Biomaterial Database

Block and inactivation of sodium channels in nerve by amino acid derivatives. I. Dependence on voltage and sodium concentration. 1981

M V Lo, and P Shrager

The side chain of arginine, n-propylguanidinium (nPG), reversibly decreases peak sodium conductance and increases the speed of sodium current decay, when perfused internally. Effects are voltage dependent and are more pronounced at high depolarizations. Results are also dependent on the sodium concentration gradient. Both the decline in peak conductance and the speeding of inactivation are greater if the sodium concentration gradient is reversed from the normal. The decrease in peak sodium current is too large to be due solely to the faster decay kinetics. The difference is not due to a change in slow inactivation of the channel. Sodium current inactivation has also been studied with a double pulse procedure. Results show that at - 70 mV, nPG leaves sodium channels rapidly (less than 500 microseconds) in normal sodium gradient, but more slowly (greater than 1 ms) in reversed sodium gradient. Several structural analogs of nPG have been tested. Shortening the alkyl chain weakens effects significantly. Arginine itself, which contains extra charged groups, is also less effective. n-Propylammonium is active but with an apparent affinity only one-fifth that of arginine. We conclude that nPG acts within the sodium channel, and has at least two modes of action.

UI	MeSH Term	Description	Entries
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
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D002621	Chemistry	A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
D003400	Astacoidea	A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.	Astacus,Crayfish,Procambarus,Astacoideas,Crayfishs
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D006146	Guanidines	A family of iminourea derivatives. The parent compound has been isolated from mushrooms, corn germ, rice hulls, mussels, earthworms, and turnip juice. Derivatives may have antiviral and antifungal properties.
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
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23