Determinants of deoxyglucose uptake in cultured astrocytes: the role of the sodium pump

J Neurochem. 1985 Feb;44(2):473-9. doi: 10.1111/j.1471-4159.1985.tb05438.x.

Abstract

Glucose utilization in primary cell cultures of mouse cerebral astrocytes was studied by measuring uptake of tracer concentrations of [3H]2-deoxyglucose ([3H]2-DG). The resting rate of glucose utilization, estimated at an extracellular K+ concentration ([K+]o) of 5.4 mM, was high (7.5 nmol glucose/mg protein/min) and was similar in morphologically undifferentiated and "differentiated" (dibutyryl cyclic AMP-pretreated) cultures. Resting uptake of [3H]2-DG was depressed by ouabain, by reducing [K+]o, and by cooling. These observations suggest that resting glucose utilization in astrocytes was dependent on sodium pump activity. Sodium pump-dependent uptake in 2-3-week-old cultures was about 50% of total [3H]2-DG uptake but this fraction declined with culture age from 1 to 5 weeks. Uptake was not affected by changes in extracellular bicarbonate concentration ([HCO3-]o) in the range of 5-50 mM but was significantly reduced in bicarbonate-free solution. At high [HCO3-]o (50 mM) uptake was insensitive to pH (pH 6-8), whereas at low [HCO3-]o (less than 5 mM) uptake was markedly pH-dependent. Elevation of [K+]o from 2.3 mM to 14.2-20 mM (corresponding to extremes of the physiological range of [K+]o) resulted in a 35-43% increase in [3H]2-DG uptake that was not affected by culture age or by morphological differentiation. Our results indicate a high apparent rate of glucose utilization in astrocytes. This rate is dynamically responsive to changes in extracellular K+ concentration in the physiological range and is partially dependent on sodium pump activity.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Astrocytes / metabolism*
  • Bicarbonates / pharmacology
  • Bucladesine / pharmacology
  • Cells, Cultured
  • Cold Temperature
  • Deoxy Sugars / metabolism*
  • Deoxyglucose / metabolism*
  • Hydrogen-Ion Concentration
  • Ion Channels / drug effects
  • Ion Channels / physiology*
  • Kinetics
  • Mice
  • Ouabain / pharmacology
  • Potassium / pharmacology
  • Rats
  • Sodium / metabolism*

Substances

  • Bicarbonates
  • Deoxy Sugars
  • Ion Channels
  • Ouabain
  • Bucladesine
  • Deoxyglucose
  • Sodium
  • Potassium