Table 3. Mean and confidence interval for hypercapnic condition raw respiratory frequency and peak inspiratory airflow after saline and morphine intraperitoneal injection.

	Arrb2 -/- mean ± SEM	Arrb2 -/-95% CI	Arrb2+/- mean ± SEM	Arrb2 +/-95% CI	Arrb2 +/+ mean ± SEM	Arrb2 +/+95% CI
Freq. saline (Hz)	7.68 ± 0.19	7.31 → 8.05	7.69 ± 0.16	7.38 → 8.00	7.77 ± 0.39	7.01 → 8.53
Freq. morphine	5.20 ± 0.10	5.00 → 5.40	4.79 ± 0.19	4.42 → 5.16	5.38 ± 0.18	5.02 → 5.73
PIF saline (mL/s)	–5.34 ± 0.27	–4.81 → –5.87	–5.75 ± 0.25	–5.26 → –6.24	–5.71 ± 0.20	–5.32 → –6.10
PIF morphine	–3.54 ± 0.16	–3.22 → –3.85	–3.86 ± 0.15	–3.57 → –4.15	–3.93 ± 0.24	–3.46 → –4.40