Abstract

Comparative actions of CO₂ and salicylate upon the respiration were assessed by means of their effects on spontaneous breathing and electrical reactivity of the medullary inspiratory integrator. CO₂ and salicylate differed in the following respects. 1) CO₂ stimulated depth of respiration to a proportionately greater extent than rate, whereas salicylate produced the reverse effect. 2) After vagotomy CO₂ reduced the rate of breathing although it continued to augment depth, whereas salicylate still effected its characteristic stimulation of rate and depth. 3) In regard to their effects upon central electrical reactivity, both CO₂ and salicylate caused an elevation in threshold for sustained inspiration (prevention of expiratory breakthrough), but they differed in their effects upon threshold for baseline shift and upon maximum inspiration. It is concluded that CO₂ and salicylate have independent actions in their respective influences upon central control of respiration.