DigoxinOuabainSodium-Potassium-Exchanging ATPaseCardiac GlycosidesDigitoxinCardiotonic AgentsCardenolidesPotassiumSodiumDigitalis GlycosidesRubidiumMedigoxinEleutherococcusSaponinsBiological Transport, ActiveBufanolidesDrug InteractionsAnti-Arrhythmia AgentsNeriumStrophanthinsRadioimmunoassayP-GlycoproteinQuinidineRubidium Radioisotopes