Effects of ONO-5046, a specific neutrophil elastase inhibitor, on endotoxin-induced lung injury in sheep

Abstract

The purpose of the present study was to assess the role of polymorphonuclear leukocyte (neutrophil) elastase in endotoxin-induced acute lung injury in sheep with lung lymph fistula. We studied the effects of ONO-5046, a specific inhibitor of neutrophil elastase, on the lung dysfunction induced by the intravenous infusion of 1 microgram/kg of Escherichia coli endotoxin. Endotoxin alone produced a biphasic response as previously reported. Early (0.5–1 h) after endotoxin, pulmonary arterial pressure increased from 19.5 +/- 0.9 cmH2O at baseline to a peak of 46.8 +/- 2.4 cmH2O (P > 0.05). Pulmonary vascular resistance increased from 3.03 +/- 0.17 cmH2O.l–1.min at baseline to a peak of 9.77 +/- 0.70 cmH2O.l–1.min (P < 0.05). Circulating neutrophils decreased from 7,355 +/- 434/mm3 at baseline to a nadir of 1,762 +/- 32/mm3 (P < 0.05). Thromboxane B2 and 6-ketoprostaglandin F1 alpha concentrations in plasma and lung lymph were significantly increased. Late (3–5 h) after endotoxin, pulmonary arterial pressure and pulmonary vascular resistance returned to baseline levels, but lung lymph flow remained increased from 4.2 +/- 0.3 ml/0.5 h at baseline to 7.3 +/- 0.7 ml/0.5 h (P < 0.05), with a slight increase in lung lymph-to-plasma protein concentration ratio, suggesting increased pulmonary vascular permeability. The histopathological features of the lungs during the early period in sheep treated with endotoxin alone revealed a large increase in neutrophils per 100 alveoli and changes of pulmonary edema such as thickening of the interstitium of the lung and alveolar flooding.(ABSTRACT TRUNCATED AT 250 WORDS)