Fig. 4. Adaptation processes upon chronic hypoxia in WT and AOX transgenic mice.

(A) Right ventricular systolic pressure (RVSP) after normoxia (NOX) or hypoxia (HOX, 10% O₂) for 28 days. Data are shown as means ± SEM of n ≥ 9 experiments. Horizontal bars indicate significant difference with P < 0.05 analyzed by two-way ANOVA and Tukey’s multiple comparisons test. (B) Ratios of right ventricle (RV) and left ventricle (LV) plus septum (S) (Fulton index). Data are shown as means ± SEM of n = 10 experiments. Horizontal bars indicate significant difference with P < 0.05 analyzed by two-way ANOVA and Tukey’s multiple comparisons test. (C) Cardiac output (CO) measured by echocardiography. Data are shown as means ± SEM of n = 10 experiments. Horizontal bars indicate significant difference with P < 0.05 analyzed by two-way ANOVA and Tukey’s multiple comparisons test. (D) Vascular remodeling quantified as degree of muscularization of small (20- to 70-μm diameter) pulmonary arterial vessels. Vessel muscularization categorized as non, partial, or full after immunostaining against α-smooth muscle actin as marker for PASMC and von Willebrand factor to discard endothelium. Data are shown as means ± SEM of n ≥ 4 experiments. ****P < 0.0001 NOX versus HOX analyzed by two-way ANOVA and Tukey’s multiple comparisons test. Note, no difference observed between WT versus AOX. (E) Western blots showing HIF-1α and β-actin expression in WT and AOX transgenic PASMC under normoxia and hypoxia. (F) Quantification of protein expression shown in (E). Data are shown as means ± SEM of n = 3 experiments. Horizontal bars indicate significant difference with P < 0.05 analyzed by two-way ANOVA and Sidak’s multiple comparisons test. (G) Proliferation assay of WT and AOX PASMC cultured under normoxia (NOX) or hypoxia (HOX, 1% O₂) for 48 hours. Data are shown as means ± SEM of n = 9 experiments. Horizontal bars indicate significant difference with P < 0.05 analyzed by two-way ANOVA and Tukey’s multiple comparisons test. BrdU, bromodeoxyuridine.