RÔLE OF THE VAGI IN THE CROSSED PHRENIC PHENOMENON

Abstract

Crossing of descending respiratory impulses after a hemisection of the cord above C3 can occur in rabbits on section of the vagi alone. Crossing was produced also by activation of Hering-Breuer afferents by partial occlusion of a tracheal cannula and by high frequency stimulation of the central end of the cut vagus. Low frequency vagal stimulation inhibited crossing. After bilateral vagal section had produced crossing, an increase in crossing still occurred after inactivation of the functioning phrenic. No aff erents inhibitory to crossing could be demonstrated in the cut phrenic. It was concluded that in certain instances crossing may be produced by changes in afferent vagal impulses brought about by inactivation of the functioning phrenic.