Effect of acute lung injury on metabolism of adenine nucleotides in rat perfused lung.

1. The hydrolysis of adenosine di- and monophosphate (ADP, AMP) was studied in perfused lungs isolated from rats treated with alpha-naphthylthiourea (ANTU) to induce acute lung injury. This injury is associated with damage to the endothelium, the locus of the ADP and AMP hydrolysing enzymes. 2. Treatment with ANTU did not change the proportion of [3H]-ADP surviving a single passage through the pulmonary circulation, at any time up to 50 h after ANTU. Less than 8% and 2% respectively of 1 or 0.1 mumol ADP, given as a bolus, appeared in lung effluent. 3. The metabolites of ADP, AMP and adenosine in lung effluent were increased fro 2 h after ANTU. 4. Metabolism of [3H]-AMP as substrate was always low but, following ANTU treatment, the adenosine content of lung effluent increased four fold. 5. It appears that, in spite of considerable endothelial cell damage, as demonstrated by pulmonary oedema, the ectoenzymes catalysing ADP and AMP hydrolysis were relatively little affected by ANTU.