Am J Physiol Cell Physiol Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Cell Physiol 255: C323-C330, 1988;
0363-6143/88 $5.00
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
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Matlib, M. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Matlib, M. A.

AJP - Cell Physiology, Vol 255, Issue 3 C323-C330, Copyright © 1988 by American Physiological Society

ARTICLES

Na+-Ca2+ exchange in sarcolemmal membrane vesicles of dog mesenteric artery

M. A. Matlib
Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Ohio 45267-0575.

The kinetic characteristics of a Na+-Ca2+ exchange system in the cell membrane of vascular smooth muscle were explored in vitro in isolated sarcolemmal membrane vesicles of dog mesenteric artery. Na+-loaded vesicles rapidly accumulated Ca2+ when an outwardly directed Na+ concentration gradient was created by suspension of the vesicles in a Na+-free medium. This Ca2+ uptake process was reversible depending on the direction and the magnitude of the Na+ concentration gradient across the membrane of the vesicles. Low temperature, monensin, and external Na+ drastically decreased Ca2+ uptake in Na+-loaded vesicles. Monovalent cations K+, Rb+, Li+, and Cs+ did not substitute for Na+ in the exchange process. Divalent cations Ba2+, Cd2+, Mg2+, Mn2+, and Sr2+ inhibited Ca2+ uptake in Na+-loaded vesicles. The order of potency of these divalent cations and concentration which produced 50% inhibition (IC50, microM) were Cd2+(38) greater than Sr2+(110) greater than Ba2+(405) greater than Mn2+(500) greater than Mg2+(greater than 2,500). The trivalent cation La3+ also inhibited Ca2+ uptake (IC50 = 0.175 microM). The apparent Km for free Ca2+ in vesicles loaded with 150 mM NaCl was 2.64 +/- 0.5 microM, and the apparent maximum velocity was 14.8 +/- 1.9 nmol.min-1.mg protein-1. The half of the apparent maximum rate (K0.5) of Ca2+ uptake was observed at 45.5 mM Na+ when loaded internally in the vesicles. Valinomycin in the presence of K+ increased the magnitude of Ca2+ uptake by 16% in Na+-loaded vesicles, indicating that the process may be electrogenic. These data indicate the existence and operation of a specific carrier-mediated Na+-Ca2+ exchange system in sarcolemmal membrane vesicles isolated from a small blood vessel.


This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
M. A. Matlib, Z. Zhou, S. Knight, S. Ahmed, K. M. Choi, J. Krause-Bauer, R. Phillips, R. Altschuld, Y. Katsube, N. Sperelakis, et al.
Oxygen-bridged Dinuclear Ruthenium Amine Complex Specifically Inhibits Ca2+ Uptake into Mitochondria in Vitro and in Situ in Single Cardiac Myocytes
J. Biol. Chem., April 24, 1998; 273(17): 10223 - 10231.
[Abstract] [Full Text] [PDF]


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