Increased Ca2+ sparks and sarcoplasmic reticulum Ca2+ stores potentially determine the spontaneous activity of pulmonary vein cardiomyocytes

Sheng Hsiung Chang, Yao Chang Chen, Shuo Ju Chiang, Satoshi Higa, Chen Chuan Cheng, Yi Jen Chen, Shih Ann Chen

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Pulmonary veins (PVs) contain cardiomyocytes with spontaneous activity that may be responsible for PV arrhythmia. Abnormal Ca2+ regulation is known to contribute to PV arrhythmogenesis. The purpose of this study was to investigate whether PV cardiomyocytes with spontaneous activity have different intracellular Ca2+ ([Ca2+]i) transients, Ca2+ sparks and responses to isoproterenol and ryanodine receptor modulators (magnesium and FK506) than do PV cardiomyocytes without spontaneous activity and left atrial (LA) cardiomyocytes. Through fluorescence and confocal microscopy, we evaluated the [Ca2+]i transients and Ca2+ sparks in isolated rabbit PV and LA cardiomyocytes. PV cardiomyocytes with spontaneous activity had larger [Ca2+]i transients and sarcoplasmic reticulum (SR) Ca2+ stores than PV cardiomyocytes without spontaneous activity or LA cardiomyocytes. PV cardiomyocytes with spontaneous activity also had a higher incidence and frequency of Ca2+ sparks, and had Ca2+ sparks with larger amplitudes than other cardiomyocytes. Magnesium (5.4 mM) reduced the [Ca2+]i transient amplitude and beating rate in PV cardiomyocytes with spontaneous activity. However, in contrast with other cardiomyocytes, low doses (1.8 mM) of magnesium did not reduce the [Ca2+]i transients amplitude in PV cardiomyocytes with spontaneous activity. FK506 (1 μM) diminished the SR Ca2+ stores in PV cardiomyocytes with spontaneous activity to a lesser extent than that in other cardiomyocytes. Isoproterenol (10 nM) increased the [Ca2+]i transient amplitude to a lesser extent in LA cardiomyocytes than in PV cardiomyocytes with or without spontaneous activity. In conclusion, our results suggest that enhanced [Ca2+]i transients, increased Ca2+ sparks and SR Ca2+ stores may contribute to the spontaneous activity of PV cardiomyocytes.

Original languageEnglish
Pages (from-to)284-292
Number of pages9
JournalLife Sciences
Volume83
Issue number7-8
DOIs
Publication statusPublished - Aug 15 2008

Fingerprint

Pulmonary Veins
Sarcoplasmic Reticulum
Electric sparks
Cardiac Myocytes
Magnesium
Tacrolimus
Isoproterenol
Ryanodine Receptor Calcium Release Channel
Confocal microscopy
Fluorescence microscopy
Modulators

Keywords

  • Atrial fibrillation
  • Calcium spark
  • Calcium transient
  • FK506
  • Magnesium
  • Pulmonary veins

ASJC Scopus subject areas

  • Pharmacology

Cite this

Increased Ca2+ sparks and sarcoplasmic reticulum Ca2+ stores potentially determine the spontaneous activity of pulmonary vein cardiomyocytes. / Chang, Sheng Hsiung; Chen, Yao Chang; Chiang, Shuo Ju; Higa, Satoshi; Cheng, Chen Chuan; Chen, Yi Jen; Chen, Shih Ann.

In: Life Sciences, Vol. 83, No. 7-8, 15.08.2008, p. 284-292.

Research output: Contribution to journalArticle

Chang, Sheng Hsiung ; Chen, Yao Chang ; Chiang, Shuo Ju ; Higa, Satoshi ; Cheng, Chen Chuan ; Chen, Yi Jen ; Chen, Shih Ann. / Increased Ca2+ sparks and sarcoplasmic reticulum Ca2+ stores potentially determine the spontaneous activity of pulmonary vein cardiomyocytes. In: Life Sciences. 2008 ; Vol. 83, No. 7-8. pp. 284-292.
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AU - Chang, Sheng Hsiung

AU - Chen, Yao Chang

AU - Chiang, Shuo Ju

AU - Higa, Satoshi

AU - Cheng, Chen Chuan

AU - Chen, Yi Jen

AU - Chen, Shih Ann

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N2 - Pulmonary veins (PVs) contain cardiomyocytes with spontaneous activity that may be responsible for PV arrhythmia. Abnormal Ca2+ regulation is known to contribute to PV arrhythmogenesis. The purpose of this study was to investigate whether PV cardiomyocytes with spontaneous activity have different intracellular Ca2+ ([Ca2+]i) transients, Ca2+ sparks and responses to isoproterenol and ryanodine receptor modulators (magnesium and FK506) than do PV cardiomyocytes without spontaneous activity and left atrial (LA) cardiomyocytes. Through fluorescence and confocal microscopy, we evaluated the [Ca2+]i transients and Ca2+ sparks in isolated rabbit PV and LA cardiomyocytes. PV cardiomyocytes with spontaneous activity had larger [Ca2+]i transients and sarcoplasmic reticulum (SR) Ca2+ stores than PV cardiomyocytes without spontaneous activity or LA cardiomyocytes. PV cardiomyocytes with spontaneous activity also had a higher incidence and frequency of Ca2+ sparks, and had Ca2+ sparks with larger amplitudes than other cardiomyocytes. Magnesium (5.4 mM) reduced the [Ca2+]i transient amplitude and beating rate in PV cardiomyocytes with spontaneous activity. However, in contrast with other cardiomyocytes, low doses (1.8 mM) of magnesium did not reduce the [Ca2+]i transients amplitude in PV cardiomyocytes with spontaneous activity. FK506 (1 μM) diminished the SR Ca2+ stores in PV cardiomyocytes with spontaneous activity to a lesser extent than that in other cardiomyocytes. Isoproterenol (10 nM) increased the [Ca2+]i transient amplitude to a lesser extent in LA cardiomyocytes than in PV cardiomyocytes with or without spontaneous activity. In conclusion, our results suggest that enhanced [Ca2+]i transients, increased Ca2+ sparks and SR Ca2+ stores may contribute to the spontaneous activity of PV cardiomyocytes.

AB - Pulmonary veins (PVs) contain cardiomyocytes with spontaneous activity that may be responsible for PV arrhythmia. Abnormal Ca2+ regulation is known to contribute to PV arrhythmogenesis. The purpose of this study was to investigate whether PV cardiomyocytes with spontaneous activity have different intracellular Ca2+ ([Ca2+]i) transients, Ca2+ sparks and responses to isoproterenol and ryanodine receptor modulators (magnesium and FK506) than do PV cardiomyocytes without spontaneous activity and left atrial (LA) cardiomyocytes. Through fluorescence and confocal microscopy, we evaluated the [Ca2+]i transients and Ca2+ sparks in isolated rabbit PV and LA cardiomyocytes. PV cardiomyocytes with spontaneous activity had larger [Ca2+]i transients and sarcoplasmic reticulum (SR) Ca2+ stores than PV cardiomyocytes without spontaneous activity or LA cardiomyocytes. PV cardiomyocytes with spontaneous activity also had a higher incidence and frequency of Ca2+ sparks, and had Ca2+ sparks with larger amplitudes than other cardiomyocytes. Magnesium (5.4 mM) reduced the [Ca2+]i transient amplitude and beating rate in PV cardiomyocytes with spontaneous activity. However, in contrast with other cardiomyocytes, low doses (1.8 mM) of magnesium did not reduce the [Ca2+]i transients amplitude in PV cardiomyocytes with spontaneous activity. FK506 (1 μM) diminished the SR Ca2+ stores in PV cardiomyocytes with spontaneous activity to a lesser extent than that in other cardiomyocytes. Isoproterenol (10 nM) increased the [Ca2+]i transient amplitude to a lesser extent in LA cardiomyocytes than in PV cardiomyocytes with or without spontaneous activity. In conclusion, our results suggest that enhanced [Ca2+]i transients, increased Ca2+ sparks and SR Ca2+ stores may contribute to the spontaneous activity of PV cardiomyocytes.

KW - Atrial fibrillation

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KW - Calcium transient

KW - FK506

KW - Magnesium

KW - Pulmonary veins

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