Fig. 1.
Endothelin-1 (ET-1) increases hypoxia inducible factor 1α (HIF-1α) expression. A: immunoblot assays were performed to assess the time dependence of HIF-1α protein accumulation in pulmonary arterial smooth muscle cells (PASMCs) treated with ET-1 (10−8 M). Bar graph shows values for 3–4 independent experiments. B: electrophoretic mobility shift assay of nuclear extracts isolated from rat PASMCs that were treated with vehicle control (C) or ET-1 (10−8 M) for 48 h. Similar results were observed in 3 independent experiments. C–E: real-time PCR was used to measure mRNA expression in PASMCs treated with ET-1. C: HIF-1 target gene expression in PASMCs treated with ET-1 (48 h; 10−8 M; n = 3–4). D: HIF-1α mRNA levels in PASMCs exposed to ET-1 (10−8 M) for the indicated periods of time relative to vehicle-treated cells (n = 3–4). E: HIF-1α mRNA levels in PASMCs exposed to varying concentrations of ET-1 for 48 h (n = 3). For all bar graphs, mean ± SE values are shown. Data are normalized to cyclophilin B or actin for mRNA and protein, respectively, and expressed relative to control. *P < 0.05 vs. control. NHE1, Na+/H+ exchanger isoform 1; TRPC1, canonical transient receptor potential 1; KV1.5, voltage-gated potassium channel.