ISSN:
1432-2013
Keywords:
Cl Transport
;
Na Transport
;
H/HCO3 Transport
;
Negative SCC
;
Amiloride
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Using a modified Ussing chamber, transepithelial Cl transport in isolated skin of Rana esculenta was determined throughout the year. Unidirectional36Cl fluxes were measured in the absence of electrochemical gradients across the skin. The correlations between unidirectional Cl influx and Cl efflux respectively and the Cl concentration in Na containing solutions were not linear in the 0 to 90 meq/I range. The net Cl influx calculated from these two correlations was, in the same concentration range, also not linearly correlated and was significantly different, from zero. At 0.5 meq/l Cl it averaged 0.7 μA/cm2 and increased between 10 and 90 meq/l from 2.0 to 3.4 μA/cm2. This net Cl influx was inhibited to ca. 50% by 10−4 M/l amiloride in the epithelial bathing solution; it became zero when Na was removed completely from both bathing solutions and, occasionally, negative OCV and SCC values could be measured. Therefore, an active Cl transport exists in the skin of R. esculenta which is in normal NaCl Ringer solution about one tenth of the magnitude of the active Na transport occurring simultaneously in the same direction. An at most partial flux coupling between Na and Cl ion cannot be excluded, although the pump of this Cl transport could be activated by intracellular Na. Probably the active step of the Cl transport is located in the epithelial membrane of the outermost functional cell layer (stratum granulosum). The negativity of OCV and SCC in Na free solution is probably a measure of active H/HCO3 transport, which has been found in the skin of other frog species. As a consequence, the SCC in a skin in normal NaCl Ringer accounts for ca. 90% of the active net Na transport. Where H/HCO3 transport is present, this discrepancy is correspondingly larger.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00581827
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