Different action of ethosuximide on low- and high-threshold calcium currents in rat sensory neurons.
The effects of ethosuximide on calcium channels were studied on dorsal root ganglion neurons from one-day-old rats using the patch-clamp technique. Bath application of ethosuximide induced dose-dependent and reversible suppression of calcium currents without affecting their time-course. Substantial differences between the effects of ethosuximide on the low-threshold and high-threshold (T- and L-) currents were observed. Ethosuximide reduced the T-current with greater potency than the L-current (Kd for T-current is 7 microM vs 15 microM for L-current). This relative specificity of its action still remained if applied at concentrations up to 1 mM. These data support the hypothesis according to which the anti-epileptic action of ethosuximide is related to reduction of the low-threshold calcium currents in sensory neurons.
Kostyuk
P G
PG
Department of General Physiology of the Nervous System, A.A. Bogomoletz Institute of Physiology, Kiev, Ukraine.
Molokanova
E A
EA
Pronchuk
N F
NF
Savchenko
A N
AN
Verkhratsky
A N
AN
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D005013:Ethosuximide / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007700:Kinetics; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*; D051381:Rats
D015220:Calcium Channels; D005013:Ethosuximide