Biomaterial Database

Tetrodotoxin-resistant sodium current of rat nodose neurones: monovalent cation selectivity and divalent cation block. 1987

S R Ikeda, and G G Schofield

Section of Electrophysiology, National Institute of Alcohol Abuse and Alcoholism, Rockville, MD 20852.

1. Monovalent cation selectivity and divalent cation sensitivity of the tetrodotoxin (TTX)-resistant Na+ current in dissociated adult rat nodose ganglion neurones were investigated using the whole-cell patch-clamp technique. 2. The TTX-resistant Na+ current was isolated using ion substitution and pharmacological agents. Under these conditions, the current reversal potential shifted 52 mV per tenfold change in external [Na+]. 3. Inorganic and organic monovalent cation permeability ratios (Px/PNa) were determined from changes in reversal potential and the Goldman-Hodgkin-Katz equation. The Px/PNa values determined by the former method were HONH3+, 1.38; Li+, 1.00; H2NNH3+, 0.66; NH4+, 0.28; CH3NH3+, less than 0.13; K+, less than 0.13; Rb+, less than 0.12; Cs+, less than 0.10; (CH3)4N+, less than 0.10. The values determined by either method agreed within 10%. 4. The effects of Cd2+, Co2+, Mn2+ and Ni2+ on the TTX-resistant Na+ current were analysed from peak-conductance values. These ions shifted the activation of the current to more positive potentials and decreased the maximal conductance. At 3 mM concentrations, Cd2+, Ni2+, Co2+ and Mn2+ decreased the maximal conductance 64.6, 50.7, 25.0 and 20.3%, respectively. 5. The results indicate that: (a) the monovalent cation selectivity of the TTX-resistant Na+ current is similar to that of the TTX-sensitive Na+ current in other tissues; and (b) the TTX-resistant Na+ current is less sensitive to divalent cations than the Ca2+ current in these neurones. These observations suggest that the structure determining the monovalent cation permeability of the TTX-resistant Na+ current is similar to that of the TTX-sensitive Na+ current in other tissues, and that the channels carrying the TTX-resistant Na+ current are distinct from those responsible for the Ca2+ current.

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
D008297	Male		Males
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
D009620	Nodose Ganglion	The inferior (caudal) ganglion of the vagus (10th cranial) nerve. The unipolar nodose ganglion cells are sensory cells with central projections to the medulla and peripheral processes traveling in various branches of the vagus nerve.	Nodose Ganglia,Ganglia, Nodose,Ganglion, Nodose
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
D002413	Cations, Divalent	Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.	Divalent Cations
D002414	Cations, Monovalent	Positively charged atoms, radicals or group of atoms with a valence of plus 1, which travel to the cathode or negative pole during electrolysis.	Monovalent Cation,Cation, Monovalent,Monovalent Cations
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
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
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