Compliance measured in vivo for whole lung (CLUNG, by SV/PP) and ex vivo for extralobar left PAs (CLPA, by ΔV/ΔP) in mice with a collagen mutation (see (Wang et al., 2013b) for a description of this strain and the experimental protocol for CLPA measurements) exposed to normoxia, 10 days of hypoxia, and 10 days of hypoxia with beta-aminopropionitrile (BAPN). The hypoxia+BAPN group showed persistently low in vivo compliance compared to the hypoxia group, suggesting similar levels of overall pulmonary vascular stiffening. However, extralobar left PA compliance tended to increase in the hypoxia+BAPN group compared to the hypoxia group, suggesting more compliant proximal large PAs with BAPN treatment. Results are shown as mean ±SE. *p<0.05 vs. Normoxia.