Cervical spinal cord injury alters the pattern of breathing in anesthetized rats

The mechanisms by which chronic cervical spinal cord injury alters respirat ory function and plasticity are not well understood. We speculated that spi nal hemisection at C-2 would alter the respiratory pattern controlled by va gal mechanisms. Expired volume (VE) and respiratory rate (RR) were measured in anesthetized control and C-2-hemisected rats at 1 and 2 mo postinjury. C-2 hemisection altered the pattern of breathing at both postinjury time in tervals. Injured rats utilized a higher RR and lower VE to maintain the sam e minute ventilation as control rats. After bilateral vagotomy, the pattern of breathing in injured rats was not different from controls. The frequenc y of augmented breaths was higher in injured rats at 2 mo postinjury before vagotomy; however, the VE of augmented breaths was not different between g roups, In conclusion, C-2 hemisection alters the pattern of breathing at 1 and 2 mo postinjury via vagal mechanisms.