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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

Attenuation of negatively regulated ANP secretion by calcium in hypertrophied atria

Suhn Hee Kim1, Chunhua Cao, Jeong Hee Han

  • 1Department of Physiology, Medical School, Institute for Medical Sciences, Jeonbug National University, 2-20 Keum-Am-Dong-San, Jeonju 560-180, South Korea. shkim@moak.chonbuk.ac.kr

Regulatory Peptides
|April 18, 2002
PubMed

Insights

Cardiac hypertrophy impairs atrial natriuretic peptide (ANP) secretion regulation by calcium. Hypertrophied atria show reduced responsiveness to calcium depletion, suggesting disrupted intracellular calcium handling affects ANP release.

Area of Science:

  • Cardiovascular Physiology
  • Cellular Biology
  • Endocrinology

Background:

  • Abnormal intracellular calcium handling is linked to heart diseases and cardiac hypertrophy.
  • The precise role of calcium in atrial cardiomyocyte excitation-secretion coupling remains unclear.
  • Atrial natriuretic peptide (ANP) secretion is crucial for cardiovascular homeostasis.

Purpose of the Study:

  • To investigate how calcium modulates atrial natriuretic peptide (ANP) secretion in hypertrophied atria.
  • To determine the responsiveness of stretch-induced ANP secretion to calcium variations in cardiac hypertrophy.
  • To elucidate the impact of altered intracellular calcium regulation on ANP secretion in hypertrophied atrial tissue.

Main Methods:

  • Utilized isolated perfused quiescent hypertrophied rat atria induced by monocrotaline (MCT) injection.
  • Studied mechanically stimulated extracellular fluid (ECF) translocation and stretch-induced ANP secretion.
  • Assessed the effects of extracellular calcium depletion on ANP secretion and intracellular calcium levels in atrial myocytes.

Main Results:

  • Increased atrial volume led to proportional increases in ECF translocation and stretch-induced ANP secretion.
  • Extracellular calcium depletion markedly increased ANP secretion in control atria but this effect was attenuated in hypertrophied atria.
  • Hypertrophied atrial myocytes exhibited attenuated decreases in intracellular calcium upon extracellular calcium depletion compared to control myocytes.

Conclusions:

  • Stretch-induced ANP secretion in hypertrophied atria is less responsive to extracellular calcium depletion.
  • Disturbances in intracellular calcium regulation in hypertrophied atria likely contribute to the attenuated negative regulation of ANP secretion.
  • These findings highlight altered calcium handling as a key factor in abnormal ANP secretion during cardiac hypertrophy.

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