Effects of 100% O2 breathing on permeability of alveolar epithelium to solute

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Abstract
Effects of 100% O2 exposure at 1 atm for 48 (n = 5) and 63 h (n = 6) on the solute permeability of the alveolar epithelium of rabbits was measured. Saline containing trace amounts of 131I-albumin (r [radius] .apprxeq. 35 .ANG.), 125I-cytochrome c (r .apprxeq. 17 .ANG.) and [57Co]cyanocobalamin (r .apprxeq. 6.5 .ANG.) [10-15 ml] was instilled into an atelectatic segment of the right lower lobe. Egress of these tracers was determined from their change in concentration in the alveolar saline and their detection in arterial blood. All tracers left the alveolar space and appeared in the arterial blood on the 63 h O2 group, cytochrome c and cyanocobalamin in the 48 h O2 group and only cyanocobalamin in controls (air breathing). O2-exposed animals had PaO2 [alveolar O2 pressure] values higher than 500 Torr, normal PaCO2 [alveolar CO2 pressure] and pH and wet-to-dry lung weight ratios not different from control. Increasing the length of O2 exposure increased the solute permeability of the alveolar epithelium; this preceded the appearance of pulmonary edema.