scholarly journals Potential, Current, and Ionic Fluxes across the Isolated Retinal Pigment Epithelium and Choroid

1966 ◽  
Vol 49 (5) ◽  
pp. 913-924 ◽  
Author(s):  
Arnaldo Lasansky ◽  
Felisa W. de Fisch
Keyword(s):  
Retinal Pigment Epithelium ◽  
Short Circuit ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Short Circuit Current ◽  
Bufo Marinus ◽  
Flux Chamber ◽  
Epithelial Surface ◽  
The Mean

A flux chamber was utilized for in vitro studies of a membrane formed by the retinal pigment epithelium and choroid of the eye of the toad (Bufo arenarum and Bufo marinus). A transmembrane potential of 20 to 30 mv was found, the pigment epithelium surface positive with respect to the choroidal surface. Unidirectional fluxes of chloride, sodium, potassium, and calcium were determined in the absence of an electrochemical potential difference. A net transfer of chloride from pigment epithelium to choroid accounted for a major fraction of the mean short-circuit current. A small net flux of sodium from choroid to pigment epithelium was detected in Bufo marinus. In both species of toads, however, about one-third of the mean short-circuit current remained unaccounted for. Manometric determinations of bicarbonate suggested an uptake of this ion at the epithelial surface of the membrane but did not provide evidence of a relationship between this process and the short-circuit current.

Aspects of electrolyte transport across isolated dog retinal pigment epithelium

1986 ◽  
Vol 250 (5) ◽  
pp. F781-F784 ◽  
Author(s):  
S. Tsuboi ◽  
R. Manabe ◽  
S. Iizuka
Keyword(s):  
Retinal Pigment Epithelium ◽  
Apical Membrane ◽  
Short Circuit ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Apical Side ◽  
Net Flux ◽  
Net Fluxes

Transport of Na and Cl across the isolated dog retinal pigment epithelium (RPE) choroid was investigated. Under the short-circuit condition, a net Na flux was observed from choroid to retina and a net Cl flux was determined in the opposite direction. The current created by the net flux of these two ions was larger than the short-circuit current (SCC). Addition of 10(-5) M ouabain to the apical side inhibited net fluxes of both Na and Cl, whereas it reduced the SCC 84%. Addition of 10(-4) M furosemide to the apical side inhibited net Cl flux but had no effect on the net Na transport. The 10(-4) M furosemide reduced the SCC 38%. These drugs had no effect when applied to the basal side. Thus the transport of both Na and Cl depends on the Na-K-ATPase in the apical membrane of the dog RPE. A furosemide-sensitive neutral carrier at the apical membrane is suggested for the transport of Cl. Replacement of HCO3 with SO4 in the bathing solution caused an increase in the SCC, indicating the choroid-to-retina movement of HCO3 across the short-circuited dog RPE choroid.

Acidification stimulates chloride and fluid absorption across frog retinal pigment epithelium

1994 ◽  
Vol 266 (4) ◽  
pp. C946-C956 ◽  
Author(s):  
J. L. Edelman ◽  
H. Lin ◽  
S. S. Miller
Keyword(s):  
Retinal Pigment Epithelium ◽  
Short Circuit ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Ringer Solution ◽  
Open Circuit ◽  
Disulfonic Acid ◽  
Fluid Absorption

Radioactive tracers and a modified capacitance-probe technique were used to characterize the mechanisms that mediate Cl and fluid absorption across the bullfrog retinal pigment epithelium (RPE)-choroid. In control (HCO3/CO2) Ringer solution, 36Cl was actively absorbed (retina to choroid) at a mean rate of 0.34 mu eq.cm-2.h-1 (n = 34) and accounted for approximately 25% of the short-circuit current. Apical bumetanide (100 microM) or basal 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS; 1 mM) inhibited active Cl transport by 70 and 62%, respectively. Active Cl absorption was doubled, either by removing HCO3 from the bathing media or by elevating CO2 from 5 to 13%, and the increased flux was inhibited by apical bumetanide or basal DIDS. Open-circuit measurements of fluid absorption rate (Jv) and the net fluxes of 36Cl, 22Na, and 86Rb (K substitute) indicated that CO2-induced acidification stimulated NaCl and fluid absorption across the RPE. During acidification, bumetanide produced a twofold larger inhibition of Jv compared with control. Stimulation of net Cl absorption was most likely caused by inhibition of the the basolateral membrane intracellular pH-dependent Cl-HCO3 exchanger.

scholarly journals Retinoid processing in retinal pigment epithelium of toad (Bufo marinus).

1994 ◽  
Vol 269 (35) ◽  
pp. 21983-21989 ◽  
Author(s):  
T.I. Okajima ◽  
B. Wiggert ◽  
G.J. Chader ◽  
D.R. Pepperberg
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Bufo Marinus ◽  
Toad Bufo

Maintenance of adult porcine retina and retinal pigment epithelium in perfusion culture: Characterisation of an organotypic in vitro model

2008 ◽  
Vol 86 (4) ◽  
pp. 661-668 ◽  
Author(s):  
Karin Kobuch ◽  
Wolfgang A. Herrmann ◽  
Carsten Framme ◽  
Helmut G. Sachs ◽  
Veit-Peter Gabel ◽  
...  
Keyword(s):  
Retinal Pigment Epithelium ◽  
In Vitro Model ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Perfusion Culture ◽  
Vitro Model

The cytoskeletal elements of human retinal pigment epithelium: in vitro and in vivo

1988 ◽  
Vol 91 (2) ◽  
pp. 303-312
Author(s):  
N.M. McKechnie ◽  
M. Boulton ◽  
H.L. Robey ◽  
F.J. Savage ◽  
I. Grierson
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Cytokeratin 18 ◽  
Rpe Cells ◽  
Human Retinal Pigment Epithelium ◽  
Cytoskeletal Elements

The cytoskeletal elements of normal (in situ) and cultured human retinal pigment epithelium (RPE) were studied by a variety of immunocytochemical techniques. Primary antibodies to vimentin and cytokeratins were used. Positive immunoreactivity for vimentin was obtained with in situ and cultured material. The pattern of reactivity obtained with antisera and monoclonals to cytokeratins was more complex. Cytokeratin immunoreactivity could be demonstrated in situ and in cultured cells. The pattern of cytokeratin expression was similar to that of simple or glandular epithelia. A monoclonal antibody that specifically recognizes cytokeratin 18 identified a population of cultured RPE cells that had particularly well-defined filamentous networks within their cytoplasm. Freshly isolated RPE was cytokeratin 18 negative by immunofluorescence, but upon culture cytokeratin 18 positive cells were identifiable. Cytokeratin 18 positive cells were identified in all RPE cultures (other than early primaries), regardless of passage number, age or sex of the donor. In post-confluent cultures cytokeratin 18 cells were identified growing over cytokeratin 18 negative cells, suggesting an association of cytokeratin 18 immunoreactivity with cell proliferation. Immunofluorescence studies of retinal scar tissue from two individuals revealed the presence of numerous cytokeratin 18 positive cells. These findings indicate that RPE cells can be identified by their cytokeratin immunoreactivity and that the overt expression of cytokeratin 18 may be associated with proliferation of human RPE both in vitro and in vivo.

Coexpression of FGF-5 and bFGF by the retinal pigment epithelium in vitro

1992 ◽  
Vol 55 (5) ◽  
pp. 727-734 ◽  
Author(s):  
Laurie M. Bost ◽  
Amy E. Aotaki-Keen ◽  
Leonard M. Hjelmeland
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Retinal Pigment
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