The effect of vanadate on Na+,K+-ATPase activity of mouse cerebral cortex during bicuculline-induced seizures.
The effect of bicuculline-induced seizures on Na+,K+-ATPase activity of mouse cerebral cortex homogenates, using two different procedures of sample preparation (freezing in situ or decapitation of animals without freezing) is described. Regardless of tissue treatment Na+,K+-ATPase activities during bicuculline-induced seizures did not differ significantly from the appropriate controls when vanadate-free ATP was used as substrate. The response of Na+,K+-ATPase to K+ activation was also similar; the increase in potassium concentration from 2 to 20 mM caused a 33.0 and 32.3% increase of enzyme activity in cortical homogenates from control and convulsing mice, respectively. Vanadate added to the assay medium inhibited Na+,K+-ATPase activity in a dose-dependent manner; with both types of tissue treatment there was, however, a tendency towards lesser inhibition of the enzyme from convulsing mice and at 1 X 10(-7) M vanadate this difference, though slight, was statistically significant: -22.59 vs -27.55% (freezing) and -28.73 vs -38.42% (decapitation) for seizures vs controls, respectively. The reduced sensitivity of Na+,K+-ATPase towards vanadate inhibition in cortical homogenates prepared from mice with convulsions suggests that vanadate might play a role in the modulation of enzyme activity during seizures in vivo.
D000818:Animals; D001640:Bicuculline; D002540:Cerebral Cortex / Q000201:enzymology*; D005615:Freezing; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012640:Seizures / Q000139:chemically induced / Q000201:enzymology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014021:Tissue Preservation; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology*
D014639:Vanadium; D014638:Vanadates; D000254:Sodium-Potassium-Exchanging ATPase; D001640:Bicuculline