The Effective Stimulus for Increased Pulmonary Ventilation during Muscular Exertion.

The control of the pulmonary ventilation is a central problem in the physiology of muscular exercise. The hypothesis that the respiratory center is stimulated by chemical changes in the arterial blood has been defended by Gesell (1), Haldane (2), and Henderson (3). In addition to this type of stimulation, Krogh and Lindhard (4) have discussed the anticipatory hyperventilation preceding and immediately following the onset of exercise. This they attribute to cerebral cortical stimulation. Recently, Harrison and his associates (5, 6) have maintained that the stimulus for the increase in pulmonary ventilation in men and dogs during very moderate exercise, either active or passive, is not chemical, but is reflex. Comroe and Schmidt (7) confirmed these findings in anesthetized dogs, using either electrical stimulation of the lumbar anterior spiral roots, or else passive movements of the limbs. In view of the importance of this problem, we have repeated Harrison's experiments, which