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[Increase of 5'-nucleotidase activity in liver plasma membranes during fasting in the rat]
C Minassian1, F Véga, G Mithieux
1Institut National de la Santé et de la Recherche Médicale, INSERM U197, Faculté de Médecine A.-Carrel, Lyon, France.
Abstract:
The effect of fasting on 5'-nucleotidase activity was assessed in microsomes and purified plasma membranes from rat liver. The microsomal 5'-nucleotidase activity (mean value: 0.062 mumol/min/mg protein at 37 degrees C in the fed rat) is increased about twice in the fasted rat (mean values: 0.11, 0.125 and 0.11 mumol/min/mg protein after 24, 48 and 72 hours of fasting, respectively). This result was further confirmed after separation of plasma membranes from the bulk of microsomial membranes by sucrose gradient centrifugation. The results are discussed with respect to the phosphatidylinositol glycan-mediated anchoring of the ectoenzyme to the cell membrane and to the putative biological effect of extracellular adenosine on the liver metabolism.
Insights
Fasting significantly elevates 5'-nucleotidase activity in rat liver microsomes and plasma membranes. This enzyme
Area of Science:
- Biochemistry
- Cell Biology
- Enzymology
Context:
- Investigates the impact of physiological states on enzyme activity.
- Focuses on liver cell membrane-associated enzymes.
- Examines 5 '-nucleotidase, an important ectoenzyme.
Purpose:
- To determine the effect of fasting on rat liver 5 '-nucleotidase activity.
- To localize changes in enzyme activity within cellular compartments.
- To explore potential mechanisms and biological implications of observed changes.
Summary:
- Fasting approximately doubles the activity of 5 '-nucleotidase in rat liver microsomes.
- Enzyme activity was measured in microsomes and purified plasma membranes after 24, 48, and 72 hours of fasting.
- Results indicate a substantial increase in 5 '-nucleotidase activity during fasting.
Impact:
- Provides insights into metabolic regulation by fasting.
- Suggests a role for 5 '-nucleotidase in adaptive liver responses.
- Contributes to understanding ectoenzyme regulation and extracellular adenosine signaling.