Quantitative analysis of hydroxyl radicals in the anterior optic nerve of the cat following transient ischemia.
OBJECTIVE
Ischemic insults in the optic nerve are relatively common ocular disorders. This study provides quantitative data on the generation of hydroxyl radicals in the anterior optic nerve of the cat during the early reperfusion phase following 90 minutes of ischemia.


METHODS
Cats were injected intravenously with sodium salicylate that by acting as an hydroxyl radical trap, forms 2,3-dihydroxybenzoic acid (2,3-DHBA). Ischemia was achieved by intraocular pressure (IOP) elevation via cannulation of the anterior chamber. Ischemia was maintained for 60 minutes in 6 eyes and 90 minutes in 12 eyes, followed by 5 minutes of reperfusion. In an additional 6 eyes, ischemia was maintained for 90 minutes without reperfusion.


RESULTS
After 90 minutes of ischemia and reperfusion, mean normalized levels of 2,3-DHBA (ie, ng 2,3-DHBA/microg salicylate/mg protein) that represent the levels of hydroxyl radicals were 2.47 times (at least) higher in the anterior optic nerves than in the fellow sham-operated controls (P = 0.03). These levels were 3.9 times (at least) greater than in the corresponding levels after 90 minutes of ischemia without reperfusion (P= 0.005).


CONCLUSIONS
This study provides a quantitative analysis and evidence for the generation of hydroxyl radicals in the optic nerve of the cat following transient ischemia. A quantitative analysis may provide an important tool to detect even relatively small levels of free radicals in the tissues, and to evaluate the relative efficacy of various therapeutic agents in the inhibition of free radical generation following ischemia and reperfusion.
Ophir
A
A
Department of Ophthalmology, Hillel-Yaffe Medical Center, Hadera, Israel. Ophthalmology@hillel-yaffe.health.gov.il
Porges
Y
Y
D000818:Animals; D002415:Cats; D002851:Chromatography, High Pressure Liquid; D062385:Hydroxybenzoates / Q000032:analysis*; D017665:Hydroxyl Radical / Q000378:metabolism*; D006900:Hydroxylation; D009900:Optic Nerve / Q000378:metabolism*; D009901:Optic Nerve Diseases / Q000378:metabolism*; D015427:Reperfusion Injury / Q000378:metabolism*; D012980:Sodium Salicylate / Q000008:administration & dosage
D062385:Hydroxybenzoates; D017665:Hydroxyl Radical; C009135:2,3-dihydroxybenzoic acid; D012980:Sodium Salicylate