Oxidative stress in lung tissue induced by CO₂ pneumoperitoneum in the rat

Abstract

Background: Clinical trials have found that the pneumoperitoneum has potentially hazardous side effects. The biochemical basis of organ injury induced by pneumoperitoneum is, however, not well defined. Since oxidative stress is believed to play an important role in many pathological conditions, we set out to examine oxidative stress markers in the lung, liver, kidney, and pancreas by using a rat model of laparoscopy with CO₂ pneumoperitoneum and comparing it to a group with gasless laparoscopy.

Methods: Malondialdehyde (for lipid peroxidation), protein-bound carbonyls (for protein oxidation), reduced and oxidized glutathione, and the neutrophil marker myeloperoxidase were evaluated in tissue homogenates at 2 h, 6 h, and 18 h after laparoscopy. Immunoblotting was used to analyze the modification of lung proteins by 4-hydroxynonenal at 6 h.

Results: Significant lipid peroxidation was found selectively in lungs at 2 h and 6 h after CO₂ pneumoperitoneum. This was accompanied by a loss of glutathione but only minor protein oxidation. Further, lung proteins were clearly modified by the aldehydic product of lipid peroxidation 4-hydroxynonenal. Myeloperoxidase in lungs increased continuously up to 18 h in both experimental groups, but there were higher levels in the group with pneumoperitoneum.

Conclusion: Oxidative stress is likely to contribute to the impairment of pulmonary function after laparoscopic operations using a CO₂ pneumoperitoneum.