Characterization of ethosuximide reduction of low-threshold calcium current in thalamic neurons.
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Coulter DA, Huguenard JR, Prince DA
Characterization of ethosuximide reduction of low-threshold calcium current in thalamic neurons.
Ann Neurol. 1989 Jun;25(6):582-93.
- PubMed ID
- 2545161 [ View in PubMed]
- Abstract
The mechanism by which ethosuximide reduces thalamic low-threshold calcium current (LTCC) was analyzed using voltage-clamp techniques in acutely isolated ventrobasal complex neurons from rats and guinea pigs. The ethosuximide-induced reduction of LTCC was voltage dependent: it was most pronounced at more-hyperpolarized potentials and did not affect the time course of activation or inactivation of the current. Ethosuximide reduced LTCC without altering the voltage dependence of steady-state inactivation or the time course of recovery from inactivation. Dimethadione reduced LTCC by a similar mechanism, while valproic acid had no effect on LTCC. We conclude that ethosuximide reduction of LTCC in thalamic neurons is consistent with a reduction in the number of available LTCC channels or in the single LTCC channel conductance, perhaps indicating a direct channel-blocking action of this drug. Given the importance of LTCC in thalamic oscillatory behavior, a reduction in this current by ethosuximide would be a mechanism of action compatible with the known anticonvulsant effects of this drug in typical absence seizures.
DrugBank Data that Cites this Article
- Drugs
- Drug Targets
Drug Target Kind Organism Pharmacological Action Actions Methsuximide Voltage-dependent T-type calcium channel subunit alpha-1G Protein Humans YesInhibitorDetails