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. Author manuscript; available in PMC: 2014 Jan 15.
Published in final edited form as: Neuroscience. 2012 Nov 14;229:77–87. doi: 10.1016/j.neuroscience.2012.10.066

Figure 3.

Figure 3

Integrated phrenic nerve amplitude (black bars = contralateral phrenic nerve, gray bars = ipsilateral phrenic nerve, A) and average ipsi- to contralateral voltage ratios (B) in SHAM-injected (all time points combined) or EB-injected rats at 7 and 14 days post-injection at baseline (left panel), hypoxia (FIO2 = 11%, middle panel) and maximal stimulation (FIO2 = 11%, PETCO2 = 40 torr above baseline, right panel). (A) Baseline ipsilateral phrenic nerve amplitude 7 days post-EB was significantly lower than the ipsilateral amplitude of the SHAM rats and 14 days post-EB (P<0.01 and P=0.02, respectively). Ipsilateral nerve amplitudes at both 7 and 14 days post-EB were significantly lower than the amplitudes of their corresponding contralateral nerves at both times (7 days: P=0.01, 14 days: P<0.01). Contralateral phrenic nerve amplitude 7 days post-EB was also significantly lower than the contralateral amplitude of 14 days post-EB (P=0.03) and was significantly higher than the ipsilateral side (P=0.06). With chemosensory stimulation (hypoxia, hypoxia/hypercapnia), ipsilateral phrenic nerve amplitude 7 days post-EB was significantly lower versus ipsilateral amplitude in SHAM rats (hypoxia, hypoxia/hypercapnia: both P<0.001) and 14 days post-EB (hypoxia, hypoxia/hypercapnia: P<0.01). Further, the ipsilateral phrenic amplitude 7 days post-EB was significantly lower than the contralateral amplitude at the same time point (hypoxia, hypoxia/hypercapnia: both P<0.001). *P<0.05 versus ipsilateral amplitude of SHAM and 14 days post-EB groups, †P<0.05 versus contralateral amplitude within the same corresponding group, #P<0.05 versus 14 days post-EB contralateral amplitude; two-way RM ANOVA. (B) Baseline average ipsi/contra ratios at 7 days post-EB were significantly lower than SHAM rats and 14 days post-EB (P<0.001 and P=0.02, respectively). However, the baseline ratio at day 14 remained significantly lower than SHAM levels (P=0.03). The ratios were significantly lower at 7 days post-EB than in SHAM rats or rats 14 days post-EB in hypoxia (P<0.001, P<0.01, respectively) and hypoxia/hypercapnia (P<0.01, P=0.02, respectively). Thus, EB elicits considerable impairment in phrenic nerve output ipsilateral to injury, and this impairment recovers, at least with chemosensory stimulation, by 14 days. *P<0.05 versus SHAM and day 14 post-EB injection rat groups, **P<0.05 versus SHAM group only; one-way ANOVA.