Effects of peroxynitrite on rabbit cornea

Background: Nitric oxide (NO) reacts rapidly with the superoxide anion to g enerate peroxynitrite, which has been found in the aqueous humor in eyes wi th uveitis. We evaluated the functional and anatomic effects of peroxynitri te on rabbit cornea. Methods: One eye of each rabbit received an anterior c hamber injection of 3-morpholino-sydonimine N-ethylcarbamide (SIN-1), which simultaneously generates both NO and the superoxide anion. The corneal thi ckness was measured using an ultrasonic pachymeter before and after the inj ection. The eyes were fixed and the corneal specimens were prepared for ele ctron microscopy. Results: Anterior chamber injections of SIN-1 caused a si gnificant increase in the corneal thickness (25.1+/-3.0 mu m) 30 min after injection. Transmission electron microscopy showed swollen mitochondria and large vacuoles in the cytoplasm, and scanning electron micros copy reveale d obscuring of the mosaic pattern by increased ruffling of endothelial cell surface and borders. Conclusions: The results suggest that peroxynitrite g enerated in the aqueous humor may cause corneal endothelial cell damage, wh ich leads to transient corneal edema.