Transport of Ions and Metabolites across the Corneal Endothelium

Riley, Michael V.

doi:10.1016/b978-0-12-483180-3.50007-1

Cited by 10 publications

(7 citation statements)

References 115 publications

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“…This view is further supported by the present findings on the presence of NaK-ATPase immunoreactivity in the corneal endothelium. Endothelial carbonic anhydrase has also been suggested to be responsible for stromal dehydration (Fischbarg & Lim 1982;Riley 1982); in support of this we found Ca-I1 immunoreactivity not only in the corneal endothelium, but also in the capillary endothelium of the limbus.…”

Section: Discussionsupporting

confidence: 86%

“…For its action, the endothelial pump needs sodium and bicarbonate ions (Dickstein &Maurice 1972;Hodson 1979;Doughty & Maurice 1988;Savion et al 1989). The view that the endothelial pump is inhibited by ouabain and stimulated by sodium suggests the involvement of NaK-ATPase in this process (Riley 1982;Savion & Farzame 1986). This view is further supported by the present findings on the presence of NaK-ATPase immunoreactivity in the corneal endothelium.…”

Section: Discussionmentioning

confidence: 99%

“…AH is transported into the anterior chamber through the pupillary aperture, leaves the globe via the trabecular meshwork and enters the aqueous veins (Cole 1977). In the cornea, the endothelium is mainly responsible for the regulation of dehydrating and retaining of the transparency of the corneal stroma by compensating the leakage of AH into the stroma by active pumping of water and electrolytes back into the anterior chamber (Bonting & Becker 1964;Maurice 1957Maurice , 1972Riley 1982). Various enzyme activities in the ciliary epithelium (Cole 1964;Shiose & Sears 1966) and corneal endothelium are known to be crucially involved in both the production of AH (Bonting et al 1961;Riley & Peters 1981) and in the regulation of the intraocular pressure or maintenance of corneal transparency (Maurice 1957;Riley 1982).…”

mentioning

confidence: 99%

“…In the cornea, the endothelium is mainly responsible for the regulation of dehydrating and retaining of the transparency of the corneal stroma by compensating the leakage of AH into the stroma by active pumping of water and electrolytes back into the anterior chamber (Bonting & Becker 1964;Maurice 1957Maurice , 1972Riley 1982). Various enzyme activities in the ciliary epithelium (Cole 1964;Shiose & Sears 1966) and corneal endothelium are known to be crucially involved in both the production of AH (Bonting et al 1961;Riley & Peters 1981) and in the regulation of the intraocular pressure or maintenance of corneal transparency (Maurice 1957;Riley 1982). Particularly, carbonic anhydrase, catalyzing the hydration of carbon dioxide to ultimately yield bicarbonate and protons, is important in transport physiology as evidenced by the clinical efficiency of acetazolamide to decrease aqueous humour formation (Becker 1959;Becker & Constant 1955).…”

mentioning

confidence: 99%

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Immunocytochemical localization of carbonic anhydrase, NaK‐ATPase and the bicarbonate chloride exchanger in the anterior segment of the human eye

Holthöfer

Siegel

Tarkkanen

et al. 1991

Acta Ophthalmologica

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We examined immunohistochemically the localization of three transport enzymes (carbonic anhydrase, Ca-II; sodium-potassium-activated adenosine triphosphatase, NaK-ATPase; bicarbonate-chloride exchanger, band III) in the anterior segment of the human eye. In accord with earlier studies, NaK-ATPase was primarily found in the corneal endothelium, but also in the corneal basal epithelial cell membranes. In addition, immunoreactivity for NaK-ATPase was observed in the non-pigmented epithelium of the ciliary processes and between the two epithelial cell layers. Ca-II immunoreactivity was found in the corneal endothelium as well as in the non-pigmented epithelial layer of the ciliary processes. Interestingly, band III immunoreactivity was found in the corneal endothelium, as similar to Ca-II, but not in the ciliary processes. These results show that, similar to many other tissues, Ca-II and band III immunoreactivities colocalize in the same cytologic site in the human corneal endothelium. Immunocytochemical detection of these key transport enzymes not only gives their accurate and reliable anatomical distribution, but also provides information on the electrolyte transport at these sites.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Immunocytochemical localization of carbonic anhydrase, NaK‐ATPase and the bicarbonate chloride exchanger in the anterior segment of the human eye

Holthöfer

Siegel

Tarkkanen

et al. 1991

Acta Ophthalmologica

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“…This greatly enhances the penetration of hydrophilic, water-soluble compounds which normally traverse the epithelium primarily via pericellular routes. The endothelium is a single layer of mesothelium only 3 pm thick which can be disregarded as a reservoir for solutes (7). It is lipid in nature and consists of both leaky and tight junctions.…”

Section: Introductionmentioning

confidence: 99%

Age-Related Permeability Changes in Rabbit Corneas

Ke¹,

Clark²,

Gracy³

1999

Journal of Ocular Pharmacology and Therapeutics

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The present study was designed to determine whether the corneal penetration of test compounds is altered in aging. Experiments were carried out by means of passive transport under steady-state conditions using in vitro diffusion cells. Permeabilities of a variety of compounds with different physicochemical properties were measured in young (six weeks) and old (three to four years) intact and denuded (wounded) rabbit corneas. There was a marked difference in penetration of compounds between young and aged corneas. A significant decrease in permeability with age was observed. The degree of difference depended on the lipophilicity and molecular weight of the compound and the integrity of the epithelial cell layer. The difference was more pronounced for large hydrophilic than small lipophilic compounds in the intact corneas. The difference in permeabilities of test compounds between young and old denuded corneas was essentially the same (about 2-fold). These studies provide clues to the fundamental biochemical difference in young and old corneas and better enables the development of rationales for efficient drug and nutrient delivery across the cornea.

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Cornea

Berman¹

1991

Biochemistry of the Eye

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Transport of Ions and Metabolites across the Corneal Endothelium

Cited by 10 publications

References 115 publications

Immunocytochemical localization of carbonic anhydrase, NaK‐ATPase and the bicarbonate chloride exchanger in the anterior segment of the human eye

Immunocytochemical localization of carbonic anhydrase, NaK‐ATPase and the bicarbonate chloride exchanger in the anterior segment of the human eye

Age-Related Permeability Changes in Rabbit Corneas

Cornea

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