CHEMILUMINESCENT REAL-TIME IMAGING OF POSTISCHEMIC OXYGEN-FREE RADICALS FORMATION IN LIVERS ISOLATED FROM YOUNG AND OLD RATS

Oxygen free radicals generation is a major cause of liver injury durin g reperfusion. Luminescence analysis has been recently proposed to mea sure free radical generation by isolated cells or organs, but it allow s only global tissue luminescence. Using a special Saticon videocamera with image intensifier we aimed to visualize and localize oxygen free radical generation in isolated perfused livers exposed to an oxydativ e stress. Livers isolated from rats aged 4 and 30 months were exposed to ischemia/reperfusion; photons emission by the organs was continuous ly recorded. Lucigenin was utilized as a chemiluminigenic probe to ass ess superoxide anion generation. In both groups, chemiluminescence was not detectable during ischemia, while it was observed after reperfusi on. Photons emission started after few minutes of reperfusion, was max imal after 15-20 min and disappeared within 50-60 min. Chemiluminescen ce emitted by livers from younger rats however, was significantly high er when compared to chemiluminescence emitted by organs isolated from old rats (0.8 +/- 0.1 vs 0.44 +/- 0.08 photons x 10(5)/s, respectively , after 15 min; p < .01). The superimposition of chemiluminescent and live image permitted to determine the regional production rate and dis tribution of photons. In conclusion, the age of the rats influences si gnificantely the amount of oxyradicals produced in the liver during po st-ischemic reperfusion. The method described, allowing the visualizat ion in real time of oxygen free radicals generation on the surface of isolated intact organs, represents a novel and potent tool for the stu dy of oxidative stress. (C) 1998 Elsevier Science Inc.