Direct measurement of free radicals in ischemic/reperfused diabetic rat retina.
Electron paramagnetic resonance (EPR) spectroscopy was used to directly measure free radical generation in ischemic/reperfused diabetic rat retina. Tissue was frozen at 77 degrees K after 90 min ischemia, and 90 min ischemia followed by 1 min, 3 min, 5 min, and 24 hours reperfusion, respectively. After 90 min of ischemia followed by 1 min, 3 min, 5 min, and 24 hours of reperfusion (n = 10 in each group), free radical signal intensity was increased from its diabetic nonischemic control value of 12 +/- 3 arbitrary units to 58 +/- 6 (P < 0.05), 62 +/- 7 (P < 0.05), 32 +/- 5 (P < 0.05), and 14 +/- 4 arbitrary units, respectively. The peak intensity of free radical production was observed after 90 min ischemia followed by 3 min of reperfusion; therefore, this time point was selected to study the retinal free radical production in superoxide dismutase (conjugated with polyethylene glycol, PEG-SOD) and EGb 761 (Ginkgo biloba extract)-treated groups. With 7,500, 15,000, and 30,000 U/liter of SOD, and 25, 50, and 100 mg/kg of EGb 761, a dose-dependent reduction in oxygen free radical production was detected, respectively, which may be responsible for the attenuation of abnormal postischemic function in ischemic and reperfused diabetic retina.
Szabo
M E
ME
Department of Pharmacology, IPSEN, Paris, France.
Droy-Lefaix
M T
MT
Doly
M
M
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D020441:Ginkgo biloba; D006801:Humans; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*; D012160:Retina / Q000378:metabolism*; D012171:Retinal Vessels / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*; D000096983:Ginkgo Extract
D016166:Free Radical Scavengers; D005609:Free Radicals; D010936:Plant Extracts; D013482:Superoxide Dismutase; D013481:Superoxides; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract