Effect of osmolality and myo-inositol deprivation on the transport properties of myo-inositol in primary astrocyte cultures

R. E. Isaacks, A. S. Bender, C. Y. Kim, M. D. Norenberg

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

myo-Inositol uptake measured in primary astrocyte cultures was saturable in the presence of Na+ with a Km of 13-18 μM and a Vmax of 9.4 nmoles/mg protein/hour in myo-inositol-fed cells, indicating a high affinity transport system. In myo-inositol-deprived cells, Km was about 53 μM with a Vmax of 13.2 nmoles/mg protein/hour. Decreasing osmolality decreased the Vmax to about 1.9 nmoles/mg protein/hour whereas increasing osmolality increased Vmax about 5-fold, while Kms were essentially unchanged in myo-inositol fed cells. In cells deprived of myo-inositol, Vmax decreased in hypotonic medium and increased in hypertonic medium almost 10-fold, but with more than a doubling of the Km regardless of the osmolality. Glucose (25 mM) inhibited myo- inositol uptake 51% whereas the other hexoses used inhibited uptake much less. Our findings indicate that myo-inositol uptake in astrocytes occurs through an efficient carrier-mediated Na+-dependent co-transport system that is different from that of glucose and its kinetic properties are affected by myo-inositol availability and osmotic stress.

Original languageEnglish (US)
Pages (from-to)1461-1469
Number of pages9
JournalNeurochemical Research
Volume22
Issue number12
DOIs
StatePublished - Nov 6 1997

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Keywords

  • Astrocytes
  • Deprivation
  • Kinetic parameters
  • Myo-Inositol
  • Osmolality

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry

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