Biomaterial Database

Enhancement by Anemonia sulcata toxin II of spontaneous quantal transmitter release from mammalian motor nerve terminals. 1986

J Molgo, and M Lemeignan, and F Tazieff-Depierre

The action of Anemonia sulcata toxin II (ATX-II) on spontaneous quantal transmitter release from motor nerve terminals was investigated by recording miniature end-plate potentials (MEPPs) from isolated mouse phrenic nerve--hemidiaphragm nerve--muscle preparations. ATX-II (3.2 microM) when applied for 3-40 min to junctions bathed in a normal ionic medium enhanced about one hundred fold the rate of spontaneous MEPPs. Concomitantly, ATX-II depolarized the muscle fiber. The effect of the toxin on MEPP frequency was markedly reduced when junctions were exposed to Na-deficient solutions or pre-treated with dantrolene sodium (10 microM). ATX-II (0.24-3.2 microM) increased MEPP rate in junctions exposed to a Ca-free medium containing 2 mM EGTA and 2 mM Mg2+ in a dose- and time-dependent manner. Tetrodotoxin (0.2-1 microM) prevented the effects of ATX-II on MEPP frequency and on the resting membrane potential of muscle fibers. Tetrodotoxin also antagonized the acceleration of MEPP induced by ATX-II. The experimental findings suggest that ATX-II acts to increase quantal transmitter output from motor nerve terminals by enhancing Na+ influx through tetrodotoxin-sensitive presynaptic channels, since ATX-II action does not appear to depend upon entry of Ca2+ from the extracellular medium. It is likely that ATX-II, by increasing intraterminal Na+ concentration, may trigger calcium release from internal stores.

UI	MeSH Term	Description	Entries
D008297	Male		Males
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
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
D010791	Phrenic Nerve	The motor nerve of the diaphragm. The phrenic nerve fibers originate in the cervical spinal column (mostly C4) and travel through the cervical plexus to the diaphragm.	Nerve, Phrenic,Nerves, Phrenic,Phrenic Nerves
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
D003064	Cnidarian Venoms	Venoms from jellyfish; CORALS; SEA ANEMONES; etc. They contain hemo-, cardio-, dermo- , and neuro-toxic substances and probably ENZYMES. They include palytoxin, sarcophine, and anthopleurine.	Chironex Venoms,Jellyfish Venoms,Nematocyst Venoms,Sea Anemone Venoms,Chironex Venom,Cnidarian Venom,Jellyfish Venom,Portuguese Man-of-War Venom,Sea Anemone Venom,Portuguese Man of War Venom,Venom, Chironex,Venom, Cnidarian,Venom, Jellyfish,Venom, Portuguese Man-of-War,Venom, Sea Anemone,Venoms, Chironex,Venoms, Cnidarian,Venoms, Jellyfish,Venoms, Nematocyst,Venoms, Sea Anemone
D003620	Dantrolene	Skeletal muscle relaxant that acts by interfering with excitation-contraction coupling in the muscle fiber. It is used in spasticity and other neuromuscular abnormalities. Although the mechanism of action is probably not central, dantrolene is usually grouped with the central muscle relaxants.	Dantrium,Dantrolene Sodium,Sodium, Dantrolene
D003964	Diaphragm	The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.	Respiratory Diaphragm,Diaphragm, Respiratory,Diaphragms,Diaphragms, Respiratory,Respiratory Diaphragms
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential