Figure 5.

Cardiac glycosides induce rapid loss of glutathione, and elevation in reactive oxygen species. (a) Effect of oleandrin and digitoxin on levels of glutathione. Cells were treated with cardiac glycosides [Figure 3, part a] for different times. Cell pellets were suspended in 5% meta-phosphoric acid and vortexed thoroughly. Supernatant solutions were assayed for GSH. (Δ: Oleandrin (I, 100 nM); ◊: Digitoxin (II, 500 nM). Data are the average triplicate measurements and are representative of three independent experiments. Differences are significant at (*P < 0.05). (b) Effect of oleandrin and digitoxin on expression of reactive oxygen intermediates (ROS). HeLa cells were plated in black visiplates. Cells were then treated with either oleandrin (I, 100 nM) or digitoxin (II, 500 nM) for 1 and 3 h. Control and treated cells were then incubated 30 min with carboxy-H2DCFDA, and fluorescence read at Excitation 492 nm/ Emission 520 nm. Data are the average triplicate measurements and are representative of at least three independent experiments. Differences are significant at (*P < 0.05)