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P.S. Mettu, B. Pendurthi, D.L. Epstein, P.V. Rao; Role of Soluble Guanylate Cyclase in the Modulation of Aqueous Humor Outflow Facility . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4371.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the role of soluble guanylate cyclase (sGC) in trabecular meshwork (TM) cells and in the modulation of aqueous humor outflow facility. Methods: Expression of the α1, α2, and ß1 subunits of the heterodimer sGC was determined by PCR amplification of human TM–derived RT–PCR libraries, using sequence–specific oligonucleotide primers, with subsequent sequencing analysis. The effects of the sGC–activating compounds YC–1 and BAY 41–2272 on cell shape, actin cytoskeletal organization, and focal adhesion formation in porcine TM (PTM) cells were evaluated by phase contrast microscopy (cell shape) and immunofluorescence microscopy (cytoskeleton). YC–1 and BAY 41–2272–induced effects on myosin light–chain (MLC) phosphorylation in PTM cells were assessed by Western blot analysis. The effects of YC–1 and BAY 41–2272 on aqueous humor outflow facility were evaluated by perfusion of enucleated porcine eyes using the Grant constant–pressure system. Results:Expression of the α1 and ß1 subunits of sGC was readily detectable in RT–PCR libraries prepared from HTM cells, while α2 was expressed at low levels. YC–1 (30 and 50 µM) and BAY 41–2272 (5 µM) promoted cell rounding, actin stress fiber depolymerization, focal adhesion loss, and decreased MLC phosphorylation in PTM cells. Perfusion of YC–1 (50 µM) and BAY 41–2272 (25 µM) in a thus far limited number of enucleated cadaver porcine eyes produced an increase in aqueous humor outflow facility over baseline values by 25% (n=2) and 33% (n=3), respectively. The effects of YC–1 and BAY 41–2272 on levels of cGMP, activation of Rho, and intracellular calcium concentrations in PTM cells are currently under investigation. Conclusions: These studies confirm the expression of sGC in HTM cells and demonstrate that pharmacological agonists of sGC, YC–1 and BAY 41–2272, influence cytoskeletal organization and cell–extracellular matrix interactions and cause a decrease in MLC phosphorylation in PTM cells. Importantly, activation of sGC in the outflow pathway appears to promote an increase in outflow facility, suggesting a potential novel mechanism for the modulation of aqueous humor outflow facility.
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