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Regulation of endogenous Ca2+ channels by cyclic AMP and cyclic GMP-dependent protein kinases in Pleurodeles oocytes

F Van Coppenolle1, A Ahidouch, P Guilbault

  • 1Centre de Biologie Cellulaire, SN3, USTL, Villeneuve d'Ascq, France.

Molecular and Cellular Biochemistry
|March 1, 1997
PubMed

Insights

Cyclic AMP (cAMP) and cyclic GMP (cGMP) regulate calcium channels in Pleurodeles oocytes. Protein Kinase A (PKA) and G (PKG) activity, modulated by these second messengers, control basal Ba current, impacting oocyte maturation.

Area of Science:

  • Cellular Physiology
  • Molecular Biology
  • Reproductive Biology

Background:

  • Dihydropyridine-sensitive Ca2+ channels play crucial roles in cellular functions.
  • Second messengers like cAMP and cGMP are key regulators of cellular signaling pathways.
  • Oocyte maturation involves complex regulatory mechanisms, including ion channel modulation.

Purpose of the Study:

  • To investigate the effects of cAMP and cGMP on dihydropyridine-sensitive Ca2+ channels in Pleurodeles oocytes.
  • To elucidate the roles of Protein Kinase A (PKA) and Protein Kinase G (PKG) in regulating these channels.
  • To understand the potential implications of this regulation in oocyte maturation.

Main Methods:

  • Voltage-clamp electrophysiology was used to measure Ba2+ currents (IBa) in defolliculated Pleurodeles oocytes.
  • Intracellular injection and extracellular application of cAMP, cGMP, and their analogues (e.g., 8-Bromo cAMP) were performed.
  • Inhibitors specific for PKA and PKG (e.g., KT5823) were employed to determine kinase involvement.

Main Results:

  • Intracellular cAMP or 8-Bromo cAMP decreased IBa, an effect blocked by PKA inhibitors.
  • Internal application of PKA catalytic subunit mimicked the inhibitory effect of cAMP.
  • Intracellular cGMP or 8-Bromo cGMP increased IBa, an effect blocked by the PKG inhibitor KT5823.

Conclusions:

  • Basal Ba2+ current amplitude in Pleurodeles oocytes is regulated by the activity of PKA and PKG.
  • cAMP and cGMP act as critical second messengers modulating Ca2+ channel activity via PKA and PKG, respectively.
  • This second messenger-mediated regulation of Ca2+ channels likely plays a significant role in the maturation of Pleurodeles oocytes.

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