Effects of N-acetylcysteine on pulmonary macrophage activity after intestinal ischemia and reperfusion in rats

Background/Aims: Intestinal ischemia and reperfusion (I/R) is considered to be a critical and triggering event in the development of distal organ dysf unction after a variety of insults. It appears that activated leukocytes, e specially polymorphonuclear granulocytes (PMNs), and reactive oxygen specie s are important mediators in the process. In the present study, the aim was to evaluate the behavior of pulmonary macrophages, acute lung injury and p ulmonary endothelial permeability after intestinal I/R, together with poten tial alterations in pulmonary endothelial and epithelial ultrastructure and cellular membrane system integrity. Methods: Intestinal ischemia for 40 mi n was followed by reperfusion for 12 h in the rat. Macrophage uptake of rad iolabeled bacteria, levels of pulmonary blood content assessed by radiolabe led red blood cells and pulmonary endothelial permeability of radiolabeled albumin, as well as pulmonary endothelial and epithelial ultrastructure and cellular membrane system integrity by the use of scanning electron microsc opy and a tracer was evaluated after 12 h reperfusion. Treatment with the f ree radical scavenger N-acetylcysteine (NAC) administered prior to reperfus ion was evaluated. Results: Overactivation of pulmonary macrophages was not ed after intestinal I/R, as was a significant decrease in pulmonary blood c ontent. No increase in pulmonary albumin leakage or increase in pulmonary w ater content was found after intestinal I/R as compared to controls. Treatm ent with NAC prevented against intestinal I/R-induced overactivation of pul monary macrophages and a decrease in pulmonary blood content. Conclusion: R eactive oxygen species may be involved in the regulation of pulmonary macro phage function and pulmonary circulation after intestinal I/R. Copyright (C ) 2000 S. Karger AG, Basel.