AJP - GI Watch the video to learn how APS reaches out to developing nations.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Gastrointest Liver Physiol 277: G22-G30, 1999;
0193-1857/99 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
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
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Grunnet, M.
Right arrow Articles by Klaerke, D. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Grunnet, M.
Right arrow Articles by Klaerke, D. A.
Vol. 277, Issue 1, G22-G30, July 1999

Quantification and distribution of Ca2+-activated maxi K+ channels in rabbit distal colon

Morten Grunnet1, Hans-Günther Knaus2, Christina Solander1, and Dan A. Klaerke1

1 Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark, and 2 Institute of Biochemical Pharmacology, University of Innsbruck, A-6020 Innsbruck, Austria

The Ca2+-activated maxi K+ channel is an abundant channel type in the distal colon epithelium, but nothing is known regarding the actual number and precise localization of these channels. The aim of this study has therefore been to quantify the maxi K+ channels in colon epithelium by binding of iberiotoxin (IbTX), a selective peptidyl ligand for maxi K+ channels. In isotope flux measurements 75% of the total K+ channel activity in plasma membranes from distal colon epithelium is inhibited by IbTX (K0.5 = 4.5 pM), indicating that the maxi K+ channel is the predominant channel type in this epithelium. Consistent with the functional studies, the radiolabeled double mutant 125I-IbTX-D19Y/Y36F binds to the colon epithelium membranes with an equilibrium dissociation constant of ~10 pM. The maximum receptor concentration values (in fmol/mg protein) for 125I-IbTX-D19Y/Y36F binding to colon epithelium are 78 for surface membranes and 8 for crypt membranes, suggesting that the maxi K+ channels are predominantly expressed in the Na+-absorbing surface cells, as compared with the Cl--secreting crypt cells. However, aldosterone stimulation of this tissue induced by a low-Na+ diet does not change the total number of maxi K+ channels.

distal colon epithelium, iberiotoxin binding, aldosterone


This article has been cited by other articles:


Home page
 J. Physiol.Home page
M. V. Sorensen, J. E. Matos, M. Sausbier, U. Sausbier, P. Ruth, H. A. Praetorius, and J. Leipziger
Aldosterone increases KCa1.1 (BK) channel-mediated colonic K+ secretion
J. Physiol., September 1, 2008; 586(17): 4251 - 4264.
[Abstract] [Full Text] [PDF]

Home page
 Physiol. Rev.Home page
D. Heitzmann and R. Warth
Physiology and Pathophysiology of Potassium Channels in Gastrointestinal Epithelia
Physiol Rev, July 1, 2008; 88(3): 1119 - 1182.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Renal Physiol.Home page
J. L. Pluznick and S. C. Sansom
BK channels in the kidney: role in K+ secretion and localization of molecular components
Am J Physiol Renal Physiol, September 1, 2006; 291(3): F517 - F529.
[Abstract] [Full Text] [PDF]

Home page
 Physiol. Rev.Home page
K. Kunzelmann and M. Mall
Electrolyte Transport in the Mammalian Colon: Mechanisms and Implications for Disease
Physiol Rev, January 1, 2002; 82(1): 245 - 289.
[Abstract] [Full Text] [PDF]

Home page
 J. Biol. Chem.Home page
M. M. Zarei, N. Zhu, A. Alioua, M. Eghbali, E. Stefani, and L. Toro
A Novel MaxiK Splice Variant Exhibits Dominant-negative Properties for Surface Expression
J. Biol. Chem., May 4, 2001; 276(19): 16232 - 16239.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online