Inhibitory effects of cerebellar lesions on respiration in the spontaneously breathing, anesthetized cat

Acute cerebellectomy depressed spontaneous respiration in cats anesthetized with chloralose-urethane. After cerebellectomy there was an increased interbreath interval (TTOT) accompanied by increased inspiratory and expiratory durations (TI and TE, respectively). However, the change of TE exceeded that of TI so that TI/TTOT decreased. Tidal volume (VT) and mean inspiratory flow (VT/TI) were not affected. No respiratory variable was significantly altered when cerebellectomy was performed subsequent to bilateral vagotomy. Bilateral lesions of the rostral fastigial nuclei (FN) in cats with intact vagi also caused a reduction in ventilation due to increased TTOT. In this case TI and VT/TI increased, but VT and TI/TTOT remained unchanged. Bilateral control lesions that usually included portions of the dentate nuclei did not influence respiration. The results suggest that in the anesthetized cat the cerebellum tonically excites respiratory centers controlling respiratory rate and the termination of inspiration. A part of this influence may be mediated by the rostral FN. In addition, vagal input appears to be important in the expression of the cerebellar influence on spontaneous respiration.