Abstract
This study was undertaken to characterize endogenous digitalis-like activity in water extract from mammalian tissues. Prepurified samples obtained from guinea-pig heart were analysed by reverse-phase HPLC using an acetonitrile gradient. The eluent was assayed for its activity as inhibitor of human heart Na+, K+-ATPase and digoxin-like immunoreactivity. Both activities were recovered in the same fraction after two successive chromatographic steps. These results provide further evidence for the presence of an endogenous digitalislike factor, cardiodigin, in mammalian heart.