Evaluation of the urinary desmosine radioimmunoassay as a monitor of lung injury after endobronchial elastase instillation in sheep.

Thirty male sheep were treated with varying doses of endobronchial elastase. Urinary excretion of elastin peptides was then measured by desmosine radioimmunoassay and compared with pre-enzyme values. Mean linear intercepts were measured in treated and untreated lobes 4 wk later, and in addition, lung perfusion, ventilation, and volume were measured before enzyme treatment and 4 wk later using radionuclide-imaging techniques. Most of the elevation in urinary desmosine excretion occurred in the first 48 h after elastase administration. The increase in desmosine excretion was positively correlated with: enzyme dose (r = 0.74, p less than 0.01), increase in mean linear intercept (r = 0.61, p less than 0.05), decrease in lung perfusion (r = 0.77, p less than 0.01), and decrease in ventilation (r = 0.58, p less than 0.05). These results demonstrate that the urinary desmosine radioimmunoassay is a reliable index of pulmonary elastin breakdown and of several resultant anatomic and physiologic stigmata of pulmonary emphysema.