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The sodium–potassium pump a critical enzyme for regulating sodium and potassium levels in cells. Potassium is the main intracellular ion for all types of cells, while having a major role in maintenance of fluid and electrolyte balance. [1] [2] Potassium is necessary for the function of all living cells and is thus present in all plant and ...
Potassium channels function to conduct potassium ions down their electrochemical gradient, doing so both rapidly (up to the diffusion rate of K + ions in bulk water) and selectively (excluding, most notably, sodium despite the sub-angstrom difference in ionic radius). [4] Biologically, these channels act to set or reset the resting potential in ...
K ir export surplus potassium into collecting tubules for removal in the urine, or alternatively may be involved in the reuptake of potassium back into the body. neurons and in heart cells: G-protein activated IRKs (K ir 3) are important regulators, modulated by neurotransmitters. A mutation in the GIRK2 channel leads to the weaver mouse mutation.
This family of ion channels is, for the most part, activated by intracellular Ca 2+ and contains 8 members in the human genome. However, some of these channels (the K Ca 4 and K Ca 5 channels) are responsive instead to other intracellular ligands, such as Na +, Cl −, and pH.
Potassium homeostasis denotes the maintenance of the total body potassium content, plasma potassium level, and the ratio of the intracellular to extracellular potassium concentrations within narrow limits, in the face of pulsatile intake (meals), obligatory renal excretion, and shifts between intracellular and extracellular compartments.
BK channels (big potassium), are large conductance calcium-activated potassium channels, [1] also known as Maxi-K, slo1, or Kca1.1. BK channels are voltage-gated potassium channels that conduct large amounts of potassium ions (K + ) across the cell membrane , hence their name, big potassium .
An ATP-sensitive potassium channel (or K ATP channel) is a type of potassium channel that is gated by intracellular nucleotides, ATP and ADP. ATP-sensitive potassium channels are composed of K ir 6.x-type subunits and sulfonylurea receptor (SUR) subunits, along with additional components. [ 1 ]
The renal outer medullary potassium channel (ROMK) is an ATP-dependent potassium channel (K ir 1.1) that transports potassium out of cells. It plays an important role in potassium recycling in the thick ascending limb (TAL) and potassium secretion in the cortical collecting duct (CCD) of the nephron .