Synergistic activation of rat hepatocyte glycogen phosphorylase by A23187 and phorbol ester

John N. Fain, Shih Ying Li, Irene Litosch, Michael Wallace

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The combination of 1.6 μM rβ phorbol, 12β myristate, 13α acetate (PMA) and 1 μM A23187 produced a five-fold greater stimulation of rat hepatocyte glycogen phosphorylase activity than was seen with PMA alone. Vasopressin activation of glycogen phosphorylase was comparable to that seen with PMA plus A23187. Glycogen phosphorylase activity due to PMA plus A23187 was increased significantly after 30 sec, maximal at 120 and sustained at elevated levels for 240 sec. In contrast, activation due to vasopressin was maximal at 30 sec followed by a decrease. The addition of PMA 5 min prior to the A23187 abolished the synergism between these two agents. These data are compatible with the hypothesis that diacylglycerol and Ca2+ synergistically increase glycogen phosphorylase activity in rat hepatocytes.

Original languageEnglish (US)
Pages (from-to)88-94
Number of pages7
JournalBiochemical and biophysical research communications
Volume119
Issue number1
DOIs
StatePublished - Feb 29 1984

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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