THE REGULATION OF RESPIRATION

Abstract

Hemorrhage elicited a prompt decrease in expired CO2 and retained O. On reinjection CO2 elimination momentarily increased above the pre-hemorrhage elimination, to return approximately to the pre-hemorrhage level, these effects being accompanied by a corresponding over-oxygen retention and similar recovery to normal values. Injection of isotonic saline following hemorrhage elicited similar changes in expired gases. In general, hemorrhage caused increased respiratory movements and reinjection decreased them. Though the susceptibility to hemorrhage varied with the animal, a gross relation between reduction in blood volume and impairment of gaseous exchange was established. The later the hemorrhage in a graded series the greater was the impairment of gaseous exchange per unit of hemorrhage. An initial hemorrhage of 0.5% of the body weight sometimes produced appreciable changes in the expired gases, sometimes it did not. In other cases a decidedly smaller hemorrhage produced unmistakable effects. The effects of hemorrhage and reinjection on expiratory exchange were attributed to changes in gaseous transport associated with changes in volume-flow of blood, the improvement of gaseous exchange resulting from injection of saline being attributed to augmented flow. The decreased O retention and decreased CO2 elimination during depleted blood volume suggested increased anaerobic acid formation and acid retention in the body. The hyperoxygen retention and increased CO2 elimination on reinjection indicated increased removal of accumulated anaerobic metabolites.