Potassium channels voltage-dependent

Antidiabetic Drugs other than Insulin. Figure 1 Sulphonylureas stimulate insulin release by pancreatic (3-cells. They bind to the sulphonylurea receptor (SUR-1), which closes Kir6.2 (ATP-sensitive) potassium channels. This promotes depolarisation, voltage-dependent calcium influx, and activation of calcium-sensitive proteins that control exocytotic release of insulin. 

Brown, DA (2000) The acid test for resting potassium channels. Curr. Biol. 10 R456-R459. Dolphin, AC (1998) Mechanisms of modulation of voltage-dependent calcium channels by G proteins. J. Physiol. 506 3-11. 

Voltage-dependent Na+, K+, Ca2+ channels Ca2+-dependent potassium channels Enzymes and other proteins involved in the regulation of second messengers G proteins Phospholipases Adenylyl cyclases Guanylyl cyclases Phosphodiesterases IP3 receptor Protein kinases... 

Several different changes in mitochondria occur during apoptosis. These include a change in membrane potential (usually depolarization), increased production of reactive oxygen species, potassium channel activation, calcium ion uptake, increased membrane permeability and release of cytochrome c and apoptosis inducing factor (AIF) [25]. Increased permeability of the mitochondrial membranes is a pivotal event in apoptosis and appears to result from the formation of pores in the membrane the proteins that form such permeability transition pores (PTP) may include a voltage-dependent anion channel (VDAC), the adenine nucleotide translocator, cyclophilin D, the peripheral benzodiazepine receptor, hexokinase and... 

Nelson MT, Patlak JB, Worley JF, Standen NB 1990 Calcium channels, potassium channels, and voltage dependence of arterial smooth muscle tone. Am J Physiol 259 C3-C18 Nixon GF, Mignery GA, Somlyo AV 1994 Immunogold localization of inositol 1,4,5-trisphosphate receptors and characterization of ultrastructural features of the sarcoplasmic reticulum in phasic and tonic smooth muscle. J Muscle Res Cell Motil 15 682-700 Peng H, Matchkov V, Ivarsen A, Aalkjaer C, Nilsson H 2001 Hypothesis for the initiation of vasomotion. CircRes 88 810-815... 

The Shaker potassium channel did not yield crystals for the first potassium ion channel X-ray crystallographic structure. Rather, it was the prokaryote bacterium Streptomyces lividans, abbreviated as the KcsA K+ channel, that first produced crystals suitable for crystallography. This structure, published in 1998 by MacKinnon s group in Science magazine, was received with great praise from the scientific community. It was known at that time that the amino acid sequence of KcsA was similar to that of other K channels, including vertebrate and invertebrate voltage-dependent K (Kv) channels (such as the... 

A circuit that uses a differential amplifier to maintain constant membrane potential by electronically balancing the ion channel current. This method allows the experimenter to analyze action potentials of excitable membranes resulting from an initial transient rise in sodium ion permeability followed by a transient rise in potassium ion permeability The technique is especially valuable for studying kinetic properties of voltage-gated channels as well as voltage-dependent channels. See Membrane Potential Patch Clamp Methods... 

Dofetilide blocks IKr in all myocardial tissues. It blocks open channels, and its binding and release from the channels is voltage dependent. The effects of dofetilide are exaggerated when the extracellular potassium concentration is reduced, which is important, as many patients may be receiving diuretics concurrently. Conversely, hyperkalemia decreases the effects of dofetilide, which may limit its efficacy when local hyperkalemia occurs, such as during myocardial ischemia. Dofetilide demonstrates reverse use dependence, that is, less influence on the action potential at faster heart... 

Potassium ion channels are a veiy diverse family of membrane proteins, with numerous sub-types both in the CNS and peripheral tissues, in particular in the heart. On the basis of the amino acid sequence of the pore-forming a sub-unit, they are classified into two main super-families, the inward rectifier superfamily (which includes receptor-coupled, adenosine 5 -triphosphate (ATP)-sensitive and voltage-dependent channels) and the Sha/cer-related superfamily (which includes Ca2-H-dependent channels). 

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