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Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents
10:53

Isolation of Human Atrial Myocytes for Simultaneous Measurements of Ca2+ Transients and Membrane Currents

Published on: July 3, 2013

Heat stress responses modulate calcium regulations and electrophysiological characteristics in atrial myocytes

Yao-Chang Chen1, Yu-Hsun Kao, Chun-Feng Huang

  • 1Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan.

Journal of Molecular and Cellular Cardiology
|August 22, 2009
PubMed

Insights

Heat stress alters cardiac calcium handling by increasing protein levels of SERCA2a and NCX, impacting ionic currents and action potentials in atrial myocytes. This regulation occurs at the protein, not RNA, level.

Area of Science:

  • Cardiology
  • Molecular Biology
  • Physiology

Background:

  • Heat stress disrupts cellular ionic currents and calcium homeostasis.
  • Molecular mechanisms underlying heat stress effects on calcium regulation are not fully understood.

Purpose of the Study:

  • To investigate the impact of heat stress on calcium handling and electrophysiological properties in atrial myocytes.
  • To elucidate the molecular mechanisms of heat stress-induced alterations in calcium regulation.

Main Methods:

  • Whole-cell patch clamp technique to measure action potentials and ionic currents.
  • Indo-1 fluorimetric ratio method to assess intracellular calcium transients.
  • Western blot and real-time PCR to evaluate protein and RNA expression of SERCA2a and NCX.

Main Results:

  • Heat-stressed myocytes exhibited increased sarcoplasmic reticulum calcium content and larger, faster decaying intracellular calcium transients.
  • Significant increases in L-type calcium currents and transient outward potassium currents were observed.
  • Reduced Na(+)-Ca(2+) exchanger (NCX) currents and increased protein expression of SERCA2a and NCX were noted post-heat stress.
  • Heat stress elevated heat shock protein expression but did not alter SERCA2a or NCX RNA levels.

Conclusions:

  • Heat stress responses modulate calcium handling in atrial myocytes primarily through post-transcriptional regulation of key proteins like SERCA2a and NCX.
  • Electrophysiological characteristics, including action potentials and ionic currents, are significantly altered by heat stress exposure.

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