Abstract
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 language | English (US) |
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Pages (from-to) | 75-81 |
Number of pages | 7 |
Journal | Molecular and cellular biochemistry |
Volume | 63 |
Issue number | 1 |
DOIs | |
State | Published - Aug 1984 |
Externally published | Yes |
Keywords
- adenosine monophosphate
- glucose
- glucose-6-phospate
- intracellular glucose
- phosphorylase phosphatase