Lipid peroxidation in rat lung induced by neuroleptanalgesia and its components

The aim of the present work was to determine the likelihood of lipid peroxi dation in the lungs of rats ts subjected to neuroleptanalgesia and its comp onents. In particular, the effect of fentanyl, droperidol, a nitrous oxide/ oxygen mixture when used separately or in combination, on the lung level of lipid peroxidation was investigated. The in vitro antioxidant properties o f fentanyl and droperidol were also tested. Lipid peroxidation was evidence d by the endogenously generated conjugated dienes and fluorescent products of lipid peroxidation and the decrease in lung vitamin E content. it was fo und that fentanyl and droperidol, used,separately or in combination, did no t induce lipid peroxidation in the rat lung, while the exposure of rats for 120 min to a nitrous oxide/oxygen mixture (2:1 v/v) led to well-expressed peroxidation. The (N2O + O-2)-pro-oxidant action was significantly inhibite d in rats previously injected with fentanyl and/or droperidol. The results show that the application of fentanyl, droperidol and (N2O + O-2), as in ne uroleptanalgesia, ensures minimal lipid peroxidation in the lung. In additi on, we found that fentanyl and droperidol were able to inhibit the Fe2+-cat alysed lipid peroxidation in lung homogenate. We speculate that the inhibit ory effect of fentanyl and/or droperidol on the (N2O + O-2)induced lipid pe roxidation in the rat lung may be caused directly by their antioxidant prop erties. However, another explanation seems to be possible. The free radical s that are produced during the metabolism of fentanyl and droperidol may re act with the radicals generated during the one-electron reduction of nitrou s oxide. Such reactions will obviously reduce the free radical concentratio n in the organism and, hence, the likelihood of initiating lipid peroxidati on.