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D. Z. Ellis, W. M. Dismuke, N. A. Sharif; Time-Dependent Correlation Between Nitric Oxide-Induce Decreases in Schlemm’s Canal Cell Volume and Nitric Oxide -Induced Increases in Outflow Facility. Invest. Ophthalmol. Vis. Sci. 2010;51(13):149.
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We previously demonstrated a time-course correlation between nitric oxide (NO)-induced decreases in trabecular meshwork cell volume and NO-induced increases in outflow facility. Because the Schlemm’s canal (SC) cells also provide resistance to aqueous humor outflow, this study was conducted to test the involvement of the NO/soluble guanylyl cyclase (sGC) / protein kinase G (PKG) pathway and the BKCa-channel in mediating SC cell volume decreases.
Low passage human SC cells were grown to confluency and cell volume was measured using Calcein AM fluorescent dye; images were captured with a confocal microscope, and data quantified using NIH ImageJ software.
. Exposure of SC cells to DETA-NO (50 -100 µM) resulted in a 12% decrease in cell volume: mean voxels, 9972.9 ± SEM, 469.8; n = 143 cells. These decreases were abolished by the sGC inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 5 µM; the PKG inhibitor, (RP)-8-Br-PET-cGMP-S, (25 µM); and the BKCa channel inhibitor, iberiotoxin (IBTX), (100 nM). Furthermore, hypertonic media significantly decreased SC cell volume (14 %) while hypotonic media significantly increased cell volume (11.2 %).
These data suggest the involvement of the sGC/cGMP/PKG pathway and the BKCa-channel in mediating the NO-induced decreases in SC cell volume. These decreases correlated with the time course for NO-induced increases in outflow facility, suggesting that the NO-induced decreases in SC cell volume may also influence outflow facility.
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