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Ion Channels and The Control of Uterine Contractility
Published in Robert E. Garfield, Thomas N. Tabb, Control of Uterine Contractility, 2019
In the myometrium, an increase in the concentration of free calcium in the cytoplasm is essential for the initiation of contraction. Calcium can enter the cell through plasma membrane channels of two different classes. Voltage-sensitive ion channels mediate rapid, voltage-gated changes in ion conductance during the action potential. The calcium entering during action potentials serves as the primary intracellular second messenger for initiating excitation-contraction coupling and multiple calcium-activated biochemical processes. In addition, these channels can be regulated by receptor-dependent processes, including protein phosphorylation and interaction with GTP-binding proteins. In contrast, ligand-gated ion channels are opened in response to activation of an associated receptor. Typical channels of this class include the nonspecific channels that are opened by activation of membrane receptors. Generally, activation of ligand-gated ion channels mediates local increases in ion conductance, producing depolarization or hyperpolarization of the membrane.
Answers
Published in Calver Pang, Ibraz Hussain, John Mayberry, Pre-Clinical Medicine, 2017
Calver Pang, Ibraz Hussain, John Mayberry
There are three main groups of ion channels which are voltage gated channels, extracellular ligand activated channels and intracellular ligand gated ion channels. Examples of voltage gated channels include sodium, potassium and calcium. Examples of extracellular ligand gated ion channels include nicotinic acetylcholine receptors, GABA and ROMK channel. Example of intracellular ligated ion channels includes CFTR.
Structure and Function of the Lower Urinary Tract
Published in Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George, The Scientific Basis of Urology, 2010
The acetylcholine released from the varicosities at the ends of parasympathetic nerves has a variety of different actions depending on exactly where it is released and particularly on the nature of the receptors present. As a general rule, the same applies to all transmitters and all nerves. Many transmitters are associated with several different types of receptors and each type of receptor has several subtypes, each with different effects. When acetylcholine is released from preganglionic nerve fibers in the parasympathetic ganglia of the pelvic plexus and in the bladder wall its principal targets are the receptors on the cell bodies of the postganglionic nerves. These receptors are nicotinic in type, which are ligand-gated ion channels.
Treatment Options for Anti-N-methyl-D-aspartate Receptor Encephalitis
Published in The Neurodiagnostic Journal, 2018
N-methyl-d-aspartate (NMDA) is an excitotoxin; it destroys nerve cells by overexciting them (Watkins 2015). This water-soluble artificial element is described as not typically found in organic issue (Masuko et al. 2008). NMDA receptors are a precise type of ionotropic glutamate receptor that controls synaptic plasticity and memory function and are ubiquitous throughout the body, primarily localized in the brain and spinal cord (Kadewaga et al. 2007; Watkins 2015). These receptors are indispensable for human interaction, judgment, and memory. Ionotropic receptors are also referred to as ligand-gated ion channels (Thompson et al. 2013). The receptors are a group of transmembrane ion channel proteins that permit ions such as Ca2+ and Na+ to cross through the membrane (Thompson et al. 2013).
Cell signal transduction: hormones, neurotransmitters and therapeutic drugs relate to purine nucleotide structure
Published in Journal of Receptors and Signal Transduction, 2018
Major GPCR receptor classes aligned to Gs, Gi and Gq alpha subunits, ligand- and voltage-gated ion channels are identified within the IUPHAR/BPS Guide to Pharmacology [5]. GPCR receptors: 5-hydroxytryptamine (5-HT), acetylcholine (muscarinic), adenosine, α- and β-adrenoceptors, dopamine, GABAB, histamine, glutamate (metabotropic), opioid, prostanoid. Voltage-gated ion channels: cyclic nucleotide-regulated (CNG), potassium (KV, BKCa, KATP), calcium (VGCC), sodium. Ligand-gated ion channels (LGIC): 5-HT3, epithelial sodium channel (ENaC), GABAA, glycine, glutamate (ionotropic), acetylcholine (nicotinic). Molecular structures representative of receptor and ion channel classes are taken from the IUPHAR database (www.guidetopharmacology.org), Pubchem (http://pubchem.ncbi.nlm.nih.gov) and company websites marketing potent and selective agonist and antagonist compounds.
Brain circuits and neurochemical systems in essential tremor: insights into current and future pharmacotherapeutic approaches
Published in Expert Review of Neurotherapeutics, 2018
Sara M Schaefer, Ana Vives Rodriguez, Elan D Louis
Earlier we discussed GABAA receptors. By contrast, GABAB receptors are structurally simpler than GABAA receptors, consisting of only two subunits (GABAB1 and GABAB2) that form a heterodimer. Also, they are G-protein-coupled receptors rather than ligand-gated ion channels. They are found in many regions throughout the brain and spinal cord; their agonism results in widespread effects (Table 1) [19]. GABAA receptors are presynaptic and mediate fast responses, whereas GABAB receptors are pre- and postsynaptic and mediate slow responses [11,19]. GABAB receptor function is thus highly complex. The location of GABAB receptors on both pre- and postsynaptic terminals, and on both interneurons and principal neurons, produces a framework wherein it is difficult to predict how GABAB receptor activation would affect the intracerebellar circuit and, ultimately, the tremor circuit [37].