ISSN:
1573-6903
Keywords:
myo-Inositol
;
astrocytes
;
osmolality
;
deprivation
;
kinetic parameters
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1021950311308
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