| pubmed-article:2557036 | pubmed:abstractText | Phenytoin, a potent antiepileptic drug, has been thought to stimulate Na+, K+ transport across cell membranes, but its influence on (Na+, K+)-ATPase activity remains highly controversial. We have investigated the effects of the drug on the phosphorylation level of (Na+, K+)-ATPase partially purified from mouse, cat and human brain. (Na+, K+)-ATPase catalytic subunits [alpha(+) and alpha(-)] were resolved by sodium dodecylsulfate polyacrylamide gel electrophoresis. Previous experiments had shown that phenytoin dephosphorylates the (Na+, K+)-ATPase catalytic subunit by +/- 50% in C57/BL mice. In the present study, we showed that phenytoin (10(-4) M) decreases the phosphorylation level of (Na+, K+)-ATPase catalytic subunit by the same value in cat and human cortex. Moreover, that effect is predominant on the alpha(-) subunit, thought to be the predominant enzymatic form in non-neuronal or glial cells. The results are thus favoring the hypothesis that phenytoin stimulates the brain (Na+, K+)-ATPase. They further suggest that phenytoin mainly activates the glial enzymatic form, providing central nervous system with an enhanced ability to regulate extracellular K+. | lld:pubmed |
