Phosphorylation of brain (Na+,K+)-ATPase alpha catalytic subunits in normal and epileptic cerebral cortex: II. Partial seizures in human epilepsy.
We examined the activity and phosphorylation level of (Na+,K+)-ATPase (E.C. 3.6.1.3) partially purified from normal and epileptic human cortices. Control patients (n = 11) were operated on for a non-epileptogenic deep brain lesion, while epileptic patients (n = 10) were operated on for temporal or frontal originating partial seizures, resistant to medications or secondary to evolutive brain tumors. No differences in the specific activity of microsomal (Na+,K+)-ATPase were observed between the two groups of patients. After partial purification of the enzyme followed by SDS-polyacrylamide gel electrophoresis, (Na+,K+)-ATPase catalytic subunit had a decreased affinity for K+ in human epileptic cortex and lost its sensitivity to phenytoin dephosphorylation. Indirect evidence suggests that those abnormalities of (Na+,K+)-ATPase in human epileptic cortex hold preferentially true for the alpha(-) enzymatic subunit. Those results indicate that, in human epileptic cortex, (Na+,K+)-ATPase and most probably its glial subtype is altered in its K+ regulation and phenytoin sensitivity and could be responsible for ictal transformation and seizure spread.
Guillaume
D
D
Molecular Neuroscience Laboratories, Reed Neurological Research Center, University of California, Los Angeles.
Grisar
T
T
Delgado-Escueta
A V
AV
Laschet
J
J
Bureau-Heeren
M
M
D001921:Brain / Q000201:enzymology*; D002384:Catalysis; D002540:Cerebral Cortex / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D004828:Epilepsies, Partial / Q000201:enzymology*; D004827:Epilepsy / Q000201:enzymology*; D006801:Humans; D010672:Phenytoin / Q000494:pharmacology; D010766:Phosphorylation; D011188:Potassium / Q000494:pharmacology; D012016:Reference Values; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D010672:Phenytoin; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium