Characterization of the Equatorial Current of the Lens

Patterson, John W.

doi:10.1159/000266570

Cited by 16 publications

(12 citation statements)

References 7 publications

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“…Experimental results on expression patterns of membrane ion pumps and channels across the lens, cell electrophysiological parameters, and measurements of ion currents at the lens, all support such an electrical circulation (Mathias and Rae, 2004; Mathias et al, 1997). The large outward electric currents at the equator, and inward currents at the anterior and posterior poles, have been confirmed by many labs, ranging from ~20–40 µA/cm 2 (Candia and Zamudio, 2002; Mathias et al, 2007; Mathias and Rae, 1985a, b; Mathias et al, 1997; Parmelee, 1986; Parmelee et al, 1985; Patterson, 1988; Robinson and Patterson, 1982; Wind et al, 1988a) (Fig. 15).…”

Section: Electric Currents At the Lensmentioning

confidence: 61%

Electrical signaling in control of ocular cell behaviors

Zhao

Chalmers

Cao

et al. 2012

Progress in Retinal and Eye Research

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Epithelia of the cornea, lens and retina contain a vast array of ion channels and pumps. Together they produce a polarized flow of ions in and out of cells, as well as across the epithelia. These naturally occurring ion fluxes are essential to the hydration and metabolism of the ocular tissues, especially for the avascular cornea and lens. The directional transport of ions generates electric fields and currents in those tissues. Applied electric fields affect migration, division and proliferation of ocular cells which are important in homeostasis and healing of the ocular tissues. Abnormalities in any of those aspects may underlie many ocular diseases, for example chronic corneal ulcers, posterior capsule opacity after cataract surgery, and retinopathies. Electric field-inducing cellular responses, termed electrical signaling here, therefore may be an unexpected yet powerful mechanism in regulating ocular cell behavior. Both endogenous electric fields and applied electric fields could be exploited to regulate ocular cells. We aim to briefly describe the physiology of the naturally occurring electrical activities in the corneal, lens, and retinal epithelia, to provide experimental evidence of the effects of electric fields on ocular cell behaviors, and to suggest possible clinical implications.

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Section: Electric Currents At the Lensmentioning

confidence: 61%

Electrical signaling in control of ocular cell behaviors

Zhao

Chalmers

Cao

et al. 2012

Progress in Retinal and Eye Research

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show abstract

“…The results from Patterson's group (23,27,29,30) indicated a totally new concept for lens electrophysiology: ionic currents leaving the lens at the equatorial region and reentering at each pole. However, the reports by Patterson and coworkers did not account for all the currents that should be moving across the lens surface.…”

Section: Discussionmentioning

confidence: 99%

“…Logically, it was assumed that the activity of this monolayer was relatively uniform and that a positive current must emanate from the anterior pole to the equator. However, Patterson and coworkers (23,27,29,30), using the vibrating probe, showed in frog and rat lenses a nonhomogeneous distribution of currents around the lens surface.…”

mentioning

confidence: 99%

Regional distribution of the Na⁺ and K⁺currents around the crystalline lens of rabbit

Candia

Zamudio²

2002

American Journal of Physiology-Cell Physiology

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Early studies described asymmetrical electrical properties across the ocular lens in the anterior-to-posterior direction. More recent results obtained with a vibrating probe indicated that currents around the lens surface are not uniform by showing an outwardly directed K(+) efflux at the lens equator and Na(+) influx at the poles. The latter studies have been used to support theoretical models for fluid recirculation within the avascular lens. However, the existence of a nonuniform current distribution in the lens epithelium from the anterior pole to the equator has never been confirmed. The present work developed a modified short-circuiting technique to examine the net flows of Na(+) and K(+) across arbitrarily defined lens surface regions. Results indicate that passive inflows of Na(+) occur at both the anterior polar region and posterior lens surface, consistent with suggestions derived from the vibrating probe data, whereas K(+) efflux plus the Na(+)-K(+) pump-generated current comprise the currents at the equatorial surface and an area anterior to it. Furthermore, Na(+)-K(+) pump activity was absent at the posterior surface and its polar region in all lenses examined, as well as from the anterior polar region in most lenses. The latter unexpected observation suggests that the monolayered epithelium, which is confined to the anterior surface of the lens, does not express an active Na(+)-K(+) pump at its anterior-most aspect. Nevertheless, this report represents the first independent confirmation that positive currents leave the lens around the equator and reenter across the polar and posterior surfaces.

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“…Logically, it was assumed that the activity of this monolayer was relatively uniform, and that a positive current emanated from the anterior pole to the equator. However, Patterson and coworkers (Robinson and Patterson, 1982;Patterson, 1988;Patterson, 1988a, 1988b) using the vibrating probe, showed in frog and rat lenses a non-homogenous distribution of currents around the lens surface.…”

Section: Fluid Transport By the Crystalline Lens During Accommodationmentioning

confidence: 99%

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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Characterization of the Equatorial Current of the Lens

Cited by 16 publications

References 7 publications

Electrical signaling in control of ocular cell behaviors

Electrical signaling in control of ocular cell behaviors

Regional distribution of the Na⁺ and K⁺currents around the crystalline lens of rabbit

Fluid transport phenomena in ocular epithelia

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Characterization of the Equatorial Current of the Lens

Cited by 16 publications

References 7 publications

Electrical signaling in control of ocular cell behaviors

Electrical signaling in control of ocular cell behaviors

Regional distribution of the Na+ and K+currents around the crystalline lens of rabbit

Fluid transport phenomena in ocular epithelia

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Product

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Regional distribution of the Na⁺ and K⁺currents around the crystalline lens of rabbit