Voltage potassium channels

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. 

Basic characteristics Inward Rectifier Potassium Channels or Kir Channels are a class of potassium channels generated by Inward Rectification, which decreased conductance upon depolarization. In classical inward rectifiers, rectification is strong and currents rapidly decline at voltages positive to the reversal potential (see Fig. 2). In other Kir channels, rectification is weak and currents decline only gradually at voltages positive to the reversal potential (see Fig. 2). 

Kv 3 -subunits are auxiliary subunits of Shaker-related Kv-channels, which belong to the Kvl subfamily of voltage-gated potassium channels. Kv(3 -subunits may function as chaperones in Kva -subunit assembly and may modulate the gating properties of Kv-channels. In particular, some Kv(3 -subunits may confer a rapid inactivation to otherwise non-inactivating Kv-channels. 

Kv-channel is an abbreviation of voltage-gated potassium channels. K stands for potassium and v for voltage. 

Inhibition of voltage operated potassium channels Activation of PLCp... 

Shaker-channels, eag (ether- -go-go)-channels, slo (slow-poke)-channels were cloned from behavioral Drosophila melanogaster mutants. The channels were named according to the Drosophila mutant phenotype, Shaker, ether-go-go, slow-poke. Subsequently, eag-cDNA was used to clone related voltage-gated potassium channel subunits erg (eag-related) and elk (eag-like). The human erg ortholog (HERG) mediates cardiac DCS. 

Pongs O (1999) Voltage-gated potassium channels from hyperexcitability to excitement. FEBS Lett 452 31-35... 

Peukert S, Brendel J, Pirard B, Briiggemann A, Below P, Kleemann HW, Hem-merle H, Schmidt W. Identification, synthesis, and activity of novel blockers of the voltage-gated potassium channel Kvl.5. J Med Chem 2003 46 486-98. 

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. 

Fig. 6.21 Joint application of patch-clamp and voltage-clamp methods to the study of a single potassium channel present in the membrane of a spinal-cord neuron cultivated in the tissue culture. The values indicated before each curve are potential differences imposed on the membrane. The ion channel is either closed (C) or open (O). (A simplified drawing according to B. Hille)...

Understand the function of sodium and potassium voltage-gated channels... 

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... 

Gutman, G. A. et al. International Union of Pharmacology. XLI. Compendium of voltage-gated ion channels potassium channels. Pharmacol. Rev. 55 583-586,2003. 

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