Nitric oxide increases leukocyte granule release during simulated extracorporeal circulation

Background: Nitric Oxide (NO) is reported to posses anti-inflammatory prope rties. The aim of this study was to investigate if nitric oxide affects leu kocyte response during simulated extracorporeal circulation (SECC). Methods : Human blood was circulated for 23 hours through SECC circuit. Control gro up C (n=5) was ventilated with an oxygen/air mixture, and NO was added in t he study group (n = 5). Leukocyte response was determined by release of mye loperoxidase (MPO) and human neutrophil lipocalin (HNL) and by oxygen free radical production, estimated using chemiluminescence. Results: Addition of NO significantly increased MPO at 30 minutes and 120 minutes of SECC and H NL at 120 minutes of SECC. Oxygen free radical production in whole blood wa s generally not affected by NO. Similarly, no significant differences were observed between the groups with regard to the chemiluminescence in isolate d granulocytes. Conclusions: Nitric oxide increased release of leukocyte gr anule derived proteins; MPO and HNL at an early stage of simulated extracor poreal circulation. At the same time, nitric oxide did not affect the whole blood and leukocyte capacity to produce oxygen free radicals.