Fig. 4

Impaired contraction of intra-pulmonary arteries and increased proliferation of medial smooth muscle cells in the lung from the male Bmpr2 mutant rats. A–D Contraction and relaxation response to the vasoreactive agents were assessed using intrapulmonary artery (IPA) obtained from wild-type (WT, open circle) and Bmpr2 mutation (+/44insG, closed circle) rats at 3 weeks after monocrotaline (MCT) injection. A and B The dose–response curve showing the relaxation of IPA to acetylcholine (Ach) (n = 14 WT and +/44insG) and sodium nitroprusside (SNP) (n = 12 WT and +/44insG). 10–4 M papaverine relaxation response was taken as 100%. C and D The dose–response curve showing the contraction of IPA to prostaglandin F2α (PGF2α) (n = 17 WT and +/44insG) and endothelin-1 (ET-1) (n = 17 WT and +/44insG). 70 mM KCl contracting response was taken as 100%. E-J Representative images for Ki67 immunohistochemistry in distal PAs in control rats assessed at 3 weeks after saline injection, 3 weeks or 4 weeks after MCT injection. Scale bar: 25 μm. K–P Representative immunofluorescent images of distal PAs stained for Ki67 (green) and α-SMA (red) in control, 3 weeks or 4 weeks after MCT injection. Scale bar: 25 μm. Q Quantitative analysis of vessels with Ki67 + cells in the distal PAs in control animals, 3 weeks and 4 weeks after MCT injection respectively (n = 17 WT and +/44insG). The numbers in parentheses represent the numbers of rats examined. For panels A–D, data are presented by points and connecting lines with error bars; for panel Q, the data are presented as means ± SEM; repeated measures (two-way) ANOVA with Holm method was used for panels A–D; one-way ANOVA followed by Bonferroni’s multiple comparison test was used for panel Q. *p < 0.05, **p < 0.01. WT = wild-type; +/44insG = rats with bone morphogenetic protein receptor type 2 mutation; Ach = acetylcholine; SNP = sodium nitroprusside; PGF2α = prostaglandin F2α; ET-1 = endothelin-1; PAs = pulmonary arteries; Day = days after monocrotaline injection; α-SMA = α-smooth muscle actin; wk = weeks; PAs pulmonary arteries