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Electromechanical Assessment of Optogenetically Modulated Cardiomyocyte Activity
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Electromechanical Assessment of Optogenetically Modulated Cardiomyocyte Activity

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Opposing functional effects of cyclic GMP and cyclic AMP may act through protein phosphorylation in rabbit cardiac

L Yan1, H Lee, M W Huang

  • 1Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854-5635, USA.

Journal of Autonomic Pharmacology
|November 30, 2000
PubMed

Insights

Cyclic GMP (cGMP) and cyclic AMP (cAMP) signaling pathways interact at the protein kinase level in cardiac myocytes. This interaction explains their opposing effects on heart cell function.

Area of Science:

  • Cardiology
  • Molecular Biology
  • Cell Physiology

Background:

  • Cyclic nucleotides like cyclic AMP (cAMP) and cyclic GMP (cGMP) play critical roles in regulating cardiac function.
  • Understanding the interplay between cAMP and cGMP signaling is essential for elucidating cardiac myocyte behavior.

Purpose of the Study:

  • To investigate the hypothesis that cGMP antagonizes cAMP's effects in cardiac myocytes.
  • To determine if this opposition occurs at the level of their respective protein kinases.

Main Methods:

  • Utilized rabbit ventricular myocytes to study cell shortening via video-edge detection.
  • Measured O2 consumption using O2 electrodes.
  • Assessed protein phosphorylation patterns using SDS-PAGE and autoradiography.
  • Administered specific analogs of cGMP and cAMP, along with protein kinase inhibitors (KT 5720 for cAMP-dependent protein kinase and KT 5823 for cGMP-dependent protein kinase).

Main Results:

  • cGMP analogs decreased cell shortening and contraction rate, while cAMP analogs increased these parameters.
  • Pre-treatment with cGMP analogs diminished the positive effects of cAMP analogs on cell shortening.
  • Inhibition of cAMP-dependent protein kinase potentiated cGMP's negative effects, whereas inhibition of cGMP-dependent protein kinase reversed cGMP's effects.
  • Both cGMP and cAMP induced phosphorylation of the same five protein bands, suggesting shared or interacting targets.

Conclusions:

  • The opposing functional effects of cGMP and cAMP in cardiac myocytes are mediated through interactions at the level of their respective protein kinases.
  • This study provides molecular insights into the antagonistic roles of these cyclic nucleotides in cardiac physiology.

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