myo-inositol transport in mouse astroglia-rich primary cultures.
Uptake of radiolabeled myo-inositol was studied in astroglia-rich primary cultures derived from neonatal mouse brains. The uptake was saturable in the presence of Na+ with a Km of 25 microM and a Vmax of 60 pmol.min-1.(mg protein)-1, suggesting a high-affinity transport system for myo-inositol in astroglial cells. In addition, a Na(+)-independent, nonsaturable component was found. Carrier-mediated uptake was not inhibited by cytochalasin B (50 microM), but was reduced by depolarizing concentrations of K+ and, to different extents, in the presence of phloretin, ouabain, or amiloride (1 mM each). scyllo-Inositol, glucose, and galactose also reduced myo-inositol uptake; inhibition by the two hexoses was not reversed in the presence of 0.4 mM sorbinil. On the other hand, uptake of 2-deoxyglucose was not inhibited by high concentrations of myo-inositol. Preincubation of the cells with glucose-free or inositol-free medium stimulated uptake of myo-inositol and preincubation with 25 mM glucose in the presence of 0.4 mM sorbinil had no effect on the rate of uptake. The results suggest that myo-inositol is taken up into the astroglial cells by a transport mechanism that is distinct from that of glucose and probably is an active one. Sorbitol pathway activity does not interfere with myo-inositol uptake.
Wiesinger
H
H
Physiologisch-Chemisches Institut der Universität, Tübingen, F.R.G.
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001692:Biological Transport; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D003470:Culture Media; D005110:Extracellular Space / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D007294:Inositol / Q000378:metabolism*; D051379:Mice; D009994:Osmolar Concentration; D012964:Sodium / Q000494:pharmacology
D003470:Culture Media; D007294:Inositol; D012964:Sodium; D005947:Glucose