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

J. Biol. Chem., Vol. 278, Issue 48, 47491-47497, November 28, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/48/47491    most recent M307898200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Uetani, T. Articles by Nakayama, S. Search for Related Content PubMed PubMed Citation Articles by Uetani, T. Articles by Nakayama, S. Social Bookmarking                      What's this?

Ca²⁺-dependent Modulation of Intracellular Mg²⁺ Concentration with Amiloride and KB-R7943 in Pig Carotid Artery^*

Tadayuki Uetani, Tatsuaki Matsubara, Hideki Nomura, Toyoaki Murohara, and Shinsuke Nakayama¶||

From the Departments of Cardiology, Geriatrics, and ^¶Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan

It has long been recognized that magnesium is associated with several important diseases, including diabetes, hypertension, cardiovascular, and cerebrovascular diseases. In the present study, we measured the intracellular free Mg²⁺ concentration ([Mg²⁺]_i) using ³¹P nuclear magnetic resonance (NMR) in pig carotid artery smooth muscle. In normal solution, application of amiloride (1 mM) decreased [Mg²⁺]_i by 12% after 100 min. Subsequent washout tended to further decrease [Mg²⁺]_i. In contrast, application of amiloride significantly increased [Mg²⁺]_i (by 13% after 100 min) under Ca²⁺-free conditions, where passive Mg²⁺ influx is facilitated. The treatments had little effect on intracellular ATP and pH (pH_i). Essentially the same Ca²⁺-dependent changes in [Mg²⁺]_i were produced with KB-R7943, a selective blocker of reverse mode Na⁺-Ca²⁺ exchange. Application of dimethyl amiloride (0.1 mM) in the presence of Ca²⁺ did not significantly change [Mg²⁺]_i, although it inhibited Na⁺-H⁺ exchange at the same concentration. Removal of extracellular Na⁺ caused a marginal increase in [Mg²⁺]_i after 100–200 min, as seen in intestinal smooth muscle in which Na⁺-Mg²⁺ exchange is known to be the primary mechanism of maintaining a low [Mg²⁺]_i against electrochemical equilibrium. In Na⁺-free solution (containing Ca²⁺), neither amiloride nor KB-R7943 decreased [Mg²⁺]_i, but they rather increased it. The results suggest that these inhibitory drugs for Na⁺-Ca²⁺ exchange directly modulate Na⁺-Mg²⁺ exchange in a Ca²⁺-dependent manner, and consequently produce the paradoxical decrease in [Mg²⁺]_i in the presence of Ca²⁺.

Received for publication, July 21, 2003 , and in revised form, September 3, 2003.

^* This work was supported in part by research grants from Cardiovascular Diseases (11C-1) from the Ministry of Health and Welfare (Japan). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

^|| To whom correspondence should be addressed: Dept. of Cell Physiology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan. Tel.: 81-52-744-2045; Fax: 81-52-744-2048; E-mail: h44673a{at}nucc.cc.nagoya-u.ac.jp.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				A. Fedoruk-Wyszomirska, M. Szymanski, E. Wyszko, M. Z. Barciszewska, and J. Barciszewski Highly Active Low Magnesium Hammerhead Ribozyme J. Biochem., April 1, 2009; 145(4): 451 - 459. [Abstract] [Full Text] [PDF]