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  • 1
    ISSN: 1432-1106
    Keywords: Epilepsy ; Calcium antagonists ; Verapamil ; Flunarizine ; Neocortex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of the organic calcium antagonists verapamil and flunarizine on pentylenetetrazol induced paroxysmal depolarizations were tested in organotypic neocortical explants taken from neonatal rats. In these in vitro experiments the papaverin derivative verapamil depressed, and finally abolished, epileptic discharges in all cases. The piperazine derivative flunarizine, however, which is known to suppress epileptic discharges in hippocampal CA3 neurons (Bingmann and Speckmann 1986), showed no significant antiepileptic effects in the explanted neocortical neurons. Thus, the present findings may indicate that the suppressive action of flunarizine on the generation of paroxysmal depolarizations is restricted to distinct populations of neurons.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1106
    Keywords: Organic calcium antagonists ; Flunarizine ; Verapamil ; Epileptic discharges ; CA3 neurones in hippocampal slices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Antiepileptic actions of the organic calcium antagonists flunarizine (cinnarizine derivate) and verapamil (papaverin derivat) on pentylenetetrazol-induced epileptic bioelectric activity were tested in CA3 neurones of hippocampal slices. In all experiments both calcium antagonists reduced the amplitudes and/or durations of paroxysmal depolarizations as well as their rate of occurrence, when the bath concentrations of flunarizine or verapamil exceeded 20 μmol/l. When they were added to the bath solution before pentylenetetrazol application, recordings of the resting membrane potential, of the membrane resistance, of action potentials and of spontaneous as well as of evoked excitatory and inhibitory postsynaptic potentials gave no indication that the antiepileptic effects of these drugs are due to unspecific depressive actions on neuronal excitability or spread of excitation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 79 (1994), S. 376-384 
    ISSN: 1432-1106
    Keywords: Verapamil ; Calcium channel blockers Epilepsy ; Hippocampus ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the present study was to test whether the organic calcium channel blocker verapamil acts not only on spontaneously occurring epileptiform field potentials (EFP) but also on EFP triggered by single electrical stimuli in the low-Mg2+ epilepsy model. The experiments were carried out on hippocampal slices of guinea pigs. EFP were elicited by omission of Mg2+ from the perfusate and recorded from stratum pyramidale and stratum radiatum in the CA1 subfield. Single electrical stimuli were applied to the Schaffer collateral pathway. Verapamil was added to the bath solution in concentrations of 40 and 60 μmol verapamil/1 at normal (4 mmol/l) and elevated (8 mmol/1) K+ levels. After omission of Mg2+ from the perfusate, spontaneously occurring EFP appeared in all trials. These spontaneously occurring EFP were suppressed dose-dependently upon addition of verapamil to the perfusate. At elevated K+ levels, the latencies to suppression were significantly reduced and the dose dependency was abolished for the two doses of verapamil used. Triggered EFP reappeared upon stimulation after spontaneously occurring EFP had been suppressed, except for trials with 60 /gmmol verapamil/1 bath solution with elevated K+ levels. The stimulus-evoked EFP were abolished with continuing perfusion of verapamil except for trials with 40 μmol/1 at normal extracellular K+ concentrations. This effect was again dose dependent and enhanced by elevating the K+ level. In all experiments, stimulus-evoked EFP reappeared upon wash-out of verapamil. A primary action of verapamil on pacemaker functions in epileptogenic tissue is assumed.
    Type of Medium: Electronic Resource
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