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Bicarbonate secretion

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https://www.readbyqxmd.com/read/28795233/bicarbonate-transport-during-enamel-maturation
#1
REVIEW
Kaifeng Yin, Michael L Paine
Amelogenesis (tooth enamel formation) is a biomineralization process consisting primarily of two stages (secretory stage and maturation stage) with unique features. During the secretory stage, the inner epithelium of the enamel organ (i.e., the ameloblast cells) synthesizes and secretes enamel matrix proteins (EMPs) into the enamel space. The protein-rich enamel matrix forms a highly organized architecture in a pH-neutral microenvironment. As amelogenesis transitions to maturation stage, EMPs are degraded and internalized by ameloblasts through endosomal-lysosomal pathways...
August 9, 2017: Calcified Tissue International
https://www.readbyqxmd.com/read/28775098/influenza-virus-infection-alters-ion-channel-function-of-airway-and-alveolar-cells-mechanisms-and-physiological-sequelae
#2
James D Londino, Ahmed Lazrak, James F Collawn, Zsuzsanna Bebok, Kevin S Harrod, Sadis Matalon
The cystic fibrosis transmembrane conductance regulator (CFTR) and the amiloride-sensitive epithelial sodium channels (ENaC) are located in the apical membranes of airway and alveolar epithelial cells. These transporters play an important role in the regulation of lung fluid balance across airway and alveolar epithelia by being the conduits for chloride (Cl(-)) and bicarbonate (HCO3(-)) secretion and sodium (Na(+)) ion absorption, respectively. The functional role of these channels in the respiratory tract is to maintain the optimum volume and ionic composition of the bronchial pericilary fluid (PCL) and alveolar lining fluid (ALF) layers...
August 3, 2017: American Journal of Physiology. Lung Cellular and Molecular Physiology
https://www.readbyqxmd.com/read/28774999/sexual-dimorphic-pattern-of-renal-transporters-and-electrolyte-homeostasis
#3
Luciana C Veiras, Adriana C C Girardi, Joshua Curry, Lei Pei, Donna L Ralph, An Tran, Regiane C Castelo-Branco, Nuria Pastor-Soler, Cristina T Arranz, Alan S L Yu, Alicia A McDonough
Compared with males, females have lower BP before age 60, blunted hypertensive response to angiotensin II, and a leftward shift in pressure natriuresis. This study tested the concept that this female advantage associates with a distinct sexual dimorphic pattern of transporters along the nephron. We applied quantitative immunoblotting to generate profiles of transporters, channels, claudins, and selected regulators in both sexes and assessed the physiologic consequences of the differences. In rats, females excreted a saline load more rapidly than males did...
August 3, 2017: Journal of the American Society of Nephrology: JASN
https://www.readbyqxmd.com/read/28771454/%C3%AE-ketoglutarate-drives-electroneutral-nacl-reabsorption-in-intercalated-cells-by-activating-a-g-protein-coupled-receptor-oxgr1
#4
Paul R Grimm, Paul A Welling
PURPOSE OF REVIEW: This review describes the recent discoveries about a powerful electroneutral NaCl reabsorption mechanism in intercalated cells, and its regulation by an intrarenal metabolite paracrine, α-ketoglutartate, and the G-protein coupled receptor, Oxgr1. RECENT FINDINGS: The distal nephron fine-tunes sodium, chloride, potassium, hydrogen, bicarbonate and water transport to maintain electrolyte homeostasis and blood pressure. Intercalated cells have been traditionally viewed as the professional regulators of acid-base balance, but recent studies reveal that a specific population of intercalated cells, identified by the pendrin-transporter, have a surprising role in the regulation of salt balance...
September 2017: Current Opinion in Nephrology and Hypertension
https://www.readbyqxmd.com/read/28732801/bicarbonate-in-cystic-fibrosis
#5
REVIEW
Karl Kunzelmann, Rainer Schreiber, Hans Beat Hadorn
BACKGROUND: Cystic fibrosis (CF, mucoviscidosis) is caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), which is a chloride and bicarbonate channel necessary for fluid secretion and extracellular alkalization. For a long time, research concentrated on abnormal Cl(-) and Na(+) transport, but neglected bicarbonate as a crucial factor in CF. METHODS: The present short review reports early findings as well as recent insights into the role of CFTR for bicarbonate transport and its defects in CF...
July 18, 2017: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
https://www.readbyqxmd.com/read/28706773/why-doesn-t-primary-biliary-cholangitis-respond-to-immunosuppressive-medications
#6
REVIEW
Antonio Molinaro, Hanns-Ulrich Marschall
PURPOSE OF REVIEW: The purpose of this review is to discuss reasons why immunosuppressive therapy so far failed in Primary Biliry Cholangitis. RECENT FINDINGS: Even targeted immunosuppressive therapy seems ineffective or potentially harmful. SUMMARY: Bile acid-mediated cholangiocyte damage, facilitated by insufficient bicarbonate secretion, seems to attenuate the anti-inflammatory and anti-fibrotic actions of immunosuppressant and immunomodulatory drugs in a clinically significant way...
2017: Current Hepatology Reports
https://www.readbyqxmd.com/read/28648509/pendred-syndrome
#7
REVIEW
Jean-Louis Wémeau, Peter Kopp
Pendred syndrome is an autosomal recessive disorder that is classically defined by the combination of sensorineural deafness/hearing impairment, goiter, and an abnormal organification of iodide with or without hypothyroidism. The hallmark of the syndrome is the impaired hearing, which is associated with inner ear malformations such as an enlarged vestibular aqueduct (EVA). The thyroid phenotype is variable and may be modified by the nutritional iodine intake. Pendred syndrome is caused by biallelic mutations in the SLC26A4/PDS gene, which encodes the multifunctional anion exchanger pendrin...
March 2017: Best Practice & Research. Clinical Endocrinology & Metabolism
https://www.readbyqxmd.com/read/28596649/use-of-surrogate-samples-to-monitor-ph-during-high-dose-methotrexate-therapy
#8
Uday Yanamandra, Pooja Chauhan, Deepesh Lad, Alka Khadwal, Gaurav Prakash, Subhash Varma, Pankaj Malhotra
High dose methotrexate (Mtx) therapy is commonly used in hemato-oncological practice. Alkalization of urine is a part of high dose methotrexate therapy for preventing crystallization in urine to avert renal insufficiency. Alkalization is monitored by urine pH at regular intervals. Oral pH has occasionally been used as a surrogate for oral mucositis. To compare and correlate pH of various body secretions (venous blood, oral salivary, lacrimal and urine) among patients undergoing alkalization with intravenous sodium bicarbonate during high dose methotrexate therapy...
June 2017: Indian Journal of Hematology & Blood Transfusion
https://www.readbyqxmd.com/read/28577107/interaction-of-constitutive-nitric-oxide-synthases-with-cyclooxygenases-in-regulation-of-bicarbonate-secretion-in-the-gastric-mucosa
#9
V A Zolotarev, Yu V Andreeva, E Vershinina, R P Khropycheva
Neuronal NO synthase blocker 7-nitroindazole suppressed bicarbonate secretion in rat gastric mucosa induced by mild local irritation with 1 M NaCl (pH 2.0). Non-selective blocker of neuronal and endothelial synthases, Nω-nitro-L-arginine (L-NNA), did not affect HCO3(-) production, but inhibited secretion after pretreatment with omeprazole. Non-selective cyclooxygenase blocker indomethacin inhibited HCO3(-) production under conditions of normal synthase activity and in the presence of L-NNA, but was ineffective when co-administered with 7-nitroindazole...
June 3, 2017: Bulletin of Experimental Biology and Medicine
https://www.readbyqxmd.com/read/28526688/loss-of-the-anion-exchanger-dra-slc26a3-or-pat1-slc26a6-alters-sulfate-transport-by-the-distal-ileum-and-overall-sulfate-homeostasis
#10
Jonathan M Whittamore, Marguerite Hatch
The ileum is considered the primary site of inorganic sulfate (SO4(2-)) absorption. In the present study, we explored the contributions of the apical chloride/bicarbonate (Cl(-)/HCO3(-)) exchangers DRA (Slc26a3), and PAT1 (Slc26a6), to the underlying transport mechanism. Transepithelial (35)SO4(2-) and (36)Cl(-) fluxes were determined across isolated, short-circuited segments of the distal ileum from wild-type (WT), DRA-knockout (KO) and PAT1-KO mice, together with measurements of urine and plasma sulfate. The WT distal ileum supported net sulfate absorption (197...
May 19, 2017: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/28526687/ffa2-activation-combined-with-ulcerogenic-cox-inhibition-induces-duodenal-mucosal-injury-via-the-5-ht-pathway-in-rats
#11
Yasutada Akiba, Koji Maruta, Kazuyuki Narimatsu, Hyder Said, Izumi Kaji, Ayaka Kuri, Ken-Ichi Iwamoto, Atsukazu Kuwahara, Jonathan D Kaunitz
Serotonin (5-HT), predominantly synthesized and released by enterochromaffin cells, is implicated in gastrointestinal symptoms such as emesis, abdominal pain, and diarrhea. Because luminal short-chain fatty acids (SCFAs) release 5-HT from enterochromaffin cells, which express the SCFA receptor free fatty acid receptor 2 (FFA2) in rat duodenum, we examined the effects of the selective FFA2 agonist phenylacetamide-1 (PA1) on duodenal 5-HT release with consequent bicarbonate secretion [duodenal bicarbonate secretion (DBS)] and on indomethacin (IND)-induced enteropathy...
August 1, 2017: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/28523577/ffa3-activation-stimulates-duodenal-bicarbonate-secretion-and-prevents-nsaid-induced-enteropathy-via-the-glp-2-pathway-in-rats
#12
Hyder Said, Yasutada Akiba, Kazuyuki Narimatsu, Koji Maruta, Ayaka Kuri, Ken-Ichi Iwamoto, Atsukazu Kuwahara, Jonathan D Kaunitz
BACKGROUND: Therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with enteropathy in humans and experimental animals, a cause of considerable morbidity. Unlike foregut NSAID-associated mucosal lesions, most treatments for this condition are of little efficacy. We propose that the endogenously released intestinotrophic hormone glucagon-like peptide-2 (GLP-2) prevents the development of NSAID-induced enteropathy. Since the short-chain fatty acid receptor FFA3 is expressed on enteroendocrine L cells and on enteric nerves in the gastrointestinal tract, we further hypothesized that activation of FFA3 on L cells protects the mucosa from injury via GLP-2 release with enhanced duodenal HCO3(-) secretion...
August 2017: Digestive Diseases and Sciences
https://www.readbyqxmd.com/read/28455748/ck2-is-a-key-regulator-of-slc4a2-mediated-cl-hco3-exchange-in-human-airway-epithelia
#13
Salam H Ibrahim, Mark J Turner, Vinciane Saint-Criq, James Garnett, Iram J Haq, Malcolm Brodlie, Chris Ward, Christian Borgo, Mauro Salvi, Andrea Venerando, Michael A Gray
Transepithelial bicarbonate secretion by human airway submucosal glands and surface epithelial cells is crucial to maintain the pH-sensitive innate defence mechanisms of the lung. cAMP agonists stimulate HCO3(-) secretion via coordinated increases in basolateral HCO3(-) influx and accumulation, as well as CFTR-dependent HCO3(-) efflux at the luminal membrane of airway epithelial cells. Here, we investigated the regulation of a basolateral located, DIDS-sensitive, Cl(-)/HCO3(-) exchanger, anion exchanger 2 (AE2; SLC4A2) which is postulated to act as an acid loader, and therefore potential regulator of HCO3(-) secretion, in human airway epithelial cells...
April 28, 2017: Pflügers Archiv: European Journal of Physiology
https://www.readbyqxmd.com/read/28436589/short-chain-fatty-acids-augment-rat-duodenal-mucosal-barrier-function
#14
Wan Salman Wan Saudi, Markus Sjöblom
What is the central question of this study? Small intestinal epithelium is exposed to high concentrations of short-chain fatty acids (SCFAs), but their role in regulating intestinal mucosal barrier function and motility is not fully understood. What is the main finding and its importance? By perfusing the duodenal segment in anaesthetized rats, we show that acetate and propionate significantly decrease mucosal paracellular permeability and transepithelial net fluid flux and increase mucosal bicarbonate secretion...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28385297/renal-tubular-nhe3-is-required-in-the-maintenance-of-water-and-sodium-chloride-homeostasis
#15
Robert A Fenton, Søren B Poulsen, Samantha de la Mora Chavez, Manoocher Soleimani, Jessica A Dominguez Rieg, Timo Rieg
The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it facilitates sodium (re)absorption and proton secretion. The importance of NHE3 in the kidney for sodium chloride homeostasis, relative to the intestine, is unknown. Constitutive tubule-specific NHE3 knockout mice (NHE3(loxloxCre)) did not show significant differences compared to control mice in body weight, blood pH or bicarbonate and plasma sodium, potassium, or aldosterone levels. Fluid intake, urinary flow rate, urinary sodium/creatinine, and pH were significantly elevated in NHE3(loxloxCre) mice, while urine osmolality and GFR were significantly lower...
August 2017: Kidney International
https://www.readbyqxmd.com/read/28384243/neuropeptide-s-reduces-duodenal-bicarbonate-secretion-and-ethanol-induced-increases-in-duodenal-motility-in-rats
#16
Wan Salman Wan Saudi, Markus Sjöblom
Alcohol disrupts the intestinal mucosal barrier by inducing metabolic and functional changes in epithelial cells. Recently, we showed that neuropeptide S (NPS) decreases duodenal motility and increases mucosal paracellular permeability, suggesting a role of NPS in the pathogenesis of disorders and dysfunctions in the small intestine. The aim of the present study was to investigate the effects of NPS on ethanol- and HCl-induced changes of duodenal mucosal barrier function and motility. Rats were anaesthetized with thiobarbiturate, and a 30-mm segment of the proximal duodenum with an intact blood supply was perfused in situ...
2017: PloS One
https://www.readbyqxmd.com/read/28341416/a-physiologically-oriented-transcriptomic-analysis-of-the-midgut-of-tenebrio-molitor
#17
Nathalia R Moreira, Christiane Cardoso, Renata O Dias, Clelia Ferreira, Walter R Terra
Physiological data showed that T. molitor midgut is buffered at pH 5.6 at the two anterior thirds and at 7.9 at the posterior third. Furthermore, water is absorbed and secreted at the anterior and posterior midgut, respectively, driving a midgut counter flux of fluid. To look for the molecular mechanisms underlying these phenomena and nutrient absorption as well, a transcriptomic approach was used. For this, 11 types of transporters were chosen from the midgut transcriptome obtained by pyrosequencing (Roche 454)...
March 21, 2017: Journal of Insect Physiology
https://www.readbyqxmd.com/read/28300821/impact-of-cftr-modulation-on-intestinal-ph-motility-and-clinical-outcomes-in-patients-with-cystic-fibrosis-and-the-g551d-mutation
#18
Daniel Gelfond, Sonya Heltshe, Changxing Ma, Steven M Rowe, Carla Frederick, Ahmet Uluer, Leonard Sicilian, Michael Konstan, Elizabeth Tullis, R N Christine Roach, Katherine Griffin, Elizabeth Joseloff, Drucy Borowitz
OBJECTIVES: A defect in bicarbonate secretion contributes to the pathophysiology of gastrointestinal complications in patients with cystic fibrosis (CF). We measured gastrointestinal pH, clinical outcomes, and intestinal transit profiles in patients with the G551D mutation before and after treatment with ivacaftor, a CF transmembrane regulator channel (CFTR) potentiator. METHODS: Observational studies of ivacaftor effectiveness were conducted in the United States and Canada...
March 16, 2017: Clinical and Translational Gastroenterology
https://www.readbyqxmd.com/read/28261854/oligog-cf-5-20-normalizes-cystic-fibrosis-mucus-by-chelating-calcium
#19
Anna Ermund, Christian V Recktenwald, Gudmund Skjåk-Braek, Lauren N Meiss, Edvar Onsøyen, Philip D Rye, Arne Dessen, Astrid Hilde Myrset, Gunnar C Hansson
The goal of this study was to determine whether the guluronate (G) rich alginate OligoG CF-5/20 (OligoG) could detach cystic fibrosis (CF) mucus by calcium chelation, which is also required for normal mucin unfolding. Since bicarbonate secretion is impaired in CF, leading to insufficient mucin unfolding and thereby attached mucus and since bicarbonate has the ability to bind calcium, we hypothesized that the calcium chelating property of OligoG would lead to detachment of CF mucus. Indeed, OligoG could compete with the N-terminus of the MUC2 mucin for calcium binding as shown by microscale thermophoresis...
March 6, 2017: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/28249274/the-emerging-role-of-soluble-adenylyl-cyclase-in-primary-biliary-cholangitis
#20
REVIEW
Jung-Chin Chang, Ulrich Beuers, Ronald P J Oude Elferink
BACKGROUND: Primary biliary cholangitis (PBC; previously referred to as primary biliary cirrhosis) is a chronic fibrosing cholangiopathy with the signature of an autoimmune disease and features of intrahepatic cholestasis. Immunosuppressing treatments are largely unsuccessful. Responsiveness to ursodeoxycholic acid and reduced expression of anion exchanger 2 (AE2) on canalicular membranes and small bile ducts underline the importance of bicarbonate transportation in its disease mechanism...
2017: Digestive Diseases
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