The Experimental Investigation Of NO And Glaucoma

Objective To study the role of NO in normal tension of healthy rabbits and the role and status of NO in the pathogenesis of glaucoma.Methods The changes of intraocular tension , mean arterial pressure and ocular perfusion pressure were measured at 30min,60min,90min,120min after SNP was given in normal tension rabbits; the changes of intraocular tension , mean arterial pressure and ocular perfusion pressure were measured at 20min,40min,60min,90min after L-NAME was given in normal tension rabbits. The contents of NO in aqueous humor and vitreous body were measured by NO kit at l/2h, 1h, 2h, 4h after SNP and L-NAME were given in glaucoma rabbits; the distribution of NOS in the retina of glaucoma rabbits was observed under Optics microscope by NADPH-d histochemical staining.Results Intraocular tension was reduced from 60min to 120min and ocular perfusion pressure was increased from 90min to 120min after SNP was given in normal tension rabbits' eyes, but SNP had no effection on mean arterial pressure. The content of NO in aqueous humor was increased from l/2h to 4h and the content of NO in vitreous body was increased from 1h to 4h after SNP was given through ear vein of glaucoma rabbits.Intraocular tension was increased from 40min to 60min and mean arterial pressure and ocular perfusion pressure was increased only at 20min after L-NAME was given by vein in normal tension rabbits. The contents of NO in aqueous humor and vitreous body were reduced from half of an hour to 2 hours after L-NAME (100mg/kg) were gived in glaucoma rabbits.NOS positive cells could be observed in inner nuclear layer in the three groups by NADPH--d histochemical staining, however , the layer was more loose and more vacuoles existed in SNP group than those in the saline group. The layer was in goodorder and no vacuoles existed in the L-NAME group.Conclusion SNP could reduce intraocular tension and increase blood flow of retina, but it could aggravate retinal cells damage. L-NAME could prevented optic nerve from superoxidized damage, however, it had the potency of increasing hypertention and reducing the blood flow of retina. So NO had an important role in the pathogenesis of glaucoma. Lots of experiments must be performed before we apply SNP and L-NAME in glaucoma therapy, Reasonable administration pathway and dosage would be chosen, and the superoxidized damage of retina could be avoided.