[Role of voltage-dependent ion channels in epileptogenesis].
The aim of this review is to gather information in favour of the involvement of voltage-dependent ion channels in epileptogenesis. Although, up to now, no study has shown that epilepsy is accompanied by a modification in the activity to these channels, the recently acquired knowledge of their physiology allows to presume would favor their involvement in epileptogenesis. The results from electrophysiological studies are as follows: a persistent sodium current increases neuronal excitability whereas potassium currents have an inhibitory role. In particular, calcium-dependent potassium current are involved in the post-hyperpolarization phases which follows PDS. Calcium currents are also involved in the genesis of the "bursting pacemaker" activity displayed by the neurons presumed to be inducers of the epileptic activity. Biochemical data has shown that as a consequence of epileptic activity, sodium and calcium channels are down regulated. This down-regulation could be a way to reduces neuronal hyperexcitability. Pharmacological data demonstrate the drugs which activate calcium channels or which inhibit potassium channels have a convusilvant effect. On the contrary, agents which block calcium or sodium channels or which properties. Among the latter ones, some antiepileptic drugs can be found. In summary situations which lead to increase in calcium and sodium currents and/or to an inhibition in potassium currents are potentially epileptogenic.
Ricard-Mousnier
B
B
Service de neurologie B, CHRU Angers, France.
Couraud
F
F
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D004827:Epilepsy / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*
D000927:Anticonvulsants; D007473:Ion Channels