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Spontaneous and stimulus-triggered epileptic discharges: delayed antiepileptic effect with triggering
R Köhling1, H Straub, E J Speckmann
1Institut für Physiologie, Universität, Münster, Germany.
Experimental Brain Research
|January 1, 1994
Summary
The organic calcium channel blocker verapamil suppresses spontaneous and triggered epileptiform field potentials (EFP) in a guinea pig epilepsy model. Verapamil
Area of Science:
- Neuroscience
- Pharmacology
Background:
- Epileptiform field potentials (EFP) are abnormal neuronal activities.
- The low-magnesium (Mg2+) epilepsy model is used to study EFP.
- Verapamil is an organic calcium channel blocker.
Purpose of the Study:
- To investigate verapamil's effect on both spontaneous and stimulated EFP in the low-Mg2+ epilepsy model.
- To determine if verapamil's action is dose-dependent and influenced by extracellular potassium levels.
Main Methods:
- Experiments were conducted on guinea pig hippocampal slices.
- EFP were induced by omitting Mg2+ from the perfusate.
- Verapamil was applied at varying concentrations (40 and 60 μmol/l) and extracellular K+ levels (4 and 8 mmol/l).
Main Results:
- Verapamil dose-dependently suppressed spontaneous EFP.
- Elevated K+ reduced suppression latency and abolished dose dependency for verapamil.
- Stimulus-evoked EFP were abolished by verapamil in a dose-dependent manner, enhanced by elevated K+.
Conclusions:
- Verapamil effectively suppresses both spontaneous and stimulus-evoked EFP in this epilepsy model.
- The drug's action appears to involve pacemaker functions in epileptogenic tissue.
- Extracellular K+ levels significantly modulate verapamil's efficacy and dose-response relationship.