-polar ODC-2 was indistinguishable from digoxin in proton nuclear magnetic resonance(NMR) and fast atom bombardment(FAB) mass spectrum.