EFFECTS OF CONVULSANTS ON CORTICAL ADENOSINE TRIPHOSPHATASES¹

Abstract

Abstract Since inhibitors of Na‐K‐ATPase (EC 3.6.1.4) often produce epileptogenic foci on local application to cerebral regions, experiments were designed to determine whether systemic convulsants generally inhibit cortical ATPases either directly or indirectly. Injected convulsants (methionine sulphoximine, pentetrazole, picrotoxin, thiosemicarbazide and methyl fluoroacetate) did not alter the Na‐K‐ATPasc or Mg‐ATPase activities as measured in homogenates of specimens taken from the cerebral cortex of the dog. Picrotoxin had measurable inhibitory effects when added to a homogenate in vitro , but at a concentration higher than would probably be attained in the brain in vivo after a convulsant dose. Other systemic convulsants added in vitro were without effects on ATPase activities. Cortical tissue sampled after freezing in situ showed significantly higher ATPase activities than did tissue frozen after excision.