Abstract
Real-time imaging of the concentration of intracellular calcium ([Ca2+](i)) has been carried out in heart cells using confocal imaging and patch-clamp techniques. Here we review recent investigations that used genetically engineered mice that lack phospholamban (PL knockout) to investigate the mechanisms of excitation-contraction (EC) coupling in heart. The heart cells from PL knockout (KO) mice exhibit [Ca2+](i) transients that are larger than normal. Similarly, the elementary units of EC coupling, called Ca2+ sparks, were found to be more frequent in PL KO heart cells than normal heart cells. This finding is consistent with the findings that cell-wide [Ca2+](i) transients arise as Ca2+ sparks sum during the EC coupling process. Finally, it was determined that the amount of Ca2+ within the sarcoplasmic reticulum (SR) was greater in the PL KO cardiac myocytes than in controls. Analysis of the results indicate that the larger [Ca2+](i) transients and the more frequent Ca2+ sparks are due to the greater amount of Ca2+ within the SR of PL KO myocytes, as the Ca2+ current (I(Ca)), which triggers the Ca2+ sparks and the [Ca2+](i) transient, was the same in control and PL KO heart cells. We conclude that the amount of Ca2+ released from the SR per unit of triggering I(Ca) increases as the SR Ca2+ content is augmented. Regulation of SR Ca2+ content is thus a means by which cardiac contractility is regulated.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 44-49 |
| Number of pages | 6 |
| Journal | Heart and Vessels |
| Volume | 12 |
| Issue number | SUPPL. 12 |
| State | Published - 1997 |
| Externally published | Yes |
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Keywords
- Calcium
- Confocal
- Contraction
- Heart
- Phospholamban
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
Cite this
Amount of calcium in the sarcoplasmic reticulum : Influence on excitation-contraction coupling in heart muscle. / Santana, Luis Fernando; Gómez, Ana M.; Kranias, Evangelina G.; Jonathan Lederer, W.
In: Heart and Vessels, Vol. 12, No. SUPPL. 12, 1997, p. 44-49.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Amount of calcium in the sarcoplasmic reticulum
T2 - Influence on excitation-contraction coupling in heart muscle
AU - Santana, Luis Fernando
AU - Gómez, Ana M.
AU - Kranias, Evangelina G.
AU - Jonathan Lederer, W.
PY - 1997
Y1 - 1997
N2 - Real-time imaging of the concentration of intracellular calcium ([Ca2+](i)) has been carried out in heart cells using confocal imaging and patch-clamp techniques. Here we review recent investigations that used genetically engineered mice that lack phospholamban (PL knockout) to investigate the mechanisms of excitation-contraction (EC) coupling in heart. The heart cells from PL knockout (KO) mice exhibit [Ca2+](i) transients that are larger than normal. Similarly, the elementary units of EC coupling, called Ca2+ sparks, were found to be more frequent in PL KO heart cells than normal heart cells. This finding is consistent with the findings that cell-wide [Ca2+](i) transients arise as Ca2+ sparks sum during the EC coupling process. Finally, it was determined that the amount of Ca2+ within the sarcoplasmic reticulum (SR) was greater in the PL KO cardiac myocytes than in controls. Analysis of the results indicate that the larger [Ca2+](i) transients and the more frequent Ca2+ sparks are due to the greater amount of Ca2+ within the SR of PL KO myocytes, as the Ca2+ current (I(Ca)), which triggers the Ca2+ sparks and the [Ca2+](i) transient, was the same in control and PL KO heart cells. We conclude that the amount of Ca2+ released from the SR per unit of triggering I(Ca) increases as the SR Ca2+ content is augmented. Regulation of SR Ca2+ content is thus a means by which cardiac contractility is regulated.
AB - Real-time imaging of the concentration of intracellular calcium ([Ca2+](i)) has been carried out in heart cells using confocal imaging and patch-clamp techniques. Here we review recent investigations that used genetically engineered mice that lack phospholamban (PL knockout) to investigate the mechanisms of excitation-contraction (EC) coupling in heart. The heart cells from PL knockout (KO) mice exhibit [Ca2+](i) transients that are larger than normal. Similarly, the elementary units of EC coupling, called Ca2+ sparks, were found to be more frequent in PL KO heart cells than normal heart cells. This finding is consistent with the findings that cell-wide [Ca2+](i) transients arise as Ca2+ sparks sum during the EC coupling process. Finally, it was determined that the amount of Ca2+ within the sarcoplasmic reticulum (SR) was greater in the PL KO cardiac myocytes than in controls. Analysis of the results indicate that the larger [Ca2+](i) transients and the more frequent Ca2+ sparks are due to the greater amount of Ca2+ within the SR of PL KO myocytes, as the Ca2+ current (I(Ca)), which triggers the Ca2+ sparks and the [Ca2+](i) transient, was the same in control and PL KO heart cells. We conclude that the amount of Ca2+ released from the SR per unit of triggering I(Ca) increases as the SR Ca2+ content is augmented. Regulation of SR Ca2+ content is thus a means by which cardiac contractility is regulated.
KW - Calcium
KW - Confocal
KW - Contraction
KW - Heart
KW - Phospholamban
UR - http://www.scopus.com/inward/record.url?scp=0031283324&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031283324&partnerID=8YFLogxK
M3 - Article
C2 - 9476542
AN - SCOPUS:0031283324
VL - 12
SP - 44
EP - 49
JO - Heart and Vessels
JF - Heart and Vessels
SN - 0910-8327
IS - SUPPL. 12
ER -