Evidence for ‘Diffusion Respiration’ in Rhythmic Breathing

¹ From the National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Maryland, and Department of Physiology, Howard Medical School, Washington, D. C.

Cats and rabbits were cooled to near lethal body temperatures and denitrogenated by inhalation of oxygen. Apneustic breathing developed in most preparations with ventilatory frequencies less than one per minute. It was demonstrated that the oxygen removal from lung air during both apnea and apneusis produced volume changes in the recording spirometer—‘diffusion respiration.’ The greater uptake during apneusis (as compared to apnea) was ascribed to the greater respiratory surface and the larger amount of blood in the expanded lungs. The role of ‘diffusion respiration’ in normal breathing is also discussed.