PHYTIN, Fytiini (IP6) An interesting molecule in human food and the human biochemistry.
https://pubmed.ncbi.nlm.nih.gov/35112133/
PubMed HAKU: Na+, K+, Cl-, ENDOLYMPHA.
Abstract
The endolymphatic sac is a small sac-shaped organ at the end of the membranous labyrinth of the inner ear. The endolymphatic sac absorbs the endolymph, in which the ion balance is crucial for inner ear homeostasis. Of the three sections of the endolymphatic sac, the intermediate portion is the center of endolymph absorption, particularly sodium transport, and is thought to be regulated by aldosterone. Disorders of the endolymphatic sac may cause an excess of endolymph (endolymphatic hydrops), a histological observation in Meniere’s disease. A low-salt diet is an effective treatment for Meniere’s disease, and is based on the assumption that the absorption of endolymph in the endolymphatic sac abates endolymphatic hydrops through a physiological increase in aldosterone level. However, the molecular basis of endolymph absorption in each portion of the endolymphatic sac is largely unknown because of difficulties in gene expression analysis, resulting from its small size and intricate structure. The present study combined reverse transcription-quantitative polymerase chain reaction and laser capture microdissection techniques to analyze the difference of gene expression of the aldosterone-controlled epithelial Na+ channel, thiazide-sensitive Na+-Cl− cotransporter, and Na+, K+-ATPase genes in the three individual portions of the endolymphatic sac in a rat model. A low-salt diet increased the expression of aldosterone-controlled ion transporters, particularly in the intermediate portion of the endolymphatic sac. Our findings will contribute to the understanding of the physiological function of the endolymphatic sac and the pathophysiology of Meniere’s disease.
The cochlear stria vascularis produces endolymph and thereby plays an active role in inner ear homeostasis. We recently reported that the H+/myo-inositol cotransporter (HMIT) gene is expressed in the stria vascularis. Here, we examined the protein localization of HMIT and Na+/myo-inositol cotransporter 1 (SMIT1) in the stria vascularis by immunohistochemistry. HMIT and SMIT1 were detected in the lateral wall of the cochlear duct. HMIT was widely detected throughout the stria vascularis, while SMIT1 was enriched in the strial basal cells. To examine the localization of HMIT in the stria vascularis in more detail, dissociated strial cells were immunostained, which resulted in the detection of HMIT immunoreactivity in marginal cells. These results indicate that HMIT is expressed in marginal cells and basal cells of the stria vascularis, while SMIT1 expression is enriched in basal cells. We speculate that HMIT and SMIT1 may play important roles in the homeostasis of cochlear fluids, for example by participating in pH regulation and osmoregulation.
Keywords: Endolymph; Inner ear; Osmoregulation; Rat (Brown Norway); pH.
Genes: GeneCards
HMIT, Alias SLC2A13 (12q12)
https://www.genecards.org/cgi-bin/carddisp.pl?gene=SLC2A13&keywords=HMIT
Enables ATPase binding activity; myo-inositol:proton symporter activity;
and protease binding activity. Involved in myo-inositol transport and
positive regulation of amyloid-beta formation. Is integral component of
plasma membrane. Part of cell body; cell periphery; and cell projection.
[provided by Alliance of Genome Resources, Apr 2022]
SMIT1 (21q22.11)
https://www.genecards.org/Search/Keyword?queryString=SMIT1
Enables potassium channel regulator activity and transmembrane transporter binding activity. Predicted to be involved in inositol metabolic process; monosaccharide transmembrane transport; and myo-inositol import across plasma membrane. Predicted to act upstream of or within several processes, including peripheral nervous system development; positive regulation of reactive oxygen species biosynthetic process; and regulation of respiratory gaseous exchange. Located in plasma membrane. Part of perinuclear region of cytoplasm. [provided by Alliance of Genome Resources, Apr 2022]
Electrogenic Na(+)-coupled sugar symporter that actively transports myo-inositol and its stereoisomer scyllo-inositol across the plasma membrane, with a Na(+) to sugar coupling ratio of 2:1 (By similarity). Maintains myo-inositol concentration gradient that defines cell volume and fluid balance during osmotic stress, in particular in the fetoplacental unit and central nervous system (By similarity). Forms coregulatory complexes with voltage-gated K(+) ion channels, allosterically altering ion selectivity, voltage dependence and gating kinetics of the channel. In turn, K(+) efflux through the channel forms a local electrical gradient that modulates electrogenic Na(+)-coupled myo-inositol influx through the transporter (PubMed:24595108, 28793216). Associates with KCNQ1-KCNE2 channel in the apical membrane of choroid plexus epithelium and regulates the myo-inositol gradient between blood and cerebrospinal fluid with an impact on neuron excitability (By similarity) (PubMed:24595108). Associates with KCNQ2-KCNQ3 channel altering ion selectivity, increasing Na(+) and Cs(+) permeation relative to K(+) permeation (PubMed:28793216). Provides myo-inositol precursor for biosynthesis of phosphoinositides such as PI(4,5)P2, thus indirectly affecting the activity of phosphoinositide-dependent ion channels and Ca(2+) signaling upon osmotic stress (PubMed:27217553). ( SC5A3_HUMAN,P53794 )
KCNQ1-KCNE2 channel KCNQ1-KCNE2 channel associates with Na(+)-coupled myo-inositol symporter in the apical membrane of choroid plexus epithelium and regulates the myo-inositol gradient between blood and cerebrospinal fluid with an impact on neuron excitability (By similarity). ( KCNE2_HUMAN,Q9Y6J6 )
Potassium channel that plays an important role in a number of tissues, including heart, inner ear, stomach and colon (PubMed:10646604, 25441029). Associates with KCNE beta subunits that modulates current kinetics (PubMed:10646604, 11101505, 19687231, 8900283, 9108097, 9312006). Induces a voltage-dependent current by rapidly activating and slowly deactivating potassium-selective outward current (PubMed:10646604, 11101505, 25441029, 8900283, 9108097, 9312006). Promotes also a delayed voltage activated potassium current showing outward rectification characteristic (By similarity). During beta-adrenergic receptor stimulation participates in cardiac repolarization by associating with KCNE1 to form the I(Ks) cardiac potassium current that increases the amplitude and slows down the activation kinetics of outward potassium current I(Ks) (By similarity) (PubMed:10646604, 11101505, 8900283, 9108097, 9312006). Muscarinic agonist oxotremorine-M strongly suppresses KCNQ1/KCNE1 current (PubMed:10713961). When associated with KCNE3, forms the potassium channel that is important for cyclic AMP-stimulated intestinal secretion of chloride ions (PubMed:10646604). This interaction with KCNE3 is reduced by 17beta-estradiol, resulting in the reduction of currents (By similarity). During conditions of increased substrate load, maintains the driving force for proximal tubular and intestinal sodium ions absorption, gastric acid secretion, and cAMP-induced jejunal chloride ions secretion (By similarity). Allows the provision of potassium ions to the luminal membrane of the secretory canaliculus in the resting state as well as during stimulated acid secretion (By similarity). When associated with KCNE2, forms a heterooligomer complex leading to currents with an apparently instantaneous activation, a rapid deactivation process and a linear current-voltage relationship and decreases the amplitude of the outward current (PubMed:11101505). When associated with KCNE4, inhibits voltage-gated potassium channel activity (PubMed:19687231). When associated with KCNE5, this complex only conducts current upon strong and continued depolarization (PubMed:12324418). Also forms a heterotetramer with KCNQ5; has a voltage-gated potassium channel activity (PubMed:24855057). Binds with phosphatidylinositol 4,5-bisphosphate (PubMed:25037568). KCNQ1-KCNE2 channel associates with Na(+)-coupled myo-inositol symporter in the apical membrane of choroid plexus epithelium and regulates the myo-inositol gradient between blood and cerebrospinal fluid with an impact on neuron excitability. ( KCNQ1_HUMAN,P51787 )
Interacts with KCNE2; forms a heterooligomer complex that targets to the membrane raft and leading to currents with an apparently instantaneous activation, a rapid deactivation process and a linear current-voltage relationship and decreases the amplitude of the outward current (PubMed:11101505, 20533308). -> KCNE2 (Gene 21q22.11)
HAIR CELLS
https://pubmed.ncbi.nlm.nih.gov/34566562/
JONITASAPAINOSTA ENDOLYM;FASSA
ENDOLYMFASTA : Sisäkorvan miljööstä.
Abstract
Under normal conditions, the inner ear possesses remarkably stable homeostatic mechanisms for the maintenance of functional integrity of the inner ear fluid. The inner ear fluid maintains its homeostasis by a variety of regulatory mechanisms such as an ion transport system, a blood-labyrinth barrier, and a constant blood supply. Highly regulated transport of ions into and out of the inner ear provides for the maintenance of inner ear fluid composition necessary for auditory transduction. Any disturbance in one of these mechanisms can disrupt homeostasis expressed by ionic, osmotic, or metabolic imbalance between the compartments. Free radicals, stress hormones, noise exposure, and aminoglycoside antibiotics may induce short- and long-term effects on cellular function of the auditory or vestibular system (or both) and serve as a triggering mechanism for abrupt functional disturbances of inner ear fluid ion homeostasis. In this article, we present a comprehensive review of the mechanisms underlying inner ear fluid homeostasis necessary for normal auditory function and factors that can disrupt homeostasis and lead to functional disturbances, namely sensorineural hearing loss, tinnitus, and vertigo.
MIKÄ ON INOSITOLIN OSUUS ENDOLYMFAMILJÖÖN HOMEOSTAASISSA? Katso seuraava artikkeli.Endolymfa ja osmoottinen stressi. Inositolilla funktiota .
