spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sanders, M. J.
Right arrow Articles by Kirschner, L. B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sanders, M. J.
Right arrow Articles by Kirschner, L. B.

Journal of Experimental Biology, Vol 104, Issue 1 29-40, Copyright © 1983 by Company of Biologists

JOURNAL ARTICLES

Potassium metabolism in seawater teleosts: II. Evidence for active potassium extrusion across the gill

MJ Sanders and LB Kirschner

Unidirectional K-fluxes were estimated in unanaesthetized trout and sculpin and in anaesthetized sculpin from observed 86Rb movement (JK = 1.3 JRb). In all three groups efflux exceeded influx; Jo/Jin was 2-3. The values predicted by the flux ratio equation were 0.5 for trout and 1.0 for sculpin, so active K-extrusion is indicated. The results also show that more than one half of the total influx must be ingested with food rather than passing across the gills. Flux data show that the gills are more permeable to K+ than to Na+, PK/PNa was 5.4 in trout and 2.6 in sculpin. Changes in K-concentration in the external medium did not appear to affect efflux; there was no exchange component in the total fluxes. When both Na+ and K+ were omitted from the bathing solution, efflux decreased to about 15% of the normal seawater value. This is more than would be expected if the flux were purely diffusive and supports the conclusion that extrusion contains an active component. Repletion of the ion-deficient medium with K+ (alone) increased K-efflux. However, it also repolarized the gill and increased plasma [K+], and the flux change could be accounted for by the augmented driving force; i.e. it was diffusive. The additional plasma K came from the intracellular compartment, rather than an augmented influx from the medium.




© The Company of Biologists Ltd 1983