Fate of inhaled nitrogen dioxide in isolated perfused rat lung

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Abstract
The fate of inhaled NO2 was studied with isolated perfused rat lungs. Isolated lungs were exposed to 5 ppm NO2 for 90 min at a ventilation rate of 45 ml/min. NO2 exposure had no adverse effects on the lungs as judged from weights, glucose uptake or lactate production compared to controls. Isolated lungs absorbed 36% ventilated NO2 which was detected in perfusate and lung tissue as NO2- but not NO3-. NO2- concentration in perfusate increased linearly with time, and after 90 min of ventilation with NO2 and perfusion with erythrocyte-free medium, NO2- accumulation was 6.36 .+-. 0.39 .mu.g. If perfusate contained 10% erythrocytes, ventilated NO2 product was mostly NO3- in perfusate but NO2- in lung tissue. Protein solutions absorbed NO2 more effectively than simple salt solutions but they all yielded mainly NO2- unless erythrocytes were present, when the product was mostly NO3-. Absorbed NO2- in the lung was converted predominantly to NO2- but after its diffusion into the vascular space it was oxidized to NO3- by interactions with erythrocytes.