Rostafuroxin (PST 2238) has been used in trials studying the treatment of Essential Hypertension.

K+-ATPase:1.5 nM, Na+-ATPase:1.5 nM

Kinase assay: Activity assays are conducted using Lance Ultra time-resolved fluorescence resonance energy transfer (TR-FRET) technology from Perkin-Elmer. Briefly, 10 ng/mL FLT3 enzyme, a serial diluted G-749, 80 nM substrate of ULight-poly-GT peptide and variable amounts of ATP (8.5 μM to 1088 μM) are mixed in kinase assay buffer (50 mM HEPES pH 7.5, 10 mM MgCl2, 1 mM EGTA, 2 mM DTT and 0.01% Tween-20) and are added to a 384-well OptiPlate-384 in a volume of 10 μL. Kinase reactions are incubated at room temperature for up to 1 h and then stopped by the addition of 5 μL of 10 mM EDTA. A volume of 5 μL of the specific Eu-labeled-anti-phosphopeptide antibody diluted in LANCE Detection Buffer is then added to a final concentration of 2 nM. After 30-minute incubation, assay plates are incubated at 23°C and the LANCE signal is measured on an EnVision Multilabel Reader. Excitation wavelength is set at 320 nm and emission monitored at 615 nm (donor) and 665 nm (acceptor). The IC50 is calculated using nonlinear regression analysis analysis by GradPad Prism 5.