Change in nitric oxide in humans due to application of a pneumatic tourniquet

The nitric oxide profile produced by application of a pneumatic tourniquet was investigated in the plasma of 15 patients. Nitrite (NO2-) and nitrate (NO3-) plasma concentrations were measured simultaneously by high-performance liquid chromatography (HPLC). UV detection using the Griess reaction was done after the reduction of nitrate to nitrite. The plasma nitrate concentration 5 min after reperfusion was significantly higher than the concentrations before ischemia, immediately before reperfusion, and the next day. In contrast, there was no significant difference in the plasma nitrite concentrations before ischemia, immediately before reperfusion, 5 min after reperfusion, and the next day. These findings suggest that the generation of NO is important in ischemic reperfusion injury.