A quantitative study of lung dysfunction following haemorrhagic shock in rats

Haemorrhagic shock occasionally causes an episode of lung dysfunction, the severity of which appears to correlate with fatal outcome. Our previous study indicated that proinflammatory cytokines, such as tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta, played a key role in the development of lung dysfunction through recruitment of activated neutrophils by causing pulmonary endothelial cell damage. Here, we examined this issue quantitatively by grading four groups of severity of bleeding in rats. As the amount of bleeding increased, the expression of mRNA for TNF-alpha and IL-1beta in the lung tissue and the pulmonary serum levels of both cytokines increased progressively up to 5 h, and the frequency of activated neutrophils increased likewise. The lung dysfunction indices serum lactic dehydrogenase-3 isozyme (LDH-3), partial pressure of arterial oxygen (PaO(2)) and alveolar-arterial oxygen tension difference (AaDO(2)) in blood deteriorated as the amount of bleeding increased. The frequency of activated neutrophils in the lung correlated well with the LDH-3 level 5 h after haemorrhagic shock. The present results demonstrate that the increase of proinflammatory cytokines and the recruitment of activated neutrophils into the lung following haemorrhagic shock are quantitatively related to progression of lung dysfunction as the amount of bleeding increases.