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Stocker SD, Kinsman BJ, Farquhar WB, Gyarmati G, Peti-Peterdi J, Sved AF. Physiological Mechanisms of Dietary Salt Sensing in the Brain, Kidney, and Gastrointestinal Tract. Hypertension 2024; 81:447-455. [PMID: 37671571 PMCID: PMC10915107 DOI: 10.1161/hypertensionaha.123.19488] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023]
Abstract
Excess dietary salt (NaCl) intake is strongly correlated with cardiovascular disease and is a major contributing factor to the pathogenesis of hypertension. NaCl-sensitive hypertension is a multisystem disorder that involves renal dysfunction, vascular abnormalities, and neurogenically-mediated increases in peripheral resistance. Despite a major research focus on organ systems and these effector mechanisms causing NaCl-induced increases in arterial blood pressure, relatively less research has been directed at elucidating how NaCl is sensed by various tissues to elicit these downstream effects. The purpose of this review is to discuss how the brain, kidney, and gastrointestinal tract sense NaCl including key cell types, the role of NaCl versus osmolality, and the underlying molecular and electrochemical mechanisms.
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Affiliation(s)
- Sean D. Stocker
- Department of Neurobiology, University of Pittsburgh School of Medicine
| | - Brian J Kinsman
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital
| | | | - Georgina Gyarmati
- Department of Physiology and Neuroscience and Medicine, Zilkha Neurogenetic Institute, University of Southern California
| | - Janos Peti-Peterdi
- Department of Physiology and Neuroscience and Medicine, Zilkha Neurogenetic Institute, University of Southern California
| | - Alan F. Sved
- Department of Neuroscience, University of Pittsburgh
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2
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Wan H, Hu YH, Li WP, Wang Q, Su H, Chenshu JY, Lu X, Gao W. Quality of life, household income, and dietary habits are associated with the risk of sarcopenia among the Chinese elderly. Aging Clin Exp Res 2024; 36:29. [PMID: 38334908 PMCID: PMC10857955 DOI: 10.1007/s40520-023-02656-9] [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: 06/26/2023] [Accepted: 11/07/2023] [Indexed: 02/10/2024]
Abstract
BACKGROUND Health-related quality of life (HRQoL), which can be influenced by various aspects, especially socioeconomic status and lifestyle, has been identified as an important predictor of the prognosis of older adults. Dietary habit, a major part of lifestyle, can affect the nutritional status, which is closely correlated with the development of geriatric syndromes in the elderly. AIMS The aim of the study was to examine the association of HRQoL, socioeconomic status, and lifestyle with the risk and severity of sarcopenia, a geriatric syndrome characterized by progressive loss of skeletal muscle mass, strength and function. METHODS A cross-sectional retrospective study with 2877 participants aged ≥65 years was performed. HRQoL was assessed using EuroQoL Five Dimensions questionnaire. Socioeconomic status was assessed by the educational attainment, occupation, and household income. Lifestyle was assessed using 12 items closely related to Chinese living habits. The information of daily dietary habits including tea, alcohol, type of diet, and volume of drinking water were collected. The associations of HRQoL, socioeconomic status, and lifestyle with the risk of sarcopenia were examined by multivariate regression logistical analysis. The potential causal role of age, body mass index, and waist circumference in the effect of HRQoL on sarcopenia risk was analyzed by causal mediation analysis. RESULTS High HRQoL [adjusted odds ratio (OR) =0.85, 95% confidence interval (CI) =0.69-0.95, P=0.034] and household income levels (adjusted OR =0.74, 95% CI =0.57-0.95, P=0.019) were inversely associated with the risk of sarcopenia. Meanwhile, more consumption of spicy food (adjusted OR =1.34, 95% CI =1.09-1.81, P =0.037) and occasionally drinking (adjusted OR =1.46, 95% CI =1.07-2.00, P =0.016, as compared to those never drinking) were associated with higher risk of sarcopenia, while skipping breakfast occasionally (adjusted OR =0.37, 95% CI =0.21-0.64, P <0.001, as compared to those eating breakfast every day) and less consumption of salt (adjusted OR =0.71, 95% CI =0.52-0.96, P =0.026, as compared to those consuming high amount of salt) were associated with lower risk of sarcopenia. Further causal mediation analysis aimed to explore how much age, body mass index, and waist circumference might explain the effect of HRQoL on the risk of sarcopenia showed that the estimated proportion that mediated the effect of HRQoL on the risk of sarcopenia by age was 28.0%. CONCLUSIONS In summary, our findings demonstrate that low levels of HRQoL and household income, more intake of salt and spicy food, and occasional intake of alcohol are correlated with higher risk of sarcopenia, while skipping breakfast occasionally is associated with lower risk of sarcopenia in a Chinese population of older adults.
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Affiliation(s)
- Hua Wan
- Department of Health Management, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Yan-Hui Hu
- Department of Public Health, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Wei-Peng Li
- Department of Geriatrics, Sir Run Run Hospital, Nanjing Medical University, No.109 Longmian Avenue, Nanjing, 211166, China
| | - Quan Wang
- Department of Geriatrics, Sir Run Run Hospital, Nanjing Medical University, No.109 Longmian Avenue, Nanjing, 211166, China
| | - Hong Su
- Department of Health Management, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Jun-Yan Chenshu
- Department of Health Management, Sir Run Run Hospital, Nanjing Medical University, Nanjing, China
| | - Xiang Lu
- Department of Geriatrics, Sir Run Run Hospital, Nanjing Medical University, No.109 Longmian Avenue, Nanjing, 211166, China.
| | - Wei Gao
- Department of Geriatrics, School of Medicine, Zhongda Hospital, Southeast University, No.87 Dingjiaqiao, Nanjing, 210009, Jiangsu, China.
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3
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Johnston JG, Welch AK, Cain BD, Sayeski PP, Gumz ML, Wingo CS. Aldosterone: Renal Action and Physiological Effects. Compr Physiol 2023; 13:4409-4491. [PMID: 36994769 DOI: 10.1002/cphy.c190043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Aldosterone exerts profound effects on renal and cardiovascular physiology. In the kidney, aldosterone acts to preserve electrolyte and acid-base balance in response to changes in dietary sodium (Na+ ) or potassium (K+ ) intake. These physiological actions, principally through activation of mineralocorticoid receptors (MRs), have important effects particularly in patients with renal and cardiovascular disease as demonstrated by multiple clinical trials. Multiple factors, be they genetic, humoral, dietary, or otherwise, can play a role in influencing the rate of aldosterone synthesis and secretion from the adrenal cortex. Normally, aldosterone secretion and action respond to dietary Na+ intake. In the kidney, the distal nephron and collecting duct are the main targets of aldosterone and MR action, which stimulates Na+ absorption in part via the epithelial Na+ channel (ENaC), the principal channel responsible for the fine-tuning of Na+ balance. Our understanding of the regulatory factors that allow aldosterone, via multiple signaling pathways, to function properly clearly implicates this hormone as central to many pathophysiological effects that become dysfunctional in disease states. Numerous pathologies that affect blood pressure (BP), electrolyte balance, and overall cardiovascular health are due to abnormal secretion of aldosterone, mutations in MR, ENaC, or effectors and modulators of their action. Study of the mechanisms of these pathologies has allowed researchers and clinicians to create novel dietary and pharmacological targets to improve human health. This article covers the regulation of aldosterone synthesis and secretion, receptors, effector molecules, and signaling pathways that modulate its action in the kidney. We also consider the role of aldosterone in disease and the benefit of mineralocorticoid antagonists. © 2023 American Physiological Society. Compr Physiol 13:4409-4491, 2023.
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Affiliation(s)
- Jermaine G Johnston
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Amanda K Welch
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Brian D Cain
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Peter P Sayeski
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
| | - Michelle L Gumz
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
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McDonough AA, Fenton RA. Potassium homeostasis: sensors, mediators, and targets. Pflugers Arch 2022; 474:853-867. [PMID: 35727363 PMCID: PMC10163916 DOI: 10.1007/s00424-022-02718-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 06/08/2022] [Accepted: 06/12/2022] [Indexed: 12/16/2022]
Abstract
Transmembrane potassium (K) gradients are key determinants of membrane potential that can modulate action potentials, control muscle contractility, and influence ion channel and transporter activity. Daily K intake is normally equal to the amount of K in the entire extracellular fluid (ECF) creating a critical challenge - how to maintain ECF [K] and membrane potential in a narrow range during feast and famine. Adaptations to maintain ECF [K] include sensing the K intake, sensing ECF [K] vs. desired set-point and activating mediators that regulate K distribution between ECF and ICF, and regulate renal K excretion. In this focused review, we discuss the basis of these adaptions, including (1) potential mechanisms for rapid feedforward signaling to kidney and muscle after a meal (before a rise in ECF [K]), (2) how skeletal muscles sense and respond to changes in ECF [K], (3) effects of K on aldosterone biosynthesis, and (4) how the kidney responds to changes in ECF [K] to modify K excretion. The concepts of sexual dimorphisms in renal K handling adaptation are introduced, and the molecular mechanisms that can account for the benefits of a K-rich diet to maintain cardiovascular health are discussed. Although the big picture of K homeostasis is becoming more clear, we also highlight significant pieces of the puzzle that remain to be solved, including knowledge gaps in our understanding of initiating signals, sensors and their connection to homeostatic adjustments of ECF [K].
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Affiliation(s)
- Alicia A McDonough
- Department of Physiology and Neuroscience, University of Southern California Keck School of Medicine, Los Angeles, CA, USA.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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5
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Ito S, Nakashima H, Ando K, Machino M, Seki T, Ishizuka S, Takegami Y, Wakai K, Hasegawa Y, Imagama S. Nutritional Influences on Locomotive Syndrome. J Clin Med 2022; 11:jcm11030610. [PMID: 35160062 PMCID: PMC8836534 DOI: 10.3390/jcm11030610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/24/2022] [Accepted: 01/24/2022] [Indexed: 02/04/2023] Open
Abstract
Healthy dietary habits are important to prevent locomotive syndrome (LS). We investigated the relationship between LS and nutritional intake using community health checkup data. We included 368 participants who underwent LS staging, blood sampling, and nutritional intake assessments. Participants (163 adults < 65: 205 older adults ≥ 65) were divided into normal (N; LS stage 0) and LS (L; LS stage 1–2) groups, and blood sample data and nutritional intake were compared between groups. Among adults (N group, 71; L group, 92), low-density lipoprotein cholesterol (LDL-C) was significantly lower, and Vitamin B1 intake was significantly higher in the L than in the N group; LDL-C, p = 0.033; Vitamin B1, 0.029. Among older adults (N group, 85; L group, 120), hemoglobin (Hb), albumin, and calcium levels were significantly lower, and sodium, monounsaturated fatty acids (MUFA), and n-6 polyunsaturated fatty acids (n-6 PUFA) were significantly higher in the L than the N group; Hb, p = 0.036; albumin, 0.030; calcium, 0.025; sodium; 0.029; MUFA; 0.047, n-6 PUFA; 0.0233). Logistic regression analysis indicated that sodium was the risk factor for the L group (exp (B) 1.001, 95% CI: 1–1.001, p = 0.032). In conclusion, salt intake was associated with LS.
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Affiliation(s)
- Sadayuki Ito
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Hiroaki Nakashima
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
- Correspondence: ; Tel.: +81-52-741-2111
| | - Kei Ando
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Masaaki Machino
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Taisuke Seki
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Shinya Ishizuka
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Yasuhiko Takegami
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
| | - Kenji Wakai
- Department of Preventive Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan;
| | - Yukiharu Hasegawa
- Department of Rehabilitation, Kansai University of Welfare Science, Osaka 582-0026, Japan;
| | - Shiro Imagama
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan; (S.I.); (K.A.); (M.M.); (T.S.); (S.I.); (Y.T.); (S.I.)
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6
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Hypothalamic detection of macronutrients via multiple gut-brain pathways. Cell Metab 2021; 33:676-687.e5. [PMID: 33450178 PMCID: PMC7933100 DOI: 10.1016/j.cmet.2020.12.018] [Citation(s) in RCA: 84] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 10/30/2020] [Accepted: 12/23/2020] [Indexed: 12/24/2022]
Abstract
Food intake is tightly regulated by complex and coordinated gut-brain interactions. Nutrients rapidly modulate activity in key populations of hypothalamic neurons that regulate food intake, including hunger-sensitive agouti-related protein (AgRP)-expressing neurons. Because individual macronutrients engage specific receptors in the gut to communicate with the brain, we reasoned that macronutrients may utilize different pathways to reduce activity in AgRP neurons. Here, we revealed that AgRP neuron activity in hungry mice is inhibited by site-specific intestinal detection of different macronutrients. We showed that vagal gut-brain signaling is required for AgRP neuron inhibition by fat. In contrast, spinal gut-brain signaling relays the presence of intestinal glucose. Further, we identified glucose sensors in the intestine and hepatic portal vein that mediate glucose-dependent AgRP neuron inhibition. Therefore, distinct pathways are activated by individual macronutrients to inhibit AgRP neuron activity.
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7
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High Salt Diet Impacts the Risk of Sarcopenia Associated with Reduction of Skeletal Muscle Performance in the Japanese Population. Nutrients 2020; 12:nu12113474. [PMID: 33198295 PMCID: PMC7696631 DOI: 10.3390/nu12113474] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/02/2020] [Accepted: 11/05/2020] [Indexed: 12/12/2022] Open
Abstract
The World Health Organization has recommended 5 g/day as dietary reference intakes for salt. In Japan, the averages for men and women were 11.0 g/day and 9.3 g/day, respectively. Recently, it was reported that amounts of sodium accumulation in skeletal muscles of older people were significantly higher than those in younger people. The purpose of this study was to investigate whether the risk of sarcopenia with decreased muscle mass and strength was related to the amount of salt intake. In addition, we investigated its involvement with renalase. Four groups based on age and salt intake ("younger low-salt," "younger high-salt," "older low-salt," and "older high-salt") were compared. Stratifying by age category, body fat percentage significantly increased in high-salt groups in both younger and older people. Handgrip strength/body weight and chair rise tests of the older high-salt group showed significant reduction compared to the older low-salt group. However, there was no significant difference in renalase concentrations in plasma. The results suggest that high-salt intake may lead to fat accumulation and muscle weakness associated with sarcopenia. Therefore, efforts to reduce salt intake may prevent sarcopenia.
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8
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Li XC, Soleimani M, Zhu D, Rubera I, Tauc M, Zheng X, Zhang J, Chen X, Zhuo JL. Proximal Tubule-Specific Deletion of the NHE3 (Na +/H + Exchanger 3) Promotes the Pressure-Natriuresis Response and Lowers Blood Pressure in Mice. Hypertension 2019; 72:1328-1336. [PMID: 30571224 DOI: 10.1161/hypertensionaha.118.10884] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The present study directly tested the hypothesis that deletion of the NHE3 (Na+/H+ exchanger 3) selectively in the proximal tubules of the kidney lowers basal blood pressure by increasing the pressure-natriuresis response in mice. Adult male and female, age-matched wild-type (WT) littermates and proximal tubule-specific NHE3 knockout mice (PT- Nhe3-/-; n=6-16 per group) were studied for (1) basal phenotypes of electrolytes and pH, blood pressure, and kidney function; (2) the pressure-natriuresis response using the mesenteric, celiac, and abdominal arterial occlusion technique; and (3) the natriuretic responses to acute saline expansion (0.9% NaCl, 10% body weight, intraperitoneal) or 2-week of 2% NaCl diet. Under basal conditions, PT- Nhe3-/- mice showed significantly lower systolic, diastolic, and mean arterial blood pressure ( P<0.01) than WT mice ( P<0.01). PT- Nhe3-/- mice also exhibited significantly greater diuretic ( P<0.01) and natriuretic responses than WT mice ( P<0.01), without altering 24-hour fecal Na+ excretion, plasma pH, Na+, and bicarbonate levels. In response to increased renal perfusion pressure by 30 mm Hg, the pressure-natriuresis response increased 5-fold in WT mice ( P<0.01), but it increased 8-fold in PT- Nhe3-/- mice ( P<0.01). In response to 10% acute saline expansion or 2-week 2% NaCl diet, more pronounced natriuretic responses were demonstrated in PT- Nhe3-/- than WT mice ( P<0.01). Our results support the scientific premise and physiological relevance that NHE3 in the proximal tubules plays an essential role in maintaining basal blood pressure homeostasis, and genetic deletion of NHE3 selectively in the proximal tubules of the kidney lowers blood pressure by increasing the pressure natriuretic response.
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Affiliation(s)
- Xiao C Li
- From the Division of Nephrology, Department of Pharmacology and Toxicology and Department of Medicine, University of Mississippi Medical Center, Jackson (X.C.L., X.Z., J.Z., X.C., J.L.Z.)
| | - Manoocher Soleimani
- Division of Nephrology and Hypertension, Department of Internal Medicine, The University of Cincinnati College of Medicine, OH (M.S.)
| | - Dongmin Zhu
- Department of Outpatients, Guangxi Science and Technology University No. 1 Affiliated Hospital, Liuzhou, China (D.Z.)
| | - Isabelle Rubera
- Laboratoire Centre National de la Recherche Scientifique (CNRS) 3472 LP2M, Université de Nice Sophia Antipolis, Nice Cedex 2, France (I.R., M.T.)
| | - Michel Tauc
- Laboratoire Centre National de la Recherche Scientifique (CNRS) 3472 LP2M, Université de Nice Sophia Antipolis, Nice Cedex 2, France (I.R., M.T.)
| | - Xiaowen Zheng
- From the Division of Nephrology, Department of Pharmacology and Toxicology and Department of Medicine, University of Mississippi Medical Center, Jackson (X.C.L., X.Z., J.Z., X.C., J.L.Z.).,Department of Emergency Medicine, Second Affiliated Hospital, Guangxi Medical University, Nanning, China (X.Z., J.Z.)
| | - Jianfeng Zhang
- From the Division of Nephrology, Department of Pharmacology and Toxicology and Department of Medicine, University of Mississippi Medical Center, Jackson (X.C.L., X.Z., J.Z., X.C., J.L.Z.)
| | - Xu Chen
- From the Division of Nephrology, Department of Pharmacology and Toxicology and Department of Medicine, University of Mississippi Medical Center, Jackson (X.C.L., X.Z., J.Z., X.C., J.L.Z.)
| | - Jia L Zhuo
- From the Division of Nephrology, Department of Pharmacology and Toxicology and Department of Medicine, University of Mississippi Medical Center, Jackson (X.C.L., X.Z., J.Z., X.C., J.L.Z.).,Department of Emergency Medicine, Second Affiliated Hospital, Guangxi Medical University, Nanning, China (X.Z., J.Z.)
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9
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Potassium regulation in the neonate. Pediatr Nephrol 2017; 32:2037-2049. [PMID: 28378030 DOI: 10.1007/s00467-017-3635-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 02/13/2017] [Accepted: 02/21/2017] [Indexed: 10/19/2022]
Abstract
Potassium, the major cation in intracelluar fluids, is essential for vital biological functions. Neonates maintain a net positive potassium balance, which is fundamental to ensure somatic growth but places these infants, especially those born prematurely, at risk for life-threatening disturbances in potassium concentration [K+] in the extracellular fluid compartment. Potassium conservation is achieved by maximizing gastrointestinal absorption and minimizing renal losses. A markedly low glomerular filtration rate, plus adaptations in tubular transport along the nephron, result in low potassium excretion in the urine of neonates. Careful evaluation of clinical data using reference values that are normal for the neonate's postmenstrual age is critical to avoid over-treating infants with laboratory results that represent physiologic values for their developmental stage. The treatment should be aimed at correcting the primary cause when possible. Alterations in the levels or sensitivity to aldosterone are common in neonates. In symptomatic patients, the disturbances in [K+] should be corrected promptly, with close electrocardiographic monitoring. Plasma [K+] should be monitored during the first 72 h of life in all premature infants born before 30 weeks of postmenstrual age as these infants are prone to develop non-oliguric hyperkalemia with potential serious complications.
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10
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Epstein M, Lifschitz MD. The Unappreciated Role of Extrarenal and Gut Sensors in Modulating Renal Potassium Handling: Implications for Diagnosis of Dyskalemias and Interpreting Clinical Trials. Kidney Int Rep 2016; 1:43-56. [PMID: 29142913 PMCID: PMC5678840 DOI: 10.1016/j.ekir.2016.03.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 03/11/2016] [Indexed: 12/11/2022] Open
Abstract
In addition to the classic and well-established "feedback control" of potassium balance, increasing investigative attention has focused on a novel and not widely recognized complementary regulatory paradigm for maintaining potassium homeostasis-the "feed-forward control" of potassium balance. This regulatory mechanism, initially defined in rumen, has recently been validated in normal human subjects. Studies are being conducted to determine the location for this putative potassium sensor and to evaluate potential signals, which might increase renal potassium excretion. Awareness of this more updated integrative control mechanism for potassium homeostasis is ever more relevant today, when the medical community is increasingly focused on the challenges of managing the hyperkalemia provoked by renin-angiotensin-aldosterone system inhibitors (RAASis). Recent studies have demonstrated a wide gap between RAASi prescribing guidelines and real-world experience and have highlighted that this gap is thought to be attributable in great part to hyperkalemia. Consequently we require a greater knowledge of the complexities of the regulatory mechanisms subserving potassium homeostasis. Sodium polystyrene sulfonate has long been the mainstay for treating hyperkalemia, but its administration is fraught with challenges related to patient discomfort and colonic necrosis. The current and imminent availability of newer potassium binders with better tolerability and more predictive dose-response potassium removal should enhance the management of hyperkalemia. Consequently it is essential to better understand the intricacies of mammalian colonic K+ handling. We discuss colonic transport of K+ and review evidence for potassium (BK) channels being responsible for increased stool K+ in patients with diseases such as ulcerative colitis.
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Affiliation(s)
- Murray Epstein
- Division of Nephrology and Hypertension, University of Miami, Miller School of Medicine, South Florida Veterans Affairs Foundation for Research and Education (SFVAFRE), Miami, Florida, USA
| | - Meyer D. Lifschitz
- Adult Nephrology Unit, Shaare Zedek Medical Center, Jerusalem, Israel
- University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
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11
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Epstein M, Lifschitz MD. Potassium homeostasis and dyskalemias: the respective roles of renal, extrarenal, and gut sensors in potassium handling. Kidney Int Suppl (2011) 2016; 6:7-15. [PMID: 30675414 PMCID: PMC6340905 DOI: 10.1016/j.kisu.2016.01.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 12/11/2022] Open
Abstract
Integrated mechanisms controlling the maintenance of potassium homeostasis are well established and are defined by the classic "feedback control" of potassium balance. Recently, increasing investigative attention has focused on novel physiological paradigms that increase the complexity and precision of homeostasis. This review briefly considers the classic and well-established feedback control of potassium and then considers subsequent investigations that inform on an intriguing and not widely recognized complementary paradigm: the "feed-forward control of potassium balance." Feed-forward control refers to a pathway in a homeostatic system that responds to a signal in the environment in a predetermined manner, without responding to how the system subsequently reacts (i.e., without responding to feedback). Studies in several animal species, and recently in humans, have confirmed the presence of a feed-forward control mechanism that is capable of mediating potassium excretion independent of changes in serum potassium concentration and aldosterone. Knowledge imparted by this update of potassium homeostasis hopefully will facilitate the clinical management of hyperkalemia in patients with chronic and recurrent hyperkalemia. Awareness of this updated integrative control mechanism for potassium homeostasis is more relevant today when the medical community is increasingly focused on leveraging and expanding established renin-angiotensin-aldosterone system inhibitor treatment regimens and on successfully coping with the challenges of managing hyperkalemia provoked by renin-angiotensin-aldosterone system inhibitors. These new insights are relevant to the future design of clinical trials delineating renal potassium handling.
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Affiliation(s)
- Murray Epstein
- Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Meyer D. Lifschitz
- Adult Nephrology Unit, Shaare Zedek Medical Center, Jerusalem, Israel
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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12
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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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Abstract
Extracellular K(+) homeostasis has been explained by feedback mechanisms in which changes in extracellular K(+) concentration drive renal K(+) excretion directly or indirectly via stimulating aldosterone secretion. However, this cannot explain meal-induced kaliuresis, which often occurs without increases in plasma K(+) or aldosterone concentrations. Recent studies have produced evidence supporting a feedforward control in which gut sensing of dietary K(+) increases renal K(+) excretion (and extrarenal K(+) uptake) independent of plasma K(+) concentrations, namely, a gut factor. This review focuses on these new findings and discusses the role of gut factor in acute and chronic regulation of extracellular K(+) as well as in the beneficial effects of high K(+) intake on the cardiovascular system.
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Affiliation(s)
- Jang H Youn
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, CA 90089-9142, USA.
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14
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Abstract
The liver, well known for its role in metabolism, clearance and storage can also be regarded as a sensory organ. The liver is an ideal place to monitor the quality and quantity of absorbed substances, because portal blood delivers substances absorbed from the intestine to the liver and these substances circulate in the hepatic vasculature before substances enter the systemic circulation. Sodium (Na(+))-sensitive mechanism exists in the liver; it is stimulated by the increase in Na(+) concentration in the portal vein, and then hepatorenal reflex is triggered. Renal sympathetic nerve activity is reflexively decreased and urinary Na(+) excretion is increased. This Na(+)-sensitive hepatorenal reflex has a significant role in post-prandial natriuresis. However, the long-term role of this reflex in Na(+) homeostasis may be less important, probably because of the desensitization of Na(+)-sensitive mechanisms. Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) is involved in the hepatoportal Na(+)-sensitive mechanism, and NKCC1 expression is reduced if the hepatoportal region is exposed to high Na(+) concentrations for a long time. This situation occurs when animals intake a high-sodium chloride diet for a long time. Liver cirrhosis also impairs the Na(+)-sensitive hepatorenal reflex. Hepatoportal baroreceptor-induced renal sympathetic excitation and the impaired Na(+)-sensitive hepatorenal reflex may partially explain the Na(+) retention in liver cirrhosis.
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15
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Youn JH, McDonough AA. Recent advances in understanding integrative control of potassium homeostasis. Annu Rev Physiol 2009; 71:381-401. [PMID: 18759636 DOI: 10.1146/annurev.physiol.010908.163241] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The potassium homeostatic system is very tightly regulated. Recent studies have shed light on the sensing and molecular mechanisms responsible for this tight control. In addition to classic feedback regulation mediated by a rise in extracellular fluid (ECF) [K(+)], there is evidence for a feedforward mechanism: Dietary K(+) intake is sensed in the gut, and an unidentified gut factor is activated to stimulate renal K(+) excretion. This pathway may explain renal and extrarenal responses to altered K(+) intake that occur independently of changes in ECF [K(+)]. Mechanisms for conserving ECF K(+) during fasting or K(+) deprivation have been described: Kidney NADPH oxidase activation initiates a cascade that provokes the retraction of K(+) channels from the cell membrane, and muscle becomes resistant to insulin stimulation of cellular K(+) uptake. How these mechanisms are triggered by K(+) deprivation remains unclear. Cellular AMP kinase-dependent protein kinase activity provokes the acute transfer of K(+) from the ECF to the ICF, which may be important in exercise or ischemia. These recent advances may shed light on the beneficial effects of a high-K(+) diet for the cardiovascular system.
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Affiliation(s)
- Jang H Youn
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, California 90089-9142, USA.
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16
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Greenlee M, Wingo CS, McDonough AA, Youn JH, Kone BC. Narrative review: evolving concepts in potassium homeostasis and hypokalemia. Ann Intern Med 2009; 150:619-25. [PMID: 19414841 PMCID: PMC4944758 DOI: 10.7326/0003-4819-150-9-200905050-00008] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Humans are intermittently exposed to large variations in potassium intake, which range from periods of fasting to ingestion of potassium-rich meals. These fluctuations would abruptly alter plasma potassium concentration if not for rapid mechanisms, primarily in skeletal muscle and the liver, that buffer the changes in plasma potassium concentration by means of transcellular potassium redistribution and feedback control of renal potassium excretion. However, buffers have capacity limits, and even robust feedback control mechanisms require that the perturbation occur before feedback can initiate corrective action. In contrast, feedforward control mechanisms sense the effect of disturbances on the system's homeostasis. This review highlights recent experimental insights into the participation of feedback and feedforward control mechanisms in potassium homeostasis. New data make clear that feedforward homeostatic responses activate when decreased potassium intake is sensed, even when plasma potassium concentration is still within the normal range and before frank hypokalemia ensues, in addition to the classic feedback activation of renal potassium conservation when plasma potassium concentration decreases. Given the clinical importance of dyskalemias in patients, these novel experimental paradigms invite renewed clinical inquiry into this important area.
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Affiliation(s)
- Megan Greenlee
- University of Florida College of Medicine and Department of Veterans Affairs Medical Center, Gainesville, Florida 32610, USA
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17
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Michell A, Debnam E, Unwin R. Regulation of Renal Function by the Gastrointestinal Tract: Potential Role of Gut-Derived Peptides and Hormones. Annu Rev Physiol 2008; 70:379-403. [DOI: 10.1146/annurev.physiol.69.040705.141330] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A.R. Michell
- Department of Biochemical Pharmacology, William Harvey Research Institute, St. Bartholomew's Hospital Medical School, London EC1M 6BQ, United Kingdom;
| | - E.S. Debnam
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
| | - R.J. Unwin
- Department of Physiology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
- Centre for Nephrology, Royal Free and University College Medical School, London NW3 2PF, United Kingdom;
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18
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Abstract
High salt consumption contributes to the development of hypertension and is considered an independent risk factor for vascular remodeling, cardiac hypertrophy, and stroke incidence. In this review, we discuss the molecular origins of primary sensors involved in the phenomenon of salt sensitivity. Based on the analysis of literature data, we conclude that the kidneys and central nervous system (CNS) are two major sites for salt sensing via several distinct mechanisms: 1) [Cl(-)] sensing in renal tubular fluids, primarily by Na(+)-K(+)-Cl(-) cotransporter (NKCC) isoforms NKCC2B and NKCC2A, whose expression is mainly limited to macula densa cells; 2) [Na(+)] sensing in cerebrospinal fluid (CSF) by a novel isoform of Na(+) channels, Na(x), expressed in subfornical organs; 3) sensing of CSF osmolality by mechanosensitive, nonselective cation channels (transient receptor potential vanilloid type 1 channels), expressed in neuronal cells of supraoptic and paraventricular nuclei; and 4) osmolarity sensing by volume-regulated anion channels in glial cells of supraoptic and paraventricular nuclei. Such multiplicity of salt-sensing mechanisms likely explains the differential effects of Na(+) and Cl(-) loading on the long-term maintenance of elevated blood pressure that is documented in experimental models of salt-sensitive hypertension.
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Affiliation(s)
- Sergei N Orlov
- Department of Medicine and Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada.
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Gao S, Tanaka K, Gotoh TM, Morita H. Effects of high NaCl diet on arterial pressure in Sprague-Dawley rats with hepatic and sinoaortic denervation. ACTA ACUST UNITED AC 2005; 55:229-34. [PMID: 16246264 DOI: 10.2170/jjphysiol.s638] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Accepted: 10/25/2005] [Indexed: 11/05/2022]
Abstract
The Na(+) receptor that exists in the hepatoportal region plays an important role in postprandial natriuresis and the regulation of Na(+) balance during NaCl load. Thus it would be considered that a dysfunction of the hepatic Na(+) receptor might result in the elevation of arterial pressure under a condition of high NaCl diet. To elucidate this hypothesis, arterial pressure was continuously measured during three weeks of high NaCl diet (8% NaCl) in four groups of rats: (i) intact rats, (ii) rats with hepatic denervation (HD), (iii) rats with sinoaortic denervation (SAD), and (iv) rats with SAD+HD. During a 1-week normal NaCl diet period, there was no difference in arterial pressure among the four groups. A high NaCl diet had no influence on arterial pressure in intact or HD rats; however, it significantly increased by 11 +/- 3 mmHg in SAD rats. The addition of HD to SAD had no synergistic effect on arterial pressure; i.e., in SAD+HD rats, mean arterial pressure increased by 13 +/- 1 mmHg. In conclusion, sinoaortic baroreceptor, but not hepatic Na(+) receptor, has a significant role in the long-term regulation of arterial pressure on a high NaCl diet.
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Affiliation(s)
- Shuang Gao
- Department of Physiology, Gifu University School of Medicine, 1-1 Yanagido, Gifu 501-1194, Japan
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