Su/Hx-induced PH model in mice. (A) Schematic of the experimental design using a combination of SU5416 and hypoxia treatment to induce PH in C57BL/6J mice. RVSP was measured and tissues were collected after 3 weeks of Su/Hx treatment. (B) Significantly elevated RVSP developed in Su/Hx mice (n = 15) compared with normoxia controls (Nx, n = 18). Sugen/normoxia control mice (Su/Nx, n = 10) were also included which had similar RVSP as the Nx mice. (C) Fulton's index (RV/LV+ S) was calculated to indicate the development of RV hypertrophy in Su/Hx mice (n = 10). Nx (n = 10) and Su/Nx (n = 15) control groups were also included and had similar Fulton’s Index. Vessel wall muscularization of distal pulmonary arteriole (<50 μm in diameter) in Nx mice (n = 10), Su/Nx mice (n = 6) and Su/Hx mice (n = 6) was quantified based on immunostaining of α-SMA (D). Representative immunostaining images show increased expression of α-SMA (brown colour) in the distal pulmonary arteriole vessel walls of Su/Hx mice (F) compared with Nx controls (E). Original magnification 400×. Data in (B–D) are mean ± S.E.M. *P < 0.05, ****P < 0.0001, ordinary one-way ANOVA with multiple comparisons.