Biomaterial Database

Differential effects of the anticonvulsants phenobarbital, ethosuximide and carbamazepine on neuromuscular transmission. 1980

M T Alderdice, and B A Trommer

The actions of the anticonvulsants phenobarbital, ethosuximide and carbamazepine were examined electrophysiologically at the frog neuromuscular junction. Phenobarbital reduced miniature end-plate potential (MEPP) amplitude, did not significantly affect end-plate potential amplitude and increased quantal content. Ethosuximide decreased MEPP and end-plate potential amplitudes proportionally; quantal content was unchanged. Carbamazepine decreased end-plate potential amplitude more than MEPP amplitude; quantal content was decreased. In a solution containing elevated (7.5 mM) K+, phenobarbital and carbamazepine increased MEPP frequency, whereas ethosuximide had no effect. Carbamazepine had to be dissolved in a solvent, propylene glycol, which was shown to produce small, but sometimes statistically significant, alterations in the measured parameters of neuromuscular transmission. The results show that all three of these anticonvulsants depress postjunctional sensitivity to released acetylcholine producing parallel dose-response curves for MEPP amplitude inhibition. These experiments also show that these drugs exhibit different mechanisms of action with respect to nerve-stimulated neurotransmitter release from nerve terminals at the neuromuscular junction: phenobarbital enhances acetylcholine release, ethosuximide has no effect and carbamazepine decreases transmitter release.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009435	Synaptic Transmission	The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.	Neural Transmission,Neurotransmission,Transmission, Neural,Transmission, Synaptic
D009469	Neuromuscular Junction	The synapse between a neuron and a muscle.	Myoneural Junction,Nerve-Muscle Preparation,Junction, Myoneural,Junction, Neuromuscular,Junctions, Myoneural,Junctions, Neuromuscular,Myoneural Junctions,Nerve Muscle Preparation,Nerve-Muscle Preparations,Neuromuscular Junctions,Preparation, Nerve-Muscle,Preparations, Nerve-Muscle
D010634	Phenobarbital	A barbituric acid derivative that acts as a nonselective central nervous system depressant. It potentiates GAMMA-AMINOBUTYRIC ACID action on GABA-A RECEPTORS, and modulates chloride currents through receptor channels. It also inhibits glutamate induced depolarizations.	Phenemal,Phenobarbitone,Phenylbarbital,Gardenal,Hysteps,Luminal,Phenobarbital Sodium,Phenobarbital, Monosodium Salt,Phenylethylbarbituric Acid,Acid, Phenylethylbarbituric,Monosodium Salt Phenobarbital,Sodium, Phenobarbital
D011894	Rana pipiens	A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.	Frog, Leopard,Leopard Frog,Lithobates pipiens,Frogs, Leopard,Leopard Frogs
D002220	Carbamazepine	A dibenzazepine that acts as a sodium channel blocker. It is used as an anticonvulsant for the treatment of grand mal and psychomotor or focal SEIZURES. It may also be used in the management of BIPOLAR DISORDER, and has analgesic properties.	Amizepine,Carbamazepine Acetate,Carbamazepine Anhydrous,Carbamazepine Dihydrate,Carbamazepine Hydrochloride,Carbamazepine L-Tartrate (4:1),Carbamazepine Phosphate,Carbamazepine Sulfate (2:1),Carbazepin,Epitol,Finlepsin,Neurotol,Tegretol
D005013	Ethosuximide	An anticonvulsant especially useful in the treatment of absence seizures unaccompanied by other types of seizures.	Ethosuccimid,Emeside,Ethylmethylsuccimide,Ethymal,Etosuximida Faes,Petnidan,Pyknolepsinum,Suksilep,Suxilep,Zarontin,Faes, Etosuximida
D000109	Acetylcholine	A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.	2-(Acetyloxy)-N,N,N-trimethylethanaminium,Acetilcolina Cusi,Acetylcholine Bromide,Acetylcholine Chloride,Acetylcholine Fluoride,Acetylcholine Hydroxide,Acetylcholine Iodide,Acetylcholine L-Tartrate,Acetylcholine Perchlorate,Acetylcholine Picrate,Acetylcholine Picrate (1:1),Acetylcholine Sulfate (1:1),Bromoacetylcholine,Chloroacetylcholine,Miochol,Acetylcholine L Tartrate,Bromide, Acetylcholine,Cusi, Acetilcolina,Fluoride, Acetylcholine,Hydroxide, Acetylcholine,Iodide, Acetylcholine,L-Tartrate, Acetylcholine,Perchlorate, Acetylcholine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia