| gated ion channel | <physiology> Transmembrane proteins of excitable cells, that allow a flux of ions to pass only under defined circumstances. Channels may be either voltage gated, such as the sodium channel of neurons or ligand gated such as the acetylcholine receptor of cholinergic synapses. Channels tend to be relatively ion specific and allow fluxes of typically 1000 ions to pass in around 1ms, they are thus much faster at moving ions across a membrane than transport ATPases. (05 May 1997) |
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| voltage-gated channel | A class of ion channel's that open and close in response to change in the electrical potential across the plasma membrane of the cell; voltage-gated Na+ c.'s are important for conducting action potential along nerve cell processes. (05 Mar 2000) |
| voltage gated ion channel | <physiology> A transmembrane ion channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. These channels are essential for neuronal signal transmission and for intracellular signal transduction. See: sodium channel. (18 Nov 1997) |
| channel | A furrow, gutter, or groovelike passageway. See: canal. Origin: L. Canalis (05 Mar 2000) |
| channel forming ionophore | <chemistry> An ionophore that makes an amphipathic pore with hydrophobic exterior and hydrophilic interior. most known types are cation selective. (18 Nov 1997) |
| channel gating | <physiology> Small currents in the membrane just prior to the increase in ionic permeability, due to the movement of charged particles within the membrane. So called because they open the gates for current flow through ion channels. (20 Mar 1998) |
| channel protein | <chemistry, physiology> A protein that facilitates the diffusion of molecules/ions across lipid membranes by forming a hydrophilic pore. most frequently multimeric with the pore formed by subunit interactions. (18 Nov 1997) |
| channel transport | <radiobiology> In inertial fusion research using light ion drivers, describes the use of current-carrying plasma channels (which are magnetically confined to the channel) to transport electron or ion beams between the ion diode and the fusion target. This allows the ion source to stand back from the target. (09 Oct 1997) |
| chloride channel | Ion channels selective for chloride ions. Various types including ligand activated Cl channels at synapses (the GABA and glycine activated channels), as well as voltage gated Cl channels found in a variety of plant and animal cells. See: CFTR, MDR. (18 Nov 1997) |
| ryanodine receptor calcium release channel | Protein complexes that mediate the release of calcium from the sarcoplasmic reticulum in both skeletal and cardiac muscle cells by forming tetrametric complexes. These complexes each then act as a calcium channel. There are three isoforms of the ryr: ryr1, ryr2, and ryr3. Ryr1 is specifically expressed in skeletal muscles and ryr2 in cardiac muscles. Ryr3 is yet another isoform found in non-muscle cells such as neuronal cells. (12 Dec 1998) |
| potassium channel | Ion channel selective for potassium ions. There are diverse types with different functions, for example: delayed rectifier channels, M channels, A channels, inward rectifier channels, Ca dependent K channels. (18 Nov 1997) |
| single channel recording | Variant of patch clamp technique. (18 Nov 1997) |
| slow channel-blocking agent | calcium channel-blocking agent |
| sodium channel | <neurology, physiology> The protein responsible for electrical excitability of neurons. A transmembrane ion channel, containing an aqueous pore around 0.4nm diameter, with a negatively charged region internally (the selectivity filter) to block passage of anions. The channel is voltage gated: it opens in response to a small depolarisation of the cell (usually caused by an approaching action potential), by a multistep process. Around 1000 sodium ions pass in the next millisecond, before the channel spontaneously closes (an event with single step kinetics). The channel is then refractory to further depolarisations until returned to near the resting potential. There are around 100 channels per square micron in unmyelinated axons, in myelinated axons, they are concentrated at the nodes of Ranvier. The sodium channel is the target of many of the deadliest neurotoxins. (18 Nov 1997) |
| delayed rectifier channel | <physiology> The potassium selective ion channels of axons, so called because they change the potassium conductance with a delay after a voltage step. The name is used to denote any axon like K channel. Various roles for example regulation of pacemaker potentials, generation of bursts of action potentials or generation of long plateaus on action potentials. (18 Nov 1997) |