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Han W, Bo Z, Liang T, Liu H, Li L, Guo Z, Huan R, Hagenbuch B, Gui C. G45 and V386 in Transmembrane Domains 1 and 8 Are Critical for the Activation of OATP1B3-Mediated E17βG Uptake by Clotrimazole. Mol Pharm 2024; 21:854-863. [PMID: 38235659 PMCID: PMC10917058 DOI: 10.1021/acs.molpharmaceut.3c00934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Organic anion-transporting polypeptides (OATPs) 1B1 and 1B3 are two highly homologous transport proteins. However, OATP1B1- and 1B3-mediated estradiol-17β-glucuronide (E17βG) uptake can be differentially affected by clotrimazole. In this study, by functional characterization on chimeric transporters and single mutants, we find that G45 in transmembrane domain 1 (TM1) and V386 in TM8 are critical for the activation of OATP1B3-mediated E17βG uptake by clotrimazole. However, the effect of clotrimazole on the function of OATP1B3 is substrate-dependent as clotrimazole does not stimulate OATP1B3-mediated uptake of 4',5'-dibromofluorescein (DBF) and rosuvastatin. In addition, clotrimazole is not transported by OATP1B3, but it can efficiently permeate the plasma membrane due to its lipophilic properties. Homology modeling and molecular docking indicate that E17βG binds in a substrate binding pocket of OATP1B3 through hydrogen bonding and hydrophobic interactions, among which its sterol scaffold forms hydrophobic contacts with V386. In addition, a flexible glycine residue at position 45 is essential for the activation of OATP1B3. Finally, clotrimazole is predicted to bind at an allosteric site, which mainly consists of hydrophobic residues located at the cytoplasmic halves of TMs 4, 5, 10, and 11.
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Affiliation(s)
- Wanjun Han
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Zheyue Bo
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Ting Liang
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Han Liu
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Lanjing Li
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Zhening Guo
- Department of Pharmacy, The Second Affiliated Hospital of Soochow University, 1055 Sanxiang Road, Suzhou, Jiangsu 215004, People’s Republic of China
| | - Ru Huan
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
| | - Bruno Hagenbuch
- Department of Pharmacology, Toxicology and Therapeutics, the University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, United States
| | - Chunshan Gui
- College of Pharmaceutical Sciences, Soochow University, 199 Renai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, People’s Republic of China
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Clotrimazole Fluidizes Phospholipid Membranes and Localizes at the Hydrophobic Part near the Polar Part of the Membrane. Biomolecules 2021; 11:biom11091304. [PMID: 34572517 PMCID: PMC8464689 DOI: 10.3390/biom11091304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 08/30/2021] [Accepted: 08/30/2021] [Indexed: 11/17/2022] Open
Abstract
Clotrimazole (1-[(2-chlorophenyl)-diphenylmethyl]-imidazole) is an azole antifungal drug belonging to the imidazole subclass that is widely used in pharmacology and that can be incorporated in membranes. We studied its interaction with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipid vesicles by using differential scanning calorimetry and found that the transition temperature decreases progressively as the concentration of clotrimazole increases. However, the temperature of completion of the transition remained constant despite the increase of clotrimazole concentration, suggesting the formation of fluid immiscibility. 1H-NMR and 1H NOESY MAS-NMR were employed to investigate the location of clotrimazole in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipid membranes. In the presence of clotrimazole, all the resonances originating from POPC were shifted upfield, but mainly those corresponding to C2 and C3 of the fatty acyl, chains suggesting that clotrimazole aromatic rings preferentially locate near these carbons. In the same way, 2D-NOESY measurements showed that the highest cross-relaxation rates between protons of clotrimazole and POPC were with those bound to the C2 and C3 carbons of the fatty acyl chains. Molecular dynamics simulations indicated that clotrimazole is located near the top of the hydrocarbon-chain phase, with the nitrogen atoms of the imidazole ring of clotrimazole being closest to the polar group of the carbonyl moiety. These results are in close agreement with the NMR and the conclusion is that clotrimazole is located near the water–lipid interface and in the upper part of the hydrophobic bilayer.
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Peterková L, Kmoníčková E, Ruml T, Rimpelová S. Sarco/Endoplasmic Reticulum Calcium ATPase Inhibitors: Beyond Anticancer Perspective. J Med Chem 2020; 63:1937-1963. [PMID: 32030976 DOI: 10.1021/acs.jmedchem.9b01509] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The sarco/endoplasmic reticulum calcium ATPase (SERCA), which plays a key role in the maintenance of Ca2+ ion homeostasis, is an extensively studied enzyme, the inhibition of which has a considerable impact on cell life and death decision. To date, several SERCA inhibitors have been thoroughly studied and the most notable one, a derivative of the sesquiterpene lactone thapsigargin, is gradually approaching a clinical application. Meanwhile, new compounds with SERCA-inhibiting properties of natural, synthetic, or semisynthetic origin are being discovered and/or developed; some of these might also be suitable for the development of new drugs with improved performance. This review brings an up-to-date comprehensive overview of recently discovered compounds with the potential of SERCA inhibition, discusses their mechanism of action, and highlights their potential clinical applications, such as cancer treatment.
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Affiliation(s)
- Lucie Peterková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Eva Kmoníčková
- Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
| | - Tomáš Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Silvie Rimpelová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic.,Faculty of Medicine in Pilsen, Charles University, Alej Svobody 76, 323 00 Pilsen, Czech Republic
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Jana K, Bandyopadhyay T, Ganguly B. Designed inhibitors with hetero linkers for gastric proton pump H +,K +-ATPase: Steered molecular dynamics and metadynamics studies. J Mol Graph Model 2017; 78:129-138. [PMID: 29055186 DOI: 10.1016/j.jmgm.2017.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/06/2017] [Accepted: 10/09/2017] [Indexed: 02/07/2023]
Abstract
Acid suppressant SCH28080 and its derivatives reversibly reduce acid secretion activity of the H+,K+-ATPase in a K+ competitive manner. The results on homologation of the SCH28080 by varying the linker chain length suggested the improvement in efficacy. However, the pharmacokinetic studies reveal that the hydrophobic nature of the CH2 linker units may not help it to function as a better acid suppressant. We have exploited the role of linker unit to enhance the efficacy of such reversible acid suppressant drug molecules using hetero linker, i.e., disulfide and peroxy linkers. The logarithm of partition coefficient defined for a drug molecule relates to the partition coefficient, which allows the optimum solubility characteristics to reach the active site. The logarithm of partition coefficient calculated for the designed inhibitors suggests that inhibitors would possibly reach the active site in sufficient concentration like in the case of SCH28080. The steered molecular dynamics studies have revealed that the Inhibitor-1 with disulfide linker unit is more stable at the active site due to greater noncovalent interactions compared to the SCH28080. Centre of mass distance analysis suggests that the Cysteine-813 amino acid residue selectively plays an important role in the inhibition of H+,K+-ATPase for Inhibitor-1. Furthermore, the quantum chemical calculations with M11L/6-31+G(d,p) level of theory have been performed to account the noncovalent interactions responsible for the stabilization of inhibitor molecules in the active site gorge of the gastric proton pump at different time scale. The hydrogen bonding and hydrophobic interaction studies corroborate the center of mass distance analysis as well. Well-tempered metadynamics free energy surface and center of mass separation analysis for the Inhibitor-1 is in good agreement with the steered molecular dynamics results. The torsional angle of the linker units seems to be crucial for better efficacy of drug molecules. The torsional angle of linker units of SCH28080 (COCH2C) and of Inhibitor 1 (CSSC) prefers to lie within ∼60°-90° for a longer time during the simulations, whereas, the peroxy linker (COOC) of Inhibitor 2 prefers to adopt ∼120-160°. Therefore, it appears that the smaller torsion angle of linker units can achieve better interactions with the active site residues of H+,K+-ATPase to inhibit the acid secretion activity. The reversible drug molecules with disulfide linker unit would be a promising candidate as proton pump antagonist to H+,K+-ATPase.
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Affiliation(s)
- Kalyanashis Jana
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India; Academy of Scientific and Innovative Research, CSIR, CSMCRI, Bhavnagar 364002, Gujarat, India
| | - Tusar Bandyopadhyay
- Theoretical Chemistry Section, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.
| | - Bishwajit Ganguly
- Computation and Simulation Unit (Analytical Discipline and Centralized Instrument Facility), CSIR, Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India; Academy of Scientific and Innovative Research, CSIR, CSMCRI, Bhavnagar 364002, Gujarat, India.
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Garcia A, Pratap PR, Lüpfert C, Cornelius F, Jacquemin D, Lev B, Allen TW, Clarke RJ. The voltage-sensitive dye RH421 detects a Na + ,K + -ATPase conformational change at the membrane surface. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:813-823. [DOI: 10.1016/j.bbamem.2017.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/09/2017] [Accepted: 01/19/2017] [Indexed: 10/20/2022]
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Jana K, Chandar NB, Bandyopadhyay T, Ganguly B. Role of Noncovalent Interactions in Designing Inhibitors for H+,K+-ATPase: Combined QM and MD Based Investigations. ChemistrySelect 2016. [DOI: 10.1002/slct.201601458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Kalyanashis Jana
- Computation and Simulation Unit, Analytical Discipline & Centralized Instrument Facility, and Academy of Scientific and Innovative Research; CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar; Gujarat 364002 India
| | - Nellore Bhanu Chandar
- Computation and Simulation Unit, Analytical Discipline & Centralized Instrument Facility, and Academy of Scientific and Innovative Research; CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar; Gujarat 364002 India
| | - Tusar Bandyopadhyay
- Theorectical Chemistry Section, Chemistry Group MOD LAB; Bhabha Atomic Research Centre, Trombay; Mumbai 400 085 India
| | - Bishwajit Ganguly
- Computation and Simulation Unit, Analytical Discipline & Centralized Instrument Facility, and Academy of Scientific and Innovative Research; CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar; Gujarat 364002 India
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Electrophysiological Studies into the Safety of the Anti-diarrheal Drug Clotrimazole during Oral Rehydration Therapy. PLoS Negl Trop Dis 2015; 9:e0004098. [PMID: 26405813 PMCID: PMC4583490 DOI: 10.1371/journal.pntd.0004098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/30/2015] [Indexed: 11/19/2022] Open
Abstract
Background and Aims Morbidity and mortality from acute diarrheal disease remains high, particularly in developing countries and in cases of natural or man-made disasters. Previous work has shown that the small molecule clotrimazole inhibits intestinal Cl- secretion by blocking both cyclic nucleotide- and Ca2+-gated K+ channels, implicating its use in the treatment of diarrhea of diverse etiologies. Clotrimazole, however, might also inhibit transporters that mediate the inwardly directed electrochemical potential for Na+-dependent solute absorption, which would undermine its clinical application. Here we test this possibility by examining the effects of clotrimazole on Na+-coupled glucose uptake. Materials and Methods Short-circuit currents (Isc) following administration of glucose and secretagogues were studied in clotrimazole-treated jejunal sections of mouse intestine mounted in Ussing chambers. Results Treatment of small intestinal tissue with clotrimazole inhibited the Cl- secretory currents that resulted from challenge with the cAMP-agonist vasoactive intestinal peptide (VIP) or Ca2+-agonist carbachol in a dose-dependent fashion. A dose of 30 μM was effective in significantly reducing the Isc response to VIP and carbachol by 50% and 72%, respectively. At this dose, uptake of glucose was only marginally affected (decreased by 14%, p = 0.37). There was no measurable effect on SGLT1-mediated sugar transport, as uptake of SGLT1-restricted 3-O-methyl glucose was equivalent between clotrimazole-treated and untreated tissue (98% vs. 100%, p = 0.90). Conclusion Treatment of intestinal tissue with clotrimazole significantly reduced secretory responses caused by both cAMP- and Ca2+-dependent agonists as expected, but did not affect Na+-coupled glucose absorption. Clotrimazole could thus be used in conjunction with oral rehydration solution as a low-cost, auxiliary treatment of acute secretory diarrheas. In acute infectious diarrhea, the active secretion of Cl- ions contributes to the secondary loss of Na+ and water from the intestine. Apical Cl- secretion from intestinal epithelial cells is dependent upon cyclic nucleotide- and Ca2+-dependent intracellular signals and requires the concomitant transport of K+ through basolateral K+ channels for maintenance of an electroneutral state. Hence, when efflux of K+ in enterocytes is blocked, Cl- secretion necessarily shuts down. The FDA-approved antifungal drug clotrimazole has been demonstrated to be a potent blocker of basolateral cAMP- and Ca2+-gated K+ channels in enterocytes, and therefore likely has therapeutic efficacy for secretory diarrheas. One important concern that could compromise its clinical applicability as a novel anti-diarrheal drug, however, is that clotrimazole might affect intestinal Na+-coupled glucose absorption, which constitutes the physiological basis of oral rehydration therapies and is thus critical for the efficacy of the current golden standard treatment for acute infectious diarrheal diseases. In this work, we demonstrate that clotrimazole effectively blocks Cl- secretion in mouse intestine after stimulation with secretory stimuli, without affecting the capacity to take up Na+ and glucose. These results pave the way towards further clinical development of clotrimazole as a new pharmacologic strategy for acute diarrheal disease.
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A genomewide screen in Schizosaccharomyces pombe for genes affecting the sensitivity of antifungal drugs that target ergosterol biosynthesis. Antimicrob Agents Chemother 2012; 56:1949-59. [PMID: 22252817 DOI: 10.1128/aac.05126-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We performed a genomewide screen for altered sensitivity to antifungal drugs, including clotrimazole and terbinafine, that target ergosterol biosynthesis using a Schizosaccharomyces pombe gene deletion library consisting of 3,004 nonessential haploid deletion mutants. We identified 109 mutants that were hypersensitive and 11 mutants that were resistant to these antifungals. Proteins whose absence rendered cells sensitive to these antifungals were classified into various functional categories, including ergosterol biosynthesis, membrane trafficking, histone acetylation and deacetylation, ubiquitination, signal transduction, ribosome biosynthesis and assembly, regulation of transcription and translation, cell wall organization and biogenesis, mitochondrion function, amino acid metabolism, nucleic acid metabolism, lipid metabolism, meiosis, and other functions. Also, proteins whose absence rendered cells resistant to these antifungals were classified into functional categories including mitochondrion function, ubiquitination, membrane trafficking, cell polarity, chromatin remodeling, and some unknown functions. Furthermore, the 109 sensitive mutants were tested for sensitivity to micafungin, another antifungal drug that inhibits (1,3)-β-D-glucan synthase, and 57 hypersensitive mutants were identified, suggesting that these mutants were defective in cell wall integrity. Altogether, our findings in fission yeast have shed light on molecular pathways associated with the cellular response to ergosterol biosynthesis inhibitors and may provide useful information for developing strategies aimed at sensitizing cells to these drugs.
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Bartolommei G, Tadini-Buoninsegni F, Moncelli MR, Gemma S, Camodeca C, Butini S, Campiani G, Lewis D, Inesi G. The Ca2+-ATPase (SERCA1) is inhibited by 4-aminoquinoline derivatives through interference with catalytic activation by Ca2+, whereas the ATPase E2 state remains functional. J Biol Chem 2011; 286:38383-38389. [PMID: 21914795 DOI: 10.1074/jbc.m111.287276] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several clotrimazole (CLT) and 4-aminoquinoline derivatives were synthesized and found to exhibit in vitro antiplasmodial activity with IC(50) ranging from nm to μm values. We report here that some of these compounds produce inhibition of rabbit sarcoplasmic reticulum Ca(2+)-ATPase (SERCA1) with IC(50) values in the μm range. The highest affinity for the Ca(2+)-ATPase was observed with NF1442 (N-((3-chlorophenyl)(4-((4-(7-chloroquinolin-4-yl)piperazin-1-yl)methyl)phenyl)methyl)-7-chloro-4-aminoquinoline) and NF1058 (N-((3-chlorophenyl)(4-(pyrrolidin-1-ylmethyl)phenyl)methyl)-7-chloro-4-aminoquinoline),yielding IC(50) values of 1.3 and 8.0 μm as demonstrated by measurements of steady state ATPase activity as well as single cycle charge transfer. Characterization of sequential reactions comprising the ATPase catalytic and transport cycle then demonstrated that NF1058, and similarly CLT, interferes with the mechanism of Ca(2+) binding and Ca(2+)-dependent enzyme activation (E(2) to E(1)·Ca(2) transition) required for formation of phosphorylated intermediate by ATP utilization. On the other hand, Ca(2+) independent phosphoenzyme formation by utilization of P(i) (i.e. reverse of the hydrolytic reaction in the absence of Ca(2+)) was not inhibited by NF1058 or CLT. Comparative experiments showed that the high affinity inhibitor thapsigargin interferes not only with Ca(2+) binding and phosphoenzyme formation with ATP but also with phosphoenzyme formation by utilization of P(i) even though this reaction does not require Ca(2+). It is concluded that NF1058 and CLT inhibit SERCA by stabilization of an E(2) state that, as opposed to that obtained with thapsigargin, retains the functional ability to form E(2)-P by reacting with P(i).
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Affiliation(s)
- Gianluca Bartolommei
- Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy
| | | | - Maria Rosa Moncelli
- Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy
| | - Sandra Gemma
- European Research Centre for Drug Discovery and Development and Department of Pharmaceutical and Applied Chemistry, University of Siena, 53100 Siena, Italy
| | - Caterina Camodeca
- European Research Centre for Drug Discovery and Development and Department of Pharmaceutical and Applied Chemistry, University of Siena, 53100 Siena, Italy
| | - Stefania Butini
- European Research Centre for Drug Discovery and Development and Department of Pharmaceutical and Applied Chemistry, University of Siena, 53100 Siena, Italy
| | - Giuseppe Campiani
- European Research Centre for Drug Discovery and Development and Department of Pharmaceutical and Applied Chemistry, University of Siena, 53100 Siena, Italy
| | - David Lewis
- California Pacific Medical Center Research Institute, San Francisco, California 94107
| | - Giuseppe Inesi
- California Pacific Medical Center Research Institute, San Francisco, California 94107
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Abstract
In the absence of Na(+) and K(+) ions the Na,K-ATPase shows a pH-dependent ATP hydrolysis that can be inhibited by ouabain. At pH 7.2 this activity is 5% of the maximal under physiological conditions. It could be inferred that this activity is associated with H(+) transport in both directions across the membrane and facilitates an H-only mode of the sodium pump under such unphysiological conditions. By the analysis of experiments with reconstituted proteoliposomes an overall electroneutral transport mode has been proven. The stoichiometry was determined to be 2 H(+)/2 H(+)/1 ATP and is comparable to what is known from the closely related H,K-ATPase. By time-resolved ATP-concentration jump experiments it was found that at no time was the third, Na(+)-specific binding site of the pump occupied by protons. A modified Post-Albers pump cycle is proposed, with H(+) ions as congeners for Na(+) and K(+), by which all experiments performed can be explained.
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Affiliation(s)
- Hans-Jürgen Apell
- Department of Biology, University of Konstanz, 78464 Konstanz, Germany.
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Abstract
PURPOSE OF REVIEW This review summarizes the past year's literature regarding the regulation of gastric exocrine and endocrine secretion at the central, peripheral, and cellular levels. RECENT FINDINGS Gastric acid secretion is an intricate and dynamic process that is regulated by neural (efferent and afferent), hormonal (e.g., gastrin), and paracrine (e.g., histamine, ghrelin, somatostatin) pathways as well as mechanical (e.g., distension) and chemical (e.g., protein, glutamate, coffee, and ethanol) stimuli. Secretion of hydrochloric acid by the parietal cell involves recruitment and fusion of HK-adenosine triphosphatase (HK-ATPase)-containing cytoplasmic tubulovesicles with the apical membrane with subsequent electroneutral transport of hydronium ions in exchange for potassium; the source of the latter is the potassium channel, KCNQ1. Concomitantly, chloride exits via the cystic fibrosis transmembrane regulator. Inhibition of the HK-ATPase by proton pump inhibitors leads to a compensatory hypergastrinemia which, if prolonged, results in parietal and enterochromaffin-like cell hyperplasia. The clinical consequence is rebound acid secretion which may induce dyspeptic symptoms in healthy individuals and exacerbate reflux symptoms in patients with gastroesophageal reflux disease. SUMMARY We continue to make progress in our understanding of the regulation of gastric acid secretion in health and disease. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.
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