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Cyclic GMP signaling and regulation of SERCA activity during cardiac myocyte contraction

Qihang Zhang1, Peter M Scholz, Yiqi He

  • 1Heart and Brain Circulation Laboratory, Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854-5635, USA.

Cell Calcium
|January 27, 2005
PubMed

Insights

Cyclic GMP reduces cardiac cell function by activating SERCA and phosphorylating phospholamban. This study investigates the roles of SERCA and cGMP-dependent protein kinase in these effects.

Area of Science:

  • Cardiovascular Physiology
  • Molecular Cardiology

Background:

  • Cyclic GMP (cGMP) plays a crucial role in regulating cardiac function.
  • Reductions in cardiac myocyte function have been linked to cGMP signaling pathways.

Purpose of the Study:

  • To investigate the hypothesis that cGMP-induced reductions in cardiac myocyte function involve the sarcoplasmic reticulum Ca2+-ATPase (SERCA) and cGMP-dependent phosphorylation of phospholamban.
  • To elucidate the specific mechanisms by which cGMP signaling impacts myocyte contractility.

Main Methods:

  • Cardiac myocyte function was assessed using a video edge detector in rabbit ventricular myocytes.
  • SERCA was inhibited using Thapsigargin (TG) or cyclopiazonic acid (CPA).
  • Experiments involved the addition of 8-Bromo-cGMP, TG, CPA, and the cGMP-protein kinase inhibitor KT5823, followed by analysis of protein phosphorylation and immunoblotting.

Main Results:

  • cGMP (10(-5) M) significantly decreased myocyte shortening, an effect partially reversed by KT5823.
  • Inhibition of SERCA with TG after cGMP addition reduced the negative effects of cGMP on myocyte shortening.
  • Phospholamban was identified as a target of cGMP-dependent protein kinase, and its phosphorylation was observed.

Conclusions:

  • cGMP-induced reductions in cardiac myocyte function are partially mediated through SERCA activity.
  • cGMP signaling impacts myocyte function via phospholamban phosphorylation, which in turn regulates SERCA activity.

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