REDUCED CORTICAL ECTO-ATPASE ACTIVITY IN RAT BRAINS DURING PROLONGED STATUS EPILEPTICUS INDUCED BY SEQUENTIAL ADMINISTRATION OF LITHIUM ANDPILOCARPINE

Considerable evidence indicates that ATP, acting intracellularly or as a neurotransmitter, can influence nerve cell physiology in a variety of ways. Defects in the functioning of ATP-metabolizing enzymes could therefore lead to disturbances in neurotransmission and creation of su stained neuronal discharges characteristic of status epilepticus. in t his study we investigated synaptosomal ATPase changes in rat brains du ring lithium/pilocarpine-induced status epilepticus. After 2 h of cont inuous electroencephalographic spiking, both Mg2+- and Ca2+-dependent ecto-ATPases were significantly decreased in freshly prepared synaptos omal preparations from the status rats. The intracellulary acting Ca2M2+-ATPase (Ca-pump) was also decreased, but no changes occurred in sy naptosomal Na+K+-ATPase activity. The difference between ecto-ATPase a ctivities of the control and status rat brains was not affected by rep eated freezing-thawing and lengthy storage. Possible involvement of re duced synaptosomal divalent cation-dependent ATPases in the pathophysi ology of status epilepticus is discussed.