[Effects of anticonvulsive substances on Na,K-ATPase from the synaptic membranes of animal brain]

The distribution pattern of marker enzymes (Na, K-ATPase, acetylcholinesterase) in three fractions of synaptic membranes (SM) of rat brain were studied. The effects of three anticonvulsive agents on Na, K-ATPase from the total fraction of rat brain SM and purified membrane preparation from ox brain were estimated by different methods. Under optimal conditions (Na/K = 5) diphenylhydantoin (DPH) at a concentration of 0,1 mM activates Na, K-ATPase from the total SM fraction only in the absence of ouabain, whereas carbamazepine and pyrroxane taken at the same concentrations have no effect on Na, K-ATPase, irrespective of the type of the enzyme assay. DPH seems to compete with ouabain. Under non-optimal ionic conditions (Na/K = 250) all the anticonvulsive substances studied inhibit Na, K-ATPase of the total SM fraction. The mixture of hydrophobic agents (propylene glycol and ethanol) used to dissolve carbamazepine inhibits Na, K-ATPase from the total SM fraction only under non-optimal conditions. The inhibiting effect of the anticonvulsive substances under study on Na, K-ATPase from the purified membrane preparations is maximal at the concentration of 10(-6) M; at higher concentrations the effect is less pronounced.