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Jiang S, Wang X, Wei J, Zhang G, Zhang J, Xie P, Xu L, Wang L, Zhao L, Li L, Wilcox CS, Chen J, Lai EY, Liu R. NaHCO 3 Dilates Mouse Afferent Arteriole Via Na +/HCO 3- Cotransporters NBCs. Hypertension 2019; 74:1104-1112. [PMID: 31522618 DOI: 10.1161/hypertensionaha.119.13235] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sodium bicarbonate has long been used to treat chronic kidney disease. It has been demonstrated to slow the decline in glomerular filtration rate in chronic kidney disease patient; however, the mechanisms are not completely understood. We hypothesized that NaHCO3 dilates afferent arterioles (Af-Art) by stimulating nitric oxide (NO) release mediated by the Na+/HCO3- cotransporter (NBC) contributing to the elevation in glomerular filtration rate. Isolated microperfused mouse renal Af-Art, preconstricted with norepinephrine (1 µmol/L), dilated 45±2% (n=6, P<0.05) in response to NaHCO3 (44 mmol/L). Whereas, NaCl solution containing the same Na+ concentration was not effective. The mRNA for NBCn1 and NBCe1 were detected in microdissected Af-Art using reverse transcription-polymerase chain reaction and quantitative polymerase chain reaction. The Af-Art intracellular pH measured with 2',7'-bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein, acetoxymethyl ester increased significantly by 0.29±0.02 (n=6; P<0.05) in the presence of NaHCO3, which was blunted by N-cyanosulphonamide compound (S0859) that is an inhibitor of the NBC family. After clamping the intracellular pH with 10 μM nigericin, changing the bath solution pH from 7.4 to 7.8 still dilates the Af-Art by 53±4% (n=7; P<0.005) and increases NO generation by 22±3% (n=7; P<0.005). Both pH-induced NO generation and vasodilation were blocked by L-NG-Nitroarginine Methyl Ester. NaHCO3 increased NO generation in Af-Art by 19±4% (n=5; P<0.005) and elevated glomerular filtration rate in conscious mice by 36% (233 versus 318 ul/min; n=9-10; P<0.0001). S0859 and L-NG-nitroarginine methyl ester blocked NaHCO3-induced increases in NO generation and vasodilation. We conclude that NBCn1 and NBCe1 are expressed in Af-Art and that NaHCO3 dilates Af-Art via NBCs mediated by NO that increases the glomerular filtration rate.
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Affiliation(s)
- Shan Jiang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Ximing Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.).,Shandong Provincial Hospital, Affiliated Hospital of Shandong University, Jinan, China (X.W.)
| | - Jin Wei
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Gensheng Zhang
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Jie Zhang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Peng Xie
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - Lan Xu
- College of Public Health, University of South Florida, Tampa (L.X.)
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
| | - Liang Zhao
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Lingli Li
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Christopher S Wilcox
- Division of Nephrology and Hypertension, and Hypertension Center, Georgetown University, Washington, DC (L.L., C.S.W.)
| | - Jianghua Chen
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.)
| | - En Yin Lai
- From Kidney Disease Center, the First Affiliated Hospital, and Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China (S.J., G.Z., P.X., L.Z., L.L., J.C., E.Y.L.).,Department of Physiology, School of Basic Medical Sciences, Guangzhou Medical University, China (L.Z., E.Y.L.).,Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Germany (L.Z., E.Y.L.)
| | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, University of South Florida College of Medicine, Tampa (S.J., X.W., J.W., G.Z., J.Z., L.W., R.L.)
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Romero MF, Chen AP, Parker MD, Boron WF. The SLC4 family of bicarbonate (HCO₃⁻) transporters. Mol Aspects Med 2013; 34:159-82. [PMID: 23506864 DOI: 10.1016/j.mam.2012.10.008] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 08/28/2012] [Indexed: 01/13/2023]
Abstract
The SLC4 family consists of 10 genes (SLC4A1-5; SLC4A7-11). All encode integral membrane proteins with very similar hydropathy plots-consistent with 10-14 transmembrane segments. Nine SLC4 members encode proteins that transport HCO3(-) (or a related species, such as CO3(2-)) across the plasma membrane. Functionally, eight of these proteins fall into two major groups: three Cl-HCO3 exchangers (AE1-3) and five Na(+)-coupled HCO3(-) transporters (NBCe1, NBCe2, NBCn1, NBCn2, NDCBE). Two of the Na(+)-coupled transporters (NBCe1, NBCe2) are electrogenic; the other three Na(+)-coupled HCO3(-) transporters and all three AEs are electroneutral. In addition, two other SLC4 members (AE4, SLC4A9 and BTR1, SLC4A11) do not yet have a firmly established function. Most, though not all, SLC4 members are functionally inhibited by 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS). SLC4 proteins play important roles many modes of acid-base homeostasis: the carriage of CO2 by erythrocytes, the transport of H(+) or HCO3(-) by several epithelia, as well as the regulation of cell volume and intracellular pH.
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Affiliation(s)
- Michael F Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Swietach P, Tiffert T, Mauritz JMA, Seear R, Esposito A, Kaminski CF, Lew VL, Vaughan-Jones RD. Hydrogen ion dynamics in human red blood cells. J Physiol 2010; 588:4995-5014. [PMID: 20962000 DOI: 10.1113/jphysiol.2010.197392] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Our understanding of pH regulation within red blood cells (RBCs) has been inferred mainly from indirect experiments rather than from in situ measurements of intracellular pH (pH(i)). The present work shows that carboxy-SNARF-1, a pH fluorophore, when used with confocal imaging or flow cytometry, reliably reports pH(i) in individual, human RBCs, provided intracellular fluorescence is calibrated using a 'null-point' procedure. Mean pH(i) was 7.25 in CO(2)/HCO(3)(-)-buffered medium and 7.15 in Hepes-buffered medium, and varied linearly with extracellular pH (slope of 0.77). Intrinsic (non-CO(2)/HCO(3)(-)-dependent) buffering power, estimated in the intact cell (85 mmol (l cell)(-1) (pH unit)(-1) at resting pH(i)), was somewhat higher than previous estimates from cell lysates (50-70 mmol (l cell)(-1) (pH unit)(-1)). Acute displacement of pH(i) (superfusion of weak acids/bases) triggered rapid pH(i) recovery. This was mediated via membrane Cl(-)/HCO(3)(-) exchange (the AE1 gene product), irrespective of whether recovery was from an intracellular acid or base load, and with no evident contribution from other transporters such as Na(+)/H(+) exchange. H(+)-equivalent flux through AE1 was a linear function of [H(+)](i) and reversed at resting pH(i), indicating that its activity is not allosterically regulated by pH(i), in contrast to other AE isoforms. By simultaneously monitoring pH(i) and markers of cell volume, a functional link between membrane ion transport, volume and pH(i) was demonstrated. RBC pH(i) is therefore tightly regulated via AE1 activity, but modulated during changes of cell volume. A comparable volume-pH(i) link may also be important in other cell types expressing anion exchangers. Direct measurement of pH(i) should be useful in future investigations of RBC physiology and pathology.
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Affiliation(s)
- Pawel Swietach
- Department of Physiology, Burdon Sanderson Cardiac Science Centre, Parks Road, Oxford 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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Dunnick J, Blackshear P, Kissling G, Cunningham M, Parker J, Nyska A. Critical pathways in heart function: bis(2-chloroethoxy)methane-induced heart gene transcript change in F344 rats. Toxicol Pathol 2006; 34:348-56. [PMID: 16844662 DOI: 10.1080/01926230600798583] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gene transcript changes after exposure to the heart toxin, bis(2-chloroethoxy)methane (CEM), were analyzed to elucidate mechanisms in cardiotoxicity and recovery. CEM was administered to 5-week-old male F344/N rats at 0, 200, 400, or 600 mg/kg by dermal exposure, 5 days per week, for a total of 12 doses by study day 16. Heart toxicity occurred after 2 days of dosing in all 3 regions of the heart (atrium, ventricle, interventricular septum) and was characterized by myofiber vacuolation, necrosis, mononuclear-cell infiltration, and atrial thrombosis. Ultrastructural analysis revealed that the primary site of damage was the mitochondrion. By day 5, even though dosing was continued, the toxic lesions in the heart began to resolve, and by study day 16, the heart appeared histologically normal. RNA was extracted from whole hearts after 2 or 5 days of CEM dosing. After a screen for transcript change by microarray analysis, dose-response trends for selected transcripts were analyzed by qRT-PCR. The selected transcripts code for proteins involved in energy production, control of calcium levels, and maintenance of heart function. The down-regulation of ATP subunit transcripts (Atp5j, ATP5k), which reside in the mitochondrial membranes, indicated a decrease in energy supply at day 2 and day 5. This was accompanied by down-regulation of transcripts involved in high-energy consumption processes such as membrane transport and ion channel transcripts (e.g., abc1a, kcnj12). The up-regulation of transcripts encoding for temperature regulation and calcium binding proteins (ucp1 and calb3) only at the 2 low exposure levels, suggest that these adaptive processes cannot occur in association with severe cardiotoxicity as seen in hearts at the high exposure level. Transcript expression changes occurred within 2 days of CEM exposure, and were dose-and time-dependent. The heart transcript changes suggest that CEM cardiotoxicity activates protective processes associated energy conservation and maintenance of heart function.
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Affiliation(s)
- J Dunnick
- National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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Alvarez BV, Kieller DM, Quon AL, Markovich D, Casey JR. Slc26a6: a cardiac chloride-hydroxyl exchanger and predominant chloride-bicarbonate exchanger of the mouse heart. J Physiol 2004; 561:721-34. [PMID: 15498800 PMCID: PMC1665392 DOI: 10.1113/jphysiol.2004.077339] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Bicarbonate facilitate more than 50% of pH recovery in the acidotic myocardium, and have roles in cardiac hypertrophy and steady-state pH regulation. To determine which bicarbonate transporters are responsible for this activity, we measured the expression levels of all known HCO3(-)-anion exchange proteins in mouse heart, by quantitative real time RT-PCR. Bicarbonate-anion exchangers are members of either the SLC4A or the SLC26A gene families. In neonatal and adult myocardium, AE1 (Slc4a1), AE2 (Slc4a2), AE3 (Slc4a3) (AE3fl and AE3c variants), Slc26a3 and Slc26a6 were expressed. Adult hearts expressed Slc26a3 and Slc4a1-3 mRNAs at similar levels, while Slc26a6 mRNA was about seven-fold higher than AE3, which was more abundant than any other. Immunohistochemistry revealed that Slc26a6 and AE3 are present in the plasma membrane of ventricular myocytes. Slc26a6 expression levels were higher in ventricle than atrium, whereas AE3 was detected only in ventricle. Cl(-)-HCO(3)(-) and Cl(-)-OH(-) exchange activity of SLC26A6 and AE3 were investigated in transfected HEK293 cells, using intracellular fluorescence measurements of 2',7'-bis (2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF), to monitor intracellular pH (pH(i)). Rates of pH(i) change were measured under HCO3(-)-containing (Cl(-)-HCO(3)(-)) or nominally HCO3(-)-free (Cl(-)-OH(-)) conditions. HCO3(-) fluxes were similar for cells expressing AE3fl, SLC26A6 or Slc26a3, suggesting that they have similar transport activity. However, only SLC26A6 and Slc26a3 functioned as Cl(-)-OH(-) exchangers. Activation of alpha-adrenergic receptors, which stimulates protein kinase C, inhibited SLC26A6 Cl(-)-HCO(3)(-) exchange activity. We conclude that Slc26a6 is the predominant Cl(-)-HCO(3)(-) and Cl(-)-OH(-) exchanger of the myocardium and that Slc26a6 is negatively regulated upon alpha-adrenergic stimulation.
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Affiliation(s)
- Bernardo V Alvarez
- CIHR Membrane Protein Research Group, Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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