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| Relation between the sarcolemmal Ca2+ current and Ca2+ sparks and local control theories for cardiac excitation-contraction coupling |
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| Author(s): Santana LF, Cheng H, Gomez AM, Cannell MB, Lederer WJ |
| Source: CIRCULATION RESEARCH Volume: 78 Issue: 1 Pages: 166-171 Published: JAN 1996 |
| Times Cited: 174 References: 20 |
| Abstract: Ca2+ sparks, the elementary events underlying excitation-contraction (E-C) coupling, occur when sarcoplasmic reticulum (SR) Ca2+ release channels open. They are activated locally by Ca2+ influx through sarcolemmal (SL) Ca2+ channels. By measuring the probability of spark occurrence under conditions in which their probability of occurrence is low, we address two important questions raised by our recent work: (1) When a Ca2+ spark is triggered, how many SL Ca2+ channels (at a minimum) contribute to its activation? (2) What is the relation between the subcellular local [Ca2+](i) produced by the opening of SL Ca2+ channels and the consequent SR Ca2+ release? By comparing the voltage dependence of Ca2+ sparks in rat ventricular myocytes with the Ca2+ current, we show that the opening of a single SL Ca2+ channel can trigger a Ca2+ spark. Furthermore, we deduce that the probability of SR Ca2+ release depends of the square of the local [Ca2+](i) produced by SL Ca2+ channel openings. These results are discussed with respect to the properties of Ca2+-induced Ca2+ release (CICR) and the local control theory of excitation-contraction coupling. |
| Document Type: Article |
| Language: English |
Addresses:
1. UNIV MARYLAND, SCH MED, DEPT PHYSIOL, BALTIMORE, MD 21201 USA
2. UNIV MARYLAND, SCH MED, CTR MED BIOTECHNOL, BALTIMORE, MD 21201 USA
3. UNIV LONDON ST GEORGES HOSP, SCH MED, DEPT PHARMACOL & CLIN PHARMACOL, LONDON, ENGLAND |
| Publisher: AMER HEART ASSOC, 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 |
| Subject Category: Cardiac & Cardiovascular Systems; Hematology; Peripheral Vascular Disease |
| IDS Number: TM904 |
| ISSN: 0009-7330 |
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