Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new double-seeded insert (DSI) technique is described for culture of branchial epithelial preparations from freshwater rainbow trout on filter supports. DSI epithelia contain both pavement cells and mitochondria-rich (MR) cells (15.7+/-2.5 % of total cell numbers). MR cells occur singly or in clusters, are voluminous, open apically to the 'external environment' and exhibit ultrastructural characteristics similar to those found in the 'chloride cells' of freshwater fish gills. After 6-9 days in culture with Leibovitz's L-15 medium on both surfaces (symmetrical conditions), transepithelial resistance (TER) stabilized at values as high as 34 k capomega cm(2), indicative of electrically 'tight' epithelia. The density of MR cells, the surface area of their clusters and transepithelial potential (TEP; up to +8 mV basolateral positive, mean +1.9+/-0.2 mV) were all positively correlated with TER. In contrast, preparations cultured using an earlier single-seeded insert (SSI) technique contained only pavement cells and exhibited a negligible TEP under symmetrical conditions. Na(+)/K(+)-ATPase activities of DSI preparations were comparable with those in gill filaments, but did not differ from those of SSI epithelia. Replacement of the apical medium with fresh water to mimic the in vivo situation (asymmetrical conditions) induced a negative TEP (-6 to -15 mV) and increased permeability to the paracellular marker PEG-4000. Under symmetrical conditions, unidirectional Na(+) and Cl(-) fluxes were in balance, and there was no active transport by the Ussing flux ratio criterion. Under asymmetrical conditions, there were large effluxes, small influxes and evidence for active Cl(-) uptake and Na(+) extrusion. Unidirectional Ca(2+) fluxes were only 0.5-1.0 % of Na(+) and Cl(-) fluxes; active net Ca(2+) uptake occurred under symmetrical conditions and active net extrusion under asymmetrical conditions. Thus, DSI epithelia exhibit some of the features of the intact gill, but improvements in culture conditions are needed before the MR cells will function as true freshwater 'chloride cells'.
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PMID:Transport properties of cultured branchial epithelia from freshwater rainbow trout: a novel preparation with mitochondria-rich cells. 1076 15

The lack of a suitable flat epithelial preparation isolated directly from the freshwater fish gill has led, in recent years, to the development of cultured gill epithelia on semipermeable supports. To date, their minimal capacity to actively transport ions has limited their utility as ionoregulatory models. The current study describes a new method of culturing gill epithelia consisting either of an enriched population of pavement (PV) cells or a mixed population of PV cells and mitochondria-rich (MR) cells from the gills of adult rainbow trout. Although the cell culture approach is similar to the double-seeded insert (DSI) technique described previously, it makes use of Percoll density centrifugation to first separate populations of PV and MR cells, which are then seeded on cell culture supports in varying proportions on successive days so as to produce preparations enriched in one or the other cell types. Based on rhodamine staining, the MR cell-rich epithelia exhibited a threefold higher enrichment of MR cells compared to traditional DSI preparations. In general, MR cell-rich epithelia developed extremely high transepithelial resistances (TER; >30 kOmega cm(2)) and positive transepithelial potentials (TEP) under symmetrical conditions (i.e., L15 medium on both apical and basolateral sides). Apical exposure of cell cultures to freshwater reduced TER and produced a negative TEP in all the epithelial preparations, although MR cell-rich epithelia maintained relatively high TER and negative TEP for over 2 d under these asymmetrical conditions. Measurement of unidirectional Na(+) fluxes and application of the Ussing flux ratio criterion demonstrated active Na(+) uptake in PV cell-rich and MR cell-rich epithelia under both symmetrical and asymmetrical conditions. In comparison, Ca(2+) uptake and Na(+)/K(+)-ATPase activity were significantly elevated in MR cell-rich preparations relative to the traditional DSI or PV cell-rich cultures under symmetrical conditions. This new methodology enhances our ability to tailor cultured gill epithelia on semipermeable supports with different proportions of PV cells and MR cells, thereby illuminating the ionoregulatory functions of the two cell types.
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PMID:Cultured trout gill epithelia enriched in pavement cells or in mitochondria-rich cells provides insights into Na+ and Ca 2+ transport. 1881 May 65