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Zeng C, Xia T, Zheng S, Liang L, Chen Y. Synergistic Effect of Uroguanylin and D 1 Dopamine Receptors on Sodium Excretion in Hypertension. J Am Heart Assoc 2022; 11:e022827. [PMID: 35229618 PMCID: PMC9075328 DOI: 10.1161/jaha.121.022827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background Oral NaCl produces a greater natriuresis and diuresis than the intravenous infusion of the same amount of NaCl, indicating the existence of a gastro‐renal axis. As one of the major natriuretic hormones secreted by both the intestines and the kidney, we hypothesized that renal uroguanylin interacts with dopamine receptors to increase sodium excretion synergistically, an impaired interaction of which may be involved in the pathogenesis of hypertension. Methods and Results In Wistar‐Kyoto rats, the infusion of uroguanylin or fenoldopam (a D1‐like receptor agonist) induced natriuresis and diuresis. Although subthreshold dosages of uroguanylin or fenoldopam had no effect, the coinfusion of subthreshold dosages of those reagents significantly increased sodium excretion. The coinfusion of an antagonist against D1‐like receptors, SCH23390, or an antagonist against uroguanylin, 2‐methylthioadenosine triphosphate, prevented the fenoldopam‐ or uroguanylin‐mediated natriuresis and diuresis in Wistar‐Kyoto rats. However, the natriuretic effects of uroguanylin and fenoldopam were not observed in spontaneously hypertensive rats. The uroguanylin/D1‐like receptor interaction was also confirmed in renal proximal tubule cells. In renal proximal tubule cells from Wistar‐Kyoto rats but not spontaneously hypertensive rats, stimulation of either D1‐like receptors or uroguanylin inhibited Na+‐K+‐ATPase activity, an effect that was blocked in the presence of SCH23390 or 2‐methylthioadenosine triphosphate. In renal proximal tubule cells from Wistar‐Kyoto rats, guanylyl cyclase C receptor (uroguanylin receptor) and D1 receptor coimmunoprecipitated, which was increased after stimulation by either uroguanylin or fenoldopam; stimulation of one receptor increased renal proximal tubule cell membrane expression of the other. Conclusions These data suggest that there is synergism between uroguanylin and D1‐like receptors to increase sodium excretion. An aberrant interaction between the renal uroguanylin and D1‐like receptors may play a role in the pathogenesis of hypertension.
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Affiliation(s)
- Cindy Zeng
- Department of Cardiology of Chongqing General Hospital Cardiovascular Research Center of Chongqing CollegeUniversity of Chinese Academy of Sciences Chongqing P. R. China
| | - Tianyang Xia
- Department of Cardiology, Daping Hospital The Third Military Medical University Chongqing P. R. China.,Chongqing Key Laboratory for Hypertension Research Chongqing Cardiovascular Clinical Research Center Chongqing Institute of Cardiology Chongqing P. R. China
| | - Shuo Zheng
- Department of Cardiology, Daping Hospital The Third Military Medical University Chongqing P. R. China.,Chongqing Key Laboratory for Hypertension Research Chongqing Cardiovascular Clinical Research Center Chongqing Institute of Cardiology Chongqing P. R. China
| | - Lijia Liang
- Department of Cardiology of Chongqing General Hospital Cardiovascular Research Center of Chongqing CollegeUniversity of Chinese Academy of Sciences Chongqing P. R. China
| | - Yue Chen
- Department of Cardiology, Daping Hospital The Third Military Medical University Chongqing P. R. China.,Chongqing Key Laboratory for Hypertension Research Chongqing Cardiovascular Clinical Research Center Chongqing Institute of Cardiology Chongqing P. R. China
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Xu P, Gildea JJ, Zhang C, Konkalmatt P, Cuevas S, Bigler Wang D, Tran HT, Jose PA, Felder RA. Stomach gastrin is regulated by sodium via PPAR-α and dopamine D1 receptor. J Mol Endocrinol 2020; 64:53-65. [PMID: 31794424 PMCID: PMC7654719 DOI: 10.1530/jme-19-0053] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/03/2019] [Indexed: 12/14/2022]
Abstract
Gastrin, secreted by stomach G cells in response to ingested sodium, stimulates the renal cholecystokinin B receptor (CCKBR) to increase renal sodium excretion. It is not known how dietary sodium, independent of food, can increase gastrin secretion in human G cells. However, fenofibrate (FFB), a peroxisome proliferator-activated receptor-α (PPAR-α) agonist, increases gastrin secretion in rodents and several human gastrin-secreting cells, via a gastrin transcriptional promoter. We tested the following hypotheses: (1.) the sodium sensor in G cells plays a critical role in the sodium-mediated increase in gastrin expression/secretion, and (2.) dopamine, via the D1R and PPAR-α, is involved. Intact human stomach antrum and G cells were compared with human gastrin-secreting gastric and ovarian adenocarcinoma cells. When extra- or intracellular sodium was increased in human antrum, human G cells, and adenocarcinoma cells, gastrin mRNA and protein expression/secretion were increased. In human G cells, the PPAR-α agonist FFB increased gastrin protein expression that was blocked by GW6471, a PPAR-α antagonist, and LE300, a D1-like receptor antagonist. LE300 prevented the ability of FFB to increase gastrin protein expression in human G cells via the D1R, because the D5R, the other D1-like receptor, is not expressed in human G cells. Human G cells also express tyrosine hydroxylase and DOPA decarboxylase, enzymes needed to synthesize dopamine. G cells in the stomach may be the sodium sensor that stimulates gastrin secretion, which enables the kidney to eliminate acutely an oral sodium load. Dopamine, via the D1R, by interacting with PPAR-α, is involved in this process.
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Affiliation(s)
- Peng Xu
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
| | - John J Gildea
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
| | - Chi Zhang
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
| | - Prasad Konkalmatt
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University, School of Medicine & Health Sciences, Washington, District of Columbia, USA
| | - Santiago Cuevas
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University, School of Medicine & Health Sciences, Washington, District of Columbia, USA
| | - Dora Bigler Wang
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
| | - Hanh T Tran
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
| | - Pedro A Jose
- Division of Renal Diseases & Hypertension, Department of Medicine, The George Washington University, School of Medicine & Health Sciences, Washington, District of Columbia, USA
- Department of Pharmacology and Physiology, The George Washington University, School of Medicine & Health Sciences, Washington, District of Columbia, USA
| | - Robin A Felder
- Department of Pathology, The University of Virginia, Charlottesville, Virginia, USA
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Oral Hypertonic Saline Is Effective in Reversing Acute Mild-to-Moderate Symptomatic Exercise-Associated Hyponatremia. Clin J Sport Med 2020; 30:8-13. [PMID: 31855907 DOI: 10.1097/jsm.0000000000000573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To determine whether oral administration of 3% hypertonic saline (HTS) is as efficacious as intravenous (IV) 3% saline in reversing symptoms of mild-to-moderate symptomatic exercise-associated hyponatremia (EAH) in athletes during and after a long-distance triathlon. DESIGN Noninferiority, open-label, parallel-group, randomized control trial to IV or oral HTS. We used permuted block randomization with sealed envelopes, containing the word either "oral" or "IV." SETTING Annual long-distance triathlon (3.8-km swim, 180-km bike, and 42-km run) at Mont-Tremblant, Quebec, Canada. PARTICIPANTS Twenty race finishers with mild to moderately symptomatic EAH. INDEPENDENT VARIABLES Age, sex, race finish time, and 9 clinical symptoms. MAIN OUTCOME MEASURES Time from treatment to discharge. METHODS We successfully randomized 20 participants to receive either an oral (n = 11) or IV (n = 9) bolus of HTS. We performed venipuncture to measure serum sodium (Na) at presentation to the medical clinic and at time of symptom resolution after the intervention. RESULTS The average time from treatment to discharge was 75.8 minutes (SD 29.7) for the IV treatment group and 50.3 minutes (SD 26.8) for the oral treatment group (t test, P = 0.02). Serum Na before and after treatment was not significantly different in both groups. There was no difference on presentation between groups in age, sex, or race finish time, both groups presented with an average of 6 symptoms. CONCLUSIONS Oral HTS is effective in reversing symptoms of mild-to-moderate hyponatremia in EAH.
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Abstract
Natriuretic peptides are structurally related, functionally diverse hormones. Circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are delivered predominantly by the heart. Two C-type natriuretic peptides (CNPs) are paracrine messengers, notably in bone, brain, and vessels. Natriuretic peptides act by binding to the extracellular domains of three receptors, NPR-A, NPR-B, and NPR-C of which the first two are guanylate cyclases. NPR-C is coupled to inhibitory proteins. Atrial wall stress is the major regulator of ANP secretion; however, atrial pressure changes plasma ANP only modestly and transiently, and the relation between plasma ANP and atrial wall tension (or extracellular volume or sodium intake) is weak. Absence and overexpression of ANP-related genes are associated with modest blood pressure changes. ANP augments vascular permeability and reduces vascular contractility, renin and aldosterone secretion, sympathetic nerve activity, and renal tubular sodium transport. Within the physiological range of plasma ANP, the responses to step-up changes are unimpressive; in man, the systemic physiological effects include diminution of renin secretion, aldosterone secretion, and cardiac preload. For BNP, the available evidence does not show that cardiac release to the blood is related to sodium homeostasis or body fluid control. CNPs are not circulating hormones, but primarily paracrine messengers important to ossification, nervous system development, and endothelial function. Normally, natriuretic peptides are not powerful natriuretic/diuretic hormones; common conclusions are not consistently supported by hard data. ANP may provide fine-tuning of reno-cardiovascular relationships, but seems, together with BNP, primarily involved in the regulation of cardiac performance and remodeling. © 2017 American Physiological Society. Compr Physiol 8:1211-1249, 2018.
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Affiliation(s)
- Peter Bie
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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5
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Abstract
Vasopressin (AVP) plays a major role in the regulation of water and sodium homeostasis by its antidiuretic action on the kidney, mediated by V2 receptors. AVP secretion is stimulated by a rise in plasma osmolality, a decline in blood volume or stress. V1a receptors are expressed in vascular smooth muscle cells, but the role of vasopressin in blood pressure regulation is still a matter of debate. AVP may also play a role in some metabolic pathways, including gluconeogenesis, through its action on V1a receptors expressed in the liver. It is now understood that thirst and arginine vasopressin (AVP) release are regulated not only by the classical homeostatic, intero-sensory plasma osmolality negative feedback, but also by novel, extero-sensory, anticipatory signals. AVP measurement is time-consuming, and AVP level in the blood in the physiological range is often below the detection limit of the assays. Recently, an immunoassay has been developed for the measurement of copeptin, a fragment of the pre-provasopressin molecule that is easier to measure. It has been shown to be a good surrogate marker of AVP.
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Affiliation(s)
- L Bankir
- Centre de Recherche des Cordeliers, INSERM Unit 1138, 75006, Paris, France.,Université Pierre et Marie Curie, 75006, Paris, France
| | - D G Bichet
- Université de Montréal, Montréal, QC, Canada.,Départements de Pharmacologie, Physiologie et de Médecine, Hôpital du Sacré-Coeur de Montréal, Montréal, QC, Canada
| | - N G Morgenthaler
- Institut für Experimentelle Endokrinologie, Charité Universitätsmedizin Berlin, Berlin, Germany.,InVivo Biotech Services, Neuendorfstraße 24a, Hennigsdorf/Berlin, Germany
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Alifieris CE, Trafalis DT, Efstratopoulos AD, Alifieris EK. Evidence of the role of the vagal nerves as a monitor in the gastrointestinal-renal axis of natriuresis in human: Effects of vagotomy. Auton Neurosci 2017; 205:99-109. [PMID: 28511917 DOI: 10.1016/j.autneu.2017.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 03/27/2017] [Accepted: 05/09/2017] [Indexed: 11/30/2022]
Abstract
This study aimed to investigate the mechanism of gastrointestinal regulation of natriuresis. Sixteen subjects without (group I) and sixteen subjects with a truncal vagotomy (group II), were given a daily diet of 18mmol of sodium for 5days (D1-D5). The sodium deficit for this period was calculated for each subject and on the morning of day-6 (D6), their cumulative deficit (E) was given as 3% NaCl. In both groups the subjects were divided to receive the hypertonic saline either orally (Ior, IIor) or intravenously (Iiv, IIiv). During the period of low sodium diet when compared to group II subjects of group I (1) had a greater weight loss (p<0.005), (2) demonstrated a larger drop in pulse pressure (p<0.005), (3) achieved a positive sodium equilibrium later (D5 vs D4) and (4) developed a greater sodium deficit (p<0.005). During the two 12h periods of D6, both Ior and Iiv exhibited greater natriuresis during the first 12h period (p<0.0001) whereas both IIor and IIiv did so during the second 12h period (p<0.0001). On D6 Ior excreted the greatest percentage of E (E%; 35.63%±3.12%, p<0.0001) compared to Iiv (17.06%±1.78%), IIor (16.03%±3.54%) and IIiv (15.39%±2.77%) whereas E% was not different between the other subgroups. These results indicate that the differential natriuresis between oral and intravenous sodium loading in previously sodium deprived subjects, is due to a mechanism in which the vagal nerves play a significant role as part of neural reflex or via a natriuretic hormone.
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Affiliation(s)
- Constantinos E Alifieris
- Department of Pharmacology, Medical School, National and Kapodistrian University of Athens, Athens, Greece; Department of Surgery, Agia Olga Hospital, Athens, Greece.
| | - Dimitrios T Trafalis
- Department of Pharmacology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Aris D Efstratopoulos
- Third Internal Medicine and Hypertension Unit, General Hospital of Athens, National and Kapodistrian University of Athens, Athens, Greece
| | - Emmanuel K Alifieris
- Medical School, National and Kapodistrian University of Athens, Athens, Greece; Second Surgery Department, General Hospital of Chania "Agios Georgios", Chania, Greece; Second Surgery Department, Piraeus General Hospital "Agios Pandeleimon", Piraeus, Greece
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Affiliation(s)
- Jian Yang
- Department of Nutrition, Daping Hospital, The Third Military Medical University, Chongqing, China.,Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, China
| | - Pedro A Jose
- Division of Renal Disease & Hypertension, The George Washington University School of Medicine and Health Sciences, Washington, DC
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing, China
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8
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Affiliation(s)
- Pedro A Jose
- From the Departments of Medicine and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC (P.A.J.); Department of Pathology, The University of Virginia, Charlottesville (R.A.F.); Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Centre, Peking Union Medical College, Beijing, P.R. China (Z.Y.); Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing, P.R. China (C.Z.); and Department of Medicine, Georgetown University Medical Center, Washington, DC (G.M.E.).
| | - Robin A Felder
- From the Departments of Medicine and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC (P.A.J.); Department of Pathology, The University of Virginia, Charlottesville (R.A.F.); Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Centre, Peking Union Medical College, Beijing, P.R. China (Z.Y.); Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing, P.R. China (C.Z.); and Department of Medicine, Georgetown University Medical Center, Washington, DC (G.M.E.)
| | - Zhiwei Yang
- From the Departments of Medicine and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC (P.A.J.); Department of Pathology, The University of Virginia, Charlottesville (R.A.F.); Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Centre, Peking Union Medical College, Beijing, P.R. China (Z.Y.); Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing, P.R. China (C.Z.); and Department of Medicine, Georgetown University Medical Center, Washington, DC (G.M.E.)
| | - Chunyu Zeng
- From the Departments of Medicine and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC (P.A.J.); Department of Pathology, The University of Virginia, Charlottesville (R.A.F.); Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Centre, Peking Union Medical College, Beijing, P.R. China (Z.Y.); Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing, P.R. China (C.Z.); and Department of Medicine, Georgetown University Medical Center, Washington, DC (G.M.E.)
| | - Gilbert M Eisner
- From the Departments of Medicine and Physiology, The George Washington University School of Medicine and Health Sciences, Washington, DC (P.A.J.); Department of Pathology, The University of Virginia, Charlottesville (R.A.F.); Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences and Comparative Medicine Centre, Peking Union Medical College, Beijing, P.R. China (Z.Y.); Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing, P.R. China (C.Z.); and Department of Medicine, Georgetown University Medical Center, Washington, DC (G.M.E.)
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9
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Jose PA, Yang Z, Zeng C, Felder RA. The importance of the gastrorenal axis in the control of body sodium homeostasis. Exp Physiol 2016; 101:465-70. [PMID: 26854262 DOI: 10.1113/ep085286] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 02/01/2016] [Indexed: 12/27/2022]
Abstract
NEW FINDINGS What is the topic of this review? Sensing the amount of ingested sodium is one mechanism by which sodium balance is regulated. This review describes the role of gastrin in the cross-talk between the stomach and the kidney following the ingestion of sodium. What advances does it highlight? Neural mechanisms and several gut hormones, including cholecystokinin and uroguanylin, have been suggested to mediate the natriuresis after an oral sodium load. It is proposed that gastrin produced by G-cells via its receptor, cholecystokinin B receptor, interacts with renal D1 -like dopamine receptors to increase renal sodium excretion. Hypertension develops with chronically increased sodium intake when sodium that accumulates in the body can no longer be sequestered, extracellular fluid volume is expanded, and compensatory neural, hormonal and pressure-natriuresis mechanisms fail. Sensing the amount of ingested sodium, by the stomach, is one mechanism by which sodium balance is regulated. The natriuresis following the ingestion of a certain amount of sodium may be due to an enterokine, gastrin, secreted by G-cells in the stomach and duodenum and released into the circulation. Circulating gastrin levels are 10- to 20-fold higher than those for cholecystokinin. Of all the gut hormones circulating in the plasma, gastrin is the one that is reabsorbed to the greatest extent by renal tubules. Gastrin, via its receptor, the cholecystokinin type B receptor (CCKBR), is natriuretic in mammals, including humans, by inhibition of renal sodium transport. Germline deletion of gastrin (Gast) or Cckbr gene in mice causes salt-sensitive hypertension. Selective silencing of Gast in the stomach and duodenum impairs the ability to excrete an oral sodium load and also increases blood pressure. Thus, the gastrorenal axis, mediated by gastrin, can complement pronatriuretic hormones, such as dopamine, to increase sodium excretion after an oral sodium load. These studies in mice may be translatable to humans because the chromosomal loci of CCKBR and GAST are linked to human essential hypertension. Understanding the role of genes in the regulation of renal function and blood pressure may lead to the tailoring of antihypertensive treatment based on genetic make-up.
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Affiliation(s)
- Pedro A Jose
- Department of Medicine, The George Washington University School of Medicine, Washington, DC, USA.,Department of Physiology, The George Washington University School of Medicine, Washington, DC, USA
| | - Zhiwei Yang
- Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences & Comparative Medicine Centre, Peking Union Medical College, Beijing, PR China
| | - Chunyu Zeng
- Department of Cardiology, Daping Hospital, The Third Military Medical University, Chongqing Institute of Cardiology, Chongqing 400042, PR China
| | - Robin A Felder
- Department of Pathology, The University of Virginia, Charlottesville, VA, USA
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10
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Damkjær M, Isaksson GL, Stubbe J, Jensen BL, Assersen K, Bie P. Renal renin secretion as regulator of body fluid homeostasis. Pflugers Arch 2012; 465:153-65. [PMID: 23096366 DOI: 10.1007/s00424-012-1171-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 10/06/2012] [Accepted: 10/07/2012] [Indexed: 01/01/2023]
Abstract
The renin-angiotensin system is essential for body fluid homeostasis and blood pressure regulation. This review focuses on the homeostatic regulation of the secretion of active renin in the kidney, primarily in humans. Under physiological conditions, renin secretion is determined mainly by sodium intake, but the specific pathways involved and the relations between them are not well defined. In animals, renin secretion is a log-linear function of sodium intake. Close associations exist between sodium intake, total body sodium, extracellular fluid volume, and blood volume. Plasma volume increases by about 1.5 mL/mmol increase in daily sodium intake. Several lines of evidence indicate that central blood volume may vary substantially without measurable changes in arterial blood pressure. At least five intertwining feedback loops of renin regulation are identifiable based on controlled variables (blood volume, arterial blood pressure), efferent pathways to the kidney (nervous, humoral), and pathways operating via the macula densa. Taken together, the available evidence favors the notion that under physiological conditions (1) volume-mediated regulation of renin secretion is the primary regulator, (2) macula densa mediated mechanisms play a substantial role as co-mediator although the controlled variables are not well defined so far, and (3) regulation via arterial blood pressure is the exception rather than the rule. Improved quantitative analyses based on in vivo and in silico models are warranted.
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Affiliation(s)
- Mads Damkjær
- Department of Paediatrics, Kolding Hospital, Kolding, Denmark
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11
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Estradiol selectively reduces central neural activation induced by hypertonic NaCl infusion in ovariectomized rats. Physiol Behav 2012; 107:192-200. [PMID: 22763321 DOI: 10.1016/j.physbeh.2012.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/16/2012] [Accepted: 06/23/2012] [Indexed: 02/02/2023]
Abstract
We recently reported that the latency to begin drinking water during slow, intravenous infusion of a concentrated NaCl solution was shorter in estradiol-treated ovariectomized rats compared to oil vehicle-treated rats, despite comparably elevated plasma osmolality. To test the hypothesis that the decreased latency to begin drinking is attributable to enhanced detection of increased plasma osmolality by osmoreceptors located in the CNS, the present study used immunocytochemical methods to label fos, a marker of neural activation. Increased plasma osmolality did not activate the subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT), or the nucleus of the solitary tract (NTS) in either oil vehicle-treated rats or estradiol-treated rats. In contrast, hyperosmolality increased fos labeling in the area postrema (AP), the paraventricular nucleus of the hypothalamus (PVN) and the rostral ventrolateral medulla (RVLM) in both groups; however, the increase was blunted in estradiol-treated rats. These results suggest that estradiol has selective effects on the sensitivity of a population of osmo-/Na(+)-receptors located in the AP, which, in turn, alters activity in other central areas associated with responses to increased osmolality. In conjunction with previous reports that hyperosmolality increases blood pressure and that elevated blood pressure inhibits drinking, the current findings of reduced activation in AP, PVN, and RVLM-areas involved in sympathetic nerve activity-raise the possibility that estradiol blunts HS-induced blood pressure changes. Thus, estradiol may eliminate or reduce the initial inhibition of water intake that occurs during increased osmolality, and facilitate a more rapid behavioral response, as we observed in our recent study.
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13
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Midoh N, Tokunaga M, Isomura T, Noguchi T. Effect of Soup Temperature on Body Thermal Sensation, Body Temperature and Heart Rate. J JPN SOC FOOD SCI 2012. [DOI: 10.3136/nskkk.59.262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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14
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Dietary salt influences postprandial plasma sodium concentration and systolic blood pressure. Kidney Int 2011; 81:407-11. [PMID: 22048126 DOI: 10.1038/ki.2011.369] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The plasma sodium concentration has a direct effect on blood pressure in addition to its effects on extracellular volume regulated through changes in the endothelium. The mechanism for elevated blood pressure seen with habitually increased salt intake is unclear, especially the effect of salt in a single meal on plasma sodium concentration and blood pressure. To resolve this we compared the effect of soup with or without 6 g of salt (an amount similar to that in a single meal) on the plasma sodium concentration and blood pressure in 10 normotensive volunteers using a randomized, crossover design. The plasma sodium concentration was significantly increased by 3.13±0.75 mmol/l with salted compared with unsalted soup. Blood pressure increased in volunteers ingesting soup with added salt, and there was a significant positive correlation between plasma sodium concentration and systolic blood pressure. A 1-mmol/l increase in plasma sodium was associated with a 1.91-mm Hg increase in systolic blood pressure by linear regression. Thus, changes in plasma sodium concentration occur each time a meal containing salt is consumed. A potential mechanism for the changes in blood pressure seen with salt intake may be through its effects on plasma sodium concentration.
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Abstract
PURPOSE OF REVIEW To highlight recent developments relating perioperative fluid therapy to gastrointestinal function by reviewing clinically pertinent English language articles mainly from January 2010 to March 2011. RECENT FINDINGS The control of fluid and electrolyte balance involves multiple processes in which the gastrointestinal tract plays an integral role. Diseases affecting the gastrointestinal tract commonly cause fluid and electrolyte disturbance. Similarly, intravenous fluid therapy in the perioperative period can affect gastrointestinal function and have a bearing on postoperative outcome. Striking a balance, in terms of both fluid composition and volume, is likely to reduce the morbidity associated with interstitial edema, a frequently observed occurrence with contemporary perioperative fluid regimens. This balance may be best achieved using individualized and goal-directed approaches to fluid therapy, in order to provide fluid when it is needed and in the correct quantities. SUMMARY In planning strategies of fluid therapy, the possibility of adverse effects on the gastrointestinal tract should be considered, as this is likely to have an impact on fluid and electrolyte balance and postoperative outcome.
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Affiliation(s)
- Abeed H Chowdhury
- Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre, NIHR Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham, UK
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16
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Pedersen SF, Kapus A, Hoffmann EK. Osmosensory mechanisms in cellular and systemic volume regulation. J Am Soc Nephrol 2011; 22:1587-97. [PMID: 21852585 DOI: 10.1681/asn.2010121284] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Perturbations of cellular and systemic osmolarity severely challenge the function of all organisms and are consequently regulated very tightly. Here we outline current evidence on how cells sense volume perturbations, with particular focus on mechanisms relevant to the kidneys and to extracellular osmolarity and whole body volume homeostasis. There are a variety of molecular signals that respond to perturbations in cell volume and osmosensors or volume sensors responding to these signals. The early signals of volume perturbation include integrins, the cytoskeleton, receptor tyrosine kinases, and transient receptor potential channels. We also present current evidence on the localization and function of central and peripheral systemic osmosensors and conclude with a brief look at the still limited evidence on pathophysiological conditions associated with deranged sensing of cell volume.
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Affiliation(s)
- Stine Falsig Pedersen
- Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100, Copenhagen, Denmark.
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17
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Sudbury JR, Ciura S, Sharif-Naeini R, Bourque CW. Osmotic and thermal control of magnocellular neurosecretory neurons - role of an N-terminal variant of trpv1. Eur J Neurosci 2010; 32:2022-30. [DOI: 10.1111/j.1460-9568.2010.07512.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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18
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Mølstrøm S, Larsen NH, Simonsen JA, Washington R, Bie P. Normotensive sodium loading in normal man: regulation of renin secretion during beta-receptor blockade. Am J Physiol Regul Integr Comp Physiol 2008; 296:R436-45. [PMID: 19073901 DOI: 10.1152/ajpregu.90754.2008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Saline administration may change renin-angiotensin-aldosterone system (RAAS) activity and sodium excretion at constant mean arterial pressure (MAP). We hypothesized that such responses are elicited mainly by renal sympathetic nerve activity by beta1-receptors (beta1-RSNA), and tested the hypothesis by studying RAAS and renal excretion during slow saline loading at constant plasma sodium concentration (Na+ loading; 12 micromol Na+.kg(-1).min(-1) for 4 h). Normal subjects were studied on low-sodium intake with and without beta1-adrenergic blockade by metoprolol. Metoprolol per se reduced RAAS activity as expected. Na+ loading decreased plasma renin concentration (PRC) by one-third, plasma ANG II by one-half, and plasma aldosterone by two-thirds (all P < 0.05); surprisingly, these changes were found without, as well as during, acute metoprolol administration. Concomitantly, sodium excretion increased indistinguishably with and without metoprolol (16 +/- 2 to 71 +/- 14 micromol/min; 13 +/- 2 to 55 +/- 13 micromol/min, respectively). Na+ loading did not increase plasma atrial natriuretic peptide, glomerular filtration rate (GFR by 51Cr-EDTA), MAP, or cardiac output (CO by impedance cardiography), but increased central venous pressure (CVP) by approximately 2.0 mmHg (P < 0.05). During Na+ loading, sodium excretion increased with CVP at an average slope of 7 micromol.min(-1).mmHg(-1). Concomitantly, plasma vasopressin decreased by 30-40% (P < 0.05). In conclusion, beta1-adrenoceptor blockade affects neither the acute saline-mediated deactivation of RAAS nor the associated natriuretic response, and the RAAS response to modest saline loading seems independent of changes in MAP, CO, GFR, beta1-mediated effects of norepinephrine, and ANP. Unexpectedly, the results do not allow assessment of the relative importance of RAAS-dependent and -independent regulation of renal sodium excretion. The results are compatible with the notion that at constant arterial pressure, a volume receptor elicited reduction in RSNA via receptors other than beta1-adrenoceptors, decreases renal tubular sodium reabsorption proximal to the macula densa leading to increased NaCl concentration at the macula densa, and subsequent inhibition of renin secretion.
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Affiliation(s)
- Simon Mølstrøm
- Department of Physiology and Pharmacology, Institute of Medical Biology, University of Southern Denmark, 21 Winslowparken, Odense, DK-5000, Denmark
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19
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Abstract
Systemic osmoregulation is a vital process whereby changes in plasma osmolality, detected by osmoreceptors, modulate ingestive behaviour, sympathetic outflow and renal function to stabilize the tonicity and volume of the extracellular fluid. Furthermore, changes in the central processing of osmosensory signals are likely to affect the hydro-mineral balance and other related aspects of homeostasis, including thermoregulation and cardiovascular balance. Surprisingly little is known about how the brain orchestrates these responses. Here, recent advances in our understanding of the molecular, cellular and network mechanisms that mediate the central control of osmotic homeostasis in mammals are reviewed.
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Affiliation(s)
- Charles W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, Room L7-216, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec, H3G 1A4, Canada.
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20
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Kompanowska-Jezierska E, Wolff H, Kuczeriszka M, Gramsbergen JB, Walkowska A, Johns EJ, Bie P. Renal nerves and nNOS: roles in natriuresis of acute isovolumetric sodium loading in conscious rats. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1130-9. [DOI: 10.1152/ajpregu.00908.2007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It was hypothesized that renal sympathetic nerve activity (RSNA) and neuronal nitric oxide synthase (nNOS) are involved in the acute inhibition of renin secretion and the natriuresis following slow NaCl loading (NaLoad) and that RSNA participates in the regulation of arterial blood pressure (MABP). This was tested by NaLoad after chronic renal denervation with and without inhibition of nNOS by S-methyl-thiocitrulline (SMTC). In addition, the acute effects of renal denervation on MABP and sodium balance were assessed. Rats were investigated in the conscious, catheterized state, in metabolic cages, and acutely during anesthesia. NaLoad was performed over 2 h by intravenous infusion of hypertonic solution (50 μmol·min−1·kg body mass−1) at constant body volume conditions. SMTC was coinfused in amounts (20 μg·min−1·kg−1) reported to selectively inhibit nNOS. Directly measured MABPs of acutely and chronically denervated rats were less than control (15% and 9%, respectively, P < 0.005). Plasma renin concentration (PRC) was reduced by renal denervation (14.5 ± 0.2 vs. 19.3 ± 1.3 mIU/l, P < 0.005) and by nNOS inhibition (12.4 ± 2.3 vs. 19.6 ± 1.6 mlU/l, P < 0.005). NaLoad reduced PRC ( P < 0.05) and elevated MABP modestly ( P < 0.05) and increased sodium excretion six-fold, irrespective of renal denervation and SMTC. The metabolic data demonstrated that renal denervation lowered sodium balance during the first days after denervation ( P < 0.001). These data show that renal denervation decreases MABP and renin secretion. However, neither renal denervation nor nNOS inhibition affects either the renin down-regulation or the natriuretic response to acute sodium loading. Acute sodium-driven renin regulation seems independent of RSNA and nNOS under the present conditions.
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21
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Michell A, Debnam E, Unwin R. Regulation of Renal Function by the Gastrointestinal Tract: Potential Role of Gut-Derived Peptides and Hormones. Annu Rev Physiol 2008; 70:379-403. [DOI: 10.1146/annurev.physiol.69.040705.141330] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A.R. Michell
- Department of Biochemical Pharmacology, William Harvey Research Institute, St. Bartholomew's Hospital Medical School, London EC1M 6BQ, United Kingdom;
| | - E.S. Debnam
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
| | - R.J. Unwin
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
- Centre for Nephrology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
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22
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Abstract
In 1958, Edelman and colleagues empirically showed plasma sodium concentration ([Na+]p) to be primarily a function of the sum of exchangeable sodium and potassium (E) divided by total body water (TBW). Based on Edelman's equation, Nguyen and Kurtz derived an equation to show how [Na+]p changes as a function of TBW, change in TBW (DeltaTBW), and change in the sum of exchangeable sodium and potassium (DeltaE). Using the Nguyen-Kurtz equation, the present study examines the sensitivity of [Na+]p to these parameters: [Na+]p is very sensitive to DeltaTBW and moderately sensitive to DeltaE, and is modulated by TBW. For example, for a person with 50 L TBW, a net increase of 1L water lowers [Na+]p by 3.2 mEq/L, but for a person with 25 L TBW it lowers [Na+]p by 6.3 mEq/L (assuming initial [Na+]p is 140 mEq/L). In each case, a loss of 159 mEq of sodium plus potassium (roughly equivalent to 1.5 teaspoons of table salt) would be required to produce the same effect as the net increase of 1 L water. The present review demonstrates why fluid overload predominates over electrolyte loss in the aetiology of exercise-associated hyponatraemia (EAH), and why the excretion of electrolyte-dilute urine is highly effective in correcting EAH (nonetheless, loss of sodium and potassium is significant in long events in warm weather). Sports drinks will, if overconsumed, result in hyponatraemia. Administration of a sports drink to an athlete with fluid overload hyponatraemia further lowers [Na+]p and increases fluid overload. Administration of either a sports drink or normal (0.9%) saline increases fluid overload.
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23
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Abstract
Body fluid regulation depends on regulation of renal excretion. This includes a fast vasopressin-mediated water-retaining mechanism, and slower, complex sodium-retaining systems dominated by the renin-angiotensin aldosterone cascade. The sensory mechanisms of sodium control are not identified; effectors may include renal arterial pressure, renal reflexes, extrarenal hormones and other regulatory factors. Since the pioneering work of Guyton more than three decades ago, pressure natriuresis has been in focus. Dissociations between sodium excretion and blood pressure are explained as conditions where regulatory performance exceeds the precision of the measurements. It is inherent to the concept, however, that sudden transition from low to high sodium intake elicits an arterial pressure increase, which is reversed by the pressure natriuresis mechanism. However, such transitions elicit parallel changes in extracellular fluid volume thereby activating volume receptors. Recently we studied the orchestration of sodium homeostasis by chronic and acute sodium loading in normal humans and trained dogs. Small increases in arterial blood pressure are easily generated by acute sodium loading, and dogs appear more sensitive than humans. However, with suitable loading procedures it is possible - also acutely - to augment renal sodium excretion by at least one order of magnitude without any change in arterial pressure whatsoever. Although pressure natriuresis is a powerful mechanism capable of overriding any other controller, it seems possible that it is not operative under normal conditions. Consequently, it is suggested that physiological control of sodium excretion is neurohumoral based on extracellular volume with neural control of renin system activity as an essential component.
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Affiliation(s)
- P Bie
- Physiology and Pharmacology, Institute of Medical Biology, University of Southern Denmark, Winslowparken, Odense C, Denmark
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24
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Holte K, Sharrock NE, Kehlet H. Pathophysiology and clinical implications of perioperative fluid excess. Br J Anaesth 2002; 89:622-32. [PMID: 12393365 DOI: 10.1093/bja/aef220] [Citation(s) in RCA: 456] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- K Holte
- Department of Surgical Gastroenterology, Hvidovre University Hospital, DK-2650 Hvidovre, Denmark
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25
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Andersen LJ, Andersen JL, Pump B, Bie P. Natriuresis induced by mild hypernatremia in humans. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1754-61. [PMID: 12010758 DOI: 10.1152/ajpregu.00732.2001] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The hypothesis that increases in plasma sodium induce natriuresis independently of changes in body fluid volume was tested in six slightly dehydrated seated subjects on controlled sodium intake (150 mmol/day). NaCl (3.85 mmol/kg) was infused intravenously over 90 min as isotonic (Iso) or as hypertonic saline (Hyper, 855 mmol/l). After Hyper, plasma sodium increased by 3% (142.0 +/- 0.6 to 146.2 +/- 0.5 mmol/l). During Iso a small decrease occurred (142.3 +/- 0.6 to 140.3 +/- 0.7 mmol/l). Iso increased estimates of plasma volume significantly more than Hyper. However, renal sodium excretion increased significantly more with Hyper (291 +/- 25 vs. 199 +/- 24 micromol/min). This excess was not mediated by arterial pressure, which actually decreased slightly. Creatinine clearance did not change measurably. Plasma renin activity, ANG II, and aldosterone decreased very similarly in Iso and Hyper. Plasma atrial natriuretic peptide remained unchanged, whereas plasma vasopressin increased with Hyper (1.4 +/- 0.4 to 3.1 +/- 0.5 pg/ml) and decreased (1.3 +/- 0.4 to 0.6 +/- 0.1 pg/ml) after Iso. In conclusion, the natriuretic response to Hyper was 50% larger than to Iso, indicating that renal sodium excretion may be determined partly by plasma sodium concentration. The mechanism is uncertain but appears independent of changes in blood pressure, glomerular filtration rate, the renin system, and atrial natriuretic peptide.
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Affiliation(s)
- Lars Juel Andersen
- Department of Medical Physiology, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
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26
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Affiliation(s)
- Ole Skøtt
- Physiology and Pharmacology, University of Southern Denmark, DK-5000 Odense, Denmark
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