Respiratory data following 4 weeks post viral shRNA injection. (A) breathing frequency (ƒR,), (B) tidal volume (VT), (C) allometric minute ventilation (VE ALLO), (D) convective requirement ratio (VE/VO2 ALLO), (E) hypercapnic ventilatory response (HCVR, absolute change in VE ALLO vs. corresponding room air), (F) HCVR at baseline, week 2 and week 4 post-viral injections in naïve (black n=8), non-target control shRNA (NT-shRNA, grey n=10) and PHOX2B-shRNA (PHOX2B- shRNA, red n=6). ƒR is equally impaired in all experimental group compared to baseline but no treatment effect was observed (A). VT is significantly impaired following RTN injection in PHOX2B- shRNA group compared to baseline pre-surgery (p<0.001), naïve rats p<0.001), and NT-shRNA rats (p=0.002) at 7.2% CO2. (B). VE ALLO is impaired in PHOX2B-shRNA rats during exposure to hypercapnia (7.2% CO2) compared to baseline (p=0.0025), naïve rats (p=0.007), and NT-shRNA rats (p=0.002). (C). VE/VO2 ALLO is reduced in PHOX2B-shRNA animals compared to NT-shRNA rats both at 5% (p=0.023) and 7.2% (p=0.004.) CO2 (D). HCVR during 7.2% CO2 is lower in PHOX2B- shRNA rats compared to baseline (p=0.007), naïve rats (p=0.001), and NT-shRNA rats (p=0.016) (E). Boxplots: median, 1st – 3rd quartiles and 10th – 90th percentiles, outliers = dots, “+” indicates arithmetic mean. Bonferroni post-hoc as indicated. HCVR is significantly impaired only in PHOX2B- shRNA rats 4-weeks post-surgery (One-way ANOVA p=0.007) (F). Black*, different from naïve; Grey*, different from NT-shRNA; Red*, different from PHOX2B- shRNA.