TY - JOUR
T1 - Endogenous regulation of human schlemm's canal cell volume by nitric oxide signaling
AU - Ellis, Dorette Z.
AU - Sharif, Najam A.
AU - Dismuke, William M.
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2010/11
Y1 - 2010/11
N2 - PURPOSE. There is a time-course correlation between nitric oxide (NO)-induced decreases in trabecular meshwork (TM) cell volume and NO-induced increases in outflow facility. The Schlemm's canal (SC) cells may also provide resistance to aqueous humor outflow; therefore, this study tests the involvement of the nitric oxide synthase (NOS) and NO signaling pathway and the BK Ca-channel in mediating SC cell volume decreases. METHODS. Cell volume was measured in low-passage human SC cells using calcein AM fluorescent dye; images were captured with a confocal microscope, and data were quantified using NIH ImageJ software. RESULTS. Inhibition of endogenous NOS resulted in a 7% increase in SC cell volume. Exposure of SC cells to DETA-NO resulted in a 12% to 16% decrease in cell volume that was abolished by the soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (5 μM), the protein kinase G (PKG) inhibitor (RP)-8-Br-PET-cGMP-S (50 μM), and the high-conductance calcium-activated potassium channel (BK Ca channel) inhibitor iberiotoxin (50 nM). Hypertonic media significantly decreased SC cell volume by 14%, whereas hypotonic media significantly increased cell volume by 11.2%. CONCLUSIONS. These data suggest that endogenous NOS regulates steady state cell volume and the involvement of the NOS/NO/sGC/cGMP/PKG pathway and the BK Ca-channel in mediating NO-induced reductions in SC cell volume. These decreases in cell volume correlated with the time-course for NO-induced increases in outflow facility, suggesting that the NO-induced reduction in SC cell volume may also influence outflow facility.
AB - PURPOSE. There is a time-course correlation between nitric oxide (NO)-induced decreases in trabecular meshwork (TM) cell volume and NO-induced increases in outflow facility. The Schlemm's canal (SC) cells may also provide resistance to aqueous humor outflow; therefore, this study tests the involvement of the nitric oxide synthase (NOS) and NO signaling pathway and the BK Ca-channel in mediating SC cell volume decreases. METHODS. Cell volume was measured in low-passage human SC cells using calcein AM fluorescent dye; images were captured with a confocal microscope, and data were quantified using NIH ImageJ software. RESULTS. Inhibition of endogenous NOS resulted in a 7% increase in SC cell volume. Exposure of SC cells to DETA-NO resulted in a 12% to 16% decrease in cell volume that was abolished by the soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (5 μM), the protein kinase G (PKG) inhibitor (RP)-8-Br-PET-cGMP-S (50 μM), and the high-conductance calcium-activated potassium channel (BK Ca channel) inhibitor iberiotoxin (50 nM). Hypertonic media significantly decreased SC cell volume by 14%, whereas hypotonic media significantly increased cell volume by 11.2%. CONCLUSIONS. These data suggest that endogenous NOS regulates steady state cell volume and the involvement of the NOS/NO/sGC/cGMP/PKG pathway and the BK Ca-channel in mediating NO-induced reductions in SC cell volume. These decreases in cell volume correlated with the time-course for NO-induced increases in outflow facility, suggesting that the NO-induced reduction in SC cell volume may also influence outflow facility.
UR - http://www.scopus.com/inward/record.url?scp=79956039694&partnerID=8YFLogxK
U2 - 10.1167/iovs.09-5072
DO - 10.1167/iovs.09-5072
M3 - Article
C2 - 20484594
AN - SCOPUS:79956039694
SN - 0146-0404
VL - 51
SP - 5817
EP - 5824
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 11
ER -