α-Adrenergic regulation of phosphoinositide metabolism and protein kinase C in isolated cardiac myocytes

T. Kaku, E. Lakatta, C. Filburn

Research output: Contribution to journalArticle

Abstract

α1-Adrenergic regulation of phosphoinositide metabolism and protein kinase C translocation was studied in isolated rat cardiac myocytes. Exposure of [3H]inositol-labeled myocytes to norepinephrine in the presence of propranolol caused a dose-dependent increase in [3H]inositol phosphates. Norepinephrine also increased the level of membrane-associated protein kinase C from ~10% of total activity to 18%, with a dose response similar to that for generation of inositol phosphates. Depolarization of myocytes with 30 mM KCl had no effect on inositol phosphates or membrane-associated protein kinase C but potentiated the effect of submaximal norepinephrine on both parameters. The potentiation of protein kinase C translocation was amplified when extracellular Ca2+ was increased to 4 mM, resulting in membrane association of one-third of the total cellular activity. These data show that activation of protein kinase C occurs during α1-adrenergic stimulation of cardiac myocytes and that elevation of intracellular Ca2+ amplifies this effect at least in part through increased phosphoinositide metabolism.

Original languageEnglish (US)
Pages (from-to)C635-C642
JournalAmerican Journal of Physiology - Cell Physiology
Volume260
Issue number3 29-3
StatePublished - Apr 29 1991
Externally publishedYes

Keywords

  • Cardiac contractility
  • Inositol trisphosphate
  • Myocardial lipid metabolism
  • Protein kinase C translocation

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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