CHANGES IN RESPIRATION ON INFLATION AND DEFLATION OF THE CHEST

Abstract

Inflation and deflation of the chest is accomplished by the application of positive and negative pressures to the exterior of the chest with the animal in a body plethysmograph. Quantitative measurements of fluctuations in lung vol. are obtained by attaching the animal''s trachea to a recording spirometer. Changes in resistance to inflation and deflation (i.e., changes in lung vol. at specified distorting pressures) and changes in arterial CO2 and O2 are used to analyze the effects of vagotomy on the respiration of decerebrate and anesthetized cats. The CO2 content increases slightly and O2 decreases slightly as an immediate consequence of vagotomy. The results are interpreted as inconsistent with the hypothesis that afferent impulses in the pulmonary fibers of the vagi excited by inflation are sufficient to account for the functional effects of the vagi on respiration. The results indicate the existence of afferent impulses augmentative to expiration (hence probably reciprocally inhibitory to inspiration) excited by inflation, and augmentative to inspiration on deflation, as postulated by Hering-Breuer.