[Influence of nitric oxide on superoxide anion radical generation in vivo]

We studied the effect of NO on superoxide anion radical (O2-) generation using chemiluminescence method by examining influence of NO gas on superoxide radical generation in rat lung induced by paraquat (PQ) on CLA-phenyl hybrid paper filters. SD rats were allocated into four groups. Group 1 received i.v. injection of physiological saline as a control group; Group 2 received 70 mg x kg-1 of PQ i.v.; Group 3 received 50,000 unit x kg-1 of SOD i.v., 1, 2, and 3 hours after i.v. PQ administration. Group 4 inhaled 50 ppm NO gas after i.v. injection of PQ. Three hours after administration of each drug in respective group, the right lower lobe of the lung was removed and immediately immersed into liquid nitrogen and then was sliced in width of 20 microns at -20 degrees C using cryostat. The results were summarized as representing overall level of superoxide radicals in each lung sample. PQ increased O2- production by 48% in comparison with the control. However, SOD and NO gas decreased O2- production significantly approximately up to the control level. These results confirmed that NO depresses O2- production in vivo.