Protein kinase C regulation of cardiac calcium channels expressed in Xenopus oocytes

Pflugers Arch. 1992 Jun;421(2-3):247-55. doi: 10.1007/BF00374834.


L-Type cardiac Ca2+ channels expressed in Xenopus oocyte were studied following rat heart ribonucleic acid, messenger (mRNA) injection. We demonstrate that exogenous Ca2+ channels are sensitive to intracellular regulation by protein kinase C (PKC). This was performed by using two types of PKC activators [phorbol esters and a structural analogue of diacyl-glycerol (DAG)] and a specific peptidic inhibitor. Ca2+ channel modulation resulted in an initial increase of the inward current, without any modification of the voltage-dependent properties, and a second delayed phase, specifically observed with phorbol esters, characterized by a progressive decrease in current amplitude. Concomitantly, a reduction of membrane capacitance, reflecting a reduction of the total membrane surface area, was observed. We suggest that this phenomenon underlies the irreversible decrease of the expressed Ba2+ current via sequestration of Ca2+ channels and/or PKC. We also demonstrate that regulation of cardiac mRNA-directed Ca2+ channels by PKC activators was strictly dependent on intracellular Ca2+ concentration, and was partially additive with cyclic-adenosine-monophosphate-(cAMP) dependent regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / drug effects
  • Calcium Channels / metabolism*
  • Cyclic AMP / metabolism
  • Diglycerides / pharmacology
  • Down-Regulation / drug effects
  • Electrophysiology
  • Enzyme Activation / drug effects
  • Myocardium / enzymology
  • Myocardium / metabolism*
  • Oocytes / metabolism*
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / physiology*
  • RNA, Messenger / metabolism
  • Tetradecanoylphorbol Acetate / pharmacology
  • Xenopus


  • Calcium Channels
  • Diglycerides
  • RNA, Messenger
  • Phorbol 12,13-Dibutyrate
  • Cyclic AMP
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate