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C.-Y. C. Yang, Y. Liu, H. Gong; Effects of Y27632 on Aqueous Humor Outflow Facility With Changes in Hydrodynamic Pattern and Morphology in Human Eyes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3237.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of rho-kinase inhibitor Y27632 on aqueous humor outflow facility with changes in the hydrodynamic pattern and trabecular meshwork structure in enucleated human eyes after a 3 hour perfusion.
Five pairs of enucleated human eyes were initially perfused with phosphate buffer containing 5.5 mM glucose (GPBS) at 15 mmHg to establish a stable baseline facility. One eye of each pair was then exchanged and perfused with 50 µM Y27632 in GPBS for 3 hours, while the contralateral eye was treated in a similar manner with GPBS alone. Fluorescent microspheres were exchanged and perfused to label the hydrodynamic patterns of outflow, followed by perfusion fixation. Frontal sections in four quadrants were examined by confocal, light and electron microscopy along the inner wall (IW) of Schlemm’s canal (SC). Under confocal microscopy, the total length (TL) and the tracer-decorated length (L) of the IW were measured in at least 32 images/eye, and the average percent effective filtration length (PEFL=L/TL) was calculated. The TL of the IW and the loose juxtacanalicular tissue length (LJCT) were measured in at least 24 images/eye under light microscopy, and the average percent of LJCT length (PLJCT) over TL was calculated. The number of giant vacuoles (GV) were counted and compared between the loose and dense JCT region.
A 3 hour perfusion with Y27632 increased outflow facility (2.3-fold, P=0.039) and PEFL (1.4-fold, P=0.032) significantly compared to control eyes. Confocal microscopy displayed a segmental distribution of tracer in the trabecular meshwork, with a greater concentration of tracer near the collector channel ostia. The IW and JCT appeared looser with more GV in the tracer labeled area compared to the denser non-tracer labeled region. Light microscopy showed PLJCT increased 1.3-fold in Y27632 treated eyes than in control eyes; moreover, 1.5-fold more GV were found in the region of loose JCT than in dense JCT (P<0.001).
Y27632 increases outflow facility after a 3 hour perfusion in enucleated human eyes, which is associated with an increase in PEFL and PLJCT. Our data suggest that outflow facility is regulated by the effective filtration area, which in turn is modulated by the morphological change in the IW and JCT, including an increase in loose JCT regions and GV formation.
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