HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 285/1/G45    most recent 00396.2002v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Schweigel, M. Articles by Martens, H. Search for Related Content PubMed PubMed Citation Articles by Schweigel, M. Articles by Martens, H.

MUCOSAL BIOLOGY

Anion-dependent Mg²⁺ influx and a role for a vacuolar H⁺-ATPase in sheep ruminal epithelial cells

Department of Veterinary Physiology, Free University of Berlin, 14163 Berlin, Germany

Submitted 13 September 2002 ; accepted in final form 19 February 2003

The K⁺-insensitive component of Mg²⁺ influx in primary culture of ruminal epithelial cells (REC) was examined by means of fluorescence techniques. The effects of extracellular anions, ruminal fermentation products, and transport inhibitors on the intracellular free Mg²⁺ concentration ([Mg²⁺]_i), Mg²⁺ uptake, and intracellular pH were determined. Under control conditions (HEPES-buffered high-NaCl medium), the [Mg²⁺]_i of REC increased from 0.56 ± 0.14 to 0.76 ± 0.06 mM, corresponding to a Mg²⁺ uptake rate of 15 µM/min. Exposure to butyrate did not affect Mg²⁺ uptake, but it was stimulated (by 84 ± 19%) in the presence of . In contrast, Mg²⁺ uptake was strongly diminished if REC were suspended in -buffered high-KCl medium (22.3 ± 4 µM/min) rather than in HEPES-buffered KCl medium (37.5 ± 6 µM/min). After switching from high- to low-Cl^– solution, [Mg²⁺]_i was reduced from 0.64 ± 0.09 to 0.32 ± 0.16 mM and the -stimulated Mg²⁺ uptake was completely inhibited. Bumetanide and furosemide blocked the rate of Mg²⁺ uptake by 64 and 40%, respectively. Specific blockers of vacuolar H⁺-ATPase reduced the [Mg²⁺]_i (36%) and Mg²⁺ influx (38%) into REC. We interpret this data to mean that the K⁺-insensitive Mg²⁺ influx into REC is mediated by a cotransport of Mg²⁺ and Cl^– and is energized by an H⁺-ATPase. The stimulation of Mg²⁺ transport by ruminal fermentation products may result from a modulation of the H⁺-ATPase activity.

sheep rumen; epithelial cells; intracellular magnesium; Mg²⁺-Cl^– cotransport; mag-fura-2

This article has been cited by other articles:

				B. Etschmann, K. S. Heipertz, A. von der Schulenburg, and M. Schweigel A vH+-ATPase is present in cultured sheep ruminal epithelial cells Am J Physiol Gastrointest Liver Physiol, December 1, 2006; 291(6): G1171 - G1179. [Abstract] [Full Text] [PDF]

				M. Schweigel, H.-S. Park, B. Etschmann, and H. Martens Characterization of the Na+-dependent Mg2+ transport in sheep ruminal epithelial cells Am J Physiol Gastrointest Liver Physiol, January 1, 2006; 290(1): G56 - G65. [Abstract] [Full Text] [PDF]

				S. Leonhard-Marek, F. Stumpff, I. Brinkmann, G. Breves, and H. Martens Basolateral Mg2+/Na+ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg2+ Am J Physiol Gastrointest Liver Physiol, April 1, 2005; 288(4): G630 - G645. [Abstract] [Full Text] [PDF]