SUPEROXIDE SCAVENGING ACTIVITY IN-VITRO AND IN THE CEREBRAL EXTRACELLULAR-SPACE MEASURED BY MICRODIALYSIS

Using the electron spin resonance (ESR) spin-trapping method and a hig h molecular cut-off membrane, we measured the superoxide scavenging ac tivity in dialysates obtained from microdialysis. The activity in the dialysates of the Cu,Zn-superoxide dismutase (SOD) solution and feline serum were measured in vitro, and the recovery rate was calculated to be 12.88 +/- 0.9% in Cu,Zn-SOD solution and 21.52 +/- 4.38 in feline serum, which was significantly different. This difference was believed to originate from the higher osmotic pressure due to proteins in the serum and substances other than Cu,Zn-SOD that acted as antioxidants i n the serum. In an in vivo study, microdialysis probes were implanted into the cerebral hemispheres in 6 cats. The sequential changes of sup eroxide scavenging activity were measured for 16 h and during induced cardiac arrest. No significant difference was observed and the microdi alysis technique itself did not seem to cause the significant alterati on of the activity in the extracellular space, although at cardiac arr est, the activity varied widely. This method can be used to study the reaction against superoxide injury in further experiments involving br ain insult.