Na+-K+-ATPase activity of glial, neuronal, and synaptosomal enriched fractions from normal and freezing-injured rabbit cerebral cortex.

This paper investigates the kinetic parameters of Na+-K+-ATPase in glial, neuronal, and synaptosomal enriched fractions isolated from rabbit cerebral cortex. Under normal conditions, kinetic parameters-Vmax and KK+0.5- of Na+-K+-ATPase are the same in the three fractions, suggesting that this enzyme behaves as the same molecular entity. Following a cryogenic lesion, the alterations of these parameters appear to be different in the different fractions. These data suggest that the same enzyme exhibits various responses when exposed to the same pathological event. The dissimilar lipid composition of the Na+-K+-ATPase environment, and/or different adaptative responses to abnormal ion concentrations in glial, neuronal, and synaptosomal fractions could account for these different responses.