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de Melo IS, Sabino-Silva R, Cunha TM, Goulart LR, Reis WL, Jardim ACG, Shetty AK, de Castro OW. Hydroelectrolytic Disorder in COVID-19 patients: Evidence Supporting the Involvement of Subfornical Organ and Paraventricular Nucleus of the Hypothalamus. Neurosci Biobehav Rev 2021; 124:216-223. [PMID: 33577841 PMCID: PMC7872848 DOI: 10.1016/j.neubiorev.2021.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 02/07/2023]
Abstract
Multiple neurological problems have been reported in coronavirus disease-2019 (COVID-19) patients because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) likely spreads to the central nervous system (CNS) via olfactory nerves or through the subarachnoid space along olfactory nerves into the brain's cerebrospinal fluid and then into the brain's interstitial space. We hypothesize that SARS-CoV-2 enters the subfornical organ (SFO) through the above routes and the circulating blood since circumventricular organs (CVOs) such as the SFO lack the blood-brain barrier, and infection of the SFO causes dysfunction of the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON), leading to hydroelectrolytic disorder. SARS-CoV-2 can readily enter SFO-PVN-SON neurons because these neurons express angiotensin-converting enzyme-2 receptors and proteolytic viral activators, which likely leads to neurodegeneration or neuroinflammation in these regions. Considering the pivotal role of SFO-PVN-SON circuitry in modulating hydroelectrolyte balance, SARS-CoV-2 infection in these regions could disrupt the neuroendocrine control of hydromineral homeostasis. This review proposes mechanisms by which SARS-CoV-2 infection of the SFO-PVN-SON pathway leads to hydroelectrolytic disorder in COVID-19 patients.
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Affiliation(s)
- Igor Santana de Melo
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceio, Brazil
| | - Robinson Sabino-Silva
- Department of Physiology, Institute of Biomedical Sciences, Federal University of Uberlandia (UFU), Uberlândia, MG, Brazil.
| | - Thúlio Marquez Cunha
- Department of Pulmonology, School of Medicine, Federal University of Uberlandia, Minas Gerais, Brazil
| | - Luiz Ricardo Goulart
- Institute of Biotechnology, Federal University of Uberlandia, Minas Gerais, Brazil
| | - Wagner Luis Reis
- Department of Physiological, Sciences Biological Sciences Centre Federal University of Santa Catarina (UFSC) Florianopolis, Santa Catarina, Brazil
| | - Ana Carolina Gomes Jardim
- Laboratory of Virology, Institute of Biomedical Sciences, Federal University of Uberlandia, Minas Gerais, Brazil
| | - Ashok K Shetty
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M University College of Medicine, College Station, TX, 77843, USA.
| | - Olagide Wagner de Castro
- Department of Physiology, Institute of Biological Sciences and Health, Federal University of Alagoas (UFAL), Maceio, Brazil.
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Giesecke T, Himmerkus N, Leipziger J, Bleich M, Koshimizu TA, Fähling M, Smorodchenko A, Shpak J, Knappe C, Isermann J, Ayasse N, Kawahara K, Schmoranzer J, Gimber N, Paliege A, Bachmann S, Mutig K. Vasopressin Increases Urinary Acidification via V1a Receptors in Collecting Duct Intercalated Cells. J Am Soc Nephrol 2019; 30:946-961. [PMID: 31097611 DOI: 10.1681/asn.2018080816] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 03/11/2019] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Antagonists of the V1a vasopressin receptor (V1aR) are emerging as a strategy for slowing progression of CKD. Physiologically, V1aR signaling has been linked with acid-base homeostasis, but more detailed information is needed about renal V1aR distribution and function. METHODS We used a new anti-V1aR antibody and high-resolution microscopy to investigate Va1R distribution in rodent and human kidneys. To investigate whether V1aR activation promotes urinary H+ secretion, we used a V1aR agonist or antagonist to evaluate V1aR function in vasopressin-deficient Brattleboro rats, bladder-catheterized mice, isolated collecting ducts, and cultured inner medullary collecting duct (IMCD) cells. RESULTS Localization of V1aR in rodent and human kidneys produced a basolateral signal in type A intercalated cells (A-ICs) and a perinuclear to subapical signal in type B intercalated cells of connecting tubules and collecting ducts. Treating vasopressin-deficient Brattleboro rats with a V1aR agonist decreased urinary pH and tripled net acid excretion; we observed a similar response in C57BL/6J mice. In contrast, V1aR antagonist did not affect urinary pH in normal or acid-loaded mice. In ex vivo settings, basolateral treatment of isolated perfused medullary collecting ducts with the V1aR agonist or vasopressin increased intracellular calcium levels in ICs and decreased luminal pH, suggesting V1aR-dependent calcium release and stimulation of proton-secreting proteins. Basolateral treatment of IMCD cells with the V1aR agonist increased apical abundance of vacuolar H+-ATPase in A-ICs. CONCLUSIONS Our results show that activation of V1aR contributes to urinary acidification via H+ secretion by A-ICs, which may have clinical implications for pharmacologic targeting of V1aR.
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Affiliation(s)
- Torsten Giesecke
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Berlin Institute of Health (BIH), Berlin, Germany
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Jens Leipziger
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Markus Bleich
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Taka-Aki Koshimizu
- Division of Molecular Pharmacology, Department of Pharmacology, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, Japan
| | - Michael Fähling
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alina Smorodchenko
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julia Shpak
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Carolin Knappe
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julian Isermann
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Niklas Ayasse
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Jan Schmoranzer
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Niclas Gimber
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alexander Paliege
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany; and
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russian Federation
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Karavashkina TA, Kutina AV, Shakhmatova EI, Natochin YV. Mechanism of 1-deamino-arginine vasotocin induced natriuresis in rats. Gen Comp Endocrinol 2011; 170:460-7. [PMID: 21050856 DOI: 10.1016/j.ygcen.2010.10.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 10/15/2010] [Accepted: 10/25/2010] [Indexed: 10/18/2022]
Abstract
1-Deamino-arginine vasotocin (1dAVT) induced diuresis and a considerable increase in urinary sodium excretion in female Wistar rats. Sodium fractional excretion rose up to 19.3 ± 1.1%. An increase in urine flow rate after 1dAVT (0.5 nmol/kg body-weight [bw]) injection was accompanied by a significant rise of the solute-free water reabsorption. The 1dAVT-induced natriuresis was as high as natriuresis produced by injection of a maximal dose of furosemide (10mg/kg bw). V(1)-receptor antagonists (ОРС-21268, [β-mercapto-β,β-cyclopentamethylenepropionyl(1),O-Me-Tyr(2),Arg(8)]-vasopressin) blocked the increase in urinary sodium excretion after the 1dAVT injection. The 1dAVT-induced natriuresis was strongly correlated with an increase in the urinary cGMP and prostaglandin E(2) excretion. The natriuretic effect of 1dAVT did not depend on the formation of nitric oxide (NO) or atrial natriuretic peptide of which concentration in the rat blood serum remained stable. The above results indicate that the 1dAVT has unique effects on rat kidney compared to all other known diuretics - it induces extremely high natriuresis and stimulates solute-free water reabsorption. Mechanism of the natriuretic effect of 1dAVT includes decrease in tubular sodium reabsorption due to activation of V(1)-like receptors and formation of cGMP and PGЕ(2).
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Affiliation(s)
- Tatjana A Karavashkina
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Thorez Av 44, St Petersburg 194223, Russia
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Dos Santos PM, Freitas FP, Mendes J, Tararthuch AL, Fernandez R. Differential regulation of H+-ATPases in MDCK-C11 cells by aldosterone and vasopressin. Can J Physiol Pharmacol 2009; 87:653-65. [DOI: 10.1139/y09-057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of the present work was to characterize the biochemical activity of the proton pumps present in the C11 clone of Madin–Darby canine kidney (MDCK) cells, akin to intercalated cells of the collecting duct, as well as to study their regulation by hormones like aldosterone and vasopressin. MDCK-C11 cells from passages 78 to 86 were utilized. The reaction to determine H+-ATPase activity was started by addition of cell homogenates to tubes contained the assay medium. The inorganic phosphate (Pi) released was determined by a colorimetric method modified from that described by Fiske and Subbarow. Changes in intracellular calcium concentration in the cells was determined using the Ca2+-sensing dye fluo-4 AM. Homogenates of MDCK-C11 cells present a bafilomycin-sensitive activity (vacuolar H+-ATPase), and a vanadate-sensitive activity (H+/K+-ATPase). The bafilomycin-sensitive activity showed a pH optimum of 6.12. ATPase activity was also stimulated in a dose-dependent fashion as K+ concentration was increased between 0 and 50 mmol·L–1, with an apparent Km for the release of Pi of 0.13 mmol·L–1 and Vmax of 22.01 nmol·mg–1·min–1. Incubation of cell monolayers with 10−8 mol·L–1 aldosterone for 24 h significantly increased vacuolar H+-ATPase activity, an effect prevented by 10−5 mol·L–1 spironolactone. Vacuolar H+-ATPase activity was also stimulated by 10−11 mol·L–1 vasopressin, an effect prevented by a V1 receptor-specific antagonist. This dose of vasopressin determined a sustained rise of cytosolic ionized calcium. We conclude that (i) homogenates of MDCK-C11 cells present a bafilomycin-sensitive (H+-ATPase) activity and a vanadate-sensitive (H+/K+-ATPase) activity, and (ii) vacuolar H+-ATPase activity is activated by aldosterone through a genomic pathway and by vasopressin through V1 receptors.
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Affiliation(s)
- Priscilla M.C. Dos Santos
- Department of Physiology, Division of Biological Sciences, Federal University of Paraná (UFPR), Paraná, Brazil
| | - Fabio P. Freitas
- Department of Physiology, Division of Biological Sciences, Federal University of Paraná (UFPR), Paraná, Brazil
| | - Jeane Mendes
- Department of Physiology, Division of Biological Sciences, Federal University of Paraná (UFPR), Paraná, Brazil
| | - Ana Lucia Tararthuch
- Department of Physiology, Division of Biological Sciences, Federal University of Paraná (UFPR), Paraná, Brazil
| | - Ricardo Fernandez
- Department of Physiology, Division of Biological Sciences, Federal University of Paraná (UFPR), Paraná, Brazil
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Rivarola V, Ford P, del Pilar Flamenco M, Galizia L, Capurro C. Arginine-Vasopressin Modulates Intracellular pH via V1 and V2 Receptors in Renal Collecting Duct Cells. Cell Physiol Biochem 2008; 20:549-58. [PMID: 17762181 DOI: 10.1159/000107538] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2007] [Indexed: 11/19/2022] Open
Abstract
Arginine-vasopressin (AVP) has been proposed to be involved in the modulation of acid-base transporters; however, the nature of the mechanisms underlying AVP direct action on intracellular pH (pH(i)) in the cortical collecting duct (CCD) is not yet clearly defined. The aim of the present study was to elucidate which are the proteins implicated in AVP modulation of pH(i), as well as the receptors involved in these responses using a CCD cell line (RCCD(1)); pH(i) was monitored with the fluorescent dye BCECF in basal conditions and after stimulation with basolateral 10(-8) M AVP. Specific V1- or V2-receptor antagonists were also used. RT-PCR studies demonstrated that RCCD(1) cells express V1a and V2 receptors. Functional studies showed that while V2-receptor activation induced a biphasic response (alkalinization-acidification), V1-receptor activation resulted in an intracellular acidification. The V2-mediated alkalinization phase involves the activation of basolateral NHE-1 isoform of the Na(+)/H(+) exchanger while in the acidification phase CFTR is probably implicated. On the other hand, V1-mediated acidification was due to activation of a Cl(-)/HCO(3)(-) exchanger. We conclude that in RCCD(1) cells AVP selectively activates, via a complex of V1 and V2 receptor-mediated actions, different ion transporters linked to pH(i) regulation which might have physiological implications.
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Affiliation(s)
- Valeria Rivarola
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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Amorim JBO, Musa-Aziz R, Lessa LMA, Malnic G, Fonteles MC. Effect of uroguanylin on potassium and bicarbonate transport in rat renal tubules. Can J Physiol Pharmacol 2006; 84:1003-10. [PMID: 17218966 DOI: 10.1139/y06-044] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The effect of uroguanylin (UGN) on K+and H+secretion in the renal tubules of the rat kidney was studied using in vivo stationary microperfusion. For the study of K+secretion, a tubule was punctured to inject a column of FDC-green-colored Ringer's solution with 0.5 mmol KCl/L ± 10−6mol UGN/L, and oil was used to block fluid flow. K+activity and transepithelial potential differences (PD) were measured with double microelectrodes (K+ion-selective resin vs. reference) in the distal tubules of the same nephron. During perfusion, K+activity rose exponentially, from 0.5 mmol/L to stationary concentration, allowing for the calculation of K+secretion (JK). JKincreased from 0.63 ± 0.06 nmol·cm–2·s–1in the control group to 0.85 ± 0.06 in the UGN group (p < 0.01). PD was –51.0 ± 5.3 mV in the control group and –50.3 ± 4.98 mV in the UGN group. In the presence of 10−7mol iberiotoxin/L, the UGN effect was abolished: JKwas 0.37 ± 0.038 nmol·cm–2·s–1in the absence of, and 0.38 ± 0.025 in the presence of, UGN, indicating its action on maxi-K channels. In another series of experiments, renal tubule acidification was studied, using a similar method: proximal and distal tubules were perfused with solutions containing 25 mmol NaHCO3/L. Acidification half-time was increased both in proximal and distal segments and, as a consequence, bicarbonate reabsorption decreased in the presence of UGN (in proximal tubules, from 2.40 ± 0.26 to 1.56 ± 0.21 nmol·cm–2·s–1). When the Na+/H+exchanger was inhibited by 10−4mol hexamethylene amiloride (HMA)/L, the control and UGN groups were not significantly different. In the late distal tubule, after HMA, UGN significantly reduced JHCO3–, indicating an effect of UGN on H+-ATPase. These data show that UGN stimulated JK+by acting on maxi-K channels, and decreased JHCO3–by acting on NHE3 in proximal and H+-ATPase in distal tubules.
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Abstract
Vacuolar H(+)-ATPases are ubiquitous multisubunit complexes mediating the ATP-dependent transport of protons. In addition to their role in acidifying the lumen of various intracellular organelles, vacuolar H(+)-ATPases fulfill special tasks in the kidney. Vacuolar H(+)-ATPases are expressed in the plasma membrane in the kidney almost along the entire length of the nephron with apical and/or basolateral localization patterns. In the proximal tubule, a high number of vacuolar H(+)-ATPases are also found in endosomes, which are acidified by the pump. In addition, vacuolar H(+)-ATPases contribute to proximal tubular bicarbonate reabsorption. The importance in final urinary acidification along the collecting system is highlighted by monogenic defects in two subunits (ATP6V0A4, ATP6V1B1) of the vacuolar H(+)-ATPase in patients with distal renal tubular acidosis. The activity of vacuolar H(+)-ATPases is tightly regulated by a variety of factors such as the acid-base or electrolyte status. This regulation is at least in part mediated by various hormones and protein-protein interactions between regulatory proteins and multiple subunits of the pump.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, Univ. of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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8
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Amorim JBO, Musa-Aziz R, Mello-Aires M, Malnic G. Signaling path of the action of AVP on distal K+ secretion. Kidney Int 2004; 66:696-704. [PMID: 15253724 DOI: 10.1111/j.1523-1755.2004.00800.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Previous studies from our laboratory have shown that luminal perfusion with arginine vasopressin (AVP) stimulates distal tubule secretory potassium flux (JK) via V1 receptors (Am J Physiol 278:F809-F816, 2000). In the present work, we investigate the cell signaling mechanism of this process. METHODS In vivo stationary microperfusion was performed in rat cortical distal tubules and luminal K+ was measured using double K+ resin/reference microelectrodes. RESULTS In control conditions, JK was 0.71 +/- 0.05 nmol.cm(-2).second(-1); this process was inhibited (14%) by 10(-5) mol/L 8-bromo-cyclic adenosine monophosphate (cAMP), and increased by 35% with 10(-8) mol/L phorbol ester [phorbol12-myristate 13-acetate (PMA), which activates protein kinase C (PKC)]. During luminal perfusion with 10(-11) mol/L AVP, JK increased to 0.88 +/- 0.08 nmol.cm(-2).seconds(-1). In the presence of 10(-11) mol/L AVP, JK was not affected by 10(-4) mol/L H89, a blocker of protein kinase A (PKA), but was inhibited (45%) by 10(-5) mol/L staurosporine, an inhibitor of PKC, and by 41% during perfusion with 5 x 10(-5) mol/L of the cell Ca2+ chelator bis (2-aminophenoxy) ethane-tetraacetic acid (BAPTA). In order to study the role of Ca(2+)-dependent K channels in the luminal hormonal action, the tubules were perfused with 5 mmol/L tetraethylammonium chloride (TEA) or 10(-7) mol/L iberiotoxin, in the presence of AVP, and JK was significantly reduced by both agents. Iberiotoxin reduced AVP-stimulated JK by 36.4%, and AVP-independent JK (after blocking V1 receptors) by only 16%. CONCLUSION The results suggest that the luminal V1-receptor effect of AVP on JK was mediated by the phospholipase C (PLC)/Ca2+/PKC signaling path and not byadenylate cyclase/cAMP/PKA, therefore probably acting on maxi-potassium channels.
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Affiliation(s)
- José B O Amorim
- Basic Science Deparment, Faculdade de Odontologia de São José dos Campos, UNESP, São Paulo, Brazil
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9
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Oliveira-Souza M, Musa-Aziz R, Malnic G, De Mello Aires M. Arginine vasopressin stimulates H+-ATPase in MDCK cells via V1 (cell Ca2+) and V2 (cAMP) receptors. Am J Physiol Renal Physiol 2004; 286:F402-8. [PMID: 12965889 DOI: 10.1152/ajprenal.00121.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of arginine vasopressin (AVP) and/or atrial natriuretic peptide (ANP) on the regulation of intracellular pH (pHi) via H+-ATPase and of cytosolic calcium ([Ca2+]i) was investigated in Madin-Darby canine kidney (MDCK) cells by the fluorescent probes BCECF-AM and fluo-4-AM, respectively. The pHi recovery rate was examined after intracellular acidification following an NH4Cl pulse, in the presence of zero Na+ plus Schering 28080 (a specific inhibitor of H+-K+-ATPase). AVP (10-12-10-6 M) increased the rate of pHi recovery and [Ca2+]i in a dose-dependent manner. V1- or V2-receptor antagonists impaired the effect of AVP on both processes, and DDAVP (10-12-10-6 M; a V2-selective agonist) caused a dose-dependent stimulation of them. [Ca2+]i or cAMP (as increased by 10-5 M thapsigargin or 8-BrcAMP, respectively) alone had no effect on H+-ATPase, but their synergic action was necessary to stimulate H+-ATPase. In agreement with these findings, ANP (10-6 M) or dimethyl-BAPTA-AM (5 x 10-5 M), impairing the increase of [Ca2+]i in response to AVP, blocks the stimulatory effect of AVP on H+-ATPase.
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Affiliation(s)
- Maria Oliveira-Souza
- Department of Physiology and Biophysics, Instituto de Ciências Biomédicas, Univ. of São Paulo, SP 05508-900, Brazil
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Musa-Aziz R, Barreto-Chaves MLM, De Mello-Aires M. Peritubular AVP regulates bicarbonate reabsorption in cortical distal tubule via V(1) and V(2) receptors. Am J Physiol Renal Physiol 2002; 282:F256-64. [PMID: 11788439 DOI: 10.1152/ajprenal.00056.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Peritubular arginine vasopressin (AVP) regulates bicarbonate reabsorption in the cortical distal tubule via V(1) and V(2) receptors. The dose-dependent effects of peritubular AVP on net bicarbonate reabsorption (J(HCO)) were evaluated by stationary microperfusion of in vivo early (ED; distal convoluted tubule) and late distal (LD; connecting tubule and initial collecting duct) segments of rat kidney, using double-barreled H(+)-sensitive, ion-exchange resin/reference (1 M KCl) microelectrodes. AVP (10(-11) M) perfused into peritubular capillaries increased J(HCO), compared with basal levels during intact capillary perfusion with blood, in ED and LD segments. AVP (10(-9) M) also increased J(HCO) in both segments, but the effect of AVP (10(-11) M) was significantly higher. A specificV(1)-receptor antagonist alone or with AVP (10(-11) or 10(-9) M) reduced J(HCO) below basal levels. A specific V(2)-receptor antagonist alone or plus AVP (10(-11) M) did not affect J(HCO) but increased AVP (10(-9) M)-mediated stimulation. 8-Bromoadenosine 3',5'-cyclic monophosphate alone reduced J(HCO) below basal levels and also reduced AVP (10(-11) M)-mediated stimulation. (Deamino-Cys(1), D-Arg(8)) vasopressin (a V(2)-selective agonist) also reduced J(HCO) below basal levels. These results show that peritubular AVP stimulates J(HCO) in ED and LD segments via basolateral V(1) receptors and that basolateral V(2) receptors have a dose-dependent inhibitory effect mediated by cAMP. The data also indicate that endogenous AVP stimulates distal J(HCO) via basolateral V(1) receptors.
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Affiliation(s)
- Raif Musa-Aziz
- Department of Physiology and Biophysics, Instituto de Ciências Biomédicas, University of São Paulo, São Paulo 05508-900, Brazil
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11
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Campos DM, Reyes CE, Sarmiento J, Navarro J, González CB. Polarized expression of the GFP-tagged rat V(1a) vasopressin receptor. Biochem Biophys Res Commun 2001; 289:325-8. [PMID: 11716475 DOI: 10.1006/bbrc.2001.5981] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the targeting of the V(1a) receptor fused with the green fluorescence protein (V(1a)R-GFP) in polarized MDCK cells. Cells expressing V(1a)R-GFP displayed binding to vasopressin (AVP) and AVP-induced calcium responses, similar to cells expressing the wild-type V1a receptor. Interestingly, as with the wild-type V(1a)R, V(1a)R-GFP is preferentially distributed in the basolateral side of MDCK cells as monitored by confocal microscopy. Furthermore, AVP induced internalization of GFP-tagged receptors. Therefore, the GFP-tagged V(1a) receptor retains all the sorting signals of the wild-type receptor and offers an excellent system to elucidate the mechanisms of cell trafficking of V(1a) receptors.
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Affiliation(s)
- D M Campos
- Department of Physiology, Universidad Austral de Chile, Valdivia, Chile
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12
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Oliveira-Souza M, Mello-Aires M. Effect of arginine vasopressin and ANP on intracellular pH and cytosolic free [Ca2+] regulation in MDCK cells. Kidney Int 2001; 60:1800-8. [PMID: 11703598 DOI: 10.1046/j.1523-1755.2001.00993.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The effects of arginine vasopressin (AVP) on intracellular pH (pHi) are not clearly defined, and may vary with cell membrane surface and the hormonal doses being studied. Since cytosolic free calcium concentration ([Ca2+]i) has an important effect on cellular H+ extrusion and it was shown that AVP increases [Ca2+]i while atrial natriuretic peptide (ANP) reduces it, there may be some interaction between AVP and ANP during the regulation of pHi. METHODS The effects of AVP and/or ANP on pHi and [Ca2+]i were investigated in Madin-Darby canine kidney (MDCK) cells by the fluorescent probes BCECF-AM and Fluo 4-AM, respectively. The pHi recovery rate was examined in the first two minutes following the acidification of pHi with a NH4Cl pulse. RESULTS AVP (10(-12) or 10(-9) mol/L) stimulated the rate of the Na+-dependent pHi recovery, but AVP (10(-6) mol/L) impaired it. At the apical membrane surface, specific V1 or V2 receptor antagonists did not alter the effects of AVP. At the basolateral membrane surface, the V1 antagonist returned both the stimulatory and inhibitory effects of AVP to control levels, and the V2 antagonist converted the inhibitory effect of AVP to a stimulatory effect. ANP (10(-6) mol/L) or dimethyl-BAPTA-AM (50 micromol/L) impaired both the stimulatory and inhibitory effects of AVP. AVP increased [Ca2+]i in a dose-dependent manner. ANP or dimethyl-BAPTA-AM decreased [Ca2+]i, and the subsequent addition of AVP caused only a partial recovery of [Ca2+]i. CONCLUSIONS The results are compatible with stimulation of the Na+/H+ exchanger by increases of [Ca2+]i in the lower range (at 10(-12) or 10(-9) mol/L AVP, via basolateral V1 receptors) and inhibition at high [Ca2+]i levels (at 10(-6) mol/L AVP, via basolateral V1 and V2 receptors). ANP, by impairing the path causing the increase in [Ca2+]i, blocks both the stimulatory and inhibitory effects of AVP on Na+-dependent pHi recovery.
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Affiliation(s)
- M Oliveira-Souza
- Department of Physiology and Biophysics, Instituto de Ciências Biomédicas, University of São Paulo, São Paulo 05508-900, Brazil
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Amorim JB, Malnic G. V(1) receptors in luminal action of vasopressin on distal K(+) secretion. Am J Physiol Renal Physiol 2000; 278:F809-16. [PMID: 10807593 DOI: 10.1152/ajprenal.2000.278.5.f809] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Luminal perfusion with collected proximal fluid increases distal K(+) secretion compared with artificial solutions. Arginine vasopressin (AVP), present in luminal fluid, might be responsible for this observation. K(+) secretion rate (J(K)) was measured by K(+)-sensitive microelectrodes during paired luminal stationary microperfusion with control and AVP-containing 0.5 mM K(+) solutions. J(K) was 1.34 +/- 0.35 (n = 24 tubules) nmol x cm(-2) x s(-1) during perfusion with 10(-9) M AVP, against 0.90+/-0.12 nmol x cm(-2) x s(-1) (n = 21) in control (P<0.02). With 10(-9) M AVP+10(-6) M beta-mercapto-beta-beta-cyclopenta-methylenepropionyl(1), O-Me-Tyr(2)-Arg(8) vasopressin (MCMV), a specific peptide V(1)-receptor antagonist, J(K) was 0.36+/-0.067 against 0.77+/-0.10 (control; n = 9) nmol x cm(-2) x s(-1) (P<0.01). With 10(-6) M MCMV alone, J(K) was 0.37+/-0.04 against a control of 0.62+/-0.06 (n = 19) nmol. cm(-2). s(-1) (P<0.01). A peptide V(2) antagonist had no such effect. In Brattleboro rats, which do not produce endogenous AVP, MCMV had no effect when given alone, although AVP still stimulated J(K). In conclusion, luminal AVP stimulates distal J(K) significantly. The V(1) antagonist MCMV inhibits the effect of AVP but also reduces J(K) when given alone. This suggests that AVP acts luminally via V(1) receptors but also that there appears to be a background effect of endogenous AVP blocked by the antagonist.
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Affiliation(s)
- J B Amorim
- Department Physiology and Biophysics, Instituto Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508-900, Brazil
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