Fig. 2.

Cardiac glycosides inhibit hypoxia-induced expression of HIF-1 target genes. In two separate experiments, Hep3B cells were exposed to 20% or 1% O₂ for 24 h in the presence of: vehicle (V), 50 nM proscillaridin A (P), or 100 nM ouabain (O); and vehicle (V) or 100 nM digoxin (D). Total RNA was extracted from the cells and analyzed by quantitative real-time RT-PCR for mRNAs encoding hexokinase 1 (HK1; A), glucose transporter 1 (GLUT1; B), hexokinase 2 (HK2; C), and hypoxia-inducible factor 1α (HIF-1α; D). For each mRNA in each experiment, expression was normalized to the levels in vehicle-treated cells at 20% O₂. The bars show mean ± SD (n = 4 each). [*, significant decrease compared to vehicle (P < 0.05, Student's t test); #, significant increase compared to vehicle (P < 0.05, Student's t test).]