SELENIUM DEFICIENCY AUGMENTS THE PULMONARY TOXIC EFFECTS OF OXYGEN EXPOSURE IN THE RAT

Selenium (Se) is a component of the antioxidant enzyme glutathione per oxidase (GSHPx). We wanted to determined whether Se deficiency predisp oses to pulmonary O2 toxicity. Sixteen weanling rats were fed a Se-fre e diet (Se-). Sixteen rats fed the same diet had drinking water supple mented with 400 mug.l-1 sodium selenite (Se+). After 5 weeks, rats wer e killed after exposure to either 95% O2 or air for 36 h. Se concentra tion in blood, lung, liver, heart, muscle and spleen, and blood GSHPx activity were higher in Se+ than in Se- groups. Pulmonary oedema devel oped in both O2-exposed groups, but was more severe in Se-O2 group tha n in the Se+O2 group, as judged by the presence of pleural effusions ( 7 out of 8 versus 0 out of 8), elevated lavage protein concentration ( 173+/-17 versus 120+/-14 mug/ml-1), and higher wet/dry weight ratio (W :D) (5.8+/-0.07 versus 5.4+/-0.07). W:D correlated inversely with lung Se content in O2-exposed rats. Both O2-exposed groups had a reduction in the amount of less aggregated lavage phospholipid (PL) compared wi th the Se+air group However, the Se-O2 group had increased total PL, b ecause of an increase in more aggregated PL. We conclude that Se defic iency exacerbates pulmonary injury in O2-exposed rats, and that O2 tox icity is associated with an altered physical form of alveolar surfacta nt.