Effects of acute hypoxia on intracellular-pH regulation in astrocytes cultured from rat hippocampus

Academic Article

Abstract

  • We used the pH-sensitive dye BCECF to evaluate the effect of acute (5-10 min) hypoxia (∼ 3% O ) on the regulation of intracellular pH (pH ) in astrocyte populations cultured from rat hippocampus. For cells in the nominal absence of CO /HCO at an extracellular pH of 7.40 (37 °C), acute hypoxia caused a small (0.05) decrease in steady-state pH , but increased the pH recovery rate from an acid load during all but the late phase of the pH recovery. During such pH recoveries, the total acid extrusion rate (φ , the product of dpH /dt and proton buffering power) decreased with increasing pH . Hypoxia alkali shifted the plot of φ vs. pH ; over the upper ∼ 85% of the φ range, this shift was 0.15-0.30. Hypoxia also stimulated the pH recovery rate from an alkali load. Under normoxic conditions, switching the extracellular buffer to 5% CO /22 mM HCO also alkali shifted the φ -pH plot (upper ~ 85%) by 0.4-0.5. Superimposing hypoxia on CO /HCO further alkali shifted the φ -pH plot (upper ∼ 85% of the φ range) by 0.05-0.15. The SITS-insensitive component of φ was alkali shifted by 0.20-0.30, whereas the SITS-sensitive component of φ was depressed in the low pH range. Thus, in the nominal absence of CO /HCO , acute hypoxia has little effect on steady-state pH but stimulates acid extrusion and acid loading, whereas in the presence of CO /HCO , hypoxia stimulates the SITS-insensitive but inhibits the SITS-sensitive acid extrusion. © 2007 Elsevier B.V. All rights reserved. 2 i 2 3 i i i i E i i E i E i 2 3 E i 2 3 E i E E E i 2 3 i 2 3 - - - - -
  • Authors

    Published In

  • Brain Research  Journal
  • Digital Object Identifier (doi)

    Author List

  • Bevensee MO; Boron WF
  • Start Page

  • 143
  • End Page

  • 152
  • Volume

  • 1193