Glucose stimulation of heart phosphorylase phosphatase activity in vitro and in vivo

Frank Q. PJuttall, Mary C. Gannon

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


To determine the mechanism of the glucose stimulation, glucose or glucose-6-phospate was added to dilute heart extracts in the presence or absence of AMP. The intracellular glucose, tissue glucose-6-phosphate, and tissue AMP concentrations were also determined in 24-h starved animals given glucose; 24-h starved animals given insulin as well as diabetic starved and diabetic starved insulin-treated animals were also studied. The A0.5 for glucose stimulation of cardiac phosphorylase phosphatase activity was approximately 1 .2 mM. The A0.5 for glucose-6-phosphate was approximately 0.02 mM. The glucose-6-phosphate concentration in all animals exceeded the Ao.5 by 10-fold. However, the intracellular glucose concentration in the glucose-treated, insulin-treated, diabetic, and diabetic insulin-treated rats was in the range of the A0.5 for stimulation of phosphorylase phosphatase activity. AMP completely inhibited phosphorylase phosphatase activity at a concentration of 0.2 mM. Physiological concentrations of glucose and glucose-6-phosphate partially reversed this inhibition. Administration of glucose or insulin resulted in an increase in intracellular glucose concentration, an increase in tissue glucose-6-phosphate and a decrease in tissue AMP concentrations. These data suggest that glucose may be a physiological regulator of phosphorylase phosphatase in heart muscle as it is in liver.

Original languageEnglish (US)
Pages (from-to)75-81
Number of pages7
JournalMolecular and cellular biochemistry
Issue number1
StatePublished - Aug 1 1984


  • adenosine monophosphate
  • glucose
  • glucose-6-phospate
  • intracellular glucose
  • phosphorylase phosphatase


Dive into the research topics of 'Glucose stimulation of heart phosphorylase phosphatase activity in vitro and in vivo'. Together they form a unique fingerprint.

Cite this