Effect of N-acetylcysteine on pulmonary damage due to microembolism in the rat.

Abstract

The effect of N-acetylcysteine (NAC), a free radical scavenger, was investigated in a microembolism rat model of adult respiratory distress syndrome (ARDS). Microembolism was induced by an intravenous injection of bovine thrombin and an intraperitoneal injection of a fibrinolysis inhibitor, trans-4-aminomethyl-cyclohexane-carboxylic acid (AMCA). NAC counteracted the experimentally induced increase in lung weight, the development of alveolar oedema, and the amount of fibrin in precapillary vessels. There was also a tendency to a decrease of the experimentally induced interstitial oedema caused by the NAC treatment, although it was not statistically significant. Surprisingly, NAC reduced plasma viscosity in both experimental and control animals. It also seemed to increase PaO2 in animals with pulmonary damage, but had a lowering effect on PaO2 in control animals. The results indicate that NAC has a significant preventive effect in this microembolism rat model of ARDS, and that this effect may be achieved through decreased deposition of fibrin, thus counteracting pulmonary oedema, and a decrease in plasma viscosity.