Evidence for pulmonary hypertension in sph/sph mice. (A) RVSP is increased in sph/sph mice compared with normal mice. (B) RV/BW in increased in sph/sph mice compared with normal mice. Anesthetized control (normal, □) and sph/sph (■) mice were placed in a supine position while breathing room air. RvSP (A) was measured as described under “Methods.” After measurement of RvSP, mice were euthanized, hearts were resected, and RV/BW (B) was determined as described under “Methods.” Data are presented as mean (± SEM) for n = 4 normal and n = 6 sph/sph mice. Normal mice were between 6 and 12 weeks of age; n = 3 sph/sph mice were 6 weeks of age, and n = 2 were 12 weeks of age and n = 1 was 22 weeks of age. No differences in RvSP or RV/BW were noted between the younger and older sph/sph mice used for these experiments. *P < .03 for RVSP (A) and P < .0001 for RV/BW (B) sph/sph compared with normal mice.