Fig. 1.

SCA7 mice have pronounced respiratory deficits at 8 weeks of age. (A-F) Measurements of respiratory function at baseline and during a hypercapnic/hypoxic challenge (FiCO₂, 0.07; FiO₂, 0.10; N₂ balance) in wild-type (WT, black lines) and SCA7-266Q mice (gray lines) at 4 and 8 weeks of age. MV (A), TV (B), f (C), PIF (D), PEF (E) and TV/Ti (F) were comparable in wild-type and SCA7 mice at 4 weeks of age. However, at 8 weeks of age, SCA7 mice showed a compensatory increase in frequency (C), PIF (D), PEF (E) and TV/Ti (F) at baseline during normoxia. This increased work of breathing at rest foreshadows respiratory compromise appearing during the challenge. Compared to wild-type controls, the response of SCA7 mice to hypercapnia and hypoxia was significantly blunted, as shown by significant reductions in all measures except breath frequency. Wild-type respiratory parameters improve with age but SCA7 respiratory function was significantly reduced at 8 weeks compared to 4 weeks. Data are mean±s.e.m. Statistical significance (*/#) was determined using a two-way RM ANOVA, followed by a Bonferroni's post-hoc analysis (*/#P<0.05, **/##P<0.01, ***/###P<0.001, ****/####P<0.0001, n=10 mice per group). Asterisks (*) are shown for comparisons between groups at a single time point, and number signs (#) are shown for comparisons between time points for a single group.