Hypoxia-inducible factor-1α (HIF-1α) shRNA inhibits the hypoxia-induced upregulation of HIF-1α in primary pulmonary artery smooth muscle cells (PASMCs). PASMCs were isolated from 6–8 weeks-old SD rats, and cultured in vitro. (A) Primary PASMCs were identified by the expression of α-smooth muscle actin (α-SMA) using immunofluorescence staining. The cells were photographed under a fluorescence microscope under ×600 magnification (scale bar, 20 µm). PASMCs were infected with lentiviruses harboring HIF-1α shRNA #1 or scramble shRNA prior to exposure to hypoxia for 48 h (5% O2), and the levels of (B) HIF-1α mRNA and (C) HIF-1α protein were assessed by RT-qPCR and western blot analysis, respectively. The figure shows the representative images from 3 independent experiments, and the values are expressed as the means ± SD of triplicate experiments. ***P<0.001, hypoxia vs. normoxia; ###P<0.001, hypoxia + HIF-1α shRNA vs. hypoxia.