The Effects of Topical Carbonic Anhydrase Inhibitors on Nitric Oxide Production in Trabecular Meshwork Cells

PURPOSE: To investigate and compare the effects of topical carbonic anhydrase inhibitors on the production and expression of nitric oxide in cultured human trabecular meshwork cells (HTMC). METHODS: Primarily cultured HTMC were exposed to 0, 10, and 100 microM dorzolamide and brinzolamide using serum-deprived media for 3 days. Production of nitric oxide was assessed with Griess assay. Expressions of eNOS mRNA were assessed with RT-PCR. RESULTS: Both dorzolamide and brinzolamide increased the production of nitric oxide eNOS activity (p < 0.05). Dorzolamide had a more potent effect than brinzolamide on the production of nitric oxide and the expression of eNOS mRNA. CONCLUSIONS: Topical carbonic anhydrase inhibitors increased the production of nitric oxide, which was accompanied by increased eNOS activity. Dorzolamide had a more potent effect than brinzolamide on the production of nitric oxide and expression of eNOS mRNA in HTMC. The increased production of nitric oxide by topical carbonic anhydrase inhibitors involves mechanisms other than carbonic anhydrase inhibition.

Influence of topical carbonic anhydrase inhibitor on the expression of aquaporin-1 in rat cornea with neovascularization / 中华实验眼科杂志

Background Researches showed that aquaporin-1 (AQP1) is closely associated with corneal neovescularization(CNV).Carbonic anhydrase inhibitor has the inhibitory effect on the AQP1 and further suppresses the CNV.However,the systemic adverse effect of Carbonic anhydrase inhibitor limit its clinical application.Therefore,the influence of topical carbonic anhydrase inhibitor on CNV is concerned.Objective Present study was to investigate the effects of topical carbonic anhydrase inhibitors on the expression of AQP1 in rat cornea after alkali burn and explore its role in corneal neovascularization (CNV).Methods The alkali-burn animal models were established in 60 eyes of 30 clean Sprague Dawley rats by putting the filter paper soaked 1 mol/L NaOH solution at the central cornea for 40 seconds.1％ Brinzolamide was topically administered in the 30 eyes of 15 models (Brinzolamide group),and the normal saline solution was used at the same way in other 30 eyes of 15 rats (model group).The 10 eyes of 5 normal Sprague Dawley received the eye drops of normal saline solution as the normal control group.The corneal burning degree was graded on the Mahoney ' s criteria in the third day,and Ee ' s method was used to score the opacification of cornea and the CNV area was analyzed in 3,5,7,10 days under the slit lamp microscope.The cornea tissue was obtained in the tenth day after burning for the observation of the pathology under the light microscope and the ultrastructure under the transmission electron microscope.The expressions of AQP1 and vascular endothelial growth factor(VEGF) in cornea tissue were detected using immunohistochemistry.The use of animals complied with the Statement of ARVO.Results No significant difference was seen in the scores of rat corneal alkali burn between the model group and brinzolamide group( t=0.97,P＞0.05 ).The scores of corneal edema and opacification and neovascular area were lower in brinzolamide group compared with model group ( t =2.18,P＜0.05 ;t =6.58,P＜0.01 ).The pathological and ultrastructural examinations showed less CNV and inflammatory cells in rat corneal tissue of the brinzolamide group in comparison with model group.The grey values of VEGF were 84.92±9.49 and 78.18± 11.41,and those of AQP1 were 88.01 ± 11.03 and 58.10 ± 12.14 in the model group and brinzolamidegroup respectively,showing statistically significant differences ( VEGF:t =2.48,P =0.02 ; AQPI:t =9.99,P =0.00 ).Conclusions 1％ Brinzolamide suppresses alkali burn-induced CNV by downregulating the expressions of AQP1 and VEGF in cornea in rat.