1
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Das S, Kumar P. Exploring the carbonic anhydrase-mimetic [(PMDTA) 2ZnII2(OH -) 2] 2+ for nitric oxide monooxygenation. Dalton Trans 2024; 53:6173-6177. [PMID: 38501600 DOI: 10.1039/d4dt00407h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
In biology, nitrite (NO2-) serves as a storage pool of nitric oxide (NO); however, the formation of NO2- from NO is still under investigation. Here, we report the NO monooxygenation (NOM) reaction of a ZnII-hydroxide complex (1), producing a ZnII-nitrito complex {2, (ZnII-NO2-)} + H2.
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Affiliation(s)
- Sandip Das
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Tirupati 517507, India.
| | - Pankaj Kumar
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Tirupati 517507, India.
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2
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Sheikh AS, Altaf R, Nadeem H, Khan MT, Murtaza B. Formation of morpholine-acetamide derivatives as potent anti-tumor drug candidates: Pharmacological evaluation and molecular docking studies. Heliyon 2023; 9:e22183. [PMID: 38053851 PMCID: PMC10694180 DOI: 10.1016/j.heliyon.2023.e22183] [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: 06/16/2023] [Revised: 10/31/2023] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
Heterocyclic amines and acetamide derivatives are known for their chemotherapeutic potential. Hence, in the present study, morpholine was taken as a principal product and novel morpholine derivatives were designed, formulated, characterized, and screened for the mechanism of inhibition of carbonic anhydrase and their anticancer potential. In addition, in vitro inhibition of hypoxia-inducible factor-1 (HIF-1) protein was also investigated. Results revealed that compounds 1c, 1d, and 1h possessed significant inhibitory activities against carbonic anhydrase with IC50 of 8.80, 11.13, and 8.12 μM, respectively. Interestingly, the carbonic anhydrase inhibitory activity of compound 1h was comparable with that of standard acetazolamide (IC50 7.51 μM). The compounds 1h and 1i significantly inhibited the proliferation of ovarian cancer cell line ID8 with IC50 of 9.40, and 11.2 μM, respectively while the standard cisplatin exhibited an IC50 8.50 μM. In addition, compounds 1c, 1b, 1h and 1i also exhibited significant inhibitory effects on HIF-1α. In conclusion, we report first time the biological potential of morpholine based compounds against ovarian cancer and HIF-1α that may serve as lead molecules for drug discovery.
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Affiliation(s)
- Ahmed Sadiq Sheikh
- Department of Pharmaceutical Chemistry, Riphah Institute of Pharmaceutical Sciences, RIU, Islamabad, Pakistan
| | - Reem Altaf
- Department of Pharmacy, Iqra University, Islamabad, Pakistan
| | - Humaira Nadeem
- Department of Pharmaceutical Chemistry, Riphah Institute of Pharmaceutical Sciences, RIU, Islamabad, Pakistan
| | | | - Babar Murtaza
- Department of Pharmaceutical Chemistry, Riphah Institute of Pharmaceutical Sciences, RIU, Islamabad, Pakistan
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3
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Almathami S, Venezuela J, Yang N, Wang Y, Mardina Z, Dargusch M. Exploring the Influence of Biologically Relevant Ions on the Corrosion Behavior of Biodegradable Zinc in Physiological Fluids. ACS Biomater Sci Eng 2023; 9:2301-2316. [PMID: 37072291 DOI: 10.1021/acsbiomaterials.2c00901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
This work presents a study on the influence of biologically relevant ions on the corrosion of zinc (Zn) in physiological fluids. Electrochemical techniques were used to investigate the degradation of pure Zn exposed to different physiological electrolytes containing chlorides, carbonates, sulfates, and phosphates. The corrosion behavior of Zn in the solutions over a 7-day period was also assessed. SEM, EDS, and FTIR were used to analyze corrosion products. With respect to corrosion, the most aggressive ions are chlorides, which induce localized corrosion, while carbonates and phosphates reduce the corrosive attack of the chloride on Zn while inducing uniform corrosion. Sulfates reduce the corrosion rate by disrupting Zn's passive layer. The overall corrosion rate of Zn changed in each electrolyte depending on the nature of the solution and the corrosion product formed. These findings will be useful in predicting the in-service behavior of future biodegradable Zn medical implants.
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Affiliation(s)
- Sharifah Almathami
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
| | - Jeffrey Venezuela
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
| | - Nan Yang
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
| | - Yuan Wang
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
| | - Zahrina Mardina
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
| | - Matthew Dargusch
- Centre for Advanced Materials Processing and Manufacturing (AMPAM), Advanced Engineering Building, The University of Queensland, Brisbane, Queensland, 4072 Australia
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4
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Milliken AS, Ciesla JH, Nadtochiy SM, Brookes PS. Distinct effects of intracellular vs. extracellular acidic pH on the cardiac metabolome during ischemia and reperfusion. J Mol Cell Cardiol 2023; 174:101-114. [PMID: 36481511 PMCID: PMC9868090 DOI: 10.1016/j.yjmcc.2022.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/22/2022] [Accepted: 11/25/2022] [Indexed: 12/10/2022]
Abstract
Tissue ischemia results in intracellular pH (pHIN) acidification, and while metabolism is a known driver of acidic pHIN, less is known about how acidic pHIN regulates metabolism. Furthermore, acidic extracellular (pHEX) during early reperfusion confers cardioprotection, but how this impacts metabolism is unclear. Herein we employed LCMS based targeted metabolomics to analyze perfused mouse hearts exposed to: (i) control perfusion, (ii) hypoxia, (iii) ischemia, (iv) enforced acidic pHIN, (v) control reperfusion, and (vi) acidic pHEX (6.8) reperfusion. Surprisingly little overlap was seen between metabolic changes induced by hypoxia, ischemia, and acidic pHIN. Acidic pHIN elevated metabolites in the top half of glycolysis, and enhanced glutathione redox state. Meanwhile, acidic pHEX reperfusion induced substantial metabolic changes in addition to those seen in control reperfusion. This included elevated metabolites in the top half of glycolysis, prevention of purine nucleotide loss, and an enhancement in glutathione redox state. These data led to hypotheses regarding potential roles for methylglyoxal inhibiting the mitochondrial permeability transition pore, and for acidic inhibition of ecto-5'-nucleotidase, as potential mediators of cardioprotection by acidic pHEX reperfusion. However, neither hypothesis was supported by subsequent experiments. In contrast, analysis of cardiac effluents revealed complex effects of pHEX on metabolite transport, suggesting that mildly acidic pHEX may enhance succinate release during reperfusion. Overall, each intervention had distinct and overlapping metabolic effects, suggesting acidic pH is an independent metabolic regulator regardless which side of the cell membrane it is imposed.
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Affiliation(s)
- Alexander S Milliken
- Department of Pharmacology and Physiology, University of Rochester Medical Center, USA
| | - Jessica H Ciesla
- Department of Biochemistry, University of Rochester Medical Center, USA
| | - Sergiy M Nadtochiy
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, USA
| | - Paul S Brookes
- Department of Pharmacology and Physiology, University of Rochester Medical Center, USA; Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, USA.
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5
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Sood P, Lin A, Yan C, McGillivary R, Diaz U, Makushok T, Nadkarni A, Tang SKY, Marshall WF. Modular, cascade-like transcriptional program of regeneration in Stentor. eLife 2022; 11:80778. [PMID: 35924891 PMCID: PMC9371601 DOI: 10.7554/elife.80778] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 08/04/2022] [Indexed: 11/15/2022] Open
Abstract
The giant ciliate Stentor coeruleus is a classical model system for studying regeneration and morphogenesis in a single cell. The anterior of the cell is marked by an array of cilia, known as the oral apparatus, which can be induced to shed and regenerate in a series of reproducible morphological steps, previously shown to require transcription. If a cell is cut in half, each half regenerates an intact cell. We used RNA sequencing (RNAseq) to assay the dynamic changes in Stentor’s transcriptome during regeneration, after both oral apparatus shedding and bisection, allowing us to identify distinct temporal waves of gene expression including kinases, RNA -binding proteins, centriole biogenesis factors, and orthologs of human ciliopathy genes. By comparing transcriptional profiles of different regeneration events, we identified distinct modules of gene expression corresponding to oral apparatus regeneration, posterior holdfast regeneration, and recovery after wounding. By measuring gene expression after blocking translation, we show that the sequential waves of gene expression involve a cascade mechanism in which later waves of expression are triggered by translation products of early-expressed genes. Among the early-expressed genes, we identified an E2F transcription factor and the RNA-binding protein Pumilio as potential regulators of regeneration based on the expression pattern of their predicted target genes. RNAi-mediated knockdown experiments indicate that Pumilio is required for regenerating oral structures of the correct size. E2F is involved in the completion of regeneration but is dispensable for earlier steps. This work allows us to classify regeneration genes into groups based on their potential role for regeneration in distinct cell regeneration paradigms, and provides insight into how a single cell can coordinate complex morphogenetic pathways to regenerate missing structures.
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Affiliation(s)
- Pranidhi Sood
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Athena Lin
- Department of Biochemistry and BioPhysics, University of California, San Francisco, San Francisco, United States
| | - Connie Yan
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Rebecca McGillivary
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Ulises Diaz
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Tatyana Makushok
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Ambika Nadkarni
- Department of Mechanical Engineering, Stanford University, palo alto, United States
| | - Sindy K Y Tang
- Department of Mechanical Engineering, Stanford University, Palo Alto, United States
| | - Wallace F Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
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6
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Abstract
The hydrogen ion concentration ([H+]) in intracellular cytoplasmic fluid (ICF) must be maintained in a narrow range in all species for normal protein functions. Thus, mechanisms regulating ICF are of fundamental biological importance. Studies on the regulation of ICF [H+] have been hampered by use of pH notation, failure to consider the roles played by differences in the concentration of strong ions (strong ion difference, SID), the conservation of mass, the principle of electrical neutrality, and that [H+] and bicarbonate ions [HCO3-] are dependent variables. This argument is based on the late Peter Stewart's physical-chemical analysis of [H+] regulation reported in this journal nearly forty years ago (Stewart. 1983. Can. J. Physiol. Pharmacol. 61: 1444-1461. Doi:10.1139/y83-207). We start by outlining the principles of Stewart's analysis and then provide a general understanding of its significance for regulation of ICF [H+]. The system may initially appear complex, but it becomes evident that changes in SID dominate regulation of [H+]. The primary strong ions are Na+, K+, and Cl-, and a few organic strong anions. The second independent variable, partial pressure of carbon dioxide (PCO2), can easily be assessed. The third independent variable, the activity of intracellular weak acids ([Atot]), is much more complex but largely plays a modifying role. Attention to these principles will potentially provide new insights into ICF pH regulation.
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Affiliation(s)
- Sheldon Magder
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
| | - Alexandr Magder
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
| | - Gordan Samoukovic
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
- Department of Critical Care, McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada
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7
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Oh JH, Yang JH, Choi H, Kim SK. Bicarbonate Recognition Features of a
Naphthobipyrrole‐strapped
Calix[4]pyrrole. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.12159] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Ju Hyun Oh
- Department of Chemistry and Research Institute of Natural Science Gyeongsang National University Jinju 52828 Korea
| | - Ju Ho Yang
- Department of Chemistry and Research Institute of Natural Science Gyeongsang National University Jinju 52828 Korea
| | - Han‐Byeol Choi
- Department of Chemistry and Research Institute of Natural Science Gyeongsang National University Jinju 52828 Korea
| | - Sung Kuk Kim
- Department of Chemistry and Research Institute of Natural Science Gyeongsang National University Jinju 52828 Korea
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8
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Optimal timing of renal replacement therapy for favourable outcome in patients of acute renal failure following cardiac surgery. Indian J Thorac Cardiovasc Surg 2020; 36:127-133. [PMID: 33061111 DOI: 10.1007/s12055-019-00856-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 07/17/2019] [Accepted: 07/19/2019] [Indexed: 11/09/2022] Open
Abstract
Objectives Acute renal failure is a serious complication following cardiac surgery. This may lead to fatal outcome if not treated timely. Continuous renal replacement therapy (RRT) has shown improvement in outcome. There is no clear consensus on the timing of the initiation of RRT in these patients. This study evaluates the factors predicting favourable outcome in this group of patients. Methods Patients undergoing cardiac surgery between January 2015 and December 2018 are included in this retrospective study. RRT is required in 24 patients out of 2254 operated during this period. Patients are divided into groups, survivors (group 1, n = 8) and dead (group 2, n = 16). The preoperative information is accessed from the hospital information system and intensive care unit data. Multivariate analysis of pre continuous renal replacement therapy (CRRT) bicarbonate level, pH, potassium, time of initiating CRRT and central venous pressure is performed. Results The incidence of acute renal failure requiring RRT is 1.06%. Patients in two groups were similar in demographics and presence of risk factors. There was difference in the pre RRT bicarbonate level (p = 0.007). On multivariate analysis, pre RRT bicarbonate levels predict survival (p = 0.003). ROC curve for pre RRT bicarbonate predicts survival for value above 16.83 mg/dl with 80% sensitivity and 78.6% specificity. Conclusion Bicarbonate level in blood predicts the best evidence for initiating the renal replacement therapy in of acute renal failure following cardiac surgery. When urine output drops to < 0.5 ml/kg and not responding to infusion of furosemide, RRT must be initiated at sodium bicarbonate in blood above 16.9 mg%.
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9
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Heo NJ, Yang JH, Lynch VM, Ko BJ, Sessler JL, Kim SK. Capture and displacement-based release of the bicarbonate anion by calix[4]pyrroles with small rigid straps. Chem Sci 2020; 11:8288-8294. [PMID: 34094182 PMCID: PMC8163245 DOI: 10.1039/d0sc03445b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 07/24/2020] [Indexed: 11/21/2022] Open
Abstract
Two-phenoxy walled calix[4]pyrroles 1 and 2 strapped with small rigid linkers containing pyridine and benzene, respectively, have been synthesized. 1H NMR spectroscopic analyses carried out in CDCl3 revealed that both of receptors 1 and 2 recognize only F- and HCO3 - among various test anions with high preference for HCO3 - (as the tetraethylammonium, TEA+ salt) relative to F- (as the TBA+ salt). The bound HCO3 - anion was completely released out of the receptors upon the addition of F- (as the tetrabutylammonium, TBA+ salt) as a result of significantly enhanced affinities and selectivities of the receptors for F- once converted to the TEAHCO3 complexes. Consequently, relatively stable TEAF complexes of receptors 1 and 2 were formed via anion metathesis occurring within the receptor cavities. By contrast, the direct addition of TEAF to receptors 1 and 2 produces different complexation products initially, although eventually the same TEAF complexes are produced as via sequential TEAHCO3 and TBAF addition. These findings are rationalized in terms of the formation of different ion pair complexes involving interactions both inside and outside of the core receptor framework.
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Affiliation(s)
- Nam Jung Heo
- Department of Chemistry, Research Institute of Natural Science, Gyeongsang National University Jinju 660-701 Korea
| | - Ju Ho Yang
- Department of Chemistry, Research Institute of Natural Science, Gyeongsang National University Jinju 660-701 Korea
| | - Vincent M Lynch
- Department of Chemistry, The University of Texas at Austin 105 E. 24th Street-Stop A5300 Austin Texas 78712-1224 USA
| | - Byoung Joon Ko
- New Drug Development Center, Osong Medical Innovation Foundation Chungbuk Korea 28160
| | - Jonathan L Sessler
- Department of Chemistry, The University of Texas at Austin 105 E. 24th Street-Stop A5300 Austin Texas 78712-1224 USA
| | - Sung Kuk Kim
- Department of Chemistry, Research Institute of Natural Science, Gyeongsang National University Jinju 660-701 Korea
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10
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Heo NJ, Oh JH, Lee JT, He Q, Sessler JL, Kim SK. Phenanthroline-strapped calix[4]pyrroles: anion receptors displaying affinity reversal as a function of solvent polarity. Org Chem Front 2020. [DOI: 10.1039/c9qo01377f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Calix[4]pyrroles 1 and 2, diametrically strapped with a phenanthroline via ester and amide linkages, respectively, have been synthesized as anion receptors.
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Affiliation(s)
- Nam Jung Heo
- Department of Chemistry and Research Institute of Natural Science
- Gyeongsang National University
- Jinju 52828
- Korea
| | - Ju Hyun Oh
- Department of Chemistry and Research Institute of Natural Science
- Gyeongsang National University
- Jinju 52828
- Korea
| | - Jeong Tae Lee
- Department of Chemistry and Institute of Applied Chemistry
- Hallym University
- Chuncheon 24252
- Korea
| | - Qing He
- State Key Laboratory of Chemo/Biosensing and Chemometrics
- College of Chemistry and Chemical Engineering
- Hunan University
- Changsha 410082
- P. R. China
| | | | - Sung Kuk Kim
- Department of Chemistry and Research Institute of Natural Science
- Gyeongsang National University
- Jinju 52828
- Korea
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11
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Vairamani K, Wang HS, Medvedovic M, Lorenz JN, Shull GE. RNA SEQ Analysis Indicates that the AE3 Cl -/HCO 3- Exchanger Contributes to Active Transport-Mediated CO 2 Disposal in Heart. Sci Rep 2017; 7:7264. [PMID: 28779178 PMCID: PMC5544674 DOI: 10.1038/s41598-017-07585-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/29/2017] [Indexed: 02/06/2023] Open
Abstract
Loss of the AE3 Cl−/HCO3− exchanger (Slc4a3) in mice causes an impaired cardiac force-frequency response and heart failure under some conditions but the mechanisms are not known. To better understand the functions of AE3, we performed RNA Seq analysis of AE3-null and wild-type mouse hearts and evaluated the data with respect to three hypotheses (CO2 disposal, facilitation of Na+-loading, and recovery from an alkaline load) that have been proposed for its physiological functions. Gene Ontology and PubMatrix analyses of differentially expressed genes revealed a hypoxia response and changes in vasodilation and angiogenesis genes that strongly support the CO2 disposal hypothesis. Differential expression of energy metabolism genes, which indicated increased glucose utilization and decreased fatty acid utilization, were consistent with adaptive responses to perturbations of O2/CO2 balance in AE3-null myocytes. Given that the myocardium is an obligate aerobic tissue and consumes large amounts of O2, the data suggest that loss of AE3, which has the potential to extrude CO2 in the form of HCO3−, impairs O2/CO2 balance in cardiac myocytes. These results support a model in which the AE3 Cl−/HCO3− exchanger, coupled with parallel Cl− and H+-extrusion mechanisms and extracellular carbonic anhydrase, is responsible for active transport-mediated disposal of CO2.
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Affiliation(s)
- Kanimozhi Vairamani
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, 45267, USA
| | - Hong-Sheng Wang
- Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, Ohio, 45267, USA
| | - Mario Medvedovic
- Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, Ohio, 45267, USA
| | - John N Lorenz
- Department of Cellular and Molecular Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, 45267, USA
| | - Gary E Shull
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, 45267, USA.
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12
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Bernardino RL, Costa AR, Martins AD, Silva J, Barros A, Sousa M, Sá R, Alves MG, Oliveira PF. Estradiol modulates Na(+) -dependent HCO3 (-) transporters altering intracellular pH and ion transport in human Sertoli cells: A role on male fertility? Biol Cell 2016; 108:179-88. [PMID: 26888167 DOI: 10.1111/boc.201500094] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/10/2016] [Accepted: 02/11/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND INFORMATION Infertile men often present deregulation of serum estrogen levels. Notably, high levels of estradiol (E2) are associated with low sperm production and quality. Sertoli cells (SCs) are responsible for spermatogenesis maintenance and are major targets for the hormonal signalling that regulates this complex process. RESULTS In this study, we used primary cultures of human SCs and studied the localisation, expression and functionality of the Na(+) -dependent HCO3 (-) transporters by confocal microscopy, immunoblot, epifluorescence and voltage clamp after 24 h of exposure to E2 (100 nM). All studied transporters were identified in human SCs. In E2-treated human SCs, there was an increase in NBCn1, NBCe1 and NDCBE protein levels, as well as an increase in intracellular pH and a decrease in transcellular transport. CONCLUSIONS We report an association between increased levels of E2 and the expression/function of Na(+) -dependent HCO3 (-) transporters in human SCs. Our results provide new evidence on the mechanisms by which E2 can regulate SCs physiology and consequently spermatogenesis. These mechanisms may have an influence on male reproductive potential and help to explain male infertility conditions associated with estrogen deregulation. SIGNIFICANCE Exposure to E2 increased human SCs intracellular pH. E2 is a modulator of ionic transcellular transport in human SCs.
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Affiliation(s)
- Raquel L Bernardino
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, Porto, Portugal
| | - Ana R Costa
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Ana D Martins
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, Porto, Portugal.,CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Joaquina Silva
- Centre for Reproductive Genetics Prof. Alberto Barros, Porto, Portugal
| | - Alberto Barros
- Centre for Reproductive Genetics Prof. Alberto Barros, Porto, Portugal.,Department of Genetics, Faculty of Medicine, University of Porto, Porto, Portugal.,I3S, Institute for Innovation and Health Research, University of Porto, Porto, Portugal
| | - Mário Sousa
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, Porto, Portugal.,Centre for Reproductive Genetics Prof. Alberto Barros, Porto, Portugal
| | - Rosália Sá
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, Porto, Portugal
| | - Marco G Alves
- CICS-UBI-Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal
| | - Pedro F Oliveira
- Department of Microscopy, Laboratory of Cell Biology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Unit for Multidisciplinary Research in Biomedicine (UMIB), University of Porto, Porto, Portugal.,I3S, Institute for Innovation and Health Research, University of Porto, Porto, Portugal
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13
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Abstract
Carbon dioxide (CO2) is an end product of aerobic cellular respiration. In healthy persons, PaCO2 is maintained by physiologic mechanisms within a narrow range (35-45 mm Hg). Both hypercapnia and hypocapnia are encountered in myriad clinical situations. In recent years, the number of hypercapnic patients has increased by the use of smaller tidal volumes to limit lung stretch and injury during mechanical ventilation, so-called permissive hypercapnia. A knowledge and appreciation of the effects of CO2 in the heart are necessary for optimal clinical management in the perioperative and critical care settings. This article reviews, from a historical perspective: (1) the effects of CO2 on coronary blood flow and the mechanisms underlying these effects; (2) the role of endogenously produced CO2 in metabolic control of coronary blood flow and the matching of myocardial oxygen supply to demand; and (3) the direct and reflexogenic actions of CO2 on myocardial contractile function. Clinically relevant issues are addressed, including the role of increased myocardial tissue PCO2 (PmCO2) in the decline in myocardial contractility during coronary hypoperfusion and the increased vulnerability to CO2-induced cardiac depression in patients receiving a β-adrenergic receptor antagonist or with otherwise compromised inotropic reserve. The potential use of real-time measurements of PmO2 to monitor the adequacy of myocardial perfusion in the perioperative period is discussed.
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Affiliation(s)
- George J Crystal
- From the Department of Anesthesiology, Advocate Illinois Masonic Medical Center, Chicago, Illinois; and Departments of Anesthesiology and of Physiology and Biophysics, University of Illinois College of Medicine, Chicago, Illinois
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14
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Iwasaki K, Yabushita H, Ueno T, Wakatsuki A. Role of hypoxia-inducible factor-1α, carbonic anhydrase-IX, glucose transporter-1 and vascular endothelial growth factor associated with lymph node metastasis and recurrence in patients with locally advanced cervical cancer. Oncol Lett 2015; 10:1970-1978. [PMID: 26622782 PMCID: PMC4579921 DOI: 10.3892/ol.2015.3524] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 03/13/2015] [Indexed: 01/02/2023] Open
Abstract
The aim of the present study was to determine whether the expression of hypoxia-inducible factor-1α (HIF-1α), carbonic anhydrase-IX (CA-IX), glucose transporter-1 (GLUT-1) or vascular endothelial growth factor (VEGF) was associated with the clinicopathological characteristics, lymph node metastasis or progression-free survival of patients with cervical cancer. Tumor tissue samples were obtained from 54 cervical cancer patients who had undergone radical hysterectomy. The expression of HIF-1α, CA-IX, GLUT-1 and VEGF was analyzed by immunohistochemical staining. Of the 54 cases, 28 were positive for HIF-1α, 35 for CA-IX, 40 for GLUT-1 and 23 for VEGF. It was revealed that HIF-1α expression was correlated with tumor stage and histology, CA-IX expression with tumor stage, tumor size, lymph node metastasis and lymph-vascular space involvement, GLUT-1 expression with tumor stage and lymph-vascular space involvement, and VEGF expression with microvessel density. The multivariate regression analysis indicated that CA-IX expression and lymph-vascular space involvement were independent variables associated with lymph node metastasis. Progression-free survival was shorter for patients who were positive for CA-IX or VEGF expression than for those who were negative for CA-IX or VEGF expression. The progression-free survival of patients treated with radiotherapy or chemo-radiotherapy following radical hysterectomy was also shorter for patients with positive CA-IX expression. These findings suggest that CA-IX expression is a possible risk factor for lymph node metastasis and disease recurrence in locally advanced cervical cancer patients.
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Affiliation(s)
- Keita Iwasaki
- Department of Obstetrics and Gynecology, School of Medicine, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Hiromitsu Yabushita
- Department of Obstetrics and Gynecology, School of Medicine, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Taiki Ueno
- Department of Obstetrics and Gynecology, School of Medicine, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
| | - Akihiko Wakatsuki
- Department of Obstetrics and Gynecology, School of Medicine, Aichi Medical University, Nagakute, Aichi 480-1195, Japan
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Sowah D, Brown BF, Quon A, Alvarez BV, Casey JR. Resistance to cardiomyocyte hypertrophy in ae3-/- mice, deficient in the AE3 Cl-/HCO3- exchanger. BMC Cardiovasc Disord 2014; 14:89. [PMID: 25047106 PMCID: PMC4120010 DOI: 10.1186/1471-2261-14-89] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/16/2014] [Indexed: 12/21/2022] Open
Abstract
Background Cardiac hypertrophy is central to the etiology of heart failure. Understanding the molecular pathways promoting cardiac hypertrophy may identify new targets for therapeutic intervention. Sodium-proton exchanger (NHE1) activity and expression levels in the heart are elevated in many models of hypertrophy through protein kinase C (PKC)/MAPK/ERK/p90RSK pathway stimulation. Sustained NHE1 activity, however, requires an acid-loading pathway. Evidence suggests that the Cl−/HCO3− exchanger, AE3, provides this acid load. Here we explored the role of AE3 in the hypertrophic growth cascade of cardiomyocytes. Methods AE3-deficient (ae3−/−) mice were compared to wildtype (WT) littermates to examine the role of AE3 protein in the development of cardiomyocyte hypertrophy. Mouse hearts were assessed by echocardiography. As well, responses of cultured cardiomyocytes to hypertrophic stimuli were measured. pH regulation capacity of ae3−/− and WT cardiomyocytes was assessed in cultured cells loaded with the pH-sensitive dye, BCECF-AM. Results ae3−/− mice were indistinguishable from wild type (WT) mice in terms of cardiovascular performance. Stimulation of ae3−/− cardiomyocytes with hypertrophic agonists did not increase cardiac growth or reactivate the fetal gene program. ae3−/− mice are thus protected from pro-hypertrophic stimulation. Steady state intracellular pH (pHi) in ae3−/− cardiomyocytes was not significantly different from WT, but the rate of recovery of pHi from imposed alkalosis was significantly slower in ae3−/− cardiomyocytes. Conclusions These data reveal the importance of AE3-mediated Cl−/HCO3− exchange in cardiovascular pH regulation and the development of cardiomyocyte hypertrophy. Pharmacological antagonism of AE3 is an attractive approach in the treatment of cardiac hypertrophy.
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Affiliation(s)
| | | | | | | | - Joseph R Casey
- Department of Biochemistry and Membrane Protein Disease Research Group, University of Alberta, Edmonton T6G 2H7, Canada.
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16
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Lascano EC, Said M, Vittone L, Mattiazzi A, Mundiña-Weilenmann C, Negroni JA. Role of CaMKII in post acidosis arrhythmias: a simulation study using a human myocyte model. J Mol Cell Cardiol 2013; 60:172-83. [PMID: 23624090 DOI: 10.1016/j.yjmcc.2013.04.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/15/2013] [Accepted: 04/15/2013] [Indexed: 02/08/2023]
Abstract
Postacidotic arrhythmias have been associated to increased sarcoplasmic reticulum (SR) Ca(2+) load and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation. However, the molecular mechanisms underlying these arrhythmias are still unclear. To better understand this process, acidosis produced by CO2 increase from 5% to 30%, resulting in intracellular pH (pHi) change from 7.15 to 6.7, was incorporated into a myocyte model of excitation-contraction coupling and contractility, including acidotic inhibition of L-type Ca(2+) channel (I(CaL)), Na(+)-Ca(2+) exchanger, Ca(2+) release through the SR ryanodine receptor (RyR2) (I(rel)), Ca(2+) reuptake by the SR Ca(2+) ATPase2a (I(up)), Na(+)-K(+) pump, K(+) efflux through the inward rectifier K(+) channel and the transient outward K(+) flow (I(to)) together with increased activity of the Na(+)-H(+) exchanger (I(NHE)). Simulated CaMKII regulation affecting I(rel), I(up), I(CaL), I(NHE) and I(to) was introduced in the model to partially compensate the acidosis outcome. Late Na(+) current increase by CaMKII was also incorporated. Using this scheme and assuming that diastolic Ca(2+) leak through the RyR2 was modulated by the resting state of this channel and the difference between SR and dyadic cleft [Ca(2+)], postacidotic delayed after depolarizations (DADs) were triggered upon returning to normal pHi after 6 min acidosis. The model showed that DADs depend on SR Ca(2+) load and on increased Ca(2+) leak through RyR2. This postacidotic arrhythmogenic pattern relies mainly on CaMKII effect on I(CaL) and I(up), since its individual elimination produced the highest DAD reduction. The model further revealed that during the return to normal pHi, DADs are fully determined by SR Ca(2+) load at the end of acidosis. Thereafter, DADs are maintained by SR Ca(2+) reloading by Ca(2+) influx through the reverse NCX mode during the time period in which [Na(+)]i is elevated.
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Affiliation(s)
- Elena C Lascano
- Department of Biology, Universidad Favaloro, Buenos Aires, Argentina.
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Miyazaki T, Ikegami T, Nagai Y, Nguyen A, Matsuzaki Y, Kobayashi K, Ceryak S. Bicarbonate Attenuates Irinotecan-Induced Cytotoxicity through Regulation of Both Extracellular and Intracellular <i>pHs</i> in Intestine Cell Line. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/jct.2013.45106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Sattler W, Parkin G. Structural characterization of zinc bicarbonate compounds relevant to the mechanism of action of carbonic anhydrase. Chem Sci 2012. [DOI: 10.1039/c2sc20167d] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Roberts BN, Christini DJ. NHE inhibition does not improve Na(+) or Ca(2+) overload during reperfusion: using modeling to illuminate the mechanisms underlying a therapeutic failure. PLoS Comput Biol 2011; 7:e1002241. [PMID: 22028644 PMCID: PMC3197652 DOI: 10.1371/journal.pcbi.1002241] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 09/10/2011] [Indexed: 11/18/2022] Open
Abstract
Reperfusion injury results from pathologies of cardiac myocyte physiology that develop when previously ischemic myocardium experiences a restoration of normal perfusion. Events in the development of reperfusion injury begin with the restoration of a proton gradient upon reperfusion, which then allows the sodium-proton exchanger (NHE) to increase flux, removing protons from the intracellular space while importing sodium. The resulting sodium overload drives increased reverse-mode sodium-calcium exchanger (NCX) activity, creating a secondary calcium overload that has pathologic consequences. One of the attempts to reduce reperfusion-related damage, NHE inhibition, has shown little clinical benefit, and only when NHE inhibitors are given prior to reperfusion. In an effort to further understand why NHE inhibitors have been largely unsuccessful, we employed a new mathematical cardiomyocyte model that we developed for the study of ischemia and reperfusion. Using this model, we simulated 20 minutes of ischemia and 10 minutes of reperfusion, while also simulating NHE inhibition by reducing NHE flux in our model by varying amounts and at different time points. In our simulations, when NHE inhibition is applied at the onset of reperfusion, increasing the degree of inhibition increases the peak sodium and calcium concentrations, as well as reducing intracellular pH recovery. When inhibition was instituted at earlier time points, some modest improvements were seen, largely due to reduced sodium concentrations prior to reperfusion. Analysis of all sodium flux pathways suggests that the sodium-potassium pump (NaK) plays the largest role in exacerbated sodium overload during reperfusion, and that reduced NaK flux is largely the result of impaired pH recovery. While NHE inhibition does indeed reduce sodium influx through that exchanger, the resulting prolongation of intracellular acidosis paradoxically increases sodium overload, largely mediated by impaired NaK function. Myocardial ischemia, commonly observed when arteries supplying the heart become occluded, results when cardiac tissue receives inadequate blood perfusion. In order to minimize the amount of cardiac damage, ischemic tissue must be reperfused. However, reperfusion can result in deleterious effects that leave the heart muscle sicker than if the ischemia had been allowed to continue. Examples of these reperfusion injuries include lethal arrhythmias and an increased region of cell death. Some of the early events that result in reperfusion injury include changes in pH and an overload of sodium inside the cell. During reperfusion, the sodium-proton exchanger (NHE) removes protons from the cell in an effort to restore normal pH, in turn importing sodium ions. Many strategies have been attempted to prevent reperfusion injury, including inhibition of the NHE, with little clinical effect. Using a mathematical model that we developed to study ischemia and reperfusion in cardiac cells, we found that NHE inhibition produces more severe sodium overload, largely due to adverse consequences of the delayed pH recovery produced by NHE inhibition. These results suggest that NHE inhibition alone may not be a viable strategy, and that therapies which prolong intracellular acidosis may be problematic.
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Affiliation(s)
- Byron N. Roberts
- Greenberg Division of Cardiology and Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical College, New York, New York, United States of America
| | - David J. Christini
- Greenberg Division of Cardiology and Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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Klier M, Schüler C, Halestrap AP, Sly WS, Deitmer JW, Becker HM. Transport activity of the high-affinity monocarboxylate transporter MCT2 is enhanced by extracellular carbonic anhydrase IV but not by intracellular carbonic anhydrase II. J Biol Chem 2011; 286:27781-91. [PMID: 21680735 DOI: 10.1074/jbc.m111.255331] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The ubiquitous enzyme carbonic anhydrase isoform II (CAII) has been shown to enhance transport activity of the proton-coupled monocarboxylate transporters MCT1 and MCT4 in a non-catalytic manner. In this study, we investigated the role of cytosolic CAII and of the extracellular, membrane-bound CA isoform IV (CAIV) on the lactate transport activity of the high-affinity monocarboxylate transporter MCT2, heterologously expressed in Xenopus oocytes. In contrast to MCT1 and MCT4, transport activity of MCT2 was not altered by CAII. However, coexpression of CAIV with MCT2 resulted in a significant increase in MCT2 transport activity when the transporter was coexpressed with its associated ancillary protein GP70 (embigin). The CAIV-mediated augmentation of MCT2 activity was independent of the catalytic activity of the enzyme, as application of the CA-inhibitor ethoxyzolamide or coexpressing the catalytically inactive mutant CAIV-V165Y did not suppress CAIV-mediated augmentation of MCT2 transport activity. Furthermore, exchange of His-88, mediating an intramolecular H(+)-shuttle in CAIV, to alanine resulted only in a slight decrease in CAIV-mediated augmentation of MCT2 activity. The data suggest that extracellular membrane-bound CAIV, but not cytosolic CAII, augments transport activity of MCT2 in a non-catalytic manner, possibly by facilitating a proton pathway other than His-88.
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Affiliation(s)
- Michael Klier
- Abteilung für Allgemeine Zoologie, Fachbereich Biologie, Technische Universität Kaiserslautern, P. O. Box 3049, 67653 Kaiserslautern, Germany
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21
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Seeber LM, Horrée N, Vooijs MA, Heintz APM, van der Wall E, Verheijen RH, van Diest PJ. The role of hypoxia inducible factor-1alpha in gynecological cancer. Crit Rev Oncol Hematol 2011; 78:173-84. [DOI: 10.1016/j.critrevonc.2010.05.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 04/07/2010] [Accepted: 05/05/2010] [Indexed: 12/27/2022] Open
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Seeber LMS, Horrée N, van der Groep P, van der Wall E, Verheijen RHM, van Diest PJ. Necrosis related HIF-1alpha expression predicts prognosis in patients with endometrioid endometrial carcinoma. BMC Cancer 2010; 10:307. [PMID: 20565904 PMCID: PMC2909981 DOI: 10.1186/1471-2407-10-307] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 06/19/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Hypoxia inducible factor 1alpha (HIF-1alpha) plays an essential role in the adaptive response of cells to hypoxia and is associated with aggressive tumour behaviour. We have shown p27kip1, which is generally reduced in endometrial cancer, to be re-expressed in hypoxic regions. This possibly contributes to survival of cancer cells. The aim of this study was to evaluate the prognostic value of HIF-1alpha and p27kip expression in patients with endometrioid endometrial cancer. METHODS Expression levels of HIF-1alpha, CAIX, Glut-1, and p27kip1 were analyzed by immunohistochemistry. Percentage of positive cells, staining pattern (perinecrotic, diffuse, or mixed) and presence of necrosis were noted. RESULTS Necrosis was correlated with shortened disease free survival (DFS) (p = 0.008) and overall survival (OS) (p = 0.045). For DFS, perinecrotic HIF-1alpha expression was also prognostic (p = 0.044). Moreover, high p27kip1 expression was an additional prognostic factor for these patients with perinecrotic HIF-1alpha expression. In multivariate Cox regression, perinecrotic HIF-expression emerged as an independent prognostic factor. Perinecrotic HIF-1alpha expression was significantly associated with CAIX and Glut-1 expression, pointing towards functional HIF-1. CONCLUSIONS In patients with endometrioid endometrial cancer, necrosis and necrosis-related expression of HIF-1alpha are important prognostic factors. More aggressive adjuvant treatment might be necessary to improve the outcome of patients with these characteristics.
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Affiliation(s)
- Laura M S Seeber
- Department of Gynaecological Oncology, University Medical Centre Utrecht, The Netherlands
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23
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A model of Na+/H+ exchanger and its central role in regulation of pH and Na+ in cardiac myocytes. Biophys J 2010; 97:2674-83. [PMID: 19917220 DOI: 10.1016/j.bpj.2009.08.053] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 07/30/2009] [Accepted: 08/21/2009] [Indexed: 01/27/2023] Open
Abstract
A new kinetic model of the Na(+)/H(+) exchanger (NHE) was developed by fitting a variety of major experimental findings, such as ion-dependencies, forward/reverse mode, and the turnover rate. The role of NHE in ion homeostasis was examined by implementing the NHE model in a minimum cell model including intracellular pH buffer, Na(+)/K(+) pump, background H(+), and Na(+) fluxes. This minimum cell model was validated by reconstructing recovery of pH(i) from acidification, accompanying transient increase in [Na(+)](i) due to NHE activity. Based on this cell model, steady-state relationships among pH(i), [Na(+)](I), and [Ca(2+)](i) were quantitatively determined, and thereby the critical level of acidosis for cell survival was predicted. The acidification reported during partial blockade of the Na(+)/K(+) pump was not attributed to a dissipation of the Na(+) gradient across the membrane, but to an increase in indirect H(+) production. This NHE model, though not adapted to the dimeric behavioral aspects of NHE, can provide a strong clue to quantitative prediction of degree of acidification and accompanying disturbance of ion homeostasis under various pathophysiological conditions.
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24
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Hypoxia-inducible factor-1 as a therapeutic target in endometrial cancer management. Obstet Gynecol Int 2010; 2010:580971. [PMID: 20169098 PMCID: PMC2821774 DOI: 10.1155/2010/580971] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2009] [Accepted: 12/22/2009] [Indexed: 01/21/2023] Open
Abstract
In the Western world, endometrial cancer (EC) is the most common malignant tumor of the female genital tract. Solid tumors like EC outgrow their vasculature resulting in hypoxia. Tumor hypoxia is important because it renders an aggressive phenotype and leads to radio- and chemo-therapy resistance. Hypoxia-inducible factor-1alpha (HIF-1alpha) plays an essential role in the adaptive cellular response to hypoxia and is associated with poor clinical outcome in EC. Therefore, HIF-1 could be an attractive therapeutic target. Selective HIF-1 inhibitors have not been identified. A number of nonselective inhibitors which target signaling pathways upstream or downstream HIF-1 are known to decrease HIF-1alpha protein levels. In clinical trials for the treatment of advanced and/or recurrent EC are the topoisomerase I inhibitor Topotecan, mTOR-inhibitor Rapamycin, and angiogenesis inhibitor Bevacizumab. Preliminary data shows encouraging results for these agents. Further work is needed to identify selective HIF-1 inhibitors and to translate these into clinical trials.
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Chiche J, Brahimi-Horn MC, Pouysségur J. Tumour hypoxia induces a metabolic shift causing acidosis: a common feature in cancer. J Cell Mol Med 2009; 14:771-94. [PMID: 20015196 PMCID: PMC3823111 DOI: 10.1111/j.1582-4934.2009.00994.x] [Citation(s) in RCA: 459] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Maintenance of cellular pH homeostasis is fundamental to life. A number of key intracellular pH (pHi) regulating systems including the Na+/H+ exchangers, the proton pump, the monocarboxylate transporters, the HCO3− transporters and exchangers and the membrane-associated and cytosolic carbonic anhydrases cooperate in maintaining a pHi that is permissive for cell survival. A common feature of tumours is acidosis caused by hypoxia (low oxygen tension). In addition to oncogene activation and transformation, hypoxia is responsible for inducing acidosis through a shift in cellular metabolism that generates a high acid load in the tumour microenvironment. However, hypoxia and oncogene activation also allow cells to adapt to the potentially toxic effects of an excess in acidosis. Hypoxia does so by inducing the activity of a transcription factor the hypoxia-inducible factor (HIF), and particularly HIF-1, that in turn enhances the expression of a number of pHi-regulating systems that cope with acidosis. In this review, we will focus on the characterization and function of some of the hypoxia-inducible pH-regulating systems and their induction by hypoxic stress. It is essential to understand the fundamentals of pH regulation to meet the challenge consisting in targeting tumour metabolism and acidosis as an anti-tumour approach. We will summarize strategies that take advantage of intracellular and extracellular pH regulation to target the primary tumour and metastatic growth, and to turn around resistance to chemotherapy and radiotherapy.
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Affiliation(s)
- Johanna Chiche
- Institute of Developmental Biology and Cancer Research, University of Nice, CNRS UMR, Centre A. Lacassagne, Nice, France
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26
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Halestrap AP, Pasdois P. The role of the mitochondrial permeability transition pore in heart disease. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1402-15. [PMID: 19168026 DOI: 10.1016/j.bbabio.2008.12.017] [Citation(s) in RCA: 277] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 12/19/2008] [Accepted: 12/20/2008] [Indexed: 01/17/2023]
Abstract
Like Dr. Jeckyll and Mr. Hyde, mitochondria possess two distinct persona. Under normal physiological conditions they synthesise ATP to meet the energy needs of the beating heart. Here calcium acts as a signal to balance the rate of ATP production with ATP demand. However, when the heart is overloaded with calcium, especially when this is accompanied by oxidative stress, mitochondria embrace their darker side, and induce necrotic cell death of the myocytes. This happens acutely in reperfusion injury and chronically in congestive heart failure. Here calcium overload, adenine nucleotide depletion and oxidative stress combine forces to induce the opening of a non-specific pore in the mitochondrial membrane, known as the mitochondrial permeability transition pore (mPTP). The molecular nature of the mPTP remains controversial but current evidence implicates a matrix protein, cyclophilin-D (CyP-D) and two inner membrane proteins, the adenine nucleotide translocase (ANT) and the phosphate carrier (PiC). Inhibition of mPTP opening can be achieved with inhibitors of each component, but targeting CyP-D with cyclosporin A (CsA) and its non-immunosuppressive analogues is the best described. In animal models, inhibition of mPTP opening by either CsA or genetic ablation of CyP-D provides strong protection from both reperfusion injury and congestive heart failure. This confirms the mPTP as a promising drug target in human cardiovascular disease. Indeed, the first clinical trials have shown CsA treatment improves recovery after treatment of a coronary thrombosis with angioplasty.
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Affiliation(s)
- Andrew P Halestrap
- Department of Biochemistry and Bristol Heart Institute, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, UK.
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Stock C, Schwab A. Protons make tumor cells move like clockwork. Pflugers Arch 2009; 458:981-92. [PMID: 19437033 DOI: 10.1007/s00424-009-0677-8] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 04/28/2009] [Indexed: 01/10/2023]
Abstract
Cancer accounts for 13% of the yearly total mortality worldwide. Most cancer deaths are the sequel of metastatic diseases rather than of primary tumor growth. Thus, the major challenge in tumor therapy is the tumor cells' ability to metastasize. The extent to which a tumor metastasizes correlates with the tumor cells' migratory activity. Tumor cell migration requires a coordinated formation and release of cell adhesion contacts, a controlled cytoskeletal dynamics, the digestion and reorganization of the extracellular matrix, and local ion and water transport across the plasma membrane. All of these operations depend on intracellular pH (pH(i)) and extracellular pH (pH(e)). Numerous H(+), HCO (3) (-) , and monocarboxylate transporters as well as different carbonic anhydrase isozymes have considerable impact on pH(i) and pH(e) which spotlights them as possible, potential targets for anticancer therapeutics. Especially in solid tumors whose vascularization is often not sufficient, tumor cells cope with hypoxia and the resulting glycolysis by overexpressing the Na(+)/H(+) exchanger NHE1, monocarboxylate transporters MCT1 and/or MCT4, and the carbonic anhydrase CA IX. NHE1, MCT, and CA IX activity lead to an acidification of the extracellular space in order to maintain the cytosolic pH homeostasis stable. The present article gives a review on how this characteristic, acidic tumor micro- and nanoenvironment controls tumor cell migration.
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Affiliation(s)
- Christian Stock
- Institut für Physiologie II, University of Münster, Robert-Koch-Str. 27b, 48149, Münster, Germany.
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Vaughan-Jones RD, Spitzer KW, Swietach P. Intracellular pH regulation in heart. J Mol Cell Cardiol 2008; 46:318-31. [PMID: 19041875 DOI: 10.1016/j.yjmcc.2008.10.024] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/11/2008] [Indexed: 12/14/2022]
Abstract
Intracellular pH (pHi) is an important modulator of cardiac excitation and contraction, and a potent trigger of electrical arrhythmia. This review outlines the intracellular and membrane mechanisms that control pHi in the cardiac myocyte. We consider the kinetic regulation of sarcolemmal H+, OH- and HCO3- transporters by pH, and by receptor-coupled intracellular signalling systems. We also consider how activity of these pHi effector proteins is coordinated spatially in the myocardium by intracellular mobile buffer shuttles, gap junctional channels and carbonic anhydrase enzymes. Finally, we review the impact of pHi regulatory proteins on intracellular Ca2+ signalling, and their participation in clinical disorders such as myocardial ischaemia, maladaptive hypertrophy and heart failure. Such multiple effects emphasise the fundamental role that pHi regulation plays in the heart.
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Affiliation(s)
- Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Oxford, Parks Road, OX1 3PT, UK.
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Measuring and modeling chloride-hydroxyl exchange in the Guinea-pig ventricular myocyte. Biophys J 2007; 94:2385-403. [PMID: 18055536 DOI: 10.1529/biophysj.107.118885] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Protons are powerful modulators of cardiac function. Their intracellular concentration is regulated by sarcolemmal ion transporters that export or import H+-ions (or their ionic equivalent: HCO3-, OH-). One such transporter, which imports H+-equivalents, is a putative Cl-/OH- exchanger (CHE). A strong candidate for CHE is SLC26A6 protein, a product of the SLC26A gene family of anion transporters, which has been detected in murine heart. SLC26A6 protein is suggested to be an electrogenic 1Cl-/2OH-(2HCO3-) exchanger. Unfortunately, there is insufficient characterization of cardiac CHE against which the properties of heterologously expressed SLC26A6 can be matched. We therefore investigated the proton, Cl-, and voltage dependence of CHE activity in guinea-pig ventricular myocytes, using voltage-clamp, intracellular pH fluorescence, and mathematical modeling techniques. We find that CHE activity is tightly regulated by intracellular and extracellular pH, is voltage-insensitive over a wide range (+/-80 mV), and displays substrate dependence suggestive of electroneutral 1Cl-/1OH- exchange. These properties exclude electrogenic SLC26A6 as sole contributor to CHE. Either the SLC26A6 product in heart is electroneutral, or CHE comprises at least two transporters with oppositely balanced voltage sensitivity. Alternatively, CHE may comprise an H+-Cl- coinflux system, which cannot be distinguished kinetically from an exchanger. Irrespective of ionic mechanism, CHE's pH sensitivity helps to define resting intracellular pH, and hence basal function in the heart.
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Horrée N, van Diest PJ, Sie-Go DMDS, Heintz APM. The invasive front in endometrial carcinoma: higher proliferation and associated derailment of cell cycle regulators. Hum Pathol 2007; 38:1232-8. [PMID: 17490724 DOI: 10.1016/j.humpath.2007.01.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 12/28/2006] [Accepted: 01/05/2007] [Indexed: 01/28/2023]
Abstract
The aim of the study was to explore whether expression of proliferation and hypoxia-related proteins differs in the central parts and the invasive front in endometrial carcinomas. Proliferation-associated proteins Ki67 and cyclin A; cell cycle regulators p16, p21, p53, cyclin D1, cyclin E, and cdk2; and hypoxia-inducible factor 1alpha and its downstream factors glucose transporter 1, carbonic anhydrase IX, and vascular endothelial growth factor were immunohistochemically stained in paraffin-embedded specimens from endometrioid (n = 33), mucinous (n = 1), and serous (n = 5) endometrial carcinomas. The percentages of positive cells at the invasive front and central tumor parts were scored and compared. Ki67 (P < .001), cyclin E (P = .018), p16 (P = .003), and cdk2 (.001) were expressed higher at the invasive front than centrally (Wilcoxon signed ranks test). Higher expression of these antigens at the invasive front was seen in 31 of 38 cases for Ki67, in 16 of 39 cases for cyclin E, in 15 of 39 cases for cdk2, and in 11 of 39 cases for p16. The other cell cycle proteins and the hypoxia-related factors did not show significant differences in expression between the central parts and the invasive front. Endometrial carcinomas clearly show an invasive front that is characterized by higher proliferation and progressive derailment of the cell cycle regulators cyclin E, p16, and cdk2, but not by an increased hypoxic response.
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Affiliation(s)
- Nicole Horrée
- Department of Surgical Gynecology and Oncology, University Medical Center Utrecht, 3508 GA Utrecht, The Netherlands
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31
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Imahashi K, Mraiche F, Steenbergen C, Murphy E, Fliegel L. Overexpression of the Na+/H+exchanger and ischemia-reperfusion injury in the myocardium. Am J Physiol Heart Circ Physiol 2007; 292:H2237-47. [PMID: 17209001 DOI: 10.1152/ajpheart.00855.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the myocardium, the Na+/H+exchanger isoform-1 (NHE1) activity is detrimental during ischemia-reperfusion (I/R) injury, causing increased intracellular Na+(Nai+) accumulation that results in subsequent Ca2+overload. We tested the hypothesis that increased expression of NHE1 would accentuate myocardial I/R injury. Transgenic mice were created that increased the Na+/H+exchanger activity specifically in the myocardium. Intact hearts from transgenic mice at 10–15 wk of age showed no change in heart performance, resting intracellular pH (pHi) or phosphocreatine/ATP levels. Transgenic and wild-type (WT) hearts were subjected to 20 min of ischemia followed by 40 min of reperfusion. Surprisingly, the percent recovery of rate-pressure product (%RPP) after I/R improved in NHE1-overexpressing hearts (64 ± 5% vs. 41 ± 5% in WT; P < 0.05). In addition, NMR spectroscopy revealed that NHE1 overexpressor hearts contained higher ATP during early reperfusion (levels P < 0.05), and there was no difference in Na+accumulation during I/R between transgenic and WT hearts. HOE642 (cariporide), an NHE1 inhibitor, equivalently protected both WT and NHE1-overexpressing hearts. When hearts were perfused with bicarbonate-free HEPES buffer to eliminate the contribution of HCO3−transporters to pHiregulation, there was no difference in contractile recovery after reperfusion between controls and transgenics, but NHE1-overexpressing hearts showed a greater decrease in ATP during ischemia. These results indicate that the basal activity of NHE1 is not rate limiting in causing damage during I/R, therefore, increasing the level of NHE1 does not enhance injury and can have some small protective effects.
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Affiliation(s)
- Kenichi Imahashi
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
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32
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Bernardo AA, Bernardo CM, Espiritu DJ, Arruda JAL. The sodium bicarbonate cotransporter: structure, function, and regulation. Semin Nephrol 2007; 26:352-60. [PMID: 17071329 DOI: 10.1016/j.semnephrol.2006.07.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The role of the Na(+)-coupled HCO(3)(-) transporter (NBC) family is indispensable in acid-base homeostasis. Almost all tissues express a member of the NBC family. NBC has been studied extensively in the kidney and plays a role in proximal tubule HCO(3)(-) reabsorption. Although the exact function of this transporter family on other tissues is not very clear, the ubiquitous expression of NBC family suggests a role in cell pH regulation. Altered NBC activity caused by mutations of the gene responsible for NBC protein expression results in pathophysiologic conditions. Mutations of NBC resulting in important clinical disorders have been reported extensively on one member of the NBC family, the kidney NBC (NBC1). These mutations have led to several structural studies to understand the mechanism of the abnormal NBC1 activity.
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Affiliation(s)
- Angelito A Bernardo
- Department of Medicine, Section of Nephrology, University of Illinois at Chicago, 820 S. Wood Street, Chicago, IL 60612, USA
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33
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Vaughan-Jones RD, Villafuerte FC, Swietach P, Yamamoto T, Rossini A, Spitzer KW. pH-Regulated Na(+) influx into the mammalian ventricular myocyte: the relative role of Na(+)-H(+) exchange and Na(+)-HCO Co-transport. J Cardiovasc Electrophysiol 2006; 17 Suppl 1:S134-S140. [PMID: 16686668 DOI: 10.1111/j.1540-8167.2006.00394.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the heart, intracellular Na(+) concentration (Na(+) (i)) is a controller of intracellular Ca(2+) signaling, and hence of key aspects of cell contractility and rhythm. Na(+) (i) will be influenced by variation in Na(+) influx. In the present work, we consider one source of Na(+) influx, sarcolemmal acid extrusion. Acid extrusion is accomplished by sarcolemmal H(+) and HCO(3) (-) transporters that import Na(+) ions while exporting H(+) or importing HCO(3) (-). The capacity of this system to import Na(+) is enormous, up to four times the maximum capacity of the Na(+)-K(+) ATPase to extrude Na(+) ions from the cell. In this review we consider the role of Na(+)-H(+) exchange (NHE) and Na(+)-HCO(3) (-)co-transport (NBC) in mediating Na(+) influx into cardiac myocytes. We consider, in particular, the role of NBC, as so little is known about Na(+) influx through this transporter. We show that both proteins mediate significant Na(+) influx and that although, in the ventricular myocyte, NBC-mediated Na(+) influx is less than through NHE, the proportions may be altered under a variety of conditions, including exposure to catecholamines, membrane depolarization, and interference with activity of the enzyme, carbonic anhydrase.
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Crampin EJ, Smith NP, Langham AE, Clayton RH, Orchard CH. Acidosis in models of cardiac ventricular myocytes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2006; 364:1171-86. [PMID: 16608702 DOI: 10.1098/rsta.2006.1763] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The effects of acidosis on cardiac electrophysiology and excitation-contraction coupling have been studied extensively. Acidosis decreases the strength of contraction and leads to altered calcium transients as a net result of complex interactions between protons and a variety of intracellular processes. The relative contributions of each of the changes under acidosis are difficult to establish experimentally, however, and significant uncertainties remain about the key mechanisms of impaired cardiac function. In this paper, we review the experimental findings concerning the effects of acidosis on the action potential and calcium handling in the cardiac ventricular myocyte, and we present a modelling study that establishes the contribution of the different effects to altered Ca2+ transients during acidosis. These interactions are incorporated into a dynamical model of pH regulation in the myocyte to simulate respiratory acidosis in the heart.
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Affiliation(s)
- Edmund J Crampin
- Bioengineering Institute, The University of Auckland, Private Bag 92019 Auckland, New Zealand.
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Clanachan AS. Contribution of Protons to Post-Ischemic Na+ and Ca2+ Overload and Left Ventricular Mechanical Dysfunction. J Cardiovasc Electrophysiol 2006; 17 Suppl 1:S141-S148. [PMID: 16686669 DOI: 10.1111/j.1540-8167.2006.00395.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intracellular accumulation of Na(+) and Ca(2+) plays a key role in ischemia-induced myocardial injury that may be manifest as left ventricular (LV) mechanical dysfunction, dysrhythmias, or infarction. This review considers the potential contributions of protons (H(+)) produced during ischemia as well as reperfusion to intracellular Na(+) and Ca(2+) homeostasis. ATP hydrolysis produces H(+) and the resulting intracellular acidosis directly impairs LV contractility. However, it is the accumulation of intracellular H(+) and the activation of Na(+)-dependent pH regulatory mechanisms, including the Na(+)-H(+) exchanger (NHE-1) and the Na(+)-HCO(3) (-) cotransporter, which contribute to Na(+) accumulation. Intracellular Na(+) accumulation, coupled with the NHE-1, then causes Ca(2+) overload and further LV mechanical dysfunction. As glycolysis uncoupled from glucose oxidation is an important determinant of the rate of H(+) production, factors that affect glucose metabolism, including degree of ischemia, myocardial workload, and competition from other energy substrates, are expected to influence Na(+) and Ca(2+) accumulation, and hence the recovery of post-ischemic LV mechanical function. Whereas an increase in the uncoupling of glycolysis from glucose oxidation accelerates H(+) production and worsens the recovery of LV mechanical function, inhibition of H(+) production improves recovery of post-ischemic LV mechanical function. Thus, alteration of glucose metabolism, either by inhibition of an excessive rate of glycolysis or by stimulation of glucose oxidation, is an attractive drug target to reduce H(+) production and limit Na(+) and Ca(2+) accumulation and thereby prevent post-ischemic LV dysfunction.
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Affiliation(s)
- Alexander S Clanachan
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
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Koo NY, Li J, Hwang SM, Choi SY, Lee SJ, Oh SB, Kim JS, Lee JH, Park K. Molecular cloning and functional expression of a sodium bicarbonate cotransporter from guinea-pig parotid glands. Biochem Biophys Res Commun 2006; 342:1114-22. [PMID: 16513089 DOI: 10.1016/j.bbrc.2006.02.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Accepted: 02/13/2006] [Indexed: 11/22/2022]
Abstract
We recently found that the concentration of HCO3- in guinea-pig saliva is very similar to that of human saliva; however, the entity that regulates HCO3- transport has not yet been fully characterized. In order to investigate the mechanism of HCO3- transport, we identified, cloned, and characterized a sodium bicarbonate (Na(+)/HCO3- cotransporter found in guinea-pig parotid glands (gpNBC1). The gpNBC1 gene encodes a 1079-amino acid protein that has 95% and 96% homology with human and mouse parotid NBC1, respectively. Oocytes expressing gpNBC1 were exposed to HCO3- or Na(+)-free solutions, which resulted in a marked change in membrane potentials (V(m)), suggesting that gpNBC1 is electrogenic. Likewise, a gpNBC1-mediated pH recovery was observed in gpNBC1 transfected human hepatoma cells; however, in the presence of 4, 4-diisothiocyanostilbene-2,2-disulfonic acid, a specific NBC1 inhibitor, such changes in V(m) and pH(i) were not observed. Together, the data show that the cloned guinea-pig gene is a functional, as well as sequence homologue of human NBC1.
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Affiliation(s)
- Na-Youn Koo
- Department of Physiology and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea
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Crampin EJ, Smith NP. A dynamic model of excitation-contraction coupling during acidosis in cardiac ventricular myocytes. Biophys J 2006; 90:3074-90. [PMID: 16473911 PMCID: PMC1432112 DOI: 10.1529/biophysj.105.070557] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acidosis in cardiac myocytes is a major factor in the reduced inotropy that occurs in the ischemic heart. During acidosis, diastolic calcium concentration and the amplitude of the calcium transient increase, while the strength of contraction decreases. This has been attributed to the inhibition by protons of calcium uptake and release by the sarcoplasmic reticulum, to a rise of intracellular sodium caused by activation of sodium-hydrogen exchange, decreased calcium binding affinity to Troponin-C, and direct effects on the contractile machinery. The relative contributions and concerted action of these effects are, however, difficult to establish experimentally. We have developed a mathematical model to examine altered calcium-handling mechanisms during acidosis. Each of the alterations was incorporated into a dynamical model of pH regulation and excitation-contraction coupling to predict the time courses of key ionic species during acidosis, in particular intracellular pH, sodium and the calcium transient, and contraction. This modeling study suggests that the most significant effects are elevated sodium, inhibition of sodium-calcium exchange, and the direct interaction of protons with the contractile machinery; and shows how the experimental data on these contributions can be reconciled to understand the overall effects of acidosis in the beating heart.
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Affiliation(s)
- Edmund J Crampin
- Bioengineering Institute and Department of Engineering Science, University of Auckland, Auckland, New Zealand.
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38
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Abstract
Organ function (the heart beat for example) can only be understood through knowledge of molecular and cellular processes within the constraints of structure-function relations at the tissue level. A quantitative modeling framework that can deal with these multiscale issues is described here under the banner of the International Union of Physiological Sciences Physiome Project.
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Affiliation(s)
- Peter Hunter
- Bioengineering Institute, University of Auckland, Auckland, New Zealand.
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39
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Rohra DK, Saito SY, Ohizumi Y. Low Extracellular Cl – Environment Attenuates Changes in Intracellular pH and Contraction following Extracellular Acidosis in Wistar Kyoto Rat Aorta. Pharmacology 2005; 75:30-6. [PMID: 15942273 DOI: 10.1159/000086152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Accepted: 04/07/2005] [Indexed: 11/19/2022]
Abstract
This study was conducted to investigate the influence of extracellular Cl- ([Cl-]o) on the intracellular pH (pHi) regulation and the contractile state of the isolated aorta from Wistar Kyoto (WKY) rats. Isometric tension recording and fluorometry techniques were utilized to measure contractile response and pHi in isolated aortic strips. Decreasing extracellular pH (pHo) from 7.4 to 6.5 produced a marked contraction, which was 75.8 +/- 5.6% of the 64.8 mmol/l KCl-induced contraction. The acidosis-induced contraction was significantly attenuated in low [Cl-]o solution, the magnitude of which was 56.0 +/- 3.0% of the 64.8 mmol/l KCl-induced contraction. Decreasing pHo of the normal solution to 6.5 rapidly decreased pHi in aortic smooth muscle cells and produced a corresponding contraction. When the pHo was decreased in low [Cl-]o solution, a rapid fall in pHi followed by reversal of pHi changes, in a time-dependent manner was observed, despite low pHo. Omission of HCO3- from the low [Cl-]o solution restored the contractile response to acidosis, which was comparable to that in normal solution. Similarly, following decrease in pHo to 6.5, no recovery of intracellular acidosis was observed. We conclude that low [Cl-]o environment causes activation of extracellular HCO3- -dependent pHi-regulating mechanism, that results in the rapid recovery of pHi following acidosis, and the attenuation of acidosis-induced contraction of WKY aorta.
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Affiliation(s)
- Dileep Kumar Rohra
- Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Sendai, Japan.
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40
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Scozzafava A, Mastrolorenzo A, Supuran CT. Modulation of carbonic anhydrase activity and its applications in therapy. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.14.5.667] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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41
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Abstract
Acid-base balance is altered in a variety of common pathologies, including COPD, ischemia, renal failure, and cancer. Because of robust cellular pH homeostatic mechanisms, most of the pathological alterations in pH are expressed as changes in the extracellular, systemic pH. There are data to indicate that altered pH is not simply an epiphenomenon of metabolic or physiologic imbalance but that chronic pH alterations can have important sequelae. MRSI and MRI measurements indicate that pH gradients of up to 1.0 pH unit can exit within 1-cm distance. Although measurement of blood pH can indicate systemic problems, it cannot pinpoint the lesion or quantitatively assess the magnitude of excursion from normal pHe. Hence, there is a need to develop pHe measurement methods with high spatiotemporal resolution. The two major approaches being investigated include magnetization transfer methods and relaxation methods. pH-dependent MT effects can observed with endogenous signals or exogenously applied CEST agents. While endogenous signals have the advantage of being fully noninvasive and relatively straightforward to apply, they lack a full biophysical characterization and dynamic range that might be afforded by future CEST agents. pH-dependent relaxivity also requires the injection or infusion of exogenous contrast reagents. In both MT and relaxographic approaches, the magnitude of the effect, and, thus, the ability to quantify pHe, depends on a spatially and temporally varying concentration of the CR. A number of approaches have been proposed to solve this problem and, once it is solved, pH imaging methods will be applicable to human clinical pathologies.
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Affiliation(s)
- Robert J Gillies
- Department of Biochemistry, Arizona Cancer Center, Tucson 85724-5024, USA.
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Swietach P, Zaniboni M, Stewart AK, Rossini A, Spitzer KW, Vaughan-Jones RD. Modelling intracellular H(+) ion diffusion. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 83:69-100. [PMID: 12865074 DOI: 10.1016/s0079-6107(03)00027-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intracellular pH, an important modulator of cell function, is regulated by plasmalemmal proteins that transport H(+), or its equivalent, into or out of the cell. The pH(i) is also stabilised by high-capacity, intrinsic buffering on cytoplasmic proteins, oligopeptides and other solutes, and by the extrinsic CO(2)/HCO(3)(-) (carbonic) buffer. As mobility of these buffers is lower than for the H(+) ion, they restrict proton diffusion. In this paper we use computational approaches, based on the finite difference and finite element methods (FDM and FEM, respectively), for analysing the spatio-temporal behaviour of [H(+)] when it is locally perturbed. We analyse experimental data obtained for various cell-types (cardiac myocytes, duodenal enterocytes, molluscan neurons) where pH(i) has been imaged confocally using intracellular pH-sensitive dyes. We design mathematical algorithms to generate solutions for two-dimensional diffusion that fit data in terms of an apparent intracellular H(+) diffusion coefficient, D(H)(app). The models are used to explore how the spatial distribution of [H(+)](i) is affected by membrane H(+)-equivalent transport and by cell geometry. We then develop a mechanistic model, describing spatio-temporal changes of [H(+)](i) in a cardiac ventricular myocyte in terms of H(+)-shuttling on mobile buffers and H(+)-anchoring on fixed buffers. We also discuss how modelling may include the effects of extrinsic carbonic-buffering. Overall, our computational approach provides a framework for future analyses of the physiological consequences of pH(i) non-uniformity.
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Affiliation(s)
- Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, University Laboratory of Physiology, OX1 3PT, Oxford, UK
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Zaniboni M, Swietach P, Rossini A, Yamamoto T, Spitzer KW, Vaughan-Jones RD. Intracellular proton mobility and buffering power in cardiac ventricular myocytes from rat, rabbit, and guinea pig. Am J Physiol Heart Circ Physiol 2003; 285:H1236-46. [PMID: 12750065 DOI: 10.1152/ajpheart.00277.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Intracellular pH (pHi) is an important modulator of cardiac function. The spatial regulation of pH within the cytoplasm depends, in part, on intracellular H+ (Hi+) mobility. The apparent diffusion coefficient for Hi+, DHapp, was estimated in single ventricular myocytes isolated from the rat, guinea pig, and rabbit. DHapp was derived by best-fitting predictions of a two-dimensional model of H+ diffusion to the local rise of intracellular [H+], recorded confocally (ratiometric seminaphthorhodafluor fluorescence) downstream from an acid-filled, whole cell patch pipette. Under CO2/HCO3--free conditions, DHapp was similar in all three species (mean values: 8-12.5 x 10-7 cm2/s) and was over 200-fold lower than that for H+ in water. In guinea pig myocytes, DHapp was increased 2.5-fold in the presence of CO2/HCO3- buffer, in agreement with previous observations in rabbit myocytes. Hi+ mobility is therefore low in cardiac cells, a feature that may predispose them to the generation of pHi gradients in response to sarcolemmal acid/base transport or local cytoplasmic acid production. Low Hi+ mobility most likely results from H+ shuttling among cytoplasmic mobile and fixed buffers. This hypothesis was explored by comparing the pHi dependence of intrinsic, intracellular buffering capacity, measured for all three species, and subdividing buffering into mobile and fixed fractions. The proportion of buffer that is mobile will be the main determinant of DHapp. At a given pHi, this proportion appeared to be similar in all three species, consistent with a common value for DHapp. Over the pHi range of 6.0-8.0, the proportion is expected to change, predicting that DHapp may display some pHi sensitivity.
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Affiliation(s)
- Massimiliano Zaniboni
- Burdon Sanderson Cardiac Science Centre, University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, UK
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