Biomaterial Database

The thiol-oxidizing agent diamide increases transmitter release by decreasing calcium requirements for neuromuscular transmission in the frog. 1976

P L Carlen, and E M Kosower, and R Werman

Diamide, which in concentrations of 10(-5) M and higher oxidizes glutathione intracellularly, produces a dose-related increase in the frequency of miniature end-plate potentials (MEPPs). With high enough doses, quantal release is blocked, apparently through exhaustion. The early phase of MEPP frequency increase is accompanied by an increase in EPP amplitude that may reach more than 10-fold and is therefore not produced by depolarization of axon terminals. Subsequently, EPP amplitude is reduced and falls to zero, associated with failure of invasion of the nerve action into the terminals while the MEPP frequency remains elevated. Both facilitation and PTP follow the time course of change in EPP amplitude. The increase in MEPP frequency with diamide does not require external Ca2+ but raising external Ca2+ increases the MEPP rate in the presence of diamide. External Ca2+ is necessary for EPP appearance and also potentiates the diamide effects. Conversely diamide reduces the requirements for Ca2+ in releasing ACh. Diamide substitutes for external Ca2+ in K+ evoked MEPP release and in the absence of external Ca2+, diamide-evoked MEPP release is increased by raising external Mg2+ levels. The action of diamide may be dependent on the actual release of Ca2+ from intracellular stores or it may work through mimicking some of the actions of Ca2+. The action of diamide bears close resemblance to the effects of prolonged stimulation of the motor axon at 10 Hz.

UI	MeSH Term	Description	Entries
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
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
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009411	Nerve Endings	Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.	Ending, Nerve,Endings, Nerve,Nerve Ending
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
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D011898	Ranidae	The family of true frogs of the order Anura. The family occurs worldwide except in Antarctica.	Frogs, True,Rana,Frog, True,True Frog,True Frogs
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
D003958	Diamide	A sulfhydryl reagent which oxidizes sulfhydryl groups to the disulfide form. It is a radiation-sensitizing agent of anoxic bacterial and mammalian cells.	Diazodicarboxylic Acid Bis(N,N-dimethyl)amide,Diazodicarboxylic Acid Bisdimethylamide,Dizene Dicarboxylic Acid Bis(N,N-dimethylamide),Dizenedicarboxylic Acid Bis(N,N-dimethylamide),Tetramethylazoformamide,Acid Bisdimethylamide, Diazodicarboxylic,Bisdimethylamide, Diazodicarboxylic Acid