title: Effects of potassium-free media and ouabain on epithelial cell composition in toad urinary bladder studied with X-ray microanalysis.
abstract: The technique of X-ray microanalysis was used to study the composition of toad urinary bladder epithelial cells incubated in Na Ringer's and K-free medium, with and without ouabain. Following incubation under short-circuit conditions, portions of tissue were coated with an external albumin standard and plunge-frozen. Cryosections were freeze-dried and analyzed. In Na Ringer's, granular and basal cells, and also the basal portion of the goblet cells, had similar water and ion compositions. In contrast, mitochondria-rich cells contained less Cl and Na. On average, the granular cells and a subpopulation of the basal cells lost K and gained Na after ouabain and in K-free medium alone. However, there was considerable variation from cell to cell in the responses, indicating differences between cells in the availabilities of ion pathways, either as a consequence of differences in the numbers of such pathways or in their control. In contrast, the compositions of both the low Cl, mitochondria-rich cells and a sub-population of the basal cells were little affected by the different incubation conditions. This is consistent with a comparatively low Na permeability of these cells. The results also indicate that (i) much, if not all, of the K in the dominant cell type, the granular cells, is potentially exchangeable with serosal medium Na, and (ii) Na is accumulated from the serosal medium under K-free conditions. They also provide information about the role of the (Na-K)-ATPase in the maintenance of cellular K in K-free medium, being consistent with other evidence that removal of serosal medium K inhibits transepithelial Na transport by decreasing Na entry to the cells from the mucosal medium, rather than solely by inhibiting the basolateral membrane (Na-K)-ATPase.
authors.affiliation: Department of Physiology, University of Otago Medical School, Dunedin, New Zealand.
authors.forename: J M
authors.initials: JM
authors.lastname: Bowler
authors.forename: R D
authors.initials: RD
authors.lastname: Purves
authors.forename: A D
authors.initials: AD
authors.lastname: Macknight
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002024:Bufo marinus / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000201:enzymology / Q000502:physiology; D002478:Cells, Cultured; D002712:Chlorides / Q000032:analysis / Q000493:pharmacokinetics; D015925:Cryopreservation; D016616:Cryoultramicrotomy; D003470:Culture Media / Q000494:pharmacology*; D004577:Electron Probe Microanalysis; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry / Q000378:metabolism; D007552:Isotonic Solutions / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000032:analysis / Q000493:pharmacokinetics; D000077331:Ringer's Solution; D012964:Sodium / Q000032:analysis / Q000493:pharmacokinetics / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D001743:Urinary Bladder / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism
chemical_list: D002712:Chlorides; D003470:Culture Media; D007552:Isotonic Solutions; D010042:Ouabain; D000077331:Ringer's Solution; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium