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Ciliary nonpigmented epithelium

Ikeda H, Ueda M, Ikeda M, Kobayashi H, Honda Y. 2003. Oxysterol 7alpha-hydroxylase CYP39A1) in the ciliary nonpigmented epithelium of bovine eye. I b Invest 83 ... [Pg.84]

The effect on lOP of the cardiac glycosides, primarily digitaUs derivatives and ouabain, has been of interest for many years. The physiologic effects of these agents are produced by their ability to inhibit Na+K+ adenosine triphosphatase, and a ouabain-sensitive Na+K+ adenosine triphosphatase has been demonstrated in the ciliary epitheUum. In the ciliary nonpigmented epithelium, as in other types of secretory epitheUum, Na+K+ adenosine triphosphatase is thought to be responsible for the active transport of sodium, a process necessary for aqueous secretion to occur. [Pg.723]

Fluid movement from the stroma of the ciliary processes into the posterior chamber requires the transepithelial movement of several ions. Assuming that Na, HCO3, and CT are the major ions involved in secretion, Figure 1014 illustrates how these ions may function in fluid movement across the nonpigmented ciliary epithelium and into the posterior chamber. Inhibition of carbonic anhydrase in the ciliary processes decreases bicarbonate, sodium, and fluid movement into the posterior chamber, with the net result being decreased aqueous humor formation. [Pg.159]

Figure 10-14 Ion and fluid movement in the nonpigmented ciliary epithelium. Na+ enters the nonpigmented ciliary epithelium from the stromal side either by diffusion or by NaVH+ exchange. Na+, the main cation involved in aqueous formation, is transported extraceUularly into the lateral intercellular channel by a Na+-K+-adenosine triphosphatase-dependent transport system. HC03 forms from the hydration of CO2, a reaction catalyzed by carbonic anhydrase. HC03", the major anion involved in aqueous formation, balances a portion of the Na+ being transported into the lateral intercellular channel. Cl" enters the intercellular space by a mechanism that is not understood. This movement of ions into the lateral intercellular space creates a hypertonic fluid, and water enters by osmosis. Because of the restriction on the stromal side of the channel, the newly formed fluid moves toward the posterior chamber. A rapid diffusional exchange of CO2 allows for its movement into the posterior chamber. (Adapted from Cole DF. Secretion of aqueous humor. Exp Eye Res 1977 25(suppl) l6l-176.)... Figure 10-14 Ion and fluid movement in the nonpigmented ciliary epithelium. Na+ enters the nonpigmented ciliary epithelium from the stromal side either by diffusion or by NaVH+ exchange. Na+, the main cation involved in aqueous formation, is transported extraceUularly into the lateral intercellular channel by a Na+-K+-adenosine triphosphatase-dependent transport system. HC03 forms from the hydration of CO2, a reaction catalyzed by carbonic anhydrase. HC03", the major anion involved in aqueous formation, balances a portion of the Na+ being transported into the lateral intercellular channel. Cl" enters the intercellular space by a mechanism that is not understood. This movement of ions into the lateral intercellular space creates a hypertonic fluid, and water enters by osmosis. Because of the restriction on the stromal side of the channel, the newly formed fluid moves toward the posterior chamber. A rapid diffusional exchange of CO2 allows for its movement into the posterior chamber. (Adapted from Cole DF. Secretion of aqueous humor. Exp Eye Res 1977 25(suppl) l6l-176.)...
The eye is an important site relevant to the glaucoma associated with loss of activity alleles (Sect. 7.3.7, vide infra). In the eye (human), P450 IB 1 mRNA is present at a high level in the iris and ciliary body and at lower levels in the cornea, retinal pigment epithelium, and retina [127, 339]. P450 IBl protein is absent in the trabecular network but present in nonpigmented ciliary epithelium, corneal epithelium and keratocytes, both layers of the iris pigmented epithelium, and retina [127, 339]. [Pg.560]

The suggestion that there may be a sodium-dependent ascorbic acid transport mechanism in the pigmented layer of the ciliary epithelium (the layer which faces the blood side) fits well with a study conducted by Chu and Candia (1988), who isolated the rabbit iris-ciliary body and measured trans-tissue fluxes of labeled ascorbic acid. A net flux of ascorbic acid was observed in what would have been the blood-to-aqueous humor direction. Importantly, this net flux could be inhibited by phloridzin added to the blood side but not when added to the aqueous side. This finding is consistent with a model where active ascorbic acid is accumulated by the pigmented cells on the blood side of the ciliary epithelium bilayer, then passes via gap junctions into the nonpigmented cells, and finally diffuses into the aqueous humor. However, the situation may be more complex since cultured cells derived from the nonpigmented ciliary epithelium have also been shown to be capable of sodium-dependent ascorbic acid accumulation (Delamere et al., 1993). [Pg.317]

Pelis, R. M. Shahidullah, M. Ghosh, S. Coca-Prados, M. Wright, S. H. Delamere, N. A. Localization of multidrug resistance-associated protein 2 in the nonpigmented ciliary epithelium... [Pg.105]


See other pages where Ciliary nonpigmented epithelium is mentioned: [Pg.498]    [Pg.501]    [Pg.781]    [Pg.498]    [Pg.501]    [Pg.781]    [Pg.911]    [Pg.343]    [Pg.494]    [Pg.495]    [Pg.499]    [Pg.588]    [Pg.153]    [Pg.96]    [Pg.734]    [Pg.23]    [Pg.23]    [Pg.723]    [Pg.316]    [Pg.318]    [Pg.103]   
See also in sourсe #XX -- [ Pg.498 , Pg.501 ]




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