Kindling-like state in rat hippocampal CA1 slices induced by the repeated short-term extracellular K+ increases: the role of L-type Ca(2+)-channels.
The repeated 30 s applications (3-6 episodes) of K+ (up to 20 mM) induced the appearance of single electric pulse-triggered population spike bursts in the rat CA1 hippocampal slices. This kindling-like state kept for a long time after the last K(+)-application and was limited by the time of slice survival. Disconnection of CA3 region did not significantly eliminate the effect of repeated short-term [K+]o increases on the establishment and maintenance of the kindling-like state in the CA1 region. This state correlated with the increases in the efficiency of the excitatory postsynaptic potential (EPSP)-spike transfer (the excitability of CA1 pyramidal neurons) but not in the glutamatergic synaptic efficiency. The selective blocker of L-type Ca2+ channels nimodipine (10 microM) abolished the development of the kindling-like state as well as the increases in the efficiency of the EPSP-spike transfer in rat hippocampal CA1 slices. Taken together, these data indicate that the described model of kindling in vitro can be useful for a study of the role of different sites of Ca2+ entry into hippocampal neurons for the cellular mechanisms of epileptogenesis.
Semyanov
A
A
Institute of Theoretical and Experimental Biophysics of Russian Academy of Science, Pushchino, Moscow Region, Russia.
Godukhin
O
O
D000200:Action Potentials; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D003714:Denervation; D005110:Extracellular Space / Q000378:metabolism*; D018698:Glutamic Acid / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D007696:Kindling, Neurologic; D008297:Male; D009553:Nimodipine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D017966:Pyramidal Cells / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission; D013997:Time Factors
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D018698:Glutamic Acid; D009553:Nimodipine; D011188:Potassium