| 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 |
| 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) |
| double-channel catheter | A catheter with two lumens, allowing irrigation and aspiration. Synonym: two-way catheter. (05 Mar 2000) |
| ion channel | <cell biology> A transmembrane pore that presents a hydrophilic channel for ions to cross a lipid bilayer down their electrochemical gradients. Some degree of ion specificity is usually observed and typically a million ions per second may flow. Channels may be permanently open, like the potassium leak channel or they may be voltage gated, like the sodium channel or ligand gated like the acetylcholine receptor. (27 Oct 1998) |
| ion channel gating | The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability. (12 Dec 1998) |
| transnexus channel | A hexagonal 15-20A |
| ligand-gated channel | A class of ion channel's whose ionic permeability is regulated by cell membrane receptors that respond to specific extracellular chemical signals. (05 Mar 2000) |
| ligand gated ion channel | A transmembrane ion channel whose permeability is increased by the binding of a specific ligand, typically a neurotransmitter at a chemical synapse. The permeability change is often drastic, such channels let through effectively no ions when shut, but allow passage at up to 10exp7 ions sexp 1 when a ligand is bound. Recently, the receptors for both acetylcholine and GABA have been found to share considerable sequence homology, implying that there may be a family of structurally related ligand gated ion channels. (18 Nov 1997) |
| calcifying epithelial odontogenic tumour | A benign epithelial odontogenic neoplasm derived from the stratum intermedium of the enamel organ; a painless, slowly growing, mixed radiolucent-radiopaque lesion characterised histologically by cords of polyhedral epithelial cells, deposits of amyloid, and spherical calcifications. Synonym: Pindborg tumour. (05 Mar 2000) |
| Malassez' epithelial rests | Epithelial remains of Hertwig's root sheath in the periodontal ligament. (05 Mar 2000) |
| retinal pigmented epithelial cell | See: pigmented retinal epithelium, retina. (18 Nov 1997) |
| Golgi epithelial cell | A glial cell found in the cerebellar cortex. See: Bergmann's fibres. (05 Mar 2000) |