ion channel

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i·on chan·nel

a specific macromolecular protein pathway, with an aqueous "pore," which traverses the lipid bilayer of a cell's plasma membrane and maintains or modulates the electrical potential across this barrier by allowing the controlled influx or exit of small inorganic ions such as Na+, K+, Cl-, and Ca2+. It plays an important role in propagation of the action potential in neurons, but also may control transduction of extracellular signals and contraction in muscle cells. In general, ion channels are characterized by their selectivity for certain ions, their specific regulation or gating of these ions, and their specific sensitivity to toxins.

ion channel

n.
A pathway through a protein molecule or complex in a cell membrane that modulates the electrical potential across the membrane by controlling the passage of small inorganic ions into and out of the cell.

ion channel

A protein that spans the lipid bilayer of the cell membrane and regulates the movement of charged particles (e.g., electrolytes) into and out of cells.
See also: channel
References in periodicals archive ?
The magnitude of fluctuations in current densities (channel noise) depends on the number of ionic channels and, thus, for fixed channel densities ([[rho].sub.Na] = 60 channels/[micro][m.sup.2], [[rho].sub.K] = 18 channels/[micro][m.sup.2]), on the area of the considered membrane patch.
The mean firing rate, i.e., the number of spikes per second, is due to the operating point fixed by the OHC and to the endogenous noise related to the number of ionic channels. To quantify the level of firing inhibition, and thus of tinnitus suppression, induced by the electric stimulation, it is necessary to introduce a sensitive technique.
Important observations indicate a coherent cluster structure of a large number (~105) of voltage-gated ionic channels [31,32], which could have transient receptor potential receptors (TRP, especially the TRPV subtypes) in one temperature-sensing domain [33].
The field-strength of the cell membrane is huge: E [approximately equal to] [10.sup.7] V / m consequently, its effect on the ionic channels is expected and it will likely polarise the transmembrane proteins until their saturated polarisation value is reached because the rotational diffusion is stronger in the membrane than the translational [60] diffusion.
The intracranial injection assay was performed to investigate whether there would be any direct activity of the toxin in the central nervous system (CNS), once peptides can promote behavioral alterations by acting on receptors and ionic channels on CNS.
Not much is known about the effects of lignans on ionic channels. The only plant lignan known to affect [K.sup.+] channels is NDGA.
In this work we examined whether arylnaphthalene lignans isolated from Taiwania cryptomerioides would affect neuronal ionic channels. For the first time we reported that they could inhibit Kv channels (Fig.
Moreover, the scorpion toxins probably act in the ionic channels at cellular membrane level.
These are further explained in the section about synapses and ionic channels.
The membranes of all these axon sprouts are enriched with ionic channels and various forms of receptors that make the neuroma excitable.
the oocytes with their surrounding follicular cells, are a very useful cellular model for studying neurotransmitter and hormone receptors, ionic channels and the intracellular mechanisms that operate them (for reviews see, Miledi et al., 1989; Arellano et al., 1996).
The results derived from this study strongly suggest that the [Ca.sup.2+]-dependent chloride currents evoked by the plant extracts are originated by activation of similar ionic channels. Further experiments will, however, be necessary to obtain information concerning the level at which the extracts activate the [Ca.sup.2+] release, and to determine if the I[P.sub.3]-diacylglycerol pathway is activated in Xenopus oocytes exposed to the extracts.