title: In vivo electrical stimulation alters sensitivity of the brain (Na+ + K+)ATPase toward inhibition by vanadate.
abstract: It has recently been shown that electrical stimulation of the brain cortex in vivo blocks invasion of cortical spreading depression (SD) into the stimulated area. The effect has been interpreted as a result of activating a K+ pumping mechanism that prevents the accumulation of this ion in the extracellular space to the high levels required for SD propagation. In the present experiments (Na+ + K+)ATPase activity was determined in the electrically stimulated region of the rat brain cortex. When ATP preparations containing vanadate were used as substrate, elevation of K concentration in the assay medium from 2 to 20 mM inhibited enzyme activity in homogenates from the normal cortex but not that from homogenates of the electrically stimulated cortical region. With vanadate-free ATP (Boehringer) as a substrate, slight stimulation by 20 mM K+ has been observed in both cases. Vanadate (0.25 microM) added to the assay medium containing Boehringer ATP and 20 mM K+ inhibited ATPase activity from the normal cortex but not that from the stimulated cortical area. Electrical stimulation may activate (Na+ + K+)ATPase at least partly by diminution of its susceptibility toward the inhibitory action of vanadate.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D002540:Cerebral Cortex / Q000201:enzymology*; D004558:Electric Stimulation; D007700:Kinetics; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
chemical_list: D014639:Vanadium; D014638:Vanadates; D010042:Ouabain; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium