Calcium sparks and excitation-contraction coupling in phospholamban-deficient mouse ventricular myocytes

Luis Fernando Santana, E. G. Kranias, W. J. Lederer

Research output: Contribution to journalArticle

123 Citations (Scopus)

Abstract

1. We examined [Ca2+](i) and L-type Ca2+ channel current (I(Ca)) in single cardiac myocytes to determine how the intracellular protein phospholamban (PLB) influences excitation-contraction (E-C) coupling in heart. Wild type (WT) and PLB-deficient (KO) mice were used. Cells were patch clamped in whole-cell mode while [Ca2+](i) was imaged simultaneously using the Ca2+ indicator fluo-3 and a confocal microscope. 2. Although I(Ca) was similar in magnitude, the decay of I(Ca) was faster in KO than in WT cells and the [Ca2+](i) transient was larger and decayed faster. Furthermore, the E-C coupling 'gain' (measured as Δ[Ca2+](i)/I(Ca)) was larger in KO cells than in WT cells. 3. Spontaneous Ca2+ sparks were three times more frequent and larger in KO cells than in WT myocytes but, surprisingly, the time constants of decay were similar. 4. SR Ca2+ content was significantly greater in KO than in WT cells. When the SR Ca2+ content in KO cells was reduced to that in WT cells, Ca2+ sparks in these 'modified' (KO') cells decayed faster. E-C coupling gain, [Ca2+](i) transient amplitude and the kinetics of decay of I(Ca) were similar in KO' and WT cells. 5. We conclude that SR Ca2+ content influences (1) I(Ca), (2) the amplitude and kinetics of Ca2+ sparks and [Ca2+](i) transients, (3) the sensitivity of the RyRs to triggering by [Ca2+](i), (4) the amount of Ca2+ released, (5) the magnitude of the E-C coupling 'gain' function, and (6) the rate of Ca2+ re-uptake by the SR Ca2+-ATPase. In KO cells, the larger [C2+](i) transients and Ca2+ sparks speed up I(Ca) inactivation. Finally, we conclude that PLB plays an important regulatory role in E-C coupling by modulating SR Ca2+-ATPase activity, which establishes the SR Ca2+ content and consequently influences the characteristics of local and global Ca2+ signalling.

Original languageEnglish (US)
Pages (from-to)21-29
Number of pages9
JournalJournal of Physiology
Volume503
Issue number1
DOIs
StatePublished - Aug 15 1997
Externally publishedYes

Fingerprint

Excitation Contraction Coupling
Calcium Signaling
Muscle Cells
Calcium-Transporting ATPases
phospholamban
Cardiac Myocytes

ASJC Scopus subject areas

  • Physiology

Cite this

Calcium sparks and excitation-contraction coupling in phospholamban-deficient mouse ventricular myocytes. / Santana, Luis Fernando; Kranias, E. G.; Lederer, W. J.

In: Journal of Physiology, Vol. 503, No. 1, 15.08.1997, p. 21-29.

Research output: Contribution to journalArticle

@article{cf297687b8b54a2886bf735b2802e9ff,
title = "Calcium sparks and excitation-contraction coupling in phospholamban-deficient mouse ventricular myocytes",
abstract = "1. We examined [Ca2+](i) and L-type Ca2+ channel current (I(Ca)) in single cardiac myocytes to determine how the intracellular protein phospholamban (PLB) influences excitation-contraction (E-C) coupling in heart. Wild type (WT) and PLB-deficient (KO) mice were used. Cells were patch clamped in whole-cell mode while [Ca2+](i) was imaged simultaneously using the Ca2+ indicator fluo-3 and a confocal microscope. 2. Although I(Ca) was similar in magnitude, the decay of I(Ca) was faster in KO than in WT cells and the [Ca2+](i) transient was larger and decayed faster. Furthermore, the E-C coupling 'gain' (measured as Δ[Ca2+](i)/I(Ca)) was larger in KO cells than in WT cells. 3. Spontaneous Ca2+ sparks were three times more frequent and larger in KO cells than in WT myocytes but, surprisingly, the time constants of decay were similar. 4. SR Ca2+ content was significantly greater in KO than in WT cells. When the SR Ca2+ content in KO cells was reduced to that in WT cells, Ca2+ sparks in these 'modified' (KO') cells decayed faster. E-C coupling gain, [Ca2+](i) transient amplitude and the kinetics of decay of I(Ca) were similar in KO' and WT cells. 5. We conclude that SR Ca2+ content influences (1) I(Ca), (2) the amplitude and kinetics of Ca2+ sparks and [Ca2+](i) transients, (3) the sensitivity of the RyRs to triggering by [Ca2+](i), (4) the amount of Ca2+ released, (5) the magnitude of the E-C coupling 'gain' function, and (6) the rate of Ca2+ re-uptake by the SR Ca2+-ATPase. In KO cells, the larger [C2+](i) transients and Ca2+ sparks speed up I(Ca) inactivation. Finally, we conclude that PLB plays an important regulatory role in E-C coupling by modulating SR Ca2+-ATPase activity, which establishes the SR Ca2+ content and consequently influences the characteristics of local and global Ca2+ signalling.",
author = "Santana, {Luis Fernando} and Kranias, {E. G.} and Lederer, {W. J.}",
year = "1997",
month = "8",
day = "15",
doi = "10.1111/j.1469-7793.1997.021bi.x",
language = "English (US)",
volume = "503",
pages = "21--29",
journal = "Journal of Physiology",
issn = "0022-3751",
publisher = "Wiley-Blackwell",
number = "1",

}

TY - JOUR

T1 - Calcium sparks and excitation-contraction coupling in phospholamban-deficient mouse ventricular myocytes

AU - Santana, Luis Fernando

AU - Kranias, E. G.

AU - Lederer, W. J.

PY - 1997/8/15

Y1 - 1997/8/15

N2 - 1. We examined [Ca2+](i) and L-type Ca2+ channel current (I(Ca)) in single cardiac myocytes to determine how the intracellular protein phospholamban (PLB) influences excitation-contraction (E-C) coupling in heart. Wild type (WT) and PLB-deficient (KO) mice were used. Cells were patch clamped in whole-cell mode while [Ca2+](i) was imaged simultaneously using the Ca2+ indicator fluo-3 and a confocal microscope. 2. Although I(Ca) was similar in magnitude, the decay of I(Ca) was faster in KO than in WT cells and the [Ca2+](i) transient was larger and decayed faster. Furthermore, the E-C coupling 'gain' (measured as Δ[Ca2+](i)/I(Ca)) was larger in KO cells than in WT cells. 3. Spontaneous Ca2+ sparks were three times more frequent and larger in KO cells than in WT myocytes but, surprisingly, the time constants of decay were similar. 4. SR Ca2+ content was significantly greater in KO than in WT cells. When the SR Ca2+ content in KO cells was reduced to that in WT cells, Ca2+ sparks in these 'modified' (KO') cells decayed faster. E-C coupling gain, [Ca2+](i) transient amplitude and the kinetics of decay of I(Ca) were similar in KO' and WT cells. 5. We conclude that SR Ca2+ content influences (1) I(Ca), (2) the amplitude and kinetics of Ca2+ sparks and [Ca2+](i) transients, (3) the sensitivity of the RyRs to triggering by [Ca2+](i), (4) the amount of Ca2+ released, (5) the magnitude of the E-C coupling 'gain' function, and (6) the rate of Ca2+ re-uptake by the SR Ca2+-ATPase. In KO cells, the larger [C2+](i) transients and Ca2+ sparks speed up I(Ca) inactivation. Finally, we conclude that PLB plays an important regulatory role in E-C coupling by modulating SR Ca2+-ATPase activity, which establishes the SR Ca2+ content and consequently influences the characteristics of local and global Ca2+ signalling.

AB - 1. We examined [Ca2+](i) and L-type Ca2+ channel current (I(Ca)) in single cardiac myocytes to determine how the intracellular protein phospholamban (PLB) influences excitation-contraction (E-C) coupling in heart. Wild type (WT) and PLB-deficient (KO) mice were used. Cells were patch clamped in whole-cell mode while [Ca2+](i) was imaged simultaneously using the Ca2+ indicator fluo-3 and a confocal microscope. 2. Although I(Ca) was similar in magnitude, the decay of I(Ca) was faster in KO than in WT cells and the [Ca2+](i) transient was larger and decayed faster. Furthermore, the E-C coupling 'gain' (measured as Δ[Ca2+](i)/I(Ca)) was larger in KO cells than in WT cells. 3. Spontaneous Ca2+ sparks were three times more frequent and larger in KO cells than in WT myocytes but, surprisingly, the time constants of decay were similar. 4. SR Ca2+ content was significantly greater in KO than in WT cells. When the SR Ca2+ content in KO cells was reduced to that in WT cells, Ca2+ sparks in these 'modified' (KO') cells decayed faster. E-C coupling gain, [Ca2+](i) transient amplitude and the kinetics of decay of I(Ca) were similar in KO' and WT cells. 5. We conclude that SR Ca2+ content influences (1) I(Ca), (2) the amplitude and kinetics of Ca2+ sparks and [Ca2+](i) transients, (3) the sensitivity of the RyRs to triggering by [Ca2+](i), (4) the amount of Ca2+ released, (5) the magnitude of the E-C coupling 'gain' function, and (6) the rate of Ca2+ re-uptake by the SR Ca2+-ATPase. In KO cells, the larger [C2+](i) transients and Ca2+ sparks speed up I(Ca) inactivation. Finally, we conclude that PLB plays an important regulatory role in E-C coupling by modulating SR Ca2+-ATPase activity, which establishes the SR Ca2+ content and consequently influences the characteristics of local and global Ca2+ signalling.

UR - http://www.scopus.com/inward/record.url?scp=0030766026&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030766026&partnerID=8YFLogxK

U2 - 10.1111/j.1469-7793.1997.021bi.x

DO - 10.1111/j.1469-7793.1997.021bi.x

M3 - Article

VL - 503

SP - 21

EP - 29

JO - Journal of Physiology

JF - Journal of Physiology

SN - 0022-3751

IS - 1

ER -