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Rosica Stoyanova Petrova, Nikhil Nair, Kevin L Schey, Paul J Donaldson; Alterations to the hydrostatic pressure gradient modulate the subcellular distribution of water channel AQP5 in the rat lens. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2098.
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To determine whether changes to the lens intracellular hydrostatic pressure gradient that drives water efflux from the lens also alters the subcellular location of AQP5 water channels in the rat lens.
Enucleated rat eyes were dissected to produce four scleral flaps that exposed the lens but left it attached to the ciliary muscle via the lens zonules. The flaps were pinned to the bottom of a recording chamber and the preparation incubated in AAH in either the absence or presence pilocarpine or tropicamide, to decrease and increase zonular tension, respectively, or different combinations of TRPV1/4 activators and/or inhibitors. The effects of perturbations on hydrostatic pressure and AQP5 membrane localization were monitored by a pico-injector-microelectrode system1 or immunohistochemistry and confocal microscopy2, respectively.1. Chen et al., IOVS 60:4416-4424, 2019.2. Petrova et al., IOVS 61:36, 2020.
Tropicamide decreased surface hydrostatic pressure but did not alter the predominately membrane localization of AQP5. In contrast, reducing zonular tension by pilocarpine resulted in a change in AQP5 immunolabeling from membranous to cytoplasmic, which was correlated with a significant and sustained increase in surface hydrostatic pressure. The increase in pressure and the removal of AQP5 from the membrane induced by pilocarpine could also be mimicked by first incubating lenses in the TRPV4 inhibitor HC067047, before then applying the TRPV1 activator capsaicin.
Our pressure measurement results showed that the hydrostatic pressure of the rat lens can be manipulated pharmacologically by changing of the zonular tension or by changing the activity of the TRPV4 and TRPV1 mechanosenors. Our immunolocalization results suggest fiber cells can respond to hydrostatic pressure by shuttling AQP5 out from the cell membrane to dynamically regulate the efflux and influx of water in the rat lens.
This is a 2021 ARVO Annual Meeting abstract.
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