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Measuring Fast Calcium Fluxes in Cardiomyocytes
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Measuring Fast Calcium Fluxes in Cardiomyocytes

Published on: November 29, 2011

Effect of platelet release products on cytosolic calcium in cardiac myocytes

W W Chien1, R Mohabir, D Newman

  • 1Division of Cardiology, Stanford University School of Medicine, CA 94305.

Biochemical and Biophysical Research Communications
|August 16, 1990
PubMed

Insights

Activated platelets release heat-sensitive peptides that increase calcium in heart cells. These findings reveal a novel mechanism by which platelet products influence cardiac cell function.

Area of Science:

  • Cardiovascular Biology
  • Cell Physiology
  • Platelet Biology

Background:

  • Platelets play a crucial role in hemostasis and thrombosis.
  • Platelet activation leads to the release of various bioactive substances.
  • The impact of platelet release products on cardiac cell calcium regulation is not fully understood.

Purpose of the Study:

  • To investigate the effect of platelet release products on cytosolic calcium levels in cardiac cells.
  • To identify the nature of the platelet-derived factor responsible for altering calcium homeostasis.

Main Methods:

  • Chick embryonic heart cells were loaded with the calcium indicator indo-1 AM.
  • Cell-free filtrate from thrombin- or collagen-activated rabbit platelets was applied.
  • Changes in cytosolic calcium concentration ([Ca++]i) were monitored via fluorescence.
  • Characterization of the active substance involved heat, trypsin, molecular weight, and chemical sensitivity assays.

Main Results:

  • Platelet release products induced a rapid, dose-dependent increase in both systolic and diastolic [Ca++]i.
  • The effect was independent of thromboxane pathways and known platelet mediators like ADP and serotonin.
  • The active component was a heat-sensitive, trypsin-sensitive peptide with a low molecular weight (<3 kD) and sensitivity to 2-mercaptoethanol.

Conclusions:

  • Activated platelets release trypsin-sensitive peptides that elevate cytosolic calcium in cardiac cells.
  • These peptides represent a novel class of platelet-derived mediators affecting cardiac function.
  • Further research is warranted to elucidate the precise molecular identity and physiological relevance of these peptides.

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