Publication Date:
1990-04-20
Description:
The role of sodium-calcium exchange at the sarcolemma in the release of calcium from cardiac sarcoplasmic reticulum was investigated in voltage-clamped, isolated cardiac myocytes. In the absence of calcium entry through voltage-dependent calcium channels, membrane depolarization elicited release of calcium from ryanodine-sensitive internal stores. This process was dependent on sodium entry through tetrodotoxin-sensitive sodium channels. Calcium release under these conditions was also dependent on extracellular calcium concentration, suggesting a calcium-induced trigger release mechanism that involves calcium entry into the cell by sodium-calcium exchange. This sodium current-induced calcium release mechanism may explain, in part, the positive inotropic effects of cardiac glycosides and the negative inotropic effects of a variety of antiarrhythmic drugs that interact with cardiac sodium channels. In response to a transient rise of intracellular sodium, sodium-calcium exchange may promote calcium entry into cardiac cells and trigger sarcoplasmic calcium release during physiologic action potentials.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Leblanc, N -- Hume, J R -- HL30143/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1990 Apr 20;248(4953):372-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Nevada School of Medicine, Reno 89557-0046.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2158146" target="_blank"〉PubMed〈/a〉
Keywords:
Action Potentials
;
Animals
;
Calcium/*metabolism/pharmacology
;
Carrier Proteins/*metabolism
;
Electric Conductivity
;
Gallopamil/pharmacology
;
Guinea Pigs
;
Myocardial Contraction
;
Myocardium/*metabolism
;
Nisoldipine/pharmacology
;
Sarcoplasmic Reticulum/*metabolism
;
Sodium/metabolism
;
Sodium Channels/drug effects/*physiology
;
Sodium-Calcium Exchanger
;
Tetrodotoxin/pharmacology
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
