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

Abstract

Acute cerebellectomy depressed spontaneous respiration in cats anesthetized with chloralose-urethane. After cerebellectomy there was an increased interbreath interval ( T TOT) accompanied by increased inspiratory and expiratory durations ( T IandT E, respectively). However, the change of T E exceeded that of T I so that T I/T TOT decreased. Tidal volume ( V T) and mean inspiratory flow ( V T/ T I) 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 T TOT. In this case T I and V T/ T I increased, but V T and T I/ T TOT remained unchanged. Bilateral control lesions that usually included protions 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.