Biomaterial Database

Behaviour of chemically modified sodium channels in frog nerve supports a three-state model of inactivation. 1985

J Schmidtmayer

Voltage clamp experiments were done on single myelinated nerve fibres of the frog, Rana esculenta, with 10 mM TEA+ in the external solutions to block potassium channels. Sodium current inactivation was measured in TEA-Ringer solution and after treatment with Anemonia sulcata toxin II (5 microM), internal iodate (20/40 mM), glutaraldehyde (10 mM), chloramine-T (0.6 mM), and 2,4,6-trinitrophenol (1 mM). The diphasic inactivation time course, observed in untreated membranes, is slowed by all these agents in a very similar way. Both time constants are increased and the proportion of inactivation components is changed favouring the slowly inactivating one. Trinitrophenol only slows inactivation, whereas in Anemonia toxin II, internal iodate, glutaraldehyde and chloramine-T inactivation becomes incomplete, so that a persistent current is flowing during depolarizations. None of these agents even at high concentrations however, totally removes inactivation. These modifications of inactivation time course are interpreted as changes of rate constants in a three-state inactivation model with one open and two closed states (o-c-c). After chemical treatment the access to the closed states is impeded and the transitions into the open state are accelerated. If the membrane is depolarized during drug application chloramine-T fails to modify inactivation. The curve relating the steady state inactivation parameter, h infinity, to the conditioning potential, V pp becomes non-monotonic in chloramine-T, i.e. dh infinity/dV pp greater than 0 for V pp greater than 60 mV. Trinitrophenol, which per se fails to produce a persistent current component, increases the persistent current in a fibre pretreated with chloramine-T.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D007452	Iodates	Inorganic salts of iodic acid (HIO3).	Iodate
D007473	Ion Channels	Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.	Membrane Channels,Ion Channel,Ionic Channel,Ionic Channels,Membrane Channel,Channel, Ion,Channel, Ionic,Channel, Membrane,Channels, Ion,Channels, Ionic,Channels, Membrane
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
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009413	Nerve Fibers, Myelinated	A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.	A Fibers,B Fibers,Fiber, Myelinated Nerve,Fibers, Myelinated Nerve,Myelinated Nerve Fiber,Myelinated Nerve Fibers,Nerve Fiber, Myelinated
D010851	Picrates	Salts or esters of PICRIC ACID.
D011893	Rana esculenta	An edible species of the family Ranidae, occurring in Europe and used extensively in biomedical research. Commonly referred to as "edible frog".	Pelophylax esculentus
D002700	Chloramines	Inorganic derivatives of ammonia by substitution of one or more hydrogen atoms with chlorine atoms or organic compounds with the general formulas R2NCl and RNCl2 (where R is an organic group).	Chloroamines
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
D005976	Glutaral	One of the protein CROSS-LINKING REAGENTS that is used as a disinfectant for sterilization of heat-sensitive equipment and as a laboratory reagent, especially as a fixative.	Glutaraldehyde,Cidex,Diswart,Gludesin,Glutardialdehyde,Glutarol,Korsolex,Novaruca,Sekumatic,Sonacide,Sporicidin