ISSN:
1432-2013
Keywords:
Amphibian skin
;
Anion transport
;
Cl conductance-Electron microprobe analysis
;
Cellular electrolyte concentrations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract To elucidate the route of transepithelial Cl transport across amphibian skins, electrolyte concentrations and uptake of Br in different epithelial cell types of toad skin were determined using electron microprobe analysis. Under short-circuited conditions, Cl concentrations were about 10 mmol/kg ww lower in MR-cells (23.9±9.6 mmol/kg ww) than in principal cells and showed a large scatter. After unitateral substitution of Br for Cl in the bathing solutions, principal cells exchanged Br for Cl only from the serosal side, whereas variable amounts of Br were gained in MR-cells from either side. The ratio of Br to Cl concentrations in MR-cells averaged 0.35 and 0.81 after incubation with NaBr-Ringer's on the apical or serosal side, respectively. After activation of transepithelial anion conductance by serosa-positive voltage-clamping to 100 mV, uptake of Br from the apical side was increased in MR-cells compared with short-circuited conditions. On the average, the ratio of cellular Br to Cl concentrations was 1.38, but the variation among individual MR-cells from the same tissue was considerable. In MR-cells with large uptake of Br and voltageactivated conditions, the sum of Br and Cl concentrations was higher than the Cl concentration under control conditions. The increase of anion content was associated by increase of the Na and corresponding decrease of the K concentrations. The MR-cells were swollen as indicated by the decrease in the cellular dry weight content from 22.2±2.5 to 17.1±4.2 g/100 g. The principal cells contained 3.5±2.6 mmol/kg ww Br after voltage activation of anion conductance which appears to be taken up from the lateral intercellular spaces across the basolateral membrane. The data indicate that principal cells are not involved in transepithelial Cl transport. The MR-cells, although representing a heterogeneous cell population, might be a site for electrodiffusional transepithelial Cl movement.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00582513
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