The present study was undertaken to assess the effect of nitric oxide on the retinal vascular relaxation and retinal toxic effect.in pigmented rabbits. S-nitroso-N-acetyl-D, L-penicillamine[SNAP], as a NO onor, dissolved in dimethyl sulfoxide[DMSO]was injected into vitreal space.N-acetyl-D, L-penicillamine[NAP]was used as a control. We used Doppler Ultrasound to measures blood flow velocity.In the flow velocity between NAP group and SNAP group, the resistance index did not differ significantly for both central retinal artery and ciliary artery[p>0.05] 3 to 6 hours after NAP &SNAP injection. On electroretinographic study, a-wave amplitude of maximal combined response was reduced in SNAP treated group.In contrast, b/a ratio was increased between 3 hours and 6 hours after injection.Histologic examinations showed vacuolar degeneration and clumping and lysis of nuclei of photoreceptors.Lysosome and autophagic vacuoles were also noted in the cytoplasm of outer neuronal cells.In conjunction with above results, further studies about should be required to find the optimal concentration of NO & NO donor with minimal retinal toxicity and maximal therapeutic effect.
Blood Flow Velocity* ; Cytoplasm ; Humans ; Neurons ; Nitric Oxide* ; Rabbits ; Relaxation ; Retinal Artery ; Retinaldehyde* ; Tissue Donors ; Ultrasonography* ; Vacuoles