1
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Hua D, Huang W, Huang W, Xie Q, Tang L, Wu X, Gao M, Xu T, Zhang Y, Li P, Sun W, Kong X. TRPV1 signaling of perirenal adipose tissue promotes DOCA-Salt-induced hypertension and kidney injury. J Hypertens 2024; 42:1409-1420. [PMID: 38690943 DOI: 10.1097/hjh.0000000000003748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
BACKGROUND Denervation of renal or perirenal adipose tissue (PRAT) can reduce arterial blood pressure in various hypertensive experimental models. Trpv1 (transient receptor potential vanillin 1) channel is highly expressed in the renal sensory nerves and the dorsal root ganglias (DRGs) projected by PRAT. However, it is currently unclear whether Trpv1 in DRGs projected from PRAT can regulate renal hypertension. METHODS We used resintoxin (RTX) to block the afferent sensory nerves of rat PRAT. We also constructed Trpv1 -/- mice and Trpv1 +/- mice or used the injection of AAV2-retro-shTrpv1 to detect the effects of Trpv1 knockout or knockdown of PRAT-projected DRGs on deoxycorticosterone acetate (DOCA)-Salt-induced hypertension and kidney injury. RESULTS Blocking the afferent sensory nerves of PRAT with RTX can alleviate DOCA-Salt-induced hypertension and renal injury in rats. And this blockade reduces the expression of Trpv1 in the DRGs projected by PRAT. Injecting AAV2-retro-shTrpv1 into the PRAT of DOCA-Salt mice also achieved the same therapeutic effect. However, DOCA-Salt-induced hypertension and renal injury can be treated in Trpv1 +/- mice but not alleviated or even worsened in Trpv1 -/- mice, possibly because of compensatory increase of Trpv5 in DRG of Trpv1 -/- mice. CONCLUSION Reducing, rather than eliminating, Trpv1 in DRG from PRAT-projection can reduce blood pressure and kidney damage in DOCA-Salt in rats or mice. Trpv1 in PRAT-DRGs may serve as a therapeutic target for salt-sensitive hypertension and its renal complications.
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Affiliation(s)
- Dongxu Hua
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Wanlin Huang
- Department of Cardiology, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, Jiangsu, P.R. China
| | - Wen Huang
- Department of Cardiology, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, Jiangsu, P.R. China
| | - Qiyang Xie
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Lu Tang
- Department of Cardiology, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, Jiangsu, P.R. China
| | - Xiaoguang Wu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Min Gao
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Tianhua Xu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Yue Zhang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
| | - Peng Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine
| | - Wei Sun
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine
| | - Xiangqing Kong
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine
- Department of Cardiology, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, Jiangsu, P.R. China
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Stock JM, Romberger NT, McMillan RK, Chung JW, Wenner MM, Stocker SD, Farquhar WB, Burciu RG. Acute hypernatremia increases functional connectivity of NaCl sensing regions in the human brain: An fMRI pilot study. Auton Neurosci 2024; 254:103182. [PMID: 38805791 DOI: 10.1016/j.autneu.2024.103182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/29/2024] [Accepted: 05/14/2024] [Indexed: 05/30/2024]
Abstract
Rodent studies demonstrated specialized sodium chloride (NaCl) sensing neurons in the circumventricular organs, which mediate changes in sympathetic nerve activity, arginine vasopressin, thirst, and blood pressure. However, the neural pathways involved in NaCl sensing in the human brain are incompletely understood. The purpose of this pilot study was to determine if acute hypernatremia alters the functional connectivity of NaCl-sensing regions of the brain in healthy young adults. Resting-state fMRI scans were acquired in 13 participants at baseline and during a 30 min hypertonic saline infusion (HSI). We used a seed-based approach to analyze the data, focusing on the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT) as regions of interest (ROIs). Blood chemistry and perceived thirst were assessed pre- and post-infusion. As expected, serum sodium increased from pre- to post-infusion in the HSI group. The primary finding of this pilot study was that the functional connectivity between the SFO and a cluster within the OVLT increased from baseline to the late-phase of the HSI. Bidirectional connectivity changes were found with cortical regions, with some regions showing increased connectivity with sodium-sensing regions while others showed decreased connectivity. Furthermore, the functional connectivity between the SFO and the posterior cingulate cortex (a control ROI) did not change from baseline to the late-phase of the HSI. This finding indicates a distinct response within the NaCl sensing network in the human brain specifically related to acute hypernatremia that will need to be replicated in large-scale studies.
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Affiliation(s)
- Joseph M Stock
- University of Delaware, Newark, DE, United States of America
| | | | | | - Jae Woo Chung
- University of Minnesota, Minneapolis, MN, United States of America
| | - Megan M Wenner
- University of Delaware, Newark, DE, United States of America
| | - Sean D Stocker
- University of Pittsburgh, Pittsburgh, PA, United States of America
| | | | - Roxana G Burciu
- University of Delaware, Newark, DE, United States of America.
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3
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Fagunwa O, Davies K, Bradbury J. The Human Gut and Dietary Salt: The Bacteroides/ Prevotella Ratio as a Potential Marker of Sodium Intake and Beyond. Nutrients 2024; 16:942. [PMID: 38612976 PMCID: PMC11013828 DOI: 10.3390/nu16070942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/09/2024] [Accepted: 03/20/2024] [Indexed: 04/14/2024] Open
Abstract
The gut microbiota is a dynamic ecosystem that plays a pivotal role in maintaining host health. The perturbation of these microbes has been linked to several health conditions. Hence, they have emerged as promising targets for understanding and promoting good health. Despite the growing body of research on the role of sodium in health, its effects on the human gut microbiome remain under-explored. Here, using nutrition and metagenomics methods, we investigate the influence of dietary sodium intake and alterations of the human gut microbiota. We found that a high-sodium diet (HSD) altered the gut microbiota composition with a significant reduction in Bacteroides and inverse increase in Prevotella compared to a low-sodium diet (LSD). However, there is no clear distinction in the Firmicutes/Bacteroidetes (F/B) ratio between the two diet types. Metabolic pathway reconstruction revealed the presence of sodium reabsorption genes in the HSD, but not LSD. Since it is currently difficult in microbiome studies to confidently associate the F/B ratio with what is considered healthy (e.g., low sodium) or unhealthy (e.g., high sodium), we suggest that the use of a genus-based ratio such as the Bacteroides/Prevotella (B/P) ratio may be more beneficial for the application of microbiome studies in health.
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Affiliation(s)
- Omololu Fagunwa
- Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 5DL, UK
| | - Kirsty Davies
- School of Applied Sciences, University of Huddersfield, Huddersfield HD1 3DH, UK;
| | - Jane Bradbury
- School of Medicine, Edge Hill University, Ormskirk L39 4QP, UK;
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4
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Ramachandran CD, Gholami K, Lam SK, Hoe SZ. Effects of a high-salt diet on MAP and expression levels of renal ENaCs and aquaporins in SHR. Exp Biol Med (Maywood) 2023; 248:1768-1779. [PMID: 37828834 PMCID: PMC10792424 DOI: 10.1177/15353702231198085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 06/05/2023] [Indexed: 10/14/2023] Open
Abstract
An increase in blood pressure by a high-salt (HS) diet may change the expression levels of renal epithelial sodium channels (ENaCs) and aquaporins (AQPs). Spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were exposed to HS and regular-salt (RS) diets for 6 weeks. Mean arterial pressure (MAP) and plasma atrial natriuretic peptide (ANP), angiotensin II (Ang II), aldosterone, and arginine vasopressin (AVP) levels were determined. Expression of mRNA levels of ENaCs and AQPs were quantified by real-time PCR. The MAP was higher in SHRs on the HS diet. Plasma Ang II and aldosterone levels were low while plasma ANP level was high in both strains of rats. Renal expression of mRNA levels of α-, β-, and γ-ENaCs was lowered in SHRs on the HS diet. Meanwhile, renal AQP1, AQP2, and AQP7 mRNA expression levels were lowered in both strains of rats on the HS diet. Suppression of mRNA expression levels of ENaC and AQP subunits suggests that the high-salt-induced increase in the MAP of SHR may not be solely due to renal sodium and water retention.
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Affiliation(s)
| | - Khadijeh Gholami
- Department of Physiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Department of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Sau-Kuen Lam
- Department of Physiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Department of Pre-Clinical Sciences, Faculty of Medicine & Health Sciences, Universiti Tunku Abdul Rahman, Kajang 43000, Malaysia
| | - See-Ziau Hoe
- Department of Physiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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5
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Sutovska H, Molcan L, Majzunova M, Sykora M, Kopkan L, Zeman M. Mineralocorticoid receptor blockade protects the kidneys but does not affect inverted blood pressure rhythm in hypertensive transgenic (mRen-2)27 rats. Mol Cell Endocrinol 2023; 572:111967. [PMID: 37210027 DOI: 10.1016/j.mce.2023.111967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/17/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023]
Abstract
Aldosterone regulates blood pressure (BP) through water and sodium balance. In our study, we studied if continuous treatment with a mineralocorticoid receptor antagonist, spironolactone (30 mg/kg/day) for 20 days can: 1) attenuate hypertension development and restore inverted 24-h BP rhythm in hypertensive transgenic (mRen-2)27 rats (TGR) measured by telemetry; 2) improve function of the kidneys and heart; 3) be protective against high salt load (1% in water) by mitigating oxidative injury and improving kidney function. Spironolactone decreased albuminuria and 8-isoprostane in normal and salt load conditions in BP-independent effects. Salt load increased BP, impaired autonomic balance, suppressed plasma aldosterone level and increased natriuresis, albuminuria and oxidative injury in TGR. Spironolactone did not restore the inverted 24-h rhythm of BP in TGR, therefore, mineralocorticoids are not crucial in regulation of BP daily profile. Spironolactone improved kidney function, decreased oxidative stress and was protective against high salt load in the BP-independent manner.
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Affiliation(s)
- Hana Sutovska
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Lubos Molcan
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Miroslava Majzunova
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
| | - Matus Sykora
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
| | - Libor Kopkan
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic.
| | - Michal Zeman
- Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak Republic.
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6
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Wu Q, Burley G, Li L, Lin S, Shi Y. The role of dietary salt in metabolism and energy balance: Insights beyond cardiovascular disease. Diabetes Obes Metab 2023; 25:1147-1161. [PMID: 36655379 PMCID: PMC10946535 DOI: 10.1111/dom.14980] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/14/2023] [Accepted: 01/18/2023] [Indexed: 01/20/2023]
Abstract
Dietary salt (NaCl) is essential to an organism's survival. However, today's diets are dominated by excessive salt intake, which significantly impacts individual and population health. High salt intake is closely linked to cardiovascular disease (CVD), especially hypertension, through a number of well-studied mechanisms. Emerging evidence indicates that salt overconsumption may also be associated with metabolic disorders. In this review, we first summarize recent updates on the mechanisms of salt-induced CVD, the effects of salt reduction and the use of salt substitution as a therapy. Next, we focus on how high salt intake can impact metabolism and energy balance, describing the mechanisms through which this occurs, including leptin resistance, the overproduction of fructose and ghrelin, insulin resistance and altered hormonal factors. A further influence on metabolism worth noting is the reported role of salt in inducing thermogenesis and increasing body temperature, leading to an increase in energy expenditure. While this result could be viewed as a positive metabolic effect because it promotes a negative energy balance to combat obesity, caution must be taken with this frame of thinking given the deleterious consequences of chronic high salt intake on cardiovascular health. Nevertheless, this review highlights the importance of salt as a noncaloric nutrient in regulating whole-body energy homeostasis. Through this review, we hope to provide a scientific framework for future studies to systematically address the metabolic impacts of dietary salt and salt replacement treatments. In addition, we hope to form a foundation for future clinical trials to explore how these salt-induced metabolic changes impact obesity development and progression, and to elucidate the regulatory mechanisms that drive these changes, with the aim of developing novel therapeutics for obesity and CVD.
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Affiliation(s)
- Qi Wu
- Obesity and Metabolic Disease Research GroupGarvan Institute of Medical ResearchSydneyNew South WalesAustralia
- Centre of Neurological and Metabolic Researchthe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
| | - George Burley
- Obesity and Metabolic Disease Research GroupGarvan Institute of Medical ResearchSydneyNew South WalesAustralia
| | - Li‐Cheng Li
- Centre of Neurological and Metabolic Researchthe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
| | - Shu Lin
- Obesity and Metabolic Disease Research GroupGarvan Institute of Medical ResearchSydneyNew South WalesAustralia
- Centre of Neurological and Metabolic Researchthe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
| | - Yan‐Chuan Shi
- Obesity and Metabolic Disease Research GroupGarvan Institute of Medical ResearchSydneyNew South WalesAustralia
- Centre of Neurological and Metabolic Researchthe Second Affiliated Hospital of Fujian Medical UniversityQuanzhouChina
- School of Clinical Medicine, St Vincent's Clinical CampusFaculty of Medicine and HealthSydneyNew South WalesAustralia
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7
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Stocker SD. Altered Neuronal Discharge in the Organum Vasculosum of the Lamina Terminalis Contributes to Dahl Salt-Sensitive Hypertension. Hypertension 2023; 80:872-881. [PMID: 36752103 PMCID: PMC10023399 DOI: 10.1161/hypertensionaha.122.20798] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 01/30/2023] [Indexed: 02/09/2023]
Abstract
BACKGROUND Salt-sensitive hypertension in humans and experimental models is associated with higher plasma and cerebrospinal fluid sodium chloride (NaCl) concentrations. Changes in extracellular NaCl concentrations are sensed by specialized neurons in the organum vasculosum of the lamina terminalis (OVLT). Stimulation of OVLT neurons increases sympathetic nerve activity (SNA) and arterial blood pressure (ABP), whereas chronic activation produces hypertension. Therefore, the present study tested whether OVLT neuronal activity was elevated and contributed to SNA and ABP in salt-sensitive hypertension. METHODS Male Dahl salt-sensitive (Dahl S) and Dahl salt-resistant (Dahl R) rats were fed 0.1% or 4.0% NaCl diets for 3 to 4 weeks and used for single-unit recordings of OVLT neurons or simultaneous recording of multiple sympathetic nerves during pharmacological inhibition of the OVLT. RESULTS Plasma and cerebrospinal fluid Na+ and Cl- concentrations were higher in Dahl S rats fed 4% versus 0.1% or Dahl R rats fed either diet. In vivo single-unit recordings revealed a significantly higher discharge of NaCl-responsive OVLT neurons in Dahl S rats fed 4% versus 0.1% or Dahl R rats. Interestingly, intracarotid infusion of hypertonic NaCl evoked greater increases in OVLT neuronal discharge of Dahl S versus Dahl R rats regardless of NaCl diet. The activity of non-NaCl-responsive OVLT neurons was not different across strain or diets. Finally, inhibition of OVLT neurons by local injection of the gamma-aminobutyric acid agonist muscimol produced a greater decrease in renal SNA, splanchnic SNA, and ABP of Dahl S rats fed 4% versus 0.1% or Dahl R rats. CONCLUSIONS A high salt diet activates NaCl-responsive OVLT neurons to increase SNA and ABP in salt-sensitive hypertension.
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Affiliation(s)
- Sean D Stocker
- Department of Neurobiology, University of Pittsburgh School of Medicine, PA
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8
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Braga DCDA, Gomes PM, Batista MAC, de Souza JA, Bastos JCSA, Rodrigues-das-Dôres RG, Alzamora AC, de Souza GHB, de Moura SAL, Talvani A, Antunes VR, Cardoso LM. Effects of Psidium guajava L. leaves extract on blood pressure control and IL-10 production in salt-dependent hypertensive rats. Biomed Pharmacother 2022; 155:113796. [DOI: 10.1016/j.biopha.2022.113796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 09/19/2022] [Accepted: 10/02/2022] [Indexed: 11/02/2022] Open
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9
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TRPV1-Mediated Sensing of Sodium and Osmotic Pressure in POMC Neurons in the Arcuate Nucleus of the Hypothalamus. Nutrients 2022; 14:nu14132600. [PMID: 35807782 PMCID: PMC9268643 DOI: 10.3390/nu14132600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/11/2022] [Accepted: 06/20/2022] [Indexed: 11/17/2022] Open
Abstract
The central melanocortin system conducted by anorexigenic pro-opiomelanocortin (POMC) neurons and orexigenic agouti-related peptide (AgRP) neurons in the arcuate nucleus of the hypothalamus (ARC) not only regulates feeding behavior but also blood pressure. Excessive salt intake raises the Na+ concentration ([Na+]) in the cerebrospinal fluid (CSF) and worsens hypertension. The blood–brain barrier is immature in the ARC. Therefore, both AgRP and POMC neurons in the ARC have easy access to the electrolytes in the blood and can sense changes in their concentrations. However, the sensitivity of AgRP and POMC neurons to Na+ remains unclear. This study aimed to explore how the changes in the extracellular Na+ concentration ([Na+]) influence these neurons by measuring the cytosolic Ca2+ concentration ([Ca2+]i) in the single neurons isolated from the ARC that were subsequently immunocytochemically identified as AgRP or POMC neurons. Both AgRP and POMC neurons responded to increases in both [Na+] and osmolarity in C57BL/6 mice. In contrast, in transient receptor potential vanilloid 1 (TRPV1) knockout (KO) mice, POMC neurons failed to respond to increases in both [Na+] and osmolarity, while they responded to high glucose and angiotensin II levels with increases in [Ca2+]i. Moreover, in KO mice fed a high-salt diet, the expression of POMC was lower than that in wild-type mice. These results demonstrate that changes in [Na+] and osmolarity are sensed by the ARC POMC neurons via the TRPV1-dependent mechanism.
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10
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Abstract
Microglial cells are derived from myelogenous cells and their chronic activation elicits brain inflammation, which influences neurological activity. Comprehensive understanding of the regulation of microglial activation could therefore contribute to overcoming neuropsychiatric disorders. Recently, the importance of serum- and glucocorticoid-inducible kinases (SGKs) has been explored in immune cells such as T cells, dendritic cells and macrophages. We have already shown that SGK1 and SGK3 are expressed in microglial cells and associated with the regulation of lipopolysaccharide (LPS)-induced inflammatory molecules. Here we investigate whether salt load influences expression of SGK1 and inflammatory responses in murine primary microglia and an immortalized microglial cell line, BV-2. Additional amounts of NaCl were administrated and immunoblotting was carried out, and SGK1 was induced in dose- and time-dependent manners. Next, the dynamics of inflammatory mediators iNOS and TNFα were investigated by administration of LPS. iNOS mRNA was induced by LPS application and enhanced by NaCl preload. In support of these results, nitric oxide was produced by LPS and accelerated by NaCl preload. In contrast, however, NaCl preload reduced the release of TNFα, suggesting the modulation of immune responses by salt load. The effects of salt load on both cases were attenuated in SGK1-deleted cells. Taken together, these results indicate that salt load modulates inflammatory responses and that SGK1 assists salt load-induced inflammatory responses.
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11
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Łabno-Kirszniok K, Kujawa-Szewieczek A, Wiecek A, Piecha G. The Effects of Short-Term Changes in Sodium Intake on Plasma Marinobufagenin Levels in Patients with Primary Salt-Sensitive and Salt-Insensitive Hypertension. Nutrients 2021; 13:nu13051502. [PMID: 33946894 PMCID: PMC8147121 DOI: 10.3390/nu13051502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 11/25/2022] Open
Abstract
Increased marinobufagenin (MBG) synthesis has been suggested in response to high dietary salt intake. The aim of this study was to determine the effects of short-term changes in sodium intake on plasma MBG levels in patients with primary salt-sensitive and salt-insensitive hypertension. In total, 51 patients with primary hypertension were evaluated during acute sodium restriction and sodium loading. Plasma or serum concentrations of MBG, natriuretic pro-peptides, aldosterone, sodium, potassium, as well as hematocrit (Hct) value, plasma renin activity (PRA) and urinary sodium and potassium excretion were measured. Ambulatory blood pressure monitoring (ABPM) and echocardiography were performed at baseline. In salt-sensitive patients with primary hypertension plasma MBG correlated positively with diastolic blood pressure (ABPM) and serum NT-proANP concentration at baseline and with serum NT-proANP concentration after dietary sodium restriction. In this subgroup plasma MBG concentration decreased during sodium restriction, and a parallel increase of PRA was observed. Acute salt loading further decreased plasma MBG concentration in salt-sensitive subjects in contrast to salt insensitive patients. No correlation was found between plasma MBG concentration and left ventricular mass index. In conclusion, in salt-sensitive hypertensive patients plasma MBG concentration correlates with 24-h diastolic blood pressure and dietary sodium restriction reduces plasma MBG levels. Decreased MBG secretion in response to acute salt loading may play an important role in the pathogenesis of salt sensitivity.
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Affiliation(s)
| | | | | | - Grzegorz Piecha
- Correspondence: ; Tel.: +48-322-591-429; Fax: +48-322-553-726
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12
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Kawada T, Nishikawa T, Suehara S, Sawada S, Tanaka T, Uenohara M, Yamamoto H, Sugimachi M. Open-loop analysis on sympathetically mediated arterial pressure and urine output responses in spontaneously hypertensive rats: effect of renal denervation. J Physiol Sci 2021; 71:13. [PMID: 33879059 PMCID: PMC10717997 DOI: 10.1186/s12576-021-00798-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 03/31/2021] [Indexed: 12/12/2022]
Abstract
Primary acute sympathetic activation (PASA) causes a subsequent arterial pressure (AP) elevation. In this case, an antidiuretic effect via the renal innervation and pressure diuresis can act antagonistically on the kidneys. We examined the effect of PASA on urine output in spontaneously hypertensive rats (SHR) 4-7 days after unilateral renal denervation (RDN) (n = 9). The slope of the plot of urine flow versus AP was positive (0.120 ± 0.031 μL min-1 kg-1 mmHg-1) on the intact side, but it was less than 1/3 of the slope observed previously in normotensive Wistar-Kyoto rats (WKY). RDN did not normalize the slope of urine flow versus AP (0.179 ± 0.025 μL min-1 kg-1 mmHg-1, P = 0.098 versus the intact side). The urine flow at the operating point of the AP tended to be greater on the denervated than the intact side (29.0 ± 1.8 vs. 25.3 ± 1.9 μL min-1 kg-1, P = 0.055). The percent increase (17.2 ± 7.2%) was not different from that observed previously in WKY. Although high-resting sympathetic nerve activity is prerequisite for maintaining hypertension in SHR, the effect of sympathetic innervation on the urine output function was not greater than that in WKY.
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Affiliation(s)
- Toru Kawada
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan.
| | - Takuya Nishikawa
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
| | - Satoru Suehara
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Satoshi Sawada
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Tetsuo Tanaka
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Minako Uenohara
- Corporate R&D Center, Terumo Corporation, Kanagawa, 259-0151, Japan
| | - Hiromi Yamamoto
- Department of Cardiology, Kurashiki Central Hospital, Ohara HealthCare Foundation, Okayama, 710-8602, Japan
| | - Masaru Sugimachi
- Department of Cardiovascular Dynamics, National Cerebral and Cardiovascular Center, Osaka, 564-8565, Japan
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13
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Kawarazaki W, Fujita T. Role of Rho in Salt-Sensitive Hypertension. Int J Mol Sci 2021; 22:ijms22062958. [PMID: 33803946 PMCID: PMC8001214 DOI: 10.3390/ijms22062958] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/09/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022] Open
Abstract
A high amount of salt in the diet increases blood pressure (BP) and leads to salt-sensitive hypertension in individuals with impaired renal sodium excretion. Small guanosine triphosphatase (GTP)ase Rho and Rac, activated by salt intake, play important roles in the pathogenesis of salt-sensitive hypertension as key switches of intracellular signaling. Focusing on Rho, high salt intake in the central nervous system increases sodium concentrations of cerebrospinal fluid in salt-sensitive subjects via Rho/Rho kinase and renin-angiotensin system activation and causes increased brain salt sensitivity and sympathetic nerve outflow in BP control centers. In vascular smooth muscle cells, Rho-guanine nucleotide exchange factors and Rho determine sensitivity to vasoconstrictors such as angiotensin II (Ang II), and facilitate vasoconstriction via G-protein and Wnt pathways, leading to increased vascular resistance, including in the renal arteries, in salt-sensitive subjects with high salt intake. In the vascular endothelium, Rho/Rho kinase inhibits nitric oxide (NO) production and function, and high salt amounts further augment Rho activity via asymmetric dimethylarginine, an endogenous inhibitor of NO synthetase, causing aberrant relaxation and increased vascular tone. Rho-associated mechanisms are deeply involved in the development of salt-sensitive hypertension, and their further elucidation can help in developing effective protection and new therapies.
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Gao H, Bigalke J, Jiang E, Fan Y, Chen B, Chen QH, Shan Z. TNFα Triggers an Augmented Inflammatory Response in Brain Neurons from Dahl Salt-Sensitive Rats Compared with Normal Sprague Dawley Rats. Cell Mol Neurobiol 2021; 42:1787-1800. [PMID: 33625627 PMCID: PMC8382783 DOI: 10.1007/s10571-021-01056-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 02/04/2021] [Indexed: 12/23/2022]
Abstract
Tumor Necrosis Factor (TNF)-α is a proinflammatory cytokine (PIC) and has been implicated in a variety of illness including cardiovascular disease. The current study investigated the inflammatory response trigged by TNFα in both cultured brain neurons and the hypothalamic paraventricular nucleus (PVN), a key cardiovascular relevant brain area, of the Sprague Dawley (SD) rats. Our results demonstrated that TNFα treatment induces a dose- and time-dependent increase in mRNA expression of PICs including Interleukin (IL)-1β and Interleukin-6 (IL6); chemokines including C-C Motif Chemokine Ligand 5 (CCL5) and C-C Motif Chemokine Ligand 12 (CCL12), inducible nitric oxide synthase (iNOS), as well as transcription factor NF-kB in cultured brain neurons from neonatal SD rats. Consistent with this finding, immunostaining shows that TNFα treatment increases immunoreactivity of IL1β, CCL5, iNOS and stimulates activation or expression of NF-kB, in both cultured brain neurons and the PVN of adult SD rats. We further compared mRNA expression of the aforementioned genes in basal level as well as in response to TNFα challenge between SD rats and Dahl Salt-sensitive (Dahl-S) rats, an animal model of salt-sensitive hypertension. Dahl-S brain neurons presented higher baseline levels as well as greater response to TNFα challenge in mRNA expression of CCL5, iNOS and IL1β. Furthermore, central administration of TNFα caused significant higher response in CCL12 in the PVN of Dahl-S rats. The increased inflammatory response to TNFα in Dahl-S rats may be indicative of an underlying mechanism for enhanced pressor reactivity to salt intake in the Dahl-S rat model.
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Affiliation(s)
- Huanjia Gao
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA.,The Second Clinical College of Guangzhou, University of Chinese Medicine, Guangzhou, China
| | - Jeremy Bigalke
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA
| | - Enshe Jiang
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA.,Institute of Nursing and Health, Henan University, Henan, China.,Henan International Joint Laboratory of Nuclear Protein Regulation, Henan University, Henan, China
| | - Yuanyuan Fan
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA.,School of Life Sciences, Henan University, Henan, China
| | - Bojun Chen
- Department of Emergency, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Qing-Hui Chen
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA.,Health Research Institute, Michigan Technological University, Houghton, MI, 49931, USA
| | - Zhiying Shan
- Department of Kinesiology & Integrative Physiology, Michigan Technological University, Houghton, MI, 49931, USA. .,Health Research Institute, Michigan Technological University, Houghton, MI, 49931, USA.
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15
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Abstract
The development of high blood pressure is influenced by genetic and environmental factors, with high salt intake being a known environmental contributor. Humans display a spectrum of sodium-sensitivity, with some individuals displaying a significant blood pressure rise in response to increased sodium intake while others experience almost no change. These differences are, in part, attributable to genetic variation in pathways involved in sodium handling and excretion. ENaC (epithelial sodium channel) is one of the key transporters responsible for the reabsorption of sodium in the distal nephron. This channel has an important role in the regulation of extracellular fluid volume and consequently blood pressure. Herein, we review the role of ENaC in the development of salt-sensitive hypertension, and present mechanistic insights into the regulation of ENaC activity and how it may accelerate sodium-induced damage and dysfunction. We discuss the traditional role of ENaC in renal sodium reabsorption and review work addressing ENaC expression and function in the brain, vasculature, and immune cells, and how this has expanded the implications for its role in the initiation and progression of salt-sensitive hypertension.
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Affiliation(s)
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, and Department of Molecular Physiology and Biophysics Vanderbilt University, Nashville, TN (A.K.)
| | - Thomas R Kleyman
- From the Department of Medicine (S.M.M., T.R.K.), University of Pittsburgh, PA.,Department of Cell Biology (T.R.K.), University of Pittsburgh, PA.,Department of Pharmacology and Chemical Biology (T.R.K.), University of Pittsburgh, PA
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16
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Kim YB, Jung WW, Lee SW, Jin X, Kang HK, Hong EH, Min SS, Kim YS, Han HC, Colwell CS, Kim YI. Excessive maternal salt intake gives rise to vasopressin-dependent salt sensitivity of blood pressure in male offspring. J Mol Cell Cardiol 2021; 150:12-22. [PMID: 33011158 DOI: 10.1016/j.yjmcc.2020.09.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/28/2020] [Accepted: 09/26/2020] [Indexed: 01/11/2023]
Abstract
Salt sensitivity of blood pressure (SSBP) is a trait carrying strong prognostic implications for various cardiovascular diseases. To test the hypothesis that excessive maternal salt intake causes SSBP in offspring through a mechanism dependent upon arginine-vasopressin (AVP), we performed a series of experiments using offspring of the rat dams salt-loaded during pregnancy and lactation with 1.5% saline drink ("experimental offspring") and those with normal perinatal salt exposure ("control offspring"). Salt challenge, given at 7-8 weeks of age with either 2% saline drink (3 days) or 8% NaCl-containing chow (4 weeks), had little or no effect on systolic blood pressure (SBP) in female offspring, whereas the salt challenge significantly raised SBP in male offspring, with the magnitude of increase being greater in experimental, than control, rats. Furthermore, the salt challenge not only raised plasma AVP level more and caused greater depressor responses to V1a and V2 AVP receptor antagonists to occur in experimental, than control, males, but it also made GABA excitatory in a significant proportion of magnocellular AVP neurons of experimental males by depolarizing GABA equilibrium potential. The effect of the maternal salt loading on the salt challenge-elicited SBP response in male offspring was precluded by maternal conivaptan treatment (non-selective AVP receptor antagonist) during the salt-loading period, whereas it was mimicked by neonatal AVP treatment. These results suggest that the excessive maternal salt intake brings about SSBP in male offspring, both the programming and the expression of which depend on increased AVP secretion that may partly result from excitatory GABAergic action.
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Affiliation(s)
- Young-Beom Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Won Woo Jung
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Seung Won Lee
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Xiangyan Jin
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Hyung Kyung Kang
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Eun-Hwa Hong
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Sun Seek Min
- Department of Physiology and Biophysics, Eulji University School of Medicine, Daejeon 34824, Republic of Korea
| | - Yoon-Sik Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Hee Chul Han
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea
| | - Christopher S Colwell
- Department of Psychiatry and Biobehavioral Sciences, University of California School of Medicine, Los Angeles, CA, United States of America.
| | - Yang In Kim
- Department of Physiology and Neuroscience Research Institute, Korea University College of Medicine, Seoul 02841, Republic of Korea.
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de Souza JA, Becker LK, Batista MAC, de Assis Braga DC, Gomes PM, Alzamora AC, Vieira MAR, de Lima WG, Andrade MGC, de Lima Sanches B, Totou NL, de Assis Dias Martins Júnior F, de Oliveira LB, Antunes VR, Cardoso LM. Swimming training improves cardiovascular autonomic dysfunctions and prevents renal damage in rats fed a high-sodium diet from weaning. Exp Physiol 2020; 106:412-426. [PMID: 33347659 DOI: 10.1113/ep088892] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/03/2020] [Indexed: 01/03/2023]
Abstract
NEW FINDINGS What is the central question of this study? How does swimming exercise training impact hydro-electrolytic balance, renal function, sympathetic contribution to resting blood pressure and cerebrospinal fluid (CSF) [Na+ ] in rats fed a high-sodium diet from weaning? What is the main finding and its importance? An exercise-dependent reduction in blood pressure was associated with decreased CSF [Na+ ], sympathetically driven vasomotor tonus and renal fibrosis indicating that the anti-hypertensive effects of swimming training in rats fed a high-sodium diet might involve neurogenic mechanisms regulated by sodium levels in the CSF rather than changes in blood volume. ABSTRACT High sodium intake is an important factor associated with hypertension. High-sodium intake with exercise training can modify homeostatic hydro-electrolytic balance, but the effects of this association are mostly unknown. In this study, we sought to investigate the effects of swimming training (ST) on cerebrospinal fluid (CSF) Na+ concentration, sympathetic drive, blood pressure (BP) and renal function of rats fed a 0.9% Na+ (equivalent to 2% NaCl) diet with free access to water for 22 weeks after weaning. Male Wistar rats were assigned to two cohorts: (1) fed standard diet (SD) and (2) fed high-sodium (HS) diet. Each cohort was further divided into trained and sedentary groups. ST normalised BP levels of HS rats as well as the higher sympathetically related pressor activity assessed by pharmacological blockade of ganglionic transmission (hexamethonium). ST preserved the renal function and attenuated the glomerular shrinkage elicited by HS. No change in blood volume was found among the groups. CSF [Na+ ] levels were higher in sedentary HS rats but were reduced by ST. Our findings showed that ST effectively normalised BP of HS rats, independent of its effects on hydro-electrolytic balance, which might involve neurogenic mechanisms regulated by Na+ levels in the CSF as well as renal protection.
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Affiliation(s)
| | - Lenice Kappes Becker
- Physical Education School at the Federal University of Ouro Preto, Ouro Preto, MG, Brazil
| | | | | | - Paula Magalhães Gomes
- Deptartment of Physiology and Biophysics, ICB; University of São Paulo, São Paulo, SP, Brazil
| | - Andréia Carvalho Alzamora
- Department of Biological Sciences, ICEB at the Federal University of Ouro Preto, Ouro Preto, MG, Brazil
| | | | - Wanderson Geraldo de Lima
- Department of Biological Sciences, ICEB at the Federal University of Ouro Preto, Ouro Preto, MG, Brazil
| | | | - Bruno de Lima Sanches
- Department of Physiology and Biophysics, ICB; Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | - Nádia Lúcia Totou
- Department of Biological Sciences, ICEB at the Federal University of Ouro Preto, Ouro Preto, MG, Brazil
| | | | | | - Vagner Roberto Antunes
- Deptartment of Physiology and Biophysics, ICB; University of São Paulo, São Paulo, SP, Brazil
| | - Leonardo Máximo Cardoso
- Department of Biological Sciences, ICEB at the Federal University of Ouro Preto, Ouro Preto, MG, Brazil
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18
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Ito K. Review of the health benefits of habitual consumption of miso soup: focus on the effects on sympathetic nerve activity, blood pressure, and heart rate. Environ Health Prev Med 2020; 25:45. [PMID: 32867671 PMCID: PMC7461326 DOI: 10.1186/s12199-020-00883-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/17/2020] [Indexed: 02/07/2023] Open
Abstract
High salt intake increases blood pressure, and dietary salt intake has been clearly demonstrated to be associated with hypertension incidence. Japanese people consume higher amounts of salt than Westerners. It has been reported that miso soup was one of the major sources of daily salt intake in Japanese people. Adding salt is indispensable to make miso, and therefore, in some cases, refraining from miso soup is recommended to reduce dietary salt intake. However, recent studies using salt-sensitive hypertensive models have revealed that miso lessens the effects of salt on blood pressure. In other word, the intake of miso dose not increase the blood pressure compared to the equivalent intake of salt. In addition, many clinical observational studies have demonstrated the absence of a relationship between the frequency of miso soup intake and blood pressure levels or hypertension incidence. The mechanism of this phenomenon seen in the subjects with miso soup intake has not been fully elucidated yet. However, in basic studies, it was found that the ingredients of miso attenuate sympathetic nerve activity, resulting in lowered blood pressure and heart rate. Therefore, this review focused on the differences between the effects of miso intake and those of the equivalent salt intake on sympathetic nerve activity, blood pressure, and heart rate.
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Affiliation(s)
- Koji Ito
- Department of Clinical Laboratory, Japan Community Healthcare Organization, Kyushu Hospital, 1-8-1, Kishinoura, Yahatanishi-ku, Kitakyushu, 806-8501, Japan.
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19
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Morphometric, Hemodynamic, and Multi-Omics Analyses in Heart Failure Rats with Preserved Ejection Fraction. Int J Mol Sci 2020; 21:ijms21093362. [PMID: 32397533 PMCID: PMC7247709 DOI: 10.3390/ijms21093362] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/30/2022] Open
Abstract
(1) Background: There are no successive treatments for heart failure with preserved ejection fraction (HFpEF) because of complex interactions between environmental, histological, and genetic risk factors. The objective of the study is to investigate changes in cardiomyocytes and molecular networks associated with HFpEF. (2) Methods: Dahl salt-sensitive (DSS) rats developed HFpEF when fed with a high-salt (HS) diet for 7 weeks, which was confirmed by in vivo and ex vivo measurements. Shotgun proteomics, microarray, Western blot, and quantitative RT-PCR analyses were further carried out to investigate cellular and molecular mechanisms. (3) Results: Rats with HFpEF showed diastolic dysfunction, impaired systolic function, and prolonged repolarization of myocytes, owing to an increase in cell size and apoptosis of myocytes. Heatmap of multi-omics further showed significant differences between rats with HFpEF and controls. Gene Set Enrichment Analysis (GSEA) of multi-omics revealed genetic risk factors involved in cardiac muscle contraction, proteasome, B cell receptor signaling, and p53 signaling pathway. Gene Ontology (GO) analysis of multi-omics showed the inflammatory response and mitochondrial fission as top biological processes that may deteriorate myocyte stiffening. GO analysis of protein-to-protein network indicated cytoskeleton protein, cell fraction, enzyme binding, and ATP binding as the top enriched molecular functions. Western blot validated upregulated Mff and Itga9 and downregulated Map1lc3a in the HS group, which likely contributed to accumulation of aberrant mitochondria to increase ROS and elevation of myocyte stiffness, and subsequent contractile dysfunction and myocardial apoptosis. (4) Conclusions: Multi-omics analysis revealed multiple pathways associated with HFpEF. This study shows insight into molecular mechanisms for the development of HFpEF and may provide potential targets for the treatment of HFpEF.
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20
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DeLalio LJ, Hahn S, Katayama PL, Wenner MM, Farquhar WB, Straub AC, Stocker SD. Excessive dietary salt promotes aortic stiffness in murine renovascular hypertension. Am J Physiol Heart Circ Physiol 2020; 318:H1346-H1355. [PMID: 32302491 PMCID: PMC7346535 DOI: 10.1152/ajpheart.00601.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 03/18/2020] [Accepted: 04/12/2020] [Indexed: 12/22/2022]
Abstract
Renovascular hypertension is characterized by activation of the renin-angiotensin-aldosterone system, blunted natriuretic responses, and elevated sympathetic nerve activity. Excess dietary salt intake exaggerates arterial blood pressure (ABP) in multiple models of experimental hypertension. The present study tested whether a high-salt diet exaggerated ABP and vascular dysfunction in a 2-kidney, 1-clip (2K1C) murine model. Male C57BL/6J mice (8-12 wk) were randomly assigned, and fed a 0.1% or 4.0% NaCl diet, and instrumented with telemetry units to measure ABP. Then, the 2K1C model was produced by placing a cuff around the right renal artery. Systolic, diastolic, and mean ABP were significantly higher in mice fed 4.0% vs. 0.1% NaCl at 1 wk but not after 3 wk. Interestingly, 2K1C hypertension progressively increased arterial pulse pressure in both groups; however, the magnitude was significantly greater in mice fed 4.0% vs. 0.1% NaCl at 3 wk. Moreover, pulse wave velocity was significantly greater in 2K1C mice fed 4.0% vs. 0.1% NaCl diet or sham-operated mice fed either diet. Histological assessment of aortas indicated no structural differences among groups. Finally, endothelium-dependent vasodilation was significantly and selectively attenuated in the aorta but not mesenteric arteries of 2K1C mice fed 4.0% NaCl vs. 0.1% NaCl or sham-operated control mice. The findings suggest that dietary salt loading transiently exaggerates 2K1C renovascular hypertension but promotes chronic aortic stiffness and selective aortic vascular dysfunction.NEW & NOTEWORTHY High dietary salt exaggerates hypertension in multiple experimental models. Here we demonstrate that a high-salt diet produces a greater increase in arterial blood pressure at 1 wk after induction of 2-kidney, 1-clip (2K1C) hypertension but not at 3 wk. Interestingly, 2K1C mice fed a high-salt diet displayed an exaggerated pulse pressure, elevated pulse wave velocity, and reduced endothelium-dependent vasodilation of the aorta but not mesenteric arteries. These findings suggest that dietary salt may interact with underlying cardiovascular disease to promote selective vascular dysfunction and aortic stiffness.
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Affiliation(s)
- Leon J DeLalio
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Scott Hahn
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Pedro L Katayama
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Adam C Straub
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania
- Pittsburgh Heart, Lung, Blood, and Vascular Medicine Institute, Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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21
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Ghaffari H, Grant SC, Petzold LR, Harrington MG. Regulation of CSF and Brain Tissue Sodium Levels by the Blood-CSF and Blood-Brain Barriers During Migraine. Front Comput Neurosci 2020; 14:4. [PMID: 32116618 PMCID: PMC7010722 DOI: 10.3389/fncom.2020.00004] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 01/10/2020] [Indexed: 11/13/2022] Open
Abstract
Cerebrospinal fluid (CSF) and brain tissue sodium levels increase during migraine. However, little is known regarding the underlying mechanisms of sodium homeostasis disturbance in the brain during the onset and propagation of migraine. Exploring the cause of sodium dysregulation in the brain is important, since correction of the altered sodium homeostasis could potentially treat migraine. Under the hypothesis that disturbances in sodium transport mechanisms at the blood-CSF barrier (BCSFB) and/or the blood-brain barrier (BBB) are the underlying cause of the elevated CSF and brain tissue sodium levels during migraines, we developed a mechanistic, differential equation model of a rat's brain to compare the significance of the BCSFB and the BBB in controlling CSF and brain tissue sodium levels. The model includes the ventricular system, subarachnoid space, brain tissue and blood. Sodium transport from blood to CSF across the BCSFB, and from blood to brain tissue across the BBB were modeled by influx permeability coefficients PBCSFB and PBBB, respectively, while sodium movement from CSF into blood across the BCSFB, and from brain tissue to blood across the BBB were modeled by efflux permeability coefficients PBCSFB′ and PBBB′, respectively. We then performed a global sensitivity analysis to investigate the sensitivity of the ventricular CSF, subarachnoid CSF and brain tissue sodium concentrations to pathophysiological variations in PBCSFB, PBBB, PBCSFB′ and PBBB′. Our results show that the ventricular CSF sodium concentration is highly influenced by perturbations of PBCSFB, and to a much lesser extent by perturbations of PBCSFB′. Brain tissue and subarachnoid CSF sodium concentrations are more sensitive to pathophysiological variations of PBBB and PBBB′ than variations of PBCSFB and PBCSFB′ within 30 min of the onset of the perturbations. However, PBCSFB is the most sensitive model parameter, followed by PBBB and PBBB′, in controlling brain tissue and subarachnoid CSF sodium levels within 3 h of the perturbation onset.
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Affiliation(s)
- Hamed Ghaffari
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Samuel C Grant
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
| | - Linda R Petzold
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Michael G Harrington
- Neuroscience, Huntington Medical Research Institutes, Pasadena, CA, United States
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22
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Souza LAC, Trebak F, Kumar V, Satou R, Kehoe PG, Yang W, Wharton W, Feng Earley Y. Elevated cerebrospinal fluid sodium in hypertensive human subjects with a family history of Alzheimer's disease. Physiol Genomics 2020; 52:133-142. [PMID: 31961762 DOI: 10.1152/physiolgenomics.00093.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
High salt (sodium) intake leads to the development of hypertension despite the fact that plasma sodium concentration ([Na+]) is usually normal in hypertensive human patients. Increased cerebrospinal fluid (CSF) sodium contributes to elevated sympathetic activity and high blood pressure (BP) in rodent models of hypertension. However, whether there is an increased accumulation of sodium in the CSF of humans with chronic hypertension is not well defined. Here, we investigated CSF [Na+] from hypertensive and normotensive human subjects with family histories of Alzheimer's disease in samples collected in a clinical trial, as spinal tap is not a routine clinical procedure for hypertensive patients. The [Na+] and osmolality in plasma and CSF were measured by flame photometry. Daytime ambulatory BP was monitored while individuals were awake. Participants were deidentified and data were analyzed in conjunction with a retrospective analysis of patient history and diagnosis. We found that CSF [Na+] was significantly higher in participants with high BP compared with normotensive participants; there was no difference in plasma [Na+], or plasma and CSF osmolality between groups. Subsequent multiple linear regression analyses controlling for age, sex, race, and body mass index revealed a significant positive correlation between CSF [Na+] and BP but showed no correlation between plasma [Na+] and BP. In sum, CSF [Na+] was higher in chronic hypertensive individuals and may play a key role in the pathogenesis of human hypertension. Collectively, our findings provide evidence for the clinical significance of CSF [Na+] in chronic hypertension in humans.
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Affiliation(s)
- Lucas A C Souza
- Departments of Pharmacology and Physiology & Cell Biology, University of Nevada, Reno, School of Medicine, Reno, Nevada.,Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno, Reno, Nevada
| | - Fatima Trebak
- Departments of Pharmacology and Physiology & Cell Biology, University of Nevada, Reno, School of Medicine, Reno, Nevada.,Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno, Reno, Nevada
| | - Veena Kumar
- Department of Neurology, Emory University School of Nursing, Atlanta, Georgia
| | - Ryousuke Satou
- Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Patrick G Kehoe
- Institute of Clinical Neurosciences, University of Bristol, Bristol, United Kingdom
| | - Wei Yang
- University of Nevada, Reno, School of Community Health Sciences, Reno, Nevada
| | - Whitney Wharton
- Department of Neurology, Emory University School of Nursing, Atlanta, Georgia
| | - Yumei Feng Earley
- Departments of Pharmacology and Physiology & Cell Biology, University of Nevada, Reno, School of Medicine, Reno, Nevada.,Center for Molecular and Cellular Signaling in the Cardiovascular System, University of Nevada, Reno, Reno, Nevada
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23
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Li Q, Fung E. Multifaceted Functions of Epithelial Na + Channel in Modulating Blood Pressure. Hypertension 2019; 73:273-281. [PMID: 30580685 DOI: 10.1161/hypertensionaha.118.12330] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Qi Li
- From the Division of Cardiology, Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Q.L., E.F.).,Laboratory for Heart Failure and Circulation Research, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Hong Kong SAR (Q.L., E.F.)
| | - Erik Fung
- From the Division of Cardiology, Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Q.L., E.F.).,Gerald Choa Cardiac Research Centre, Faculty of Medicine, The Chinese University of Hong Kong (E.F.).,Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong (E.F.).,Laboratory for Heart Failure and Circulation Research, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Hong Kong SAR (Q.L., E.F.)
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24
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Yoshimoto M, Onishi Y, Mineyama N, Ikegame S, Shirai M, Osborn JW, Miki K. Renal and Lumbar Sympathetic Nerve Activity During Development of Hypertension in Dahl Salt-Sensitive Rats. Hypertension 2019; 74:888-895. [DOI: 10.1161/hypertensionaha.119.12866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study the contribution of sympathetic nerve activity (SNA) to the development of hypertension, experiments were designed to continuously and simultaneously measure renal (RSNA) and lumbar SNA (LSNA) during the development of hypertension induced by 8% salt loading in Dahl salt-sensitive (DS) rats. Male DS and salt-resistant rats were instrumented with bipolar electrodes to record RSNA and LSNA and a telemeter to record arterial pressure (AP). AP increased during the first 3 days after the onset of salt loading by ≈10 mm Hg in both DS and Dahl salt-resistant rats. AP continued to increase progressively from day 4 to day 14 of salt loading by 33±1 mm Hg in DS rats, while it remained the same in Dahl salt-resistant rats. RSNA and LSNA increased in the initial few days by 6% to 8%, and decreased gradually thereafter, suggesting that increases in neither RSNA nor LSNA are directly linked with the progressive increase in AP induced by salt loading in DS rats. After the cessation of salt loading, AP pressure returned to the presalt loading level in both DS and Dahl salt-resistant rats. RSNA increased significantly by 32±3% after the cessation of salt loading, while LSNA remained the same in DS rats, suggesting that salt-sensitive mechanisms respond to a loss of sodium, not a gain, and selectively activate RSNA in DS rats. In summary, RSNA and LSNA are not likely to be a primary trigger to initiate the progressive increase in AP induced by 8% salt loading in DS rats.
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Affiliation(s)
- Misa Yoshimoto
- From the Department of Environmental Health, Life Science and Human Technology, Nara Women’s University, Kita-Uoya Nishimachi (M.Y., Y.O., N.M., S.I., K.M.)
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan (M.Y., M.S.)
| | - Yuko Onishi
- From the Department of Environmental Health, Life Science and Human Technology, Nara Women’s University, Kita-Uoya Nishimachi (M.Y., Y.O., N.M., S.I., K.M.)
| | - Naoko Mineyama
- From the Department of Environmental Health, Life Science and Human Technology, Nara Women’s University, Kita-Uoya Nishimachi (M.Y., Y.O., N.M., S.I., K.M.)
| | - Shizuka Ikegame
- From the Department of Environmental Health, Life Science and Human Technology, Nara Women’s University, Kita-Uoya Nishimachi (M.Y., Y.O., N.M., S.I., K.M.)
| | - Mikiyasu Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan (M.Y., M.S.)
| | - John W. Osborn
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis (J.W.O.)
| | - Kenju Miki
- From the Department of Environmental Health, Life Science and Human Technology, Nara Women’s University, Kita-Uoya Nishimachi (M.Y., Y.O., N.M., S.I., K.M.)
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Żera T, Nowiński A, Segiet A, Smykiewicz P. Microglia and brain angiotensin type 1 receptors are involved in desensitising baroreflex by intracerebroventricular hypertonic saline in male Sprague-Dawley rats. Auton Neurosci 2019; 217:49-57. [PMID: 30704975 DOI: 10.1016/j.autneu.2019.01.002] [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: 09/06/2018] [Revised: 01/04/2019] [Accepted: 01/04/2019] [Indexed: 12/09/2022]
Abstract
High salt diet alters cardiovascular control by increasing concentration of sodium ions (Na+) in cerebrospinal fluid (CSF) and is a risk factor for hypertension. Hypernatremic conditions activate microglia and upregulate renin-angiotensin system in the brain. Thus, we checked if chronic elevation of CSF Na+ affects neural control of circulatory system via microglia and brain angiotensin type 1 receptors (AT1Rs). Normotensive adult male Sprague-Dawley rats received two-week intracerebroventricular (ICV) infusion of either isoosmotic saline (0.9% NaCl); hyperosmotic saline (5% NaCl); 5% NaCl with minocycline - inhibitor of microglia; 5% NaCl with losartan - AT1R blocker. Fluid intake, urine output, and urinary Na+ excretion were measured before and during ICV infusions. At the end of ICV infusions, blood pressure and heart rate were recorded in awake rats at rest, in response to acute air jet stressor, during pharmacological evaluation of baroreflex, and after autonomic ganglia blockade. CSF and blood were collected for evaluation of Na+ concentration. Baroreflex was blunted in rats ICV infused with 5% NaCl. ICV treatment with losartan or minocycline prevented decrease in baroreflex sensitivity. Hemodynamic parameters at rest, in response to acute stressor and autonomic ganglia blockade were similar in all groups. Neither treatment affected water intake, urine output and urinary Na+ excretion. ICV infusion of 5% NaCl resulted in higher concentration of Na+ in CSF than in control group (0.9% NaCl) and in plasma. Our results indicate that chronic ICV infusion of hyperosmotic saline blunts baroreflex in normotensive rats and this desensitization is mediated by microglia and AT1Rs.
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Affiliation(s)
- Tymoteusz Żera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, the Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland.
| | - Artur Nowiński
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, the Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland
| | - Agnieszka Segiet
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, the Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland
| | - Paweł Smykiewicz
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, the Medical University of Warsaw, Banacha 1B, 02-097 Warsaw, Poland
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Nomura K, Hiyama TY, Sakuta H, Matsuda T, Lin CH, Kobayashi K, Kobayashi K, Kuwaki T, Takahashi K, Matsui S, Noda M. [Na +] Increases in Body Fluids Sensed by Central Na x Induce Sympathetically Mediated Blood Pressure Elevations via H +-Dependent Activation of ASIC1a. Neuron 2018; 101:60-75.e6. [PMID: 30503172 DOI: 10.1016/j.neuron.2018.11.017] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 10/08/2018] [Accepted: 11/08/2018] [Indexed: 02/07/2023]
Abstract
Increases in sodium concentrations ([Na+]) in body fluids elevate blood pressure (BP) by enhancing sympathetic nerve activity (SNA). However, the mechanisms by which information on increased [Na+] is translated to SNA have not yet been elucidated. We herein reveal that sympathetic activation leading to BP increases is not induced by mandatory high salt intakes or the intraperitoneal/intracerebroventricular infusions of hypertonic NaCl solutions in Nax-knockout mice in contrast to wild-type mice. We identify Nax channels expressed in specific glial cells in the organum vasculosum lamina terminalis (OVLT) as the sensors detecting increases in [Na+] in body fluids and show that OVLT neurons projecting to the paraventricular nucleus (PVN) are activated via acid-sensing ion channel 1a (ASIC1a) by H+ ions exported from Nax-positive glial cells. The present results provide an insight into the neurogenic mechanisms responsible for salt-induced BP elevations.
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Affiliation(s)
- Kengo Nomura
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
| | - Takeshi Y Hiyama
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Hiraki Sakuta
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan
| | - Takashi Matsuda
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
| | - Chia-Hao Lin
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan
| | - Kenta Kobayashi
- Section of Viral Vector Development, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan
| | - Kazuto Kobayashi
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
| | - Kunihiko Takahashi
- Department of Biostatistics, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
| | - Shigeyuki Matsui
- Department of Biostatistics, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
| | - Masaharu Noda
- Division of Molecular Neurobiology, National Institute for Basic Biology, Okazaki, Aichi 444-8787, Japan; School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan; Research Center for Cell Biology, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan.
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Mills NJ, Sharma K, Haque M, Moore M, Teruyama R. Aldosterone Mediated Regulation of Epithelial Sodium Channel (ENaC) Subunits in the Rat Hypothalamus. Neuroscience 2018; 390:278-292. [PMID: 30195057 DOI: 10.1016/j.neuroscience.2018.08.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 08/10/2018] [Accepted: 08/28/2018] [Indexed: 01/23/2023]
Abstract
Current evidence suggests that the epithelial Na+ channel (ENaC) in the brain plays a significant role in the development of hypertension. ENaC is present in vasopressin (VP) neurons in the hypothalamus, suggesting that ENaC in VP neurons is involved in the regulation of blood pressure. Our recent study demonstrated that high dietary salt intake caused an increase in the expression and activity of ENaC that were responsible for the more depolarized basal membrane potential in VP neurons. A known regulator of ENaC expression, the mineralocorticoid receptor (MR), is present in VP neurons, suggesting that ENaC expression in VP neurons is regulated by aldosterone. In this study, the effects of aldosterone and corticosterone on ENaC were examined in acute hypothalamic slices. Real-time PCR and Western blot analysis showed that aldosterone and corticosterone treatment resulted in a significant increase in the expression of γENaC, but not α- or βENaC, and that this expression was attenuated by MR and glucocorticoid receptor (GR) antagonists. Moreover, chromatin immunoprecipitation demonstrated that the aldosterone-MR complex directly interacts with the promoter region of the γENaC gene. However, the treatment with aldosterone did not cause subcellular translocation of ENaC toward the plasma membrane nor an increase in ENaC Na+-leak current. These results indicate that expression of γENaC in VP neurons is induced by aldosterone and corticosterone through their MR and GR, respectively; however, aldosterone or corticosterone alone is not sufficient enough to increase ENaC current when they are applied to hypothalamic slices in vitro.
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Affiliation(s)
- Natalie J Mills
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Kaustubh Sharma
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Masudul Haque
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Meagan Moore
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Ryoichi Teruyama
- Department of Biological Sciences, Louisiana State University, LA 70803, USA.
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Jiang E, Chapp AD, Fan Y, Larson RA, Hahka T, Huber MJ, Yan J, Chen QH, Shan Z. Expression of Proinflammatory Cytokines Is Upregulated in the Hypothalamic Paraventricular Nucleus of Dahl Salt-Sensitive Hypertensive Rats. Front Physiol 2018. [PMID: 29520237 PMCID: PMC5826963 DOI: 10.3389/fphys.2018.00104] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Accumulating evidence indicates that inflammation is implicated in hypertension. However, the role of brain proinflammatory cytokines (PICs) in salt sensitive hypertension remains to be determined. Thus, the objective of this study was to test the hypothesis that high salt (HS) diet increases PICs expression in the paraventricular nucleus (PVN) and leads to PVN neuronal activation. Eight-week-old male Dahl salt sensitive (Dahl S) rats, and age and sex matched normal Sprague Dawley (SD) rats were divided into two groups and fed with either a HS (4% NaCl) or normal salt (NS, 0.4% NaCl) diet for 5 consecutive weeks. HS diet induced hypertension and significantly increased cerebrospinal fluid (CSF) sodium concentration ([Na+]) in Dahl S rats, but not in normal SD rats. In addition, HS diet intake triggered increases in mRNA levels and immunoreactivities of PVN PICs including TNF-α, IL-6, and IL-1β, as well as Fra1, a chronic marker of neuronal activation, in Dahl S rats, but not in SD rats. Next, we investigated whether this increase in the expression of PVN PICs and Fra1 was induced by increased CSF [Na+]. Adult male SD rats were intracerebroventricular (ICV) infused with 8 μl of either hypertonic salt (4 μmol NaCl), mannitol (8 μmol, as osmolarity control), or isotonic salt (0.9% NaCl as vehicle control). Three hours following the ICV infusion, rats were euthanized and their PVN PICs expression was measured. The results showed that central administration of hypertonic saline in SD rats significantly increased the expression of PICs including TNF-α, IL-6, and IL-1β, as well as neuronal activation marker Fra1, compared to isotonic NaCl controls and osmolarity controls. Finally, we tested whether the increase in PICs expression occurred in neurons. Incubation of hypothalamic neurons with 10 mM NaCl in a culture medium for 6 h elicited significant increases in TNF-α, IL-6, and Fra1 mRNA levels. These observations, coupled with the important role of PICs in modulating neuronal activity and stimulating vasopressin release, suggest that HS intake induces an inflammatory state in the PVN, which, may in turn, augments sympathetic nerve activity and vasopressin secretion, contributing to the development of salt sensitive hypertension.
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Affiliation(s)
- Enshe Jiang
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States.,Institute for Nursing and Health Research, Henan University, Kaifeng, China
| | - Andrew D Chapp
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
| | - Yuanyuan Fan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States.,Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Robert A Larson
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
| | - Taija Hahka
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
| | - Michael J Huber
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
| | - Jianqun Yan
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, MI, United States
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Padmanabhan S, Joe B. Towards Precision Medicine for Hypertension: A Review of Genomic, Epigenomic, and Microbiomic Effects on Blood Pressure in Experimental Rat Models and Humans. Physiol Rev 2017; 97:1469-1528. [PMID: 28931564 PMCID: PMC6347103 DOI: 10.1152/physrev.00035.2016] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 12/11/2022] Open
Abstract
Compelling evidence for the inherited nature of essential hypertension has led to extensive research in rats and humans. Rats have served as the primary model for research on the genetics of hypertension resulting in identification of genomic regions that are causally associated with hypertension. In more recent times, genome-wide studies in humans have also begun to improve our understanding of the inheritance of polygenic forms of hypertension. Based on the chronological progression of research into the genetics of hypertension as the "structural backbone," this review catalogs and discusses the rat and human genetic elements mapped and implicated in blood pressure regulation. Furthermore, the knowledge gained from these genetic studies that provide evidence to suggest that much of the genetic influence on hypertension residing within noncoding elements of our DNA and operating through pervasive epistasis or gene-gene interactions is highlighted. Lastly, perspectives on current thinking that the more complex "triad" of the genome, epigenome, and the microbiome operating to influence the inheritance of hypertension, is documented. Overall, the collective knowledge gained from rats and humans is disappointing in the sense that major hypertension-causing genes as targets for clinical management of essential hypertension may not be a clinical reality. On the other hand, the realization that the polygenic nature of hypertension prevents any single locus from being a relevant clinical target for all humans directs future studies on the genetics of hypertension towards an individualized genomic approach.
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Affiliation(s)
- Sandosh Padmanabhan
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Bina Joe
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom; and Center for Hypertension and Personalized Medicine; Department of Physiology and Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
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30
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Chronic high-sodium diet intake after weaning lead to neurogenic hypertension in adult Wistar rats. Sci Rep 2017; 7:5655. [PMID: 28720883 PMCID: PMC5515999 DOI: 10.1038/s41598-017-05984-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
In this study, we investigated some mechanisms involved in sodium-dependent hypertension of rats exposed to chronic salt (NaCl) intake from weaning until adult age. Weaned male Wistar rats were placed under high (0.90% w/w, HS) or regular (0.27% w/w, Cont) sodium diets for 12 weeks. Water consumption, urine output and sodium excretion were higher in HS rats compared to control. Blood pressure (BP) was directly measured by the arterial catheter and found 13.8% higher in HS vs Cont rats. Ganglionic blockade with hexamethonium caused greater fall in the BP of HS rats (33%), and central antagonism of AT1 receptors (losartan) microinjected into the lateral ventricle reduced BP level of HS, but not of Cont group. Heart rate variability analysis revealed sympathetic prevalence on modulation of the systolic interval. HS diet did not affect creatinine clearance. Kidney histological analysis revealed no significant change in renal corpuscle structure. Sodium and potassium concentrations in CSF were found higher in HS rats despite no change in plasma concentration of these ions. Taken together, data suggest that animals exposed to chronic salt intake to a level close to that reported for human' diet since weaning lead to hypertension, which appears to rely on sodium-driven neurogenic mechanisms.
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31
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Huber MJ, Fan Y, Jiang E, Zhu F, Larson RA, Yan J, Li N, Chen QH, Shan Z. Increased activity of the orexin system in the paraventricular nucleus contributes to salt-sensitive hypertension. Am J Physiol Heart Circ Physiol 2017; 313:H1075-H1086. [PMID: 28667055 DOI: 10.1152/ajpheart.00822.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 05/08/2017] [Accepted: 06/22/2017] [Indexed: 01/29/2023]
Abstract
The orexin system is involved in arginine vasopressin (AVP) regulation, and its overactivation has been implicated in hypertension. However, its role in salt-sensitive hypertension (SSHTN) is unknown. Here, we tested the hypothesis that hyperactivity of the orexin system in the paraventricular nucleus (PVN) contributes to SSHTN via enhancing AVP signaling. Eight-week-old male Dahl salt-sensitive (Dahl S) and age- and sex-matched Sprague-Dawley (SD) rats were placed on a high-salt (HS; 8% NaCl) or normal-salt (NS; 0.4% NaCl) diet for 4 wk. HS intake did not alter mean arterial pressure (MAP), PVN mRNA levels of orexin receptor 1 (OX1R), or OX2R but slightly increased PVN AVP mRNA expression in SD rats. HS diet induced significant increases in MAP and PVN mRNA levels of OX1R, OX2R, and AVP in Dahl S rats. Intracerebroventricular infusion of orexin A (0.2 nmol) dramatically increased AVP mRNA levels and immunoreactivity in the PVN of SD rats. Incubation of cultured hypothalamus neurons from newborn SD rats with orexin A increased AVP mRNA expression, which was attenuated by OX1R blockade. In addition, increased cerebrospinal fluid Na+ concentration through intracerebroventricular infusion of NaCl solution (4 µmol) increased PVN OX1R and AVP mRNA levels and immunoreactivity in SD rats. Furthermore, bilateral PVN microinjection of the OX1R antagonist SB-408124 resulted in a greater reduction in MAP in HS intake (-16 ± 5 mmHg) compared with NS-fed (-4 ± 4 mmHg) anesthetized Dahl S rats. These results suggest that elevated PVN OX1R activation may contribute to SSHTN by enhancing AVP signaling.NEW & NOTEWORTHY To our best knowledge, this study is the first to investigate the involvement of the orexin system in salt-sensitive hypertension. Our results suggest that the orexin system may contribute to the Dahl model of salt-sensitive hypertension by enhancing vasopressin signaling in the hypothalamic paraventricular nucleus.
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Affiliation(s)
- Michael J Huber
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Yuanyuan Fan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan.,Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
| | - Enshe Jiang
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan.,Institute for Nursing and Health Research, Henan University, Kaifeng, China
| | - Fengli Zhu
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Robert A Larson
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan
| | - Jianqun Yan
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi, China
| | - Ningjun Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia; and
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan.,Biotech Research Center, Michigan Technological University, Houghton, Michigan
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, Houghton, Michigan; .,Biotech Research Center, Michigan Technological University, Houghton, Michigan
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Larson RA, Chapp AD, Gui L, Huber MJ, Cheng ZJ, Shan Z, Chen QH. High Salt Intake Augments Excitability of PVN Neurons in Rats: Role of the Endoplasmic Reticulum Ca 2+ Store. Front Neurosci 2017; 11:182. [PMID: 28428739 PMCID: PMC5382644 DOI: 10.3389/fnins.2017.00182] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 03/20/2017] [Indexed: 11/17/2022] Open
Abstract
High salt (HS) intake sensitizes central autonomic circuitry leading to sympathoexcitation. However, its underlying mechanisms are not fully understood. We hypothesized that inhibition of PVN endoplasmic reticulum (ER) Ca2+ store function would augment PVN neuronal excitability and sympathetic nerve activity (SNA). We further hypothesized that a 2% (NaCl) HS diet for 5 weeks would reduce ER Ca2+ store function and increase excitability of PVN neurons with axon projections to the rostral ventrolateral medulla (PVN-RVLM) identified by retrograde label. PVN microinjection of the ER Ca2+ ATPase inhibitor thapsigargin (TG) increased SNA and mean arterial pressure (MAP) in a dose-dependent manner in rats with a normal salt (NS) diet (0.4%NaCl). In contrast, sympathoexcitatory responses to PVN TG were significantly (p < 0.05) blunted in HS treated rats compared to NS treatment. In whole cell current-clamp recordings from PVN-RVLM neurons, graded current injections evoked graded increases in spike frequency. Maximum discharge was significantly augmented (p < 0.05) by HS diet compared to NS group. Bath application of TG (0.5 μM) increased excitability of PVN-RVLM neurons in NS (p < 0.05), yet had no significant effect in HS rats. Our data indicate that HS intake augments excitability of PVN-RVLM neurons. Inhibition of the ER Ca2+-ATPase and depletion of Ca2+ store likely plays a role in increasing PVN neuronal excitability, which may underlie the mechanisms of sympathoexcitation in rats with chronic HS intake.
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Affiliation(s)
- Robert A. Larson
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
| | - Andrew D. Chapp
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
| | - Le Gui
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
- Department of Cardiology, Affiliated Hospital of Nantong UniversityNantong, China
| | - Michael J. Huber
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
| | - Zixi Jack Cheng
- Biomolecular Science Center, Burnett School of Biomedical Sciences, College of Medicine, University of Central FloridaOrlando, FL, USA
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological UniversityHoughton, MI, USA
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Huber MJ, Chen QH, Shan Z. The Orexin System and Hypertension. Cell Mol Neurobiol 2017; 38:385-391. [PMID: 28349223 DOI: 10.1007/s10571-017-0487-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/18/2017] [Indexed: 12/18/2022]
Abstract
In this review, we focus on the role of orexin signaling in blood pressure control and its potential link to hypertension by summarizing evidence from several experimental animal models of hypertension. Studies using the spontaneously hypertensive rat (SHR) animal model of human essential hypertension show that pharmacological blockade of orexin receptors reduces blood pressure in SHRs but not in Wistar-Kyoto rats. In addition, increased activity of the orexin system contributes to elevated blood pressure and sympathetic nerve activity (SNA) in dark-active period Schlager hypertensive (BPH/2J) mice, another genetic model of neurogenic hypertension. Similar to these two models, Sprague-Dawley rats with stress-induced hypertension display an overactive central orexin system. Furthermore, upregulation of the orexin receptor 1 increases firing of hypothalamic paraventricular nucleus neurons, augments SNA, and contributes to hypertension in the obese Zucker rat, an animal model of obesity-related hypertension. Finally, we propose a hypothesis for the implication of the orexin system in salt-sensitive hypertension. All of this evidence, coupled with the important role of elevated SNA in increasing blood pressure, strongly suggests that hyperactivity of the orexin system contributes to hypertension.
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Affiliation(s)
- Michael J Huber
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA
| | - Qing-Hui Chen
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA
| | - Zhiying Shan
- Department of Kinesiology and Integrative Physiology, Michigan Technological University, SDC 231, 1400 Townsend Drive, Houghton, MI, 49931, USA.
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Huang YP, Jin HY, Yu HP. Inhibitory effects of alpha-lipoic acid on oxidative stress in the rostral ventrolateral medulla in rats with salt-induced hypertension. Int J Mol Med 2016; 39:430-436. [PMID: 28035366 DOI: 10.3892/ijmm.2016.2846] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 12/21/2016] [Indexed: 11/06/2022] Open
Abstract
Oxidative stress in the rostral ventrolateral medulla (RVLM) plays an important role in the pathophysiology of hypertension. Alpha‑lipoic acid (ALA) is widely recognized for its potent superoxide inhibitory properties, and it can safely penetrate deep into the brain. The aim of this study was to explore whether ALA supplementation attenuates hypertensive responses and cardiac hypertrophy by decreasing the NAD(P)H oxidase (NOX)-derived overproduction of reactive oxygen species (ROS) in the mitochondria in the RVLM, and thus attenuating the development of salt‑induced hypertension. For this purpose, male Wistar rats were randomly divided into 2 groups and either fed a high-salt diet or not. After 8 weeks, the rats were either administered ALA or an equal volume of the vehicle for 8 weeks. The rats fed a high‑salt diet exhibited higher mean arterial pressure (MAP) and higher plasma noradrenaline (NE) levels, as well as cardiac hypertrophy, as evidence by the increased whole heart weight/body weight (WHW/BW) ratio, WHW/tibia length (TL) ratio and left‑ventricular weight (LVW)/TL ratio. Compared with the rats in the NS group, the rats in the HS group only exhibited increased levels of superoxide, NOX2, NOX4 and mitochondrial malondialdehyde (MDA), but also decreased levels of copper/zinc (Cu/Zn)-superoxide dismutase (SOD), mitochondrial SOD and glutathione (GSH) in the RVLM. The supplementation of ALA decreased MAP, plasma NE levels and the levels of cardiac hypertrophy indicators. It also decreased the levels of superoxide, NOX2, NOX4 and mitochondrial MDA, and increased the levels of Cu/Zn‑SOD, mitochondrial SOD and GSH in the RVLM compared with the rats fed a high-salt diet and not treated with ALA. On the whole, our findings indicate that long‑term ALA supplementation attenuates hypertensive responses and cardiac hypertrophy by decreasing the expression of NAD(P)H subunits (NOX2 and NOX4), increasing the levels of mitochondrial bioenergetic enzymes, and enhancing the intracellular antioxidant capacity in the RVLM during the development of hypertension.
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Affiliation(s)
- Yu-Peng Huang
- Department of Cardiovascular Medicine, Hanyang Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Hong-Yan Jin
- Department of Cardiovascular Medicine, Hanyang Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
| | - Hui-Ping Yu
- Department of Cardiovascular Medicine, Hanyang Hospital of Wuhan, Wuhan, Hubei 430050, P.R. China
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Kinsman BJ, Simmonds SS, Browning KN, Stocker SD. Organum Vasculosum of the Lamina Terminalis Detects NaCl to Elevate Sympathetic Nerve Activity and Blood Pressure. Hypertension 2016; 69:163-170. [PMID: 27895193 DOI: 10.1161/hypertensionaha.116.08372] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/07/2016] [Accepted: 10/31/2016] [Indexed: 02/05/2023]
Abstract
High-salt diet elevates NaCl concentrations in the cerebrospinal fluid to increase sympathetic nerve activity (SNA) in salt-sensitive hypertension. The organum vasculosum of the lamina terminalis (OVLT) resides along the rostral wall of the third ventricle, lacks a complete blood-brain barrier, and plays a pivotal role in body fluid homeostasis. Therefore, the present study used a multifaceted approach to examine whether OVLT neurons of Sprague-Dawley rats are intrinsically sensitive to changes in extracellular NaCl concentrations and mediate the sympathoexcitatory responses to central NaCl loading. Using in vitro whole-cell recordings, step-wise increases in extracellular NaCl concentrations (2.5-10 mmol/L) produced concentration-dependent excitation of OVLT neurons. Additionally, these excitatory responses were intrinsic to OVLT neurons because hypertonic NaCl evoked inward currents, despite pharmacological synaptic blockade. In vivo single-unit recordings demonstrate that the majority of OVLT neurons (72%, 13/19) display concentration-dependent increases in neuronal discharge to intracarotid (50 μL/15 s) or intracerebroventricular infusion (5 μL/10 minutes) of hypertonic NaCl. Microinjection of hypertonic NaCl (30 nL/60 s) into the OVLT, but not adjacent areas, increased lumbar SNA, adrenal SNA, and arterial blood pressure in a concentration-dependent manner. Renal SNA decreased and splanchnic SNA remained unaffected. Finally, local inhibition of OVLT neurons with the GABAA receptor agonist muscimol (24 nL/10 s) significantly attenuated the sympathoexcitatory and pressor responses to intracerebroventricular infusion of 0.5 mol/L or 1.0 mol/L NaCl. Collectively, these findings indicate that OVLT neurons detect changes in extracellular NaCl concentrations to selectively alter SNA and raise arterial blood pressure.
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Affiliation(s)
- Brian J Kinsman
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Sarah S Simmonds
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Kirsteen N Browning
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.)
| | - Sean D Stocker
- From the Department of Medicine, Division of Renal-Electrolyte, University of Pittsburgh School of Medicine, PA (B.J.K., S.D.S.); and Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA (B.J.K., S.S.S., K.N.B.).
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Iatrino R, Manunta P, Zagato L. Salt Sensitivity: Challenging and Controversial Phenotype of Primary Hypertension. Curr Hypertens Rep 2016; 18:70. [DOI: 10.1007/s11906-016-0677-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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How Does Circadian Rhythm Impact Salt Sensitivity of Blood Pressure in Mice? A Study in Two Close C57Bl/6 Substrains. PLoS One 2016; 11:e0153472. [PMID: 27088730 PMCID: PMC4835052 DOI: 10.1371/journal.pone.0153472] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 03/30/2016] [Indexed: 12/29/2022] Open
Abstract
Background Mouse transgenesis has provided the unique opportunity to investigate mechanisms underlying sodium kidney reabsorption as well as end organ damage. However, understanding mouse background and the experimental conditions effects on phenotypic readouts of engineered mouse lines such as blood pressure presents a challenge. Despite the ability to generate high sodium and chloride plasma levels during high-salt diet, observed changes in blood pressure are not consistent between wild-type background strains and studies. Methods The present work was designed in an attempt to determine guidelines in the field of salt-induced hypertension by recording continuously blood pressure by telemetry in mice submitted to different sodium and potassium loaded diets and changing experimental conditions in both C57BL/6N and C57BL/6J mice strain (Normal salt vs. Low salt vs. High-salt/normal potassium vs. High salt/low potassium, standard vs. modified light cycle, Non-invasive tail cuff blood pressure vs. telemetry). Results In this study, we have shown that, despite a strong blood pressure (BP) basal difference between C57BL/6N and C57BL/6J mice, High salt/normal potassium diet increases BP and heart rate during the active phase only (dark period) in the same extent in both strains. On the other hand, while potassium level has no effect on salt-induced hypertension in C57BL/6N mice, high-salt/low potassium diet amplifies the effect of the high-salt challenge only in C57BL/6J mice. Indeed, in this condition, salt-induced hypertension can also be detected during light period even though this BP increase is lower compared to the one occurring during the dark period. Finally, from a methodological perspective, light cycle inversion has no effect on this circadian BP phenotype and tail-cuff method is less sensitive than telemetry to detect BP phenotypes due to salt challenges. Conclusions Therefore, to carry investigations on salt-induced hypertension in mice, chronic telemetry and studies in the active phase are essential prerequisites.
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Shattock MJ, Ottolia M, Bers DM, Blaustein MP, Boguslavskyi A, Bossuyt J, Bridge JHB, Chen-Izu Y, Clancy CE, Edwards A, Goldhaber J, Kaplan J, Lingrel JB, Pavlovic D, Philipson K, Sipido KR, Xie ZJ. Na+/Ca2+ exchange and Na+/K+-ATPase in the heart. J Physiol 2015; 593:1361-82. [PMID: 25772291 PMCID: PMC4376416 DOI: 10.1113/jphysiol.2014.282319] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/30/2014] [Indexed: 12/17/2022] Open
Abstract
This paper is the third in a series of reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation–contraction coupling and arrhythmias: Na+ channel and Na+ transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on cardiac Na+/Ca2+ exchange (NCX) and Na+/K+-ATPase (NKA). While the relevance of Ca2+ homeostasis in cardiac function has been extensively investigated, the role of Na+ regulation in shaping heart function is often overlooked. Small changes in the cytoplasmic Na+ content have multiple effects on the heart by influencing intracellular Ca2+ and pH levels thereby modulating heart contractility. Therefore it is essential for heart cells to maintain Na+ homeostasis. Among the proteins that accomplish this task are the Na+/Ca2+ exchanger (NCX) and the Na+/K+ pump (NKA). By transporting three Na+ ions into the cytoplasm in exchange for one Ca2+ moved out, NCX is one of the main Na+ influx mechanisms in cardiomyocytes. Acting in the opposite direction, NKA moves Na+ ions from the cytoplasm to the extracellular space against their gradient by utilizing the energy released from ATP hydrolysis. A fine balance between these two processes controls the net amount of intracellular Na+ and aberrations in either of these two systems can have a large impact on cardiac contractility. Due to the relevant role of these two proteins in Na+ homeostasis, the emphasis of this review is on recent developments regarding the cardiac Na+/Ca2+ exchanger (NCX1) and Na+/K+ pump and the controversies that still persist in the field.
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Affiliation(s)
- Michael J Shattock
- King's College London BHF Centre of Excellence, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, UK
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Stocker SD, Lang SM, Simmonds SS, Wenner MM, Farquhar WB. Cerebrospinal Fluid Hypernatremia Elevates Sympathetic Nerve Activity and Blood Pressure via the Rostral Ventrolateral Medulla. Hypertension 2015; 66:1184-90. [PMID: 26416846 DOI: 10.1161/hypertensionaha.115.05936] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 09/04/2015] [Indexed: 02/07/2023]
Abstract
Elevated NaCl concentrations of the cerebrospinal fluid increase sympathetic nerve activity (SNA) in salt-sensitive hypertension. Neurons of the rostral ventrolateral medulla (RVLM) play a pivotal role in the regulation of SNA and receive mono- or polysynaptic inputs from several hypothalamic structures responsive to hypernatremia. Therefore, the present study investigated the contribution of RVLM neurons to the SNA and pressor response to cerebrospinal fluid hypernatremia. Lateral ventricle infusion of 0.15 mol/L, 0.6 mol/L, and 1.0 mol/L NaCl (5 µL/10 minutes) produced concentration-dependent increases in lumbar SNA, adrenal SNA, and arterial blood pressure, despite no change in splanchnic SNA and a decrease in renal SNA. Ganglionic blockade with chlorisondamine or acute lesion of the lamina terminalis blocked or significantly attenuated these responses, respectively. RVLM microinjection of the gamma-aminobutyric acid (GABAA) agonist muscimol abolished the sympathoexcitatory response to intracerebroventricular infusion of 1 mol/L NaCl. Furthermore, blockade of ionotropic glutamate, but not angiotensin II type 1, receptors significantly attenuated the increase in lumbar SNA, adrenal SNA, and arterial blood pressure. Finally, single-unit recordings of spinally projecting RVLM neurons revealed 3 distinct populations based on discharge responses to intracerebroventricular infusion of 1 mol/L NaCl: type I excited (46%; 11/24), type II inhibited (37%; 9/24), and type III no change (17%; 4/24). All neurons with slow conduction velocities were type I cells. Collectively, these findings suggest that acute increases in cerebrospinal fluid NaCl concentrations selectively activate a discrete population of RVLM neurons through glutamate receptor activation to increase SNA and arterial blood pressure.
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Affiliation(s)
- Sean D Stocker
- From the Departments of Cellular and Molecular Physiology (S.D.S., S.M.L., S.S.S.) and Neural and Behavioral Sciences (S.D.S.), Pennsylvania State University College of Medicine, Hershey; and Department of Kinesiology and Applied Physiology (M.M.W., W.B.F.), University of Delaware, Newark.
| | - Susan M Lang
- From the Departments of Cellular and Molecular Physiology (S.D.S., S.M.L., S.S.S.) and Neural and Behavioral Sciences (S.D.S.), Pennsylvania State University College of Medicine, Hershey; and Department of Kinesiology and Applied Physiology (M.M.W., W.B.F.), University of Delaware, Newark
| | - Sarah S Simmonds
- From the Departments of Cellular and Molecular Physiology (S.D.S., S.M.L., S.S.S.) and Neural and Behavioral Sciences (S.D.S.), Pennsylvania State University College of Medicine, Hershey; and Department of Kinesiology and Applied Physiology (M.M.W., W.B.F.), University of Delaware, Newark
| | - Megan M Wenner
- From the Departments of Cellular and Molecular Physiology (S.D.S., S.M.L., S.S.S.) and Neural and Behavioral Sciences (S.D.S.), Pennsylvania State University College of Medicine, Hershey; and Department of Kinesiology and Applied Physiology (M.M.W., W.B.F.), University of Delaware, Newark
| | - William B Farquhar
- From the Departments of Cellular and Molecular Physiology (S.D.S., S.M.L., S.S.S.) and Neural and Behavioral Sciences (S.D.S.), Pennsylvania State University College of Medicine, Hershey; and Department of Kinesiology and Applied Physiology (M.M.W., W.B.F.), University of Delaware, Newark
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Guo L, Meng J, Xuan C, Ge J, Sun W, O'Rourke ST, Sun C. High salt-diet reduces SLC14A1 gene expression in the choroid plexus of Dahl salt sensitive rats. Biochem Biophys Res Commun 2015; 461:254-9. [PMID: 25869070 PMCID: PMC4428960 DOI: 10.1016/j.bbrc.2015.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 04/02/2015] [Indexed: 01/11/2023]
Abstract
Elevated Na(+) concentration ([Na(+)]) in the cerebrospinal fluid (CSF) contributes to the development of salt-sensitive hypertension. CSF is formed by the choroid plexus (CP) in cerebral ventricles, and [Na(+)] in CSF is controlled by transporters in CP. Here, we examined the effect of high salt diet on the expression of urea transporters (UTs) in the CP of Dahl S vs Dahl R rats using real time PCR. High salt intake (8%, for 2 weeks) did not alter the mRNA levels of UT-A (encoded by SLC14A2 gene) in the CP of either Dahl S or Dahl R rats. In contrast, the mRNA levels of UT-B (encoded by SLC14A1 gene) were significantly reduced in the CP of Dahl S rats on high salt diet as compared with Dahl R rats or Dahl S rats on normal salt diet. Reduced UT-B expression was associated with increased [Na(+)] in the CSF and elevated mean arterial pressure (MAP) in Dahl S rats treated with high salt diet, as measured by radiotelemetry. High salt diet-induced reduction in UT-B protein expression in the CP of Dahl S rats was confirmed by Western blot. Immunohistochemistry using UT-B specific antibodies demonstrated that UT-B protein was expressed on the epithelial cells in the CP. These data indicate that high salt diet induces elevations in CSF [Na(+)] and in MAP, both of which are associated with reduced UT-B expression in the CP of Dahl S rats, as compared with Dahl R rats. The results suggest that altered UT-B expression in the CP may contribute to an imbalance of water and electrolytes in the CSF of Dahl S rats on high salt diet, thereby leading to alterations in MAP.
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Affiliation(s)
- Lirong Guo
- Department of Pathophysiology, College of Basic Medical Sciences, and Second Hospital of Jilin University, Jilin University, Changchun, Jilin 130021, China; Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA.
| | - Jie Meng
- Department of Pathophysiology, College of Basic Medical Sciences, and Second Hospital of Jilin University, Jilin University, Changchun, Jilin 130021, China
| | - Chengluan Xuan
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA
| | - Jingyan Ge
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA
| | - Wenzhu Sun
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA
| | - Stephen T O'Rourke
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA
| | - Chengwen Sun
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, ND 58105, USA.
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Orlov SN, Hamet P. Salt and gene expression: evidence for [Na+]i/[K+]i-mediated signaling pathways. Pflugers Arch 2014; 467:489-98. [PMID: 25479826 DOI: 10.1007/s00424-014-1650-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 10/27/2014] [Accepted: 11/07/2014] [Indexed: 01/11/2023]
Abstract
Our review focuses on the recent data showing that gene transcription and translation are under the control of signaling pathways triggered by modulation of the intracellular sodium/potassium ratio ([Na+]i/[K+]i). Side-by-side with sensing of osmolality elevation by tonicity enhancer-binding protein (TonEBP, NFAT5), [Na+]i/[K+]i-mediated excitation-transcription coupling may contribute to the transcriptomic changes evoked by high salt consumption. This novel mechanism includes the sensing of heightened Na+ concentration in the plasma, interstitial, and cerebrospinal fluids via augmented Na+ influx in the endothelium, immune system cells, and the subfornical organ, respectively. In these cells, [Na+]i/[K+]i ratio elevation, triggered by augmented Na+ influx, is further potentiated by increased production of endogenous Na+,K+-ATPase inhibitors documented in salt-sensitive hypertension.
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Affiliation(s)
- Sergei N Orlov
- Laboratory of Biological Membranes, Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory 1/12, Moscow, 119991, Russia,
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Berret E, Smith PY, Henry M, Soulet D, Hébert SS, Toth K, Mouginot D, Drolet G. Extracellular Na(+) levels regulate formation and activity of the NaX/alpha1-Na(+)/K(+)-ATPase complex in neuronal cells. Front Cell Neurosci 2014; 8:413. [PMID: 25538563 PMCID: PMC4255601 DOI: 10.3389/fncel.2014.00413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 11/13/2014] [Indexed: 11/23/2022] Open
Abstract
MnPO neurons play a critical role in hydromineral homeostasis regulation by acting as sensors of extracellular sodium concentration ([Na+]out). The mechanism underlying Na+-sensing involves Na+-flow through the NaX channel, directly regulated by the Na+/K+-ATPase α1-isoform which controls Na+-influx by modulating channel permeability. Together, these two partners form a complex involved in the regulation of intracellular sodium ([Na+]in). Here we aim to determine whether environmental changes in Na+ could actively modulate the NaX/Na+/K+-ATPase complex activity. We investigated the complex activity using patch-clamp recordings from rat MnPO neurons and Neuro2a cells. When the rats were fed with a high-salt-diet, or the [Na+] in the culture medium was increased, the activity of the complex was up-regulated. In contrast, drop in environmental [Na+] decreased the activity of the complex. Interestingly under hypernatremic condition, the colocalization rate and protein level of both partners were up-regulated. Under hyponatremic condition, only NaX protein expression was increased and the level of NaX/Na+/K+-ATPase remained unaltered. This unbalance between NaX and Na+/K+-ATPase pump proportion would induce a bigger portion of Na+/K+-ATPase-control-free NaX channel. Thus, we suggest that hypernatremic environment increases NaX/Na+/K+-ATPase α1-isoform activity by increasing the number of both partners and their colocalization rate, whereas hyponatremic environment down-regulates complex activity via a decrease in the relative number of NaX channels controlled by the pump.
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Affiliation(s)
| | - Pascal Y Smith
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada
| | - Mélaine Henry
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada
| | - Denis Soulet
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada ; Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval QC, Canada
| | - Sébastien S Hébert
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada ; Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval QC, Canada
| | - Katalin Toth
- Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval QC, Canada ; Institut Universitaire de Santé Mentale de Québec, Université Laval QC, Canada
| | - Didier Mouginot
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada ; Institut Universitaire de Santé Mentale de Québec, Université Laval QC, Canada
| | - Guy Drolet
- Centre de Recherche du CHU de Québec, Axe Neurosciences QC, Canada ; Faculté de Médecine, Département de Psychiatrie et Neurosciences, Université Laval QC, Canada
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Hodes A, Lichtstein D. Natriuretic hormones in brain function. Front Endocrinol (Lausanne) 2014; 5:201. [PMID: 25506340 PMCID: PMC4246887 DOI: 10.3389/fendo.2014.00201] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/12/2014] [Indexed: 01/11/2023] Open
Abstract
Natriuretic hormones (NH) include three groups of compounds: the natriuretic peptides (ANP, BNP and CNP), the gastrointestinal peptides (guanylin and uroguanylin), and endogenous cardiac steroids. These substances induce the kidney to excrete sodium and therefore participate in the regulation of sodium and water homeostasis, blood volume, and blood pressure (BP). In addition to their peripheral functions, these hormones act as neurotransmitters or neuromodulators in the brain. In this review, the established information on the biosynthesis, release and function of NH is discussed, with particular focus on their role in brain function. The available literature on the expression patterns of each of the NH and their receptors in the brain is summarized, followed by the evidence for their roles in modulating brain function. Although numerous open questions exist regarding this issue, the available data support the notion that NH participate in the central regulation of BP, neuroprotection, satiety, and various psychiatric conditions, including anxiety, addiction, and depressive disorders. In addition, the interactions between the different NH in the periphery and the brain are discussed.
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Affiliation(s)
- Anastasia Hodes
- Faculty of Medicine, Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - David Lichtstein
- Faculty of Medicine, Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
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44
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Fu Y, Vallon V. Mineralocorticoid-induced sodium appetite and renal salt retention: evidence for common signaling and effector mechanisms. Nephron Clin Pract 2014; 128:8-16. [PMID: 25376899 DOI: 10.1159/000368264] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
An increase in renal sodium chloride (salt) retention and an increase in sodium appetite are the body's responses to salt restriction or depletion in order to restore salt balance. Renal salt retention and increased sodium appetite can also be maladaptive and sustain the pathophysiology in conditions like salt-sensitive hypertension and chronic heart failure. Here we review the central role of the mineralocorticoid aldosterone in both the increase in renal salt reabsorption and sodium appetite. We discuss the working hypothesis that aldosterone activates similar signaling and effector mechanisms in the kidney and brain, including the mineralocorticoid receptor, the serum- and glucocorticoid-induced kinase SGK1, the ubiquitin ligase NEDD4-2, and the epithelial sodium channel ENaC. The latter also mediates the gustatory salt sensing in the tongue, which is required for the manifestation of increased salt intake. Effects of aldosterone on both the brain and kidney synergize with the effects of angiotensin II. Thus, mineralocorticoids appear to induce similar molecular pathways in the kidney, brain, and possibly tongue, which could provide opportunities for more effective therapeutic interventions. Inhibition of renal salt reabsorption is compensated by stimulation of salt appetite and vice versa; targeting both mechanisms should be more effective. Inhibiting the arousal to consume salty food may improve a patient's compliance to reducing salt intake. While a better understanding of the molecular mechanisms is needed and will provide new therapeutic options, current pharmacological interventions that target both salt retention and sodium appetite include mineralocorticoid receptor antagonists and potentially inhibitors of angiotensin II and ENaC.
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Affiliation(s)
- Yiling Fu
- Department of Medicine, University of California San Diego, La Jolla, Calif., USA
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Pavlovic D. The role of cardiotonic steroids in the pathogenesis of cardiomyopathy in chronic kidney disease. Nephron Clin Pract 2014; 128:11-21. [PMID: 25341357 DOI: 10.1159/000363301] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cardiotonic steroids (CTS) are a new class of hormones that circulate in the blood and are divided into two distinct groups, cardenolides, such as ouabain and digoxin, and bufadienolides, such as marinobufagenin, telocinobufagin and bufalin. They have the ability to bind and inhibit the ubiquitous transport enzyme sodium potassium pump, thus regulating intracellular Na(+) concentration in every living cell. Although digoxin has been prescribed to heart failure patients for at least 200 years, the realization that CTS are endogenously produced has intensified research into their physiological and pathophysiological roles. Over the last two decades, substantial evidence has accumulated demonstrating the effects of endogenously synthesised CTS on the kidneys, vasculature and the heart. In this review, the current state of art and the controversies surrounding the manner in which CTS mediate their pathophysiological effects are discussed. Several potential therapeutic strategies have emerged as a result of our increased understanding of the role CTS play in health and disease.
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Affiliation(s)
- Davor Pavlovic
- Cardiovascular Division, King's College London, Rayne Institute, St. Thomas' Hospital, London, UK
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46
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Stocker SD, Monahan KD, Browning KN. Neurogenic and sympathoexcitatory actions of NaCl in hypertension. Curr Hypertens Rep 2014; 15:538-46. [PMID: 24052211 DOI: 10.1007/s11906-013-0385-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Excess dietary salt intake is a major contributing factor to the pathogenesis of salt-sensitive hypertension. Strong evidence suggests that salt-sensitive hypertension is attributed to renal dysfunction, vascular abnormalities, and activation of the sympathetic nervous system. Indeed, sympathetic nerve transections or interruption of neurotransmission in various brain centers lowers arterial blood pressure (ABP) in many salt-sensitive models. The purpose of this article is to discuss recent evidence that supports a role of plasma or cerebrospinal fluid hypernatremia as a key mediator of sympathoexcitation and elevated ABP. Both experimental and clinical studies using time-controlled sampling have documented that a diet high in salt increases plasma and cerebrospinal fluid sodium concentration. To the extent it has been tested, acute and chronic elevations in sodium concentration activates the sympathetic nervous system in animals and humans. A further understanding of how the central nervous system detects changes in plasma or cerebrospinal fluid sodium concentration may lead to new therapeutic treatment strategies in salt-sensitive hypertension.
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Affiliation(s)
- Sean D Stocker
- Department of Cellular & Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Drive H166, Hershey, PA, 17033, USA,
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Leenen FHH. Actions of circulating angiotensin II and aldosterone in the brain contributing to hypertension. Am J Hypertens 2014; 27:1024-32. [PMID: 24742639 DOI: 10.1093/ajh/hpu066] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In the past 1-2 decades, it has become apparent that the brain renin-angiotensin-aldosterone system (RAAS) plays a crucial role in the regulation of blood pressure (BP) by the circulating RAAS. In the brain, angiotensinergic sympatho-excitatory pathways do not contribute to acute, second-to-second regulation but play a major role in the more chronic regulation of the setpoint for sympathetic tone and BP. Increases in plasma angiotensin II (Ang II) or aldosterone and in cerebrospinal fluid [Na(+)] can directly activate these pathways and chronically further activate/maintain enhanced activity by a slow neuromodulatory pathway involving local aldosterone, mineralocorticoid receptors (MRs), epithelial sodium channels, and endogenous ouabain. Blockade of any step in this slow pathway prevents Ang II-, aldosterone-, or salt and renal injury-induced forms of hypertension. It appears that the renal and arterial actions of circulating aldosterone and Ang II act as amplifiers but are not sufficient to cause chronic hypertension if their central actions are prevented, except perhaps at high concentrations. From a clinical perspective, oral treatment with an angiotensin type 1 (AT1)-receptor blocker at high doses can cause central AT1-receptor blockade and, in humans, lower sympathetic nerve activity. Low doses of the MR blocker spironolactone appear sufficient to cause central MR blockade and a decrease in sympathetic nerve activity. Integrating the brain actions of the circulating RAAS with its direct renal and arterial actions provides a better framework to understand the role of the circulating RAAS in the pathophysiology of hypertension and heart failure and to direct therapeutic strategies.
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Affiliation(s)
- Frans H H Leenen
- Hypertension Unit, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
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Büsst CJ. Blood pressure regulation via the epithelial sodium channel: from gene to kidney and beyond. Clin Exp Pharmacol Physiol 2014; 40:495-503. [PMID: 23710770 DOI: 10.1111/1440-1681.12124] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 01/11/2023]
Abstract
The epithelial sodium channel (ENaC) has long been recognized as playing a vital role in blood pressure (BP) regulation due to its involvement in fluid balance. The genes encoding the three ENaC subunits are likewise important contributors to hypertension, both in rare monogenic diseases and in the general population. The unusually high numbers of genetic variants associated with complex traits, including BP, that are located in non-coding areas suggest an involvement of these variants in regulatory functions. This may involve differential regulation of expression in different tissues. Emerging evidence indicates that the ENaC plays an important role in BP determination not only via its actions in the kidney, but also in other tissues commonly involved in BP regulation. The ENaC in the central nervous system is proposed to regulate BP via sympathetic nervous system activity. Recent evidence suggests that the ENaC contributes to vascular function and the myogenic response. Additional roles potentially include initiation of the baroreceptor reflex via ENaC in the baroreceptors and driving high salt intake with a 'taste for salt' via ENaC in the tongue. The present review describes the involvement of the ENaC in the determination of BP at a genetic and physiological level, detailing recent evidence for its role in the kidney and in other pertinent tissues.
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Affiliation(s)
- Cara J Büsst
- Departments of Physiology, The University of Melbourne and Monash University, Melbourne, Vic., Australia.
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Suwanich A, Wyss JM, Roysommuti S. Taurine supplementation in spontaneously hypertensive rats: Advantages and limitations for human applications. World J Cardiol 2013; 5:404-409. [PMID: 24340138 PMCID: PMC3857232 DOI: 10.4330/wjc.v5.i11.404] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/18/2013] [Indexed: 02/06/2023] Open
Abstract
Taurine (2-aminoethanesulfonic acid) is a β-amino acid found in many tissues particularly brain, myocardium, and kidney. It plays several physiological roles including cardiac contraction, antioxidation, and blunting of hypertension. Though several lines of evidence indicate that dietary taurine can reduce hypertension in humans and in animal models, evidence that taurine supplementation reduces hypertension in humans has not been conclusive. One reason for the inconclusive nature of past studies may be that taurine having both positive and negative effects on cardiovascular system depending on when it is assessed, some effects may occur early, while others only appear later. Further, other consideration may play a role, e.g., taurine supplementation improves hypertension in spontaneously hypertensive rats on a low salt diet but fails to attenuate hypertension on a high salt diet. In humans, some epidemiologic studies indicate that people with high taurine and low salt diets display lower arterial pressure than those with low taurine and high salt diets. Differences in techniques for measuring arterial pressure, duration of treatment, and animal models likely affect the response in different studies. This review considers both the positive and negative effects of taurine on blood pressure in animal models and their applications for human interventions.
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Zicha J, Dobešová Z, Vokurková M, Rauchová H, Hojná S, Kadlecová M, Behuliak M, Vaněčková I, Kuneš J. Age-dependent salt hypertension in Dahl rats: fifty years of research. Physiol Res 2013; 61:S35-S87. [PMID: 22827876 DOI: 10.33549/physiolres.932363] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Fifty years ago, Lewis K. Dahl has presented a new model of salt hypertension - salt-sensitive and salt-resistant Dahl rats. Twenty years later, John P. Rapp has published the first and so far the only comprehensive review on this rat model covering numerous aspects of pathophysiology and genetics of salt hypertension. When we summarized 25 years of our own research on Dahl/Rapp rats, we have realized the need to outline principal abnormalities of this model, to show their interactions at different levels of the organism and to highlight the ontogenetic aspects of salt hypertension development. Our attention was focused on some cellular aspects (cell membrane function, ion transport, cell calcium handling), intra- and extrarenal factors affecting renal function and/or renal injury, local and systemic effects of renin-angiotensin-aldosterone system, endothelial and smooth muscle changes responsible for abnormal vascular contraction or relaxation, altered balance between various vasoconstrictor and vasodilator systems in blood pressure maintenance as well as on the central nervous and peripheral mechanisms involved in the regulation of circulatory homeostasis. We also searched for the age-dependent impact of environmental and pharmacological interventions, which modify the development of high blood pressure and/or organ damage, if they influence the salt-sensitive organism in particular critical periods of development (developmental windows). Thus, severe self-sustaining salt hypertension in young Dahl rats is characterized by pronounced dysbalance between augmented sympathetic hyperactivity and relative nitric oxide deficiency, attenuated baroreflex as well as by a major increase of residual blood pressure indicating profound remodeling of resistance vessels. Salt hypertension development in young but not in adult Dahl rats can be attenuated by preventive increase of potassium or calcium intake. On the contrary, moderate salt hypertension in adult Dahl rats is attenuated by superoxide scavenging or endothelin-A receptor blockade which do not affect salt hypertension development in young animals.
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Affiliation(s)
- J Zicha
- Centre for Cardiovascular Research, Prague, Czech Republic.
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