Cardiotonic AgentsPyridazinesAmrinoneCardiac GlycosidesBufanolidesMyocardial ContractionDogsMyocardiumOuabainCardenolidesSodium-Potassium-Exchanging ATPaseDigoxinDigitoxinDigitalis GlycosidesAmphibian VenomsThiadiazinesCymarineCardanolidesDigitoxigeninAntiarisStrophanthidinCesium IsotopesMilrinoneDipterocarpaceaeHydrazonesSalvia miltiorrhizaPyridonesPapillary MusclesSaponinsGuinea PigsSea AnemonesTroponin CSodiumHeartQuinolines