Protection of the transiently ischemic cat retina by zinc-desferrioxamine.
OBJECTIVE
A previous study indicated that hydroxyl radicals are generated in the cat retina during the early reperfusion phase after 90 minutes of ischemia. Salicylate was injected intravenously, and its conversion to 2,3-dihydroxybenzoic acid (2,3-DHBA) served as a marker of hydroxyl radicals. The authors attempted to prevent this free radical generation during reperfusion.


METHODS
After salicylate administration, both eyes (15 minutes apart) of 15 cats were subjected to 90 minutes retinal ischemia. Following 5 minutes of reperfusion in the control eye, it was enucleated and processed for DHBA quantitation. Then, 7.5 mg of Zn-desferrioxamine (Zn-DFO) was injected intravenously into nine cats and saline into six cats. Five minutes later, reperfusion was induced in the experimental eye for 5 minutes, followed by enucleation. In one eye each of 12 other cats, scotopic electroretinographic (ERG) studies were carried out during 90 minutes of ischemia and 16 to 18 hours of reperfusion. Five minutes before termination of the ischemia, six animals were injected with 7.5 mg Zn-DFO and six with saline.


RESULTS
The normalized levels of 2,3-DHBA were lower in the experimental eyes than in their fellow controls only after Zn-DFO treatment (P = 0.01). In the ERG studies, after 16 to 18 hours of reperfusion, the mean b-wave-ERG amplitudes in the eyes of the saline-treated cats (n = 6) were 8.4% +/- 4.0% of the preischemic stage, and 70.5% +/- 6.7% of the Zn-DFO-treated cats (n = 6, P = 0.004).


CONCLUSIONS
Protection of the cat retina against ischemia and reperfusion injury by Zn-DFO was evident, most probably through its inhibitory effect on the generation of hydroxyl radicals during reperfusion.
Ophir
A
A
Department of Ophthalmology, Hadassah University Hospital, Jerusalem, Israel.
Berenshtein
E
E
Kitrossky
N
N
Averbukh
E
E
D000818:Animals; D002415:Cats; D003676:Deferoxamine / Q000627:therapeutic use*; D004596:Electroretinography; D005654:Fundus Oculi; D062385:Hydroxybenzoates / Q000032:analysis; D017665:Hydroxyl Radical; D007275:Injections, Intravenous; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology; D009942:Organometallic Compounds / Q000627:therapeutic use*; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D012171:Retinal Vessels / Q000378:metabolism* / Q000473:pathology; D012459:Salicylates / Q000008:administration & dosage; D020156:Salicylic Acid
D062385:Hydroxybenzoates; D009942:Organometallic Compounds; D012459:Salicylates; C086228:zinc-desferrioxamine; D017665:Hydroxyl Radical; C009135:2,3-dihydroxybenzoic acid; D003676:Deferoxamine; D020156:Salicylic Acid