Effect of hyperoxia on imipramine uptake and metabolism by the isolated, perfused rat lung.

Imipramine (IMP) is a biologically active amine which is removed from the circulation by the lungs. We evaluated the effect of high partial pressures of O2 on pulmonary uptake and metabolism of IMP. Lungs from rats previously exposed to either air (controls) or 100% O2 at 1 ATA for 12-48 hr were isolated, ventilated and perfused via the pulmonary artery. Uptake of IMP was calculated from the arteriovenous difference of 14C-IMP across the lung and lung effluents and homogenates were analyzed for the presence of metabolites of IMP. IMP was avidly concentrated in the lungs of control rats by a saturable process, and this saturable uptake was not affected by 12-48 hr exposure to 100% O2. 14C-IMP was not metabolized by control of O2-exposed lungs.