Methods: Forty rats were grouped as normal control group (n=10), sham group (n=10), IR injury (IRI) group (n=10) and L-arginine group (n=10). In the IRI and L-arginine groups, infrarenal aorta was cross-clamped for 3 hours followed by 2 hours of reperfusion; rats in L-arginine group received L-arginine monohydrochloride (2.25 mg/kg/day) in drinking water for 7 days prior the experiment. Arterial pH and pCO₂ were measured in blood before ischemia, after 90 and 180 minutes of ischemia, and 60 minutes after reperfusion. At the end of the experiment, the right lungs were removed and histologically examined for evidence of lung injury.

Results: There was no significant difference in lung injury score between the normal control and sham groups. IR resulted in a significant increase in lung injury scores in the IRI group and the lungs were less injured in the L-arginine group (3.0±0.6 and 1.5±0.4, respectively, p<0.05). In the blood gas analysis, the IRI group had lower pH than the L-arginine group in reperfusion period (7.28±0.02 and 7.33±0.03 respectively, p<0.05). There was no significant difference in the pCO₂ among all four groups.

Conclusion: These data indicate that transient infrarenal aortic occlusion with subsequent ischemia/reperfusion of the lower extremities caused a significant lung injury and that oral administration of L-arginine significantly reduced this injury.