Abstract
Abstract: :
Purpose:To investigate the topical effects of nitric oxide synthase (NOS) inhibitor nitro-L-arginine methyl ester (L-NAME) on α-chymotrypsin-induced hypertensive rabbits. Methods:L-NAME was dissolved in a isotonic, mucoadhesive, viscosized, buffered solution (vehicle) at a concentration of 1% (w/v). Ocular hypertension was induced, in the left eye of anesthetized animals, by injection of α-chymotrypsin into the posterior chamber.Intraocular pressure (IOP) was checked after 4 weeks and only rabbits in which pressure became 12-15 mmHg higher than in the untreated eye were used. IOP was measured using a Tono-Pen XL tonometer. L-NAME formulation or vehicle were instilled (50 µl) in the left eye and the IOP was monitored at different times. Results:The instillation of L-NAME formulation lowered the IOP of hypertensive rabbits with a maximum drop of 12.0 mmHg 60 min after administration and by 3 h IOP returned to baseline. The area under the curve (AUC) of the difference in IOP (mmHg) versus time (min) was 1050.3±141.7 and 15.1±2.5 for the L-NAME-treated group and vehicle-treated group respectively (p<0.0001) Conclusion:This study provides the first evidence that topical L-NAME significantly reduced the IOP in α-chymotrypsin-induced hypertensive rabbits suggesting that this effect could be due to a decrease in aqueous production. CR: N Support: Grant from the School of Medicine,University of Catania.
Keywords: 491 nitric oxide • 444 intraocular pressure