Biomaterial Database

Calcium-dependent actions of the convulsant barbiturate, CHEB, on transmitter release at the rat neuromuscular junction. 1990

G M Nicholson, and I Spence, and G A Johnston

Department of Pharmacology, University of Sydney, N.S.W., Australia.

1. The effect of convulsant barbiturates on spontaneous and evoked acetylcholine release was studied at the rat neuromuscular junction in vitro. 2. The convulsant barbiturates (+)-5-(1,3-dimethylbutyl)-5-ethyl barbituric acid [(+)-DMBB], 5-(2-cyclohexylideneethyl)-5-ethyl barbituric acid (CHEB), 5-ethyl-5-(3-methylbut-2'-enyl) barbituric acid (3M2B) and 5-ethyl-5-(1,3-dimethylbut-1'-enyl) barbituric acid (1,3M1B) all produced a concentration-dependent increase in miniature end-plate potential (MEPP) frequency. 3. With CHEB (100 microM) this increase in MEPP frequency was found to be dependent on the [Ca2+]o. CHEB in 0.5 mM [Ca2+]o did not alter MEPP amplitude, but in 1.3 and 2.5 mM [Ca2+]o CHEB significantly reduced the amplitude. 4. At a [Ca2+]o of 0.5 mM, CHEB produced an increase in both EPP amplitude and quantal content, while at 1.3 mM [Ca2+]o CHEB did not alter EPP amplitude or quantal content. 5. The plot of log quantal content vs log [Ca2+]o showed a parallel shift to the left in the presence of 100 microM CHEB. This change occurred without any alteration in the maximum quantal content. This suggests that the enhancement of transmitter release may be mediated by an effect on calcium fluxes in the pre-junctional nerve terminal.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009045	Motor Endplate	The specialized postsynaptic region of a muscle cell. The motor endplate is immediately across the synaptic cleft from the presynaptic axon terminal. Among its anatomical specializations are junctional folds which harbor a high density of cholinergic receptors.	Motor End-Plate,End-Plate, Motor,End-Plates, Motor,Endplate, Motor,Endplates, Motor,Motor End Plate,Motor End-Plates,Motor Endplates
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
D011919	Rats, Inbred Strains	Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.	August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D003292	Convulsants	Substances that act in the brain stem or spinal cord to produce tonic or clonic convulsions, often by removing normal inhibitory tone. They were formerly used to stimulate respiration or as antidotes to barbiturate overdose. They are now most commonly used as experimental tools.	Convulsant,Convulsant Effect,Convulsant Effects,Effect, Convulsant,Effects, Convulsant
D005260	Female		Females
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
D001463	Barbiturates	A class of chemicals derived from barbituric acid or thiobarbituric acid. Many of these are GABA MODULATORS used as HYPNOTICS AND SEDATIVES, as ANESTHETICS, or as ANTICONVULSANTS.