QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Krattenmacher, R Articles by Clauss, W Search for Related Content PubMed Articles by Krattenmacher, R Articles by Clauss, W

Journal of Experimental Biology, Vol 155, Issue 1 275-290, Copyright © 1991 by Company of Biologists

JOURNAL ARTICLES

Electrolyte transport through a cation-selective ion channel in large intestinal enterocytes of Xenopus laevis

R Krattenmacher, R Voigt, M Heinz and W Clauss
Institut fur Veterinarphysiologie, Freie Universitat Berlin, FRG.

Electrogenic ion transport through the colon epithelium of the African clawed toad (Xenopus laevis) was investigated with electrophysiological methods in vitro. Interest was focused on a previously described phenomenon, that removal of Ca2+ from the mucosal Ringer's solution increases electrogenic sodium absorption. Our results clearly show that Ca2+ removal reveals an apical ion channel that is not a specific Na+ channel, but a non-selective cation channel with an 'apparent' ion selectivity of the order K+ greater than Na+ = Rb+ greater than Cs+ greater than Li+. This Ca2(+)-sensitive current increased linearly with the mucosal pH, and could be inhibited by other divalent cations (Mg2+, Ba2+) and the organic ion channel blockers quinidine and verapamil. The mucosal Ca2+ concentration that induced a half-maximal inhibition of the Ca2(+)-sensitive current was about 1 mumol l-1 and was independent of the mucosal pH. Owing to the high Ca2+ sensitivity, a regulation of the channel conductivity by extracellular Ca2+ is ruled out. It is concluded that this channel, which is almost identical to similar channels found in amphibian skin and bladder, acts as a pathway for cation absorbing or secreting processes. Possibly the binding of extracellular Ca2+ is related to selectivity changes of the Ca2(+)-sensitive ion channel.

This article has been cited by other articles:

				S. Leonhard-Marek, G. Breves, and R. Busche Effect of chloride on pH microclimate and electrogenic Na+ absorption across the rumen epithelium of goat and sheep Am J Physiol Gastrointest Liver Physiol, August 1, 2006; 291(2): G246 - G252. [Abstract] [Full Text] [PDF]

				G. Schultheiss and H. Martens Ca-sensitive Na transport in sheep omasum Am J Physiol Gastrointest Liver Physiol, June 1, 1999; 276(6): G1331 - G1344. [Abstract] [Full Text] [PDF]