Figure 2. Effects of calpain inhibition by conditional knockout of calpain-4 on SBDP and collagen I in the smooth muscle of pulmonary arterioles of mice with hypoxic pulmonary hypertension.

Five days after tamoxifen administration, control and ER-Cre^+/–Capn4^fl/fl mice were exposed to room air (normoxia) or 10% oxygen (hypoxia) for 3 weeks. (A) Lung slides from ER-Cre^+/–Capn4^fl/fl and control mice exposed to normoxia or hypoxia were double stained for α-actin (red) and SBDP (green) and then counterstained for DAPI. (B) Lung slides from ER-Cre^+/–Capn4^fl/fl and control mice exposed to normoxia or hypoxia were double stained for α-actin (red) and collagen I (green). Images are representative of 8 independent experiments. Original magnification, ×400.