Annals of clinical and laboratory science
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Positive pressure ventilation with hyperdistention of the lungs (PPVHDL) causes microscopic lung injury in rats and in mice. This study compared lung lavage and serum levels of lactate dehydrogenase (LDH), aspartate aminotransferase (AST), creatinine phosphokinase (CPK), lung lavage and plasma endothelin-1 (ET-1) concentration, lung tissue ET-1 mRNA expression, angiotensin converting enzyme (ACE) activity of lung homogenates, and histology of the lung structure in control and PPVHDL rats. Rats were anesthetized with pentobarbital. ⋯ No significant difference was found in lung tissue ET-1 mRNA expression and lung protein concentration between the two groups. Lung ACE activity, in contrast, was significantly lower in PPVHDL rats. This study demonstrated that moderate alveolar hyperdistention caused significant structural lung damage accompanied by decreased ACE activity after seven hours of mechanical ventilation and that elevated lung lavage and serum LDH and AST levels in lung lavage and in serum might be early markers of ventilator-induced lung injury in this rat model.