The lens as an osmometer and the effects of medium osmolarity on water transport, 86Rb efflux and 86Rb transport by the lens

Cotlier, Edward; Kwan, Benjamin C. K.; Beaty, Claudia

doi:10.1016/0005-2736(68)90060-6

Cited by 43 publications

(24 citation statements)

References 10 publications

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“…The total content of solute in the lens can be determined from the volume of lens water and the osmolarity of the medium on the assumption that the intralenticular osmolarity is equal to that in the medium. This assumption is consistent with measurements reported for the lens [2], The content of the major electrolytes is obtained by measurement of the sodium and potassium levels and making the assumption that the anion content necessary to maintain electrical neutrality is equal to that of the measured cations minus the level of fixed anions. The level of fixed anion was assumed to be constant in all experiments at 100 mEq/kg of dry weight.…”

Section: Overall Ballance Sheetsupporting

confidence: 75%

Effect of Incubation Medium Electrolyte Concentration on Lens Volume

Patterson¹

1980

Ophthalmic Res

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In rat lenses that are incubated in anisotonic media, the initial tendency to change volume is countered by a change in the intralenticular concentration of solute so that the amount of volume change is minimized. The effect of electrolytes in the medium on solute concentration and content was determined by comparing the effects of two series of media. In one osmolarity was varied by changing the concentration of sodium chloride and in the other the osmolarity was varied by changing the concentration of sucrose. The results indicate that volume regulation in the rat lens is a dual process with the content of lens electrolytes varying with the electrolyte concentration in the medium and with the content of ‘other solute’ varying with osmolarity. Potassium fluxes were estimated from ⁸⁶Rb influx and efflux measurements. When the osmolarity is varied by changing the concentration of sodium chloride the fluxes increase with increasing osmolarity.

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Section: Overall Ballance Sheetsupporting

confidence: 75%

Effect of Incubation Medium Electrolyte Concentration on Lens Volume

Patterson¹

1980

Ophthalmic Res

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“…This had also been suggested by earlier studies (Cotlier et al, 1968) demonstrating that lenses swell or shrink when exposed to anisotonic solutions, an indication of high capsular and fibril water permeability. We thus decided to examine the possibility that fluid movement, to and from the lens, accompanies the shape changes that occur during the accommodation process.…”

Section: Fluid Transport By the Crystalline Lens During Accommodationmentioning

confidence: 58%

Fluid transport phenomena in ocular epithelia

Candia

Alvarez

2008

Progress in Retinal and Eye Research

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This article discusses three largely unrecognized aspects related to fluid movement in ocular tissues; namely, a) the dynamic changes in water permeability observed in corneal and conjunctival epithelia under anisotonic conditions; b) the indications that the fluid transport rate exhibited by the ciliary epithelium is insufficient to explain aqueous humor production; and c) the evidence for fluid movement into and out of the lens during accommodation. We have studied each of these subjects in recent years and present an evaluation of our data within the context of the results of others who have also worked on electrolyte and fluid transport in ocular tissues. We propose that 1) the corneal and conjunctival epithelia, with apical aspects naturally exposed to variable tonicities, are capable of regulating their water permeabilities as part of the cell-volume regulatory process, 2) fluid may directly enter the anterior chamber of the eye across the anterior surface of the iris, thereby representing an additional entry pathway for aqueous humor production, and 3) changes in lens volume occur during accommodation, and such changes are best explained by a net influx and efflux of fluid.

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“…Lenses were dissected, and the capsule with epithelium was removed by making an incision on the anterior surface with fine scissors and peeling it off with forceps. A posterior portion of the remaining lens was dissected, washed twice with artificial aqueous humour (AAH) 1 to remove any adhering epithelial cells, and placed in a tube containing 0.25% trypsin and 0.02% EDTA in a Ca 2 ϩ /Mg 2 ϩ free buffer for 18 min in a shaking water bath at 37 Њ C. Medium E199 (Sigma, Poole, UK) ϩ 10% fetal calf serum was added to stop the trypsin digestion. The incubation mixture was then shaken the upper portion was pipetted into a centrifuge tube, and the cells were centrifuged at 1,000 rpm for 5 min.…”

Section: Methodsmentioning

confidence: 99%

Volume regulation in the bovine lens and cataract. The involvement of chloride channels.

Zhang¹,

Jacob²

1996

J. Clin. Invest.

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The purpose of this study was to investigate volume regulation in the lens and its involvement in lens opacification (cataract) and the role of chloride channels in these processes. Single, isolated lens fiber cells from the lens were whole cell patch clamped. When exposed to hypotonic solution, an outwardly rectifying whole-cell current was activated. The current increased from 1.0 to 32.6 pA/pF, reversed at the chloride reversal potential (E Cl ϭ 0 mV), and was blocked by the chloride channel blockers 5, nitro-2-(3-phenylpropylamino) benzoate (NPPB) and tamoxifen. Replacing all but 5 mM of the external chloride with gluconate caused the reversal potential to shift ϩ 33 mV, consistent with a Cl Ϫ current with a gluconate/chloride permeability ratio of 0.26. When the whole lens of the eye was exposed to hypotonic solution, there was an initial increase in anteriorposterior diameter (5-8 min), representing lens swelling of 6.5%. This was followed by a decrease in volume to a new steady state value that lasted for up to 2 h. In the longer term ( Ն 2 h), the lenses began to swell again. The simultaneous exposure to hypotonic solution and tamoxifen or NPPB caused swelling and prevented this volume regulation. Lenses incubated in hypotonic solution and hypotonic solution containing tamoxifen became opaque after a 2-h incubation period. We conclude that the lens is able to volume regulate. It possesses volume-activated Cl Ϫ channels, the inhibition of which results in inhibition of volume regulation, lens swelling and opacification. Our data suggest the longterm prophylactic use of tamoxifen may make the patient more susceptible to cataract.

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The lens as an osmometer and the effects of medium osmolarity on water transport, 86Rb efflux and 86Rb transport by the lens

Cited by 43 publications

References 10 publications

Effect of Incubation Medium Electrolyte Concentration on Lens Volume

Effect of Incubation Medium Electrolyte Concentration on Lens Volume

Fluid transport phenomena in ocular epithelia

Volume regulation in the bovine lens and cataract. The involvement of chloride channels.

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