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| Names | |
|---|---|
| Preferred IUPAC name 2,2-Dimethyl-4-(2-oxopyridin-1(2H)-yl)-2H-1-benzopyran-6-carbonitrile | |
| Identifiers | |
3D model (JSmol) | |
| ChEMBL | |
| ChemSpider | |
PubChem CID | |
| UNII | |
CompTox Dashboard (EPA) | |
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| Properties | |
| C17H14N2O2 | |
| Molar mass | 278.311 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Bimakalim is a potassium channel opener. [1] It can be prepared from 2-acetyl-4-cyanophenol . [2]
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume. Ion channels are present in the membranes of all cells. Ion channels are one of the two classes of ionophoric proteins, the other being ion transporters.
BK channels (big potassium), are large conductance calcium-activated potassium channels, 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. These channels can be activated (opened) by either electrical means, or by increasing Ca2+ concentrations in the cell. BK channels help regulate physiological processes, such as circadian behavioral rhythms and neuronal excitability. BK channels are also involved in many processes in the body, as it is a ubiquitous channel. They have a tetrameric structure that is composed of a transmembrane domain, voltage sensing domain, potassium channel domain, and a cytoplasmic C-terminal domain, with many X-ray structures for reference. Their function is to repolarize the membrane potential by allowing for potassium to flow outward, in response to a depolarization or increase in calcium levels.
Unlike the action potential in skeletal muscle cells, the cardiac action potential is not initiated by nervous activity. Instead, it arises from a group of specialized cells known as pacemaker cells, that have automatic action potential generation capability. In healthy hearts, these cells form the cardiac pacemaker and are found in the sinoatrial node in the right atrium. They produce roughly 60–100 action potentials every minute. The action potential passes along the cell membrane causing the cell to contract, therefore the activity of the sinoatrial node results in a resting heart rate of roughly 60–100 beats per minute. All cardiac muscle cells are electrically linked to one another, by intercalated discs which allow the action potential to pass from one cell to the next. This means that all atrial cells can contract together, and then all ventricular cells.
Potassium channels are the most widely distributed type of ion channel found in virtually all organisms. They form potassium-selective pores that span cell membranes. Potassium channels are found in most cell types and control a wide variety of cell functions.
Calcium-activated potassium channels are potassium channels gated by calcium, or that are structurally or phylogenetically related to calcium gated channels. They were first discovered in 1958 by Gardos who saw that calcium levels inside of a cell could affect the permeability of potassium through that cell membrane. Then in 1970, Meech was the first to observe that intracellular calcium could trigger potassium currents. In humans they are divided into three subtypes: large conductance or BK channels, which have very high conductance which range from 100 to 300 pS, intermediate conductance or IK channels, with intermediate conductance ranging from 25 to 100 pS, and small conductance or SK channels with small conductances from 2-25 pS.
SK channels are a subfamily of calcium-activated potassium channels. They are so called because of their small single channel conductance in the order of 10 pS. SK channels are a type of ion channel allowing potassium cations to cross the cell membrane and are activated (opened) by an increase in the concentration of intracellular calcium through N-type calcium channels. Their activation limits the firing frequency of action potentials and is important for regulating afterhyperpolarization in the neurons of the central nervous system as well as many other types of electrically excitable cells. This is accomplished through the hyperpolarizing leak of positively charged potassium ions along their concentration gradient into the extracellular space. This hyperpolarization causes the membrane potential to become more negative. SK channels are thought to be involved in synaptic plasticity and therefore play important roles in learning and memory.
Kv7.3 (KvLQT3) is a potassium channel protein coded for by the gene KCNQ3.
Calcium-activated potassium channel subunit alpha-1 also known as large conductance calcium-activated potassium channel, subfamily M, alpha member 1 (KCa1.1), or BK channel alpha subunit, is a voltage gated potassium channel encoded by the KCNMA1 gene and characterized by their large conductance of potassium ions (K+) through cell membranes.
Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 4, also known as KCNN4, is a human gene encoding the KCa3.1 protein.
Calcium-activated potassium channel subunit beta-1 is a protein that in humans is encoded by the KCNMB1 gene.
Potassium voltage-gated channel, Shab-related subfamily, member 1, also known as KCNB1 or Kv2.1, is a protein that, in humans, is encoded by the KCNB1 gene.
Calcium-activated potassium channel subunit beta-2 is a protein that in humans is encoded by the KCNMB2 gene.
Calcium-activated potassium channel subunit beta-3 is a protein that in humans is encoded by the KCNMB3 gene.
Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 2, also known as KCNN2, is a protein which in humans is encoded by the KCNN2 gene. KCNN2 is an ion channel protein also known as KCa2.2.
Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 1 , also known as KCNN1 is a human gene encoding the KCa2.1 protein.
Calcium-activated potassium channel subunit beta-4 is a protein that in humans is encoded by the KCNMB4 gene.
The G protein-coupled inwardly rectifying potassium channels (GIRKs) are a family of lipid-gated inward-rectifier potassium ion channels which are activated (opened) by the signaling lipid PIP2 and a signal transduction cascade starting with ligand-stimulated G protein-coupled receptors (GPCRs). GPCRs in turn release activated G-protein βγ- subunits (Gβγ) from inactive heterotrimeric G protein complexes (Gαβγ). Finally, the Gβγ dimeric protein interacts with GIRK channels to open them so that they become permeable to potassium ions, resulting in hyperpolarization of the cell membrane. G protein-coupled inwardly rectifying potassium channels are a type of G protein-gated ion channels because of this direct interaction of G protein subunits with GIRK channels. The activation likely works by increasing the affinity of the channel for PIP2. In high concentration PIP2 activates the channel absent G-protein, but G-protein does not activate the channel absent PIP2.
Potassium channel, subfamily K, member 13 (KCNK13), also known as K2P13.1 or THIK-1, is a protein that in humans is encoded by the KCNK13 gene. It is a potassium channel containing two pore-forming P domains.
Potassium channel subfamily T, member 2, also known as KCNT2 is a human gene that encodes the KNa protein. KCNT2, also known as the Slick channel is an outwardly rectifying potassium channel activated by internal raises in sodium or chloride ions.
A potassium channel opener is a type of drug which facilitates ion transmission through potassium channels.
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