The Diffusion of 35SO2 from Tissue Fluids Into the Lungs Following Exposure of Dogs to 35SO2

The surgically isolated airways of the head and upper neck of anesthetized, paralyzed dogs were exposed to 22 ± 2 ppm of 35SO2, delivered at a rate of 3.5 l./min for 30–60 min. The lungs were ventilated with ambient air by a positive displacement respiratory pump. In ten out of twelve measurements, over 95 per cent of the 35SO2 administered to the isolated upper airways was found to be absorbed by the mucosa. In five out of five animals, 35SO2 was present in one or more expired gas samples collected either at the carina or from a bronchus; this expired 35SO2 could not have entered the lower airways in inspired air and its presence provided evidence that the lungs were releasing the gas in expiration, presumably from the pulmonary capillaries. 35S was present in the blood and urine within minutes of the onset of exposure to 35SO2.