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Abstract
The sodium-glucose cotransporter 2 (SGLT2) inhibitors have become an integral part of clinical practice guidelines to slow the progression of CKD in patients with and without diabetes mellitus. Although initially developed as antihyperglycemic drugs, their effect on the kidney is multifactorial resulting from profuse glycosuria and natriuresis consequent to their primary site of action. Hemodynamic and metabolic changes ensue that mediate kidney-protective effects, including ( 1 ) decreased workload of proximal tubular cells and prevention of aberrant increases in glycolysis, contributing to a decreased risk of AKI; ( 2 ) lowering of intraglomerular pressure by activating tubular glomerular feedback and reductions in BP and tissue sodium content; ( 3 ) initiation of nutrient-sensing pathways reminiscent of starvation activating ketogenesis, increased autophagy, and restoration of carbon flow through the mitochondria without production of reactive oxygen species; ( 4 ) body weight loss without a reduction in basal metabolic rate due to increases in nonshivering thermogenesis; and ( 5 ) favorable changes in quantity and characteristics of perirenal fat leading to decreased release of adipokines, which adversely affect the glomerular capillary and signal increased sympathetic outflow. Additionally, these drugs stimulate phosphate and magnesium reabsorption and increase uric acid excretion. Familiarity with kidney-specific mechanisms of action, potential changes in kidney function, and/or alterations in electrolytes and volume status, which are induced by these widely prescribed drugs, will facilitate usage in the patients for whom they are indicated.
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Affiliation(s)
- Biff F. Palmer
- Division of Nephrology, Department of Medicine, Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Deborah J. Clegg
- Internal Medicine, Texas Tech Health Sciences Center, El Paso, Texas
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2
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Liu R, Juncos LA, Lu Y, Wei J, Zhang J, Wang L, Lai EY, Carlstrom M, Persson AEG. The Role of Macula Densa Nitric Oxide Synthase 1 Beta Splice Variant in Modulating Tubuloglomerular Feedback. Compr Physiol 2023; 13:4215-4229. [PMID: 36715280 PMCID: PMC9990375 DOI: 10.1002/cphy.c210043] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Abnormalities in renal electrolyte and water excretion may result in inappropriate salt and water retention, which facilitates the development and maintenance of hypertension, as well as acid-base and electrolyte disorders. A key mechanism by which the kidney regulates renal hemodynamics and electrolyte excretion is via tubuloglomerular feedback (TGF), an intrarenal negative feedback between tubules and arterioles. TGF is initiated by an increase of NaCl delivery at the macula densa cells. The increased NaCl activates luminal Na-K-2Cl cotransporter (NKCC2) of the macula densa cells, which leads to activation of several intracellular processes followed by the production of paracrine signals that ultimately result in a constriction of the afferent arteriole and a tonic inhibition of single nephron glomerular filtration rate. Neuronal nitric oxide (NOS1) is highly expressed in the macula densa. NOS1β is the major splice variant and accounts for most of NO generation by the macula densa, which inhibits TGF response. Macula densa NOS1β-mediated modulation of TGF responses plays an essential role in control of sodium excretion, volume and electrolyte hemostasis, and blood pressure. In this article, we describe the mechanisms that regulate macula densa-derived NO and their effect on TGF response in physiologic and pathologic conditions. © 2023 American Physiological Society. Compr Physiol 13:4215-4229, 2023.
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Affiliation(s)
- Ruisheng Liu
- Department of Molecular Pharmacology & Physiology
- Hypertension and Kidney Research Center, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Luis A. Juncos
- Department of Internal Medicine, Central Arkansas Veterans Healthcare System, Little Rock, AR
| | - Yan Lu
- Division of Nephrology, University of Alabama at Birmingham, Birmingham AL
| | - Jin Wei
- Department of Molecular Pharmacology & Physiology
| | - Jie Zhang
- Department of Molecular Pharmacology & Physiology
| | - Lei Wang
- Department of Molecular Pharmacology & Physiology
| | - En Yin Lai
- Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Mattias Carlstrom
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - A. Erik G Persson
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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SGLT2 Inhibitors in Diabetic and Non-Diabetic Chronic Kidney Disease. Biomedicines 2023; 11:biomedicines11020279. [PMID: 36830815 PMCID: PMC9953060 DOI: 10.3390/biomedicines11020279] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/15/2023] [Accepted: 01/18/2023] [Indexed: 01/20/2023] Open
Abstract
Results from recent randomized controlled trials on inhibitors of the sodium-glucose cotransporter 2 (SGLT2) have determined a paradigm shift in the treatment of patients with type 2 diabetes mellitus. These agents have been shown not only to ameliorate metabolic control, but also to independently protect from cardiovascular events and to reduce the progression of chronic kidney disease (CKD) in these patients. The magnitude of the nephroprotective effect observed in these studies is likely to make SGLT2 inhibitors the most impactful drug class for the treatment of diabetic patients with CKD since the discovery of renin-angiotensin system inhibitors. Even more surprisingly, SGLT2 inhibitors have also been shown to slow CKD progression in non-diabetic individuals with varying degrees of proteinuria, suggesting that activation of SGLT2 is involved in the pathogenesis of CKD independent of its etiology. As indications continue to expand, it is still unclear whether the observed benefits of SGLT2 inhibitors may extend to CKD patients at lower risk of progression and if their association with other agents may confer additional protection.
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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Belardin LB, Brochu K, Légaré C, Battistone MA, Breton S. Purinergic signaling in the male reproductive tract. Front Endocrinol (Lausanne) 2022; 13:1049511. [PMID: 36419764 PMCID: PMC9676935 DOI: 10.3389/fendo.2022.1049511] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 10/21/2022] [Indexed: 11/09/2022] Open
Abstract
Purinergic receptors are ubiquitously expressed throughout the body and they participate in the autocrine and paracrine regulation of cell function during normal physiological and pathophysiological conditions. Extracellular nucleotides activate several types of plasma membrane purinergic receptors that form three distinct families: P1 receptors are activated by adenosine, P2X receptors are activated by ATP, and P2Y receptors are activated by nucleotides including ATP, ADP, UTP, UDP, and UDP-glucose. These specific pharmacological fingerprints and the distinct intracellular signaling pathways they trigger govern a large variety of cellular responses in an organ-specific manner. As such, purinergic signaling regulates several physiological cell functions, including cell proliferation, differentiation and death, smooth muscle contraction, vasodilatation, and transepithelial transport of water, solute, and protons, as well as pathological pathways such as inflammation. While purinergic signaling was first discovered more than 90 years ago, we are just starting to understand how deleterious signals mediated through purinergic receptors may be involved in male infertility. A large fraction of male infertility remains unexplained illustrating our poor understanding of male reproductive health. Purinergic signaling plays a variety of physiological and pathophysiological roles in the male reproductive system, but our knowledge in this context remains limited. This review focuses on the distribution of purinergic receptors in the testis, epididymis, and vas deferens, and their role in the establishment and maintenance of male fertility.
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Affiliation(s)
- Larissa Berloffa Belardin
- Centre Hospitalier Universitaire de Québec - Research Centre and Department of Obstetrics, Gynecology and Reproduction, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Kéliane Brochu
- Centre Hospitalier Universitaire de Québec - Research Centre and Department of Obstetrics, Gynecology and Reproduction, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Christine Légaré
- Centre Hospitalier Universitaire de Québec - Research Centre and Department of Obstetrics, Gynecology and Reproduction, Faculty of Medicine, Université Laval, Québec, QC, Canada
| | - Maria Agustina Battistone
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Sylvie Breton
- Centre Hospitalier Universitaire de Québec - Research Centre and Department of Obstetrics, Gynecology and Reproduction, Faculty of Medicine, Université Laval, Québec, QC, Canada
- *Correspondence: Sylvie Breton,
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Zhang J, Zhu J, Wei J, Jiang S, Xu L, Qu L, Yang K, Wang L, Buggs J, Cheng F, Tan X, Liu R. New Mechanism for the Sex Differences in Salt-Sensitive Hypertension: The Role of Macula Densa NOS1β-Mediated Tubuloglomerular Feedback. Hypertension 2020; 75:449-457. [PMID: 31865794 PMCID: PMC7015450 DOI: 10.1161/hypertensionaha.119.13822] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Females are relatively resistant to salt-sensitive hypertension than males, but the mechanisms are not completely elucidated. We recently demonstrated a decisive role of macula densa neuronal NOS1β (nitric oxide synthase β)-mediated tubuloglomerular feedback (TGF) in the long-term control of glomerular filtration rate, sodium excretion, and blood pressure. In the present study, we hypothesized that the macula densa NOS1β-mediated TGF mechanism is different between male and female, thereby contributing to the sexual dimorphism of salt-sensitive hypertension. We used microperfusion, micropuncture, clearance of fluorescein isothiocyanate-inulin, and radio telemetry to examine the sex differences in the changes of macula densa NOS1β expression and activity, TGF response, natriuresis, and blood pressure after salt loading in wild-type and macula densa-specific NOS1 knockout mice. In wild-type mice, a high-salt diet induced greater increases in macula densa NOS1β expression and phosphorylation at Ser 1417, greater nitric oxide generation by the macula densa, and more inhibition in TGF response in vitro and in vivo in females than in males. Additionally, the increases of glomerular filtration rate, urine flow rate, and sodium excretion in response to an acute volume expansion were significantly greater in females than in males. The blood pressure responses to angiotensin II plus a high-salt diet were significantly less in females than in males. In contrast, these sex differences in TGF, natriuretic response, and blood pressure were largely diminished in knockout mice. In conclusion, macula densa NOS1β-mediated TGF is a novel and important mechanism for the sex differences in salt-sensitive hypertension.
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Affiliation(s)
- Jie Zhang
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Jinxiu Zhu
- The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Jin Wei
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Shan Jiang
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Lan Xu
- College of Public Health, University of South Florida, Tampa, FL
| | - Larry Qu
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Kun Yang
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Lei Wang
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Jacentha Buggs
- Advanced Organ Disease & Transplantation Institute, Tampa General Hospital, Tampa, FL
| | - Feng Cheng
- Department of Pharmaceutical Science, College of Pharmacy, University of South Florida, Tampa, FL
| | - Xuerui Tan
- The First Affiliated Hospital of Shantou University Medical College, Shantou, Guangdong, China
| | - Ruisheng Liu
- Department of Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL
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Leipziger J, Praetorius H. Renal Autocrine and Paracrine Signaling: A Story of Self-protection. Physiol Rev 2020; 100:1229-1289. [PMID: 31999508 DOI: 10.1152/physrev.00014.2019] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Autocrine and paracrine signaling in the kidney adds an extra level of diversity and complexity to renal physiology. The extensive scientific production on the topic precludes easy understanding of the fundamental purpose of the vast number of molecules and systems that influence the renal function. This systematic review provides the broader pen strokes for a collected image of renal paracrine signaling. First, we recapitulate the essence of each paracrine system one by one. Thereafter the single components are merged into an overarching physiological concept. The presented survey shows that despite the diversity in the web of paracrine factors, the collected effect on renal function may not be complicated after all. In essence, paracrine activation provides an intelligent system that perceives minor perturbations and reacts with a coordinated and integrated tissue response that relieves the work load from the renal epithelia and favors diuresis and natriuresis. We suggest that the overall function of paracrine signaling is reno-protection and argue that renal paracrine signaling and self-regulation are two sides of the same coin. Thus local paracrine signaling is an intrinsic function of the kidney, and the overall renal effect of changes in blood pressure, volume load, and systemic hormones will always be tinted by its paracrine status.
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Affiliation(s)
- Jens Leipziger
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; and Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus, Denmark
| | - Helle Praetorius
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; and Aarhus Institute of Advanced Studies (AIAS), Aarhus University, Aarhus, Denmark
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8
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Vallon V, Unwin R, Inscho EW, Leipziger J, Kishore BK. Extracellular Nucleotides and P2 Receptors in Renal Function. Physiol Rev 2019; 100:211-269. [PMID: 31437091 DOI: 10.1152/physrev.00038.2018] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The understanding of the nucleotide/P2 receptor system in the regulation of renal hemodynamics and transport function has grown exponentially over the last 20 yr. This review attempts to integrate the available data while also identifying areas of missing information. First, the determinants of nucleotide concentrations in the interstitial and tubular fluids of the kidney are described, including mechanisms of cellular release of nucleotides and their extracellular breakdown. Then the renal cell membrane expression of P2X and P2Y receptors is discussed in the context of their effects on renal vascular and tubular functions. Attention is paid to effects on the cortical vasculature and intraglomerular structures, autoregulation of renal blood flow, tubuloglomerular feedback, and the control of medullary blood flow. The role of the nucleotide/P2 receptor system in the autocrine/paracrine regulation of sodium and fluid transport in the tubular and collecting duct system is outlined together with its role in integrative sodium and fluid homeostasis and blood pressure control. The final section summarizes the rapidly growing evidence indicating a prominent role of the extracellular nucleotide/P2 receptor system in the pathophysiology of the kidney and aims to identify potential therapeutic opportunities, including hypertension, lithium-induced nephropathy, polycystic kidney disease, and kidney inflammation. We are only beginning to unravel the distinct physiological and pathophysiological influences of the extracellular nucleotide/P2 receptor system and the associated therapeutic perspectives.
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Affiliation(s)
- Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Robert Unwin
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Edward W Inscho
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Jens Leipziger
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Bellamkonda K Kishore
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
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Wei J, Zhang J, Jiang S, Wang L, Persson AEG, Liu R. High-Protein Diet-Induced Glomerular Hyperfiltration Is Dependent on Neuronal Nitric Oxide Synthase β in the Macula Densa via Tubuloglomerular Feedback Response. Hypertension 2019; 74:864-871. [PMID: 31422689 DOI: 10.1161/hypertensionaha.119.13077] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
It is well known that high protein intake increases glomerular filtration rate. Evidence from several studies indicated that NO and tubuloglomerular feedback (TGF) mediate the effect. However, a recent study with a neuronal NO synthase-α knockout model refuted this mechanism and concluded that neither neuronal NO synthase nor TGF response is involved in the protein-induced hyperfiltration. To examine the discrepancy, this study tested a hypothesis that neuronal NO synthase-β in the macula densa mediates the high-protein diet-induced glomerular hyperfiltration via TGF mechanism. We examined the effects of high protein intake on NO generation at the macula densa, TGF response, and glomerular filtration rate in wild-type and macula densa-specific neuronal NO synthase KO mice. In wild-type mice, high-protein diet increased kidney weight, glomerular filtration rate, and renal blood flow, while reduced renal vascular resistance. TGF response in vivo and in vitro was blunted, and NO generation in the macula densa was increased following high-protein diet, associated with upregulations of neuronal NO synthase-β expression and phosphorylation at Ser1417. In contrast, these high-protein diet-induced changes in NO generation at the macula densa, TGF response, renal blood flow, and glomerular filtration rate in wild-type mice were largely attenuated in macula densa-specific neuronal NO synthase KO mice. In conclusion, we demonstrated that high-protein diet-induced glomerular hyperfiltration is dependent on neuronal NO synthase β in the macula densa via TGF response.
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Affiliation(s)
- Jin Wei
- From the Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa (J.W., J.Z., S.J., L.W., R.L.)
| | - Jie Zhang
- From the Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa (J.W., J.Z., S.J., L.W., R.L.)
| | - Shan Jiang
- From the Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa (J.W., J.Z., S.J., L.W., R.L.)
| | - Lei Wang
- From the Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa (J.W., J.Z., S.J., L.W., R.L.)
| | - A Erik G Persson
- Department of Medical Cell Biology, Division of Integrative Physiology, Uppsala University, Sweden (A.E.G.P.)
| | - Ruisheng Liu
- From the Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa (J.W., J.Z., S.J., L.W., R.L.)
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Exposure to Hyperchloremia Is Associated with Poor Early Recovery of Kidney Graft Function after Living-Donor Kidney Transplantation: A Propensity Score-Matching Analysis. J Clin Med 2019; 8:jcm8070955. [PMID: 31269662 PMCID: PMC6678624 DOI: 10.3390/jcm8070955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 12/11/2022] Open
Abstract
The effects of hyperchloremia on kidney grafts have not been investigated in patients undergoing living-donor kidney transplantation (LDKT). In this study, data from 200 adult patients undergoing elective LDKT between January 2016 and December 2017 were analyzed after propensity score (PS) matching. The patients were allocated to hyperchloremia and non-hyperchloremia groups according to the occurrence of hyperchloremia (i.e., ≥110 mEq/L) immediately after surgery. Poor early graft recovery was defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 during the first 48 hours after surgery. After PS matching, no significant differences in perioperative recipient or donor graft parameters were observed between groups. Although the total amount of crystalloid fluid infused during surgery did not differ between groups, the proportions of main crystalloid fluid type used (i.e., 0.9% normal saline vs. Plasma Solution-A) did. The eGFR increased gradually during postoperative day (POD) 2 in both groups. However, the proportion of patients with eGFR > 60 mL/min/1.73 m2 on POD 2 was higher in the non-hyperchloremia group than in the hyperchloremia group. In this PS-adjusted analysis, hyperchloremia was significantly associated with poor graft recovery on POD 2. In conclusion, exposure to hyperchloremia may have a negative impact on early graft recovery in LDKT.
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Hagiyama M, Nakatani Y, Takashima Y, Kato T, Inoue T, Kimura R, Otani T, Sato Y, Mori H, Arima S, Ito A. Urinary Cell Adhesion Molecule 1 Is a Novel Biomarker That Links Tubulointerstitial Damage to Glomerular Filtration Rates in Chronic Kidney Disease. Front Cell Dev Biol 2019; 7:111. [PMID: 31316980 PMCID: PMC6610501 DOI: 10.3389/fcell.2019.00111] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/03/2019] [Indexed: 12/25/2022] Open
Abstract
Cell adhesion molecule 1 (CADM1) is an immunoglobulin superfamily member strongly expressed on renal tubular epithelia in the urinary tract. Enzymatic cleavage of its ectodomain increases in chronic kidney disease (CKD), and is assumed to contribute to tubulointerstitial lesion formation. Because the cleaved ectodomain fragments are likely to be released into the urine, a sandwich enzyme-linked immunosorbent assay (ELISA) system for urinary CADM1 was developed using two anti-ectodomain antibodies. Urinary CADM1 concentrations in patients with CKD based on various forms of glomerulonephritis and nephropathy (n = 127) were measured. A total of 44 patients (35%) had elevated CADM1 concentrations over the normal upper limit (362 pg/mL), with a mean of 1,727 pg/mL. Renal biopsy specimens of all patients were pathologically scored for tubulointerstitial lesions using epithelial degeneration, interstitial inflammation, and fibrosis. There were no correlations between urinary CADM1 concentrations and pathological scores or any widely used renal markers, including glomerular filtration rate (GFR), but there was a weak inverse correlation between pathological scores and GFR (R2 = 0.292). Notably, this correlation gradually increased in patients with increasing CADM1 concentrations, and reached a maximum R2 (0.899) at a cutoff of 1,569 pg/mL. The results of this study suggest that urinary CADM1 is a useful marker indicating tubulointerstitial damage from elevated GFR levels in CKD.
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Affiliation(s)
- Man Hagiyama
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Yoshihisa Nakatani
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Yasutoshi Takashima
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Takashi Kato
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Takao Inoue
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Ryuichiro Kimura
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Tomoyuki Otani
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Yasufumi Sato
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Hideo Mori
- Department of Pathology, Osaka Rosai Hospital, Sakai, Japan
| | - Shuji Arima
- Division of Nephrology, Department of Internal Medicine, Faculty of Medicine, Kindai University, Osakasayama, Japan
| | - Akihiko Ito
- Department of Pathology, Faculty of Medicine, Kindai University, Osakasayama, Japan
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Zhang J, Wei J, Jiang S, Xu L, Wang L, Cheng F, Buggs J, Koepsell H, Vallon V, Liu R. Macula Densa SGLT1-NOS1-Tubuloglomerular Feedback Pathway, a New Mechanism for Glomerular Hyperfiltration during Hyperglycemia. J Am Soc Nephrol 2019; 30:578-593. [PMID: 30867247 DOI: 10.1681/asn.2018080844] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 01/27/2019] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Glomerular hyperfiltration is common in early diabetes and is considered a risk factor for later diabetic nephropathy. We propose that sodium-glucose cotransporter 1 (SGLT1) senses increases in luminal glucose at the macula densa, enhancing generation of neuronal nitric oxide synthase 1 (NOS1)-dependent nitric oxide (NO) in the macula densa and blunting the tubuloglomerular feedback (TGF) response, thereby promoting the rise in GFR. METHODS We used microperfusion, micropuncture, and renal clearance of FITC-inulin to examine the effects of tubular glucose on NO generation at the macula densa, TGF, and GFR in wild-type and macula densa-specific NOS1 knockout mice. RESULTS Acute intravenous injection of glucose induced hyperglycemia and glucosuria with increased GFR in mice. We found that tubular glucose blunts the TGF response in vivo and in vitro and stimulates NO generation at the macula densa. We also showed that SGLT1 is expressed at the macula densa; in the presence of tubular glucose, SGLT1 inhibits TGF and NO generation, but this action is blocked when the SGLT1 inhibitor KGA-2727 is present. In addition, we demonstrated that glucose increases NOS1 expression and NOS1 phosphorylation at Ser1417 in mouse renal cortex and cultured human kidney tissue. In macula densa-specific NOS1 knockout mice, glucose had no effect on NO generation, TGF, and GFR. CONCLUSIONS We identified a novel mechanism of acute hyperglycemia-induced hyperfiltration wherein increases in luminal glucose at the macula densa upregulate the expression and activity of NOS1 via SGLT1, blunting the TGF response and promoting glomerular hyperfiltration.
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Affiliation(s)
- Jie Zhang
- Department of Molecular Pharmacology and Physiology, College of Medicine,
| | - Jin Wei
- Department of Molecular Pharmacology and Physiology, College of Medicine
| | - Shan Jiang
- Department of Molecular Pharmacology and Physiology, College of Medicine
| | - Lan Xu
- Department of Biostatistics, College of Public Health, and
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, College of Medicine
| | - Feng Cheng
- Department of Pharmaceutical Science, College of Pharmacy, University of South Florida, Tampa, Florida
| | - Jacentha Buggs
- Advanced Organ Disease & Transplantation Institute, Tampa General Hospital, Tampa, Florida
| | - Hermann Koepsell
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany; and
| | - Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, College of Medicine
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13
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Romero CA, Carretero OA. Tubule-vascular feedback in renal autoregulation. Am J Physiol Renal Physiol 2019; 316:F1218-F1226. [PMID: 30838873 DOI: 10.1152/ajprenal.00381.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Afferent arteriole (Af-Art) diameter regulates pressure and flow into the glomerulus, which are the main determinants of the glomerular filtration rate. Thus, Af-Art resistance is crucial for Na+ filtration. Af-Arts play a role as integrative centers, where systemic and local systems interact to determine the final degree of resistance. The tubule of a single nephron contacts an Af-Art of the same nephron at two locations: in the transition of the thick ascending limb to the distal tubule (macula densa) and again in the connecting tubule. These two sites are the anatomic basis of two intrinsic feedback mechanisms: tubule-glomerular feedback and connecting tubule-glomerular feedback. The cross communications between the tubules and Af-Arts integrate tubular Na+ and water processing with the hemodynamic conditions of the kidneys. Tubule-glomerular feedback provides negative feedback that tends to avoid salt loss, and connecting tubule-glomerular feedback provides positive feedback that favors salt excretion by modulating tubule-glomerular feedback (resetting it) and increasing glomerular filtration rate. These feedback mechanisms are also exposed to systemic modulators (hormones and the nervous system); however, they can work in isolated kidneys or nephrons. The exaggerated activation or absence of any of these mechanisms may lead to disequilibrium in salt and water homeostasis, especially in extreme conditions (e.g., high-salt diet/low-salt diet) and may be part of the pathogenesis of some diseases. In this review, we focus on molecular signaling, feedback interactions, and the physiological roles of these two feedback mechanisms.
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Affiliation(s)
- Cesar A Romero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan
| | - Oscar A Carretero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital , Detroit, Michigan
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14
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Romero CA, Carretero OA. A Novel Mechanism of Renal Microcirculation Regulation: Connecting Tubule-Glomerular Feedback. Curr Hypertens Rep 2019; 21:8. [PMID: 30659366 DOI: 10.1007/s11906-019-0911-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE OF REVIEW In this review, we summarized the current knowledge of connecting tubule-glomerular feedback (CTGF), a novel mechanism of renal microcirculation regulation that integrates sodium handling in the connecting tubule (CNT) with kidney hemodynamics. RECENT FINDINGS Connecting tubule-glomerular feedback is a crosstalk communication between the CNT and the afferent arteriole (Af-Art), initiated by sodium chloride through the epithelial sodium channel (ENaC). High sodium in the CNT induces Af-Art vasodilation, increasing glomerular pressure and the glomerular filtration rate and favoring sodium excretion. CTGF antagonized and reset tubuloglomerular feedback and thus increased sodium excretion. CTGF is absent in spontaneous hypertensive rats and is overactivated in Dahl salt-sensitive rats. CTGF is also modulated by angiotensin II and aldosterone. CTGF is a feedback mechanism that integrates sodium handling in the CNT with glomerular hemodynamics. Lack of CTGF could promote hypertension, and CTGF overactivation may favor glomerular damage and proteinuria. More studies are needed to explore the alterations in renal microcirculation and the role of these alterations in the genesis of hypertension and glomerular damage in animals and humans. KEY POINTS • CTGF is a vasodilator mechanism that regulates afferent arteriole resistance. • CTGF is absent in spontaneous hypertensive rats and overactivated in Dahl salt-sensitive rats. • CTGF in excess may promote glomerular damage and proteinuria, while the absence may participate in sodium retention and hypertension.
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Affiliation(s)
- Cesar A Romero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA.
| | - Oscar A Carretero
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Boulevard, Detroit, MI, 48202-2689, USA
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15
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Rein JL, Coca SG. "I don't get no respect": the role of chloride in acute kidney injury. Am J Physiol Renal Physiol 2018; 316:F587-F605. [PMID: 30539650 DOI: 10.1152/ajprenal.00130.2018] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Acute kidney injury (AKI) is a major public health problem that complicates 10-40% of hospital admissions. Importantly, AKI is independently associated with increased risk of progression to chronic kidney disease, end-stage renal disease, cardiovascular events, and increased risk of in-hospital and long-term mortality. The chloride content of intravenous fluid has garnered much attention over the last decade, as well as its association with excess use and adverse outcomes, including AKI. Numerous studies show that changes in serum chloride concentration, independent of serum sodium and bicarbonate, are associated with increased risk of AKI, morbidity, and mortality. This comprehensive review details the complex renal physiology regarding the role of chloride in regulating renal blood flow, glomerular filtration rate, tubuloglomerular feedback, and tubular injury, as well as the findings of clinical research related to the chloride content of intravenous fluids, changes in serum chloride concentration, and AKI. Chloride is underappreciated in both physiology and pathophysiology. Although the exact mechanism is debated, avoidance of excessive chloride administration is a reasonable treatment option for all patients and especially in those at risk for AKI. Therefore, high-risk patients and those with "incipient" AKI should receive balanced solutions rather than normal saline to minimize the risk of AKI.
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Affiliation(s)
- Joshua L Rein
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai , New York, New York
| | - Steven G Coca
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai , New York, New York
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16
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Guerci P, Ergin B, Ince C. The macro- and microcirculation of the kidney. Best Pract Res Clin Anaesthesiol 2017; 31:315-329. [PMID: 29248139 DOI: 10.1016/j.bpa.2017.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 10/25/2017] [Indexed: 01/22/2023]
Abstract
Acute kidney injury (AKI) remains one of the main causes of morbidity and mortality in the intensive care medicine today. Its pathophysiology and progress to chronic kidney disease is still under investigation. In addition, the lack of techniques to adequately monitor renal function and microcirculation at the bedside makes its therapeutic resolution challenging. In this article, we review current concepts related to renal hemodynamics compromise as being the event underlying AKI. In doing so, we discuss the physiology of the renal circulation and the effects of alterations in systemic hemodynamics that lead to renal injury specifically in the context of reperfusion injury and sepsis. The ultimate key culprit of AKI leading to failure is the dysfunction of the renal microcirculation. The cellular and subcellular components of the renal microcirculation are discussed and how their injury contributes to AKI is described.
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Affiliation(s)
- Philippe Guerci
- Department of Anesthesiology and Critical Care Medicine, University Hospital of Nancy, France; INSERM U1116, University of Lorraine, Vandoeuvre-Les-Nancy, France; Department of Translational Physiology, Academic Medical Centre, Amsterdam, The Netherlands
| | - Bulent Ergin
- Department of Translational Physiology, Academic Medical Centre, Amsterdam, The Netherlands; Department of Intensive Care Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands
| | - Can Ince
- Department of Translational Physiology, Academic Medical Centre, Amsterdam, The Netherlands; Department of Intensive Care Medicine, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands.
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17
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Rajasekeran H, Lytvyn Y, Bozovic A, Lovshin JA, Diamandis E, Cattran D, Husain M, Perkins BA, Advani A, Reich HN, Kulasingam V, Cherney DZI. Urinary adenosine excretion in type 1 diabetes. Am J Physiol Renal Physiol 2017; 313:F184-F191. [DOI: 10.1152/ajprenal.00043.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/30/2017] [Accepted: 04/03/2017] [Indexed: 11/22/2022] Open
Abstract
In experimental models of diabetes, augmented sodium-glucose cotransport-2 (SGLT2) activity diminishes sodium (Na+) delivery at the macula densa. As a result, less vasoconstrictive adenosine is generated, leading to afferent arteriolar vasodilatation and hyperfiltration. The measurement and significance of urinary adenosine in humans has not been examined extensively in states of renal hemodynamic impairment like that of diabetes. Our aim was to validate a method for urine adenosine quantification in humans and perform an exploratory post hoc analysis to determine whether urinary adenosine levels change dynamically in response to natriuresis in patients with type 1 diabetes (T1D) before and after treatment with the SGLT2 inhibitor (SGLT2i) empagliflozin. We hypothesized that SGLT2i, which reduces renal hyperfiltration through increased Na+delivery to the macula densa, would increase urinary adenosine excretion. Urine adenosine corrected for creatinine was measured using our validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in 40 healthy participants and 40 patients with T1D. In the T1D cohort, measurements were performed during clamped euglycemic and hyperglycemic conditions before and following 8 wk of SGLT2i therapy. Urinary adenosine was detectable in healthy subjects (0.32 ± 0.11 µmol/mmol Cr) and patients with T1D. In response to SGLT2i, urine adenosine increased during clamped hyperglycemia (0.40 ± 0.11 vs. 0.45 ± 0.12 µmol/mmol Cr, P = 0.005). Similar trends were observed during clamped euglycemia ( P = 0.08). In conclusion, SGLT2i increases urinary adenosine excretion under clamped hyperglycemic conditions in patients with T1D. The potentially protective role of SGLT2i against glomerular hyperfiltration and its mediation by adenosine in diabetes merits further study.
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Affiliation(s)
- Harindra Rajasekeran
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Onatario, Canada
| | - Yuliya Lytvyn
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Andrea Bozovic
- Departments of Clinical Biochemistry and Laboratory Medicine and Pathobiology, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Julie A. Lovshin
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Eleftherios Diamandis
- Departments of Clinical Biochemistry and Laboratory Medicine and Pathobiology, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Daniel Cattran
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Mansoor Husain
- Division of Cardiology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada; and
| | - Bruce A. Perkins
- Division of Endocrinology and Metabolism, Department of Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Advani
- Division of Endocrinology, Department of Medicine, Saint Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Heather N. Reich
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Vathany Kulasingam
- Departments of Clinical Biochemistry and Laboratory Medicine and Pathobiology, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - David Z. I. Cherney
- Division of Nephrology, Department of Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Onatario, Canada
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18
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Olivier PY, Beloncle F, Seegers V, Tabka M, Renou de La Bourdonnaye M, Mercat A, Cales P, Henrion D, Radermacher P, Piquilloud L, Lerolle N, Asfar P. Assessment of renal hemodynamic toxicity of fluid challenge with 0.9% NaCl compared to balanced crystalloid (PlasmaLyte ®) in a rat model with severe sepsis. Ann Intensive Care 2017; 7:66. [PMID: 28616838 PMCID: PMC5471284 DOI: 10.1186/s13613-017-0286-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 06/01/2017] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND According to international guidelines, volume expansion with crystalloids is the first-line treatment for hemodynamic management in patients with severe sepsis or septic shock. Compared to balanced crystalloids, 0.9% sodium chloride (0.9% NaCl) induces hyperchloremia and metabolic acidosis and may alter renal hemodynamics and function. We compared the effects of 0.9% NaCl to a less chloride-concentrated fluid, PlasmaLyte® (PL) in targeted fluid resuscitation in a randomized, double-blind controlled study in an experimental model of severe sepsis in rats. RESULTS A sepsis with hypotension was induced by cecal ligature and puncture (CLP) in 40 male Wistar rats (20 for each crystalloid). Rats received fluid resuscitation over a period of 200 min for a targeted mean arterial pressure of 90 mm Hg. Animals received similar volumes of 0.9% NaCl or PL. Unlike PL-resuscitated rats, 0.9% NaCl-resuscitated rats experienced hyperchloremia and metabolic acidosis, whereas systemic hemodynamics, renal hemodynamics and renal function were not significantly different between both groups. CONCLUSION In our model of rats with severe sepsis resuscitated with large amounts of crystalloids, 0.9% NaCl-induced hyperchloremic acidosis, but balanced crystalloid did not improve systemic and renal hemodynamics or renal function.
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Affiliation(s)
- Pierre-Yves Olivier
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Medical Intensive Care Department, University Hospital, Angers, France.,BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France
| | - François Beloncle
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Medical Intensive Care Department, University Hospital, Angers, France.,BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France
| | - Valérie Seegers
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Statistical Department, University Hospital, Angers, France
| | - Maher Tabka
- BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France.,Faculté de médecine d'Angers, 4 rue haute de reculée, 49000, Angers, France
| | - Mathilde Renou de La Bourdonnaye
- BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France.,Faculté de médecine d'Angers, 4 rue haute de reculée, 49000, Angers, France
| | - Alain Mercat
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Medical Intensive Care Department, University Hospital, Angers, France
| | - Paul Cales
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,HIFIH, UPRE-EA 3859, SFR 4208, LUNAM University, Angers, France
| | - Daniel Henrion
- BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France.,Faculté de médecine d'Angers, 4 rue haute de reculée, 49000, Angers, France
| | - Peter Radermacher
- Universitätsklinikum, Ulm Helmholtzstr. 8/1, 89081, Ulm, Germany.,Institut für Anästhesiologische Pathophysiologie und Verfahrensentwicklung, Universitätsklinikum, Ulm, Germany
| | - Lise Piquilloud
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Medical Intensive Care Department, University Hospital, Angers, France
| | - Nicolas Lerolle
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France.,Medical Intensive Care Department, University Hospital, Angers, France.,BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France
| | - Pierre Asfar
- CHU d'Angers, 4 rue Larrey, 49000, Angers, France. .,Medical Intensive Care Department, University Hospital, Angers, France. .,BNMI Laboratory, CNRS UMR 6214-INSERM U1083, Angers University, Angers, France.
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19
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Li H, Sun SR, Yap JQ, Chen JH, Qian Q. 0.9% saline is neither normal nor physiological. J Zhejiang Univ Sci B 2016; 17:181-7. [PMID: 26984838 DOI: 10.1631/jzus.b1500201] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The purpose of this review is to objectively evaluate the biochemical and pathophysiological properties of 0.9% saline (henceforth: saline) and to discuss the impact of saline infusion, specifically on systemic acid-base balance and renal hemodynamics. Studies have shown that electrolyte balance, including effects of saline infusion on serum electrolytes, is often poorly understood among practicing physicians and inappropriate saline prescribing can cause increased morbidity and mortality. Large-volume (>2 L) saline infusion in healthy adults induces hyperchloremia which is associated with metabolic acidosis, hyperkalemia, and negative protein balance. Saline overload (80 ml/kg) in rodents can cause intestinal edema and contractile dysfunction associated with activation of sodium-proton exchanger (NHE) and decrease in myosin light chain phosphorylation. Saline infusion can also adversely affect renal hemodynamics. Microperfusion experiments and real-time imaging studies have demonstrated a reduction in renal perfusion and an expansion in kidney volume, compromising O2 delivery to the renal parenchyma following saline infusion. Clinically, saline infusion for patients post abdominal and cardiovascular surgery is associated with a greater number of adverse effects including more frequent blood product transfusion and bicarbonate therapy, reduced gastric blood flow, delayed recovery of gut function, impaired cardiac contractility in response to inotropes, prolonged hospital stay, and possibly increased mortality. In critically ill patients, saline infusion, compared to balanced fluid infusions, increases the occurrence of acute kidney injury. In summary, saline is a highly acidic fluid. With the exception of saline infusion for patients with hypochloremic metabolic alkalosis and volume depletion due to vomiting or upper gastrointestinal suction, indiscriminate use, especially for acutely ill patients, may cause unnecessary complications and should be avoided. More education regarding saline-related effects and adequate electrolyte management is needed.
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Affiliation(s)
- Heng Li
- Kidney Disease Center, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Shi-ren Sun
- Division of Nephrology, Xijin Hospital, Fourth Military University College of Medicine, Xi'an 710032, China
| | - John Q Yap
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
| | - Jiang-hua Chen
- Kidney Disease Center, the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310003, China
| | - Qi Qian
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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20
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Schnermann J. Concurrent activation of multiple vasoactive signaling pathways in vasoconstriction caused by tubuloglomerular feedback: a quantitative assessment. Annu Rev Physiol 2015; 77:301-22. [PMID: 25668021 DOI: 10.1146/annurev-physiol-021014-071829] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Tubuloglomerular feedback (TGF) describes the negative relationship between (a) NaCl concentration at the macula densa and (b) glomerular filtration rate or glomerular capillary pressure. TGF-induced vasoconstriction of the afferent arteriole results from the enhanced effect of several vasoconstrictors with an effect size sequence of adenosine = 20-HETE > angiotensin II > thromboxane = superoxide > renal nerves > ATP. TGF-mediated vasoconstriction is limited by the simultaneous release of several vasodilators with an effect size sequence of nitric oxide > carbon monoxide = kinins > adenosine. The sum of the constrictor effects exceeds that of the dilator effects by the magnitude of the TGF response. The validity of the additive model used in this analysis can be tested by determining the effect of combined inhibition of some or all agents contributing to TGF. Multiple independent contributors to TGF are consistent with the variability of TGF and of the factors contributing to TGF resetting.
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Affiliation(s)
- Jurgen Schnermann
- Kidney Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892;
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21
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Besen BAMP, Gobatto ALN, Melro LMG, Maciel AT, Park M. Fluid and electrolyte overload in critically ill patients: An overview. World J Crit Care Med 2015; 4:116-129. [PMID: 25938027 PMCID: PMC4411563 DOI: 10.5492/wjccm.v4.i2.116] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 12/24/2014] [Accepted: 03/05/2015] [Indexed: 02/06/2023] Open
Abstract
Fluids are considered the cornerstone of therapy for many shock states, particularly states that are associated with relative or absolute hypovolemia. Fluids are also commonly used for many other purposes, such as renal protection from endogenous and exogenous substances, for the safe dilution of medications and as “maintenance” fluids. However, a large amount of evidence from the last decade has shown that fluids can have deleterious effects on several organ functions, both from excessive amounts of fluids and from their non-physiological electrolyte composition. Additionally, fluid prescription is more common in patients with systemic inflammatory response syndrome whose kidneys may have impaired mechanisms of electrolyte and free water excretion. These processes have been studied as separate entities (hypernatremia, hyperchloremic acidosis and progressive fluid accumulation) leading to worse outcomes in many clinical scenarios, including but not limited to acute kidney injury, worsening respiratory function, higher mortality and higher hospital and intensive care unit length-of-stays. In this review, we synthesize this evidence and describe this phenomenon as fluid and electrolyte overload with potentially deleterious effects. Finally, we propose a strategy to safely use fluids and thereafter wean patients from fluids, along with other caveats to be considered when dealing with fluids in the intensive care unit.
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22
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Layton AT. Recent advances in renal hemodynamics: insights from bench experiments and computer simulations. Am J Physiol Renal Physiol 2015; 308:F951-5. [PMID: 25715984 DOI: 10.1152/ajprenal.00008.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/23/2015] [Indexed: 01/08/2023] Open
Abstract
It has been long known that the kidney plays an essential role in the control of body fluids and blood pressure and that impairment of renal function may lead to the development of diseases such as hypertension (Guyton AC, Coleman TG, Granger Annu Rev Physiol 34: 13-46, 1972). In this review, we highlight recent advances in our understanding of renal hemodynamics, obtained from experimental and theoretical studies. Some of these studies were published in response to a recent Call for Papers of this journal: Renal Hemodynamics: Integrating with the Nephron and Beyond.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina
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23
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Abstract
There are nineteen different receptor proteins for adenosine, adenine and uridine nucleotides, and nucleotide sugars, belonging to three families of G protein-coupled adenosine and P2Y receptors, and ionotropic P2X receptors. The majority are functionally expressed in blood vessels, as purinergic receptors in perivascular nerves, smooth muscle and endothelial cells, and roles in regulation of vascular contractility, immune function and growth have been identified. The endogenous ligands for purine receptors, ATP, ADP, UTP, UDP and adenosine, can be released from different cell types within the vasculature, as well as from circulating blood cells, including erythrocytes and platelets. Many purine receptors can be activated by two or more of the endogenous ligands. Further complexity arises because of interconversion between ligands, notably adenosine formation from the metabolism of ATP, leading to complex integrated responses through activation of different subtypes of purine receptors. The enzymes responsible for this conversion, ectonucleotidases, are present on the surface of smooth muscle and endothelial cells, and may be coreleased with neurotransmitters from nerves. What selectivity there is for the actions of purines/pyrimidines comes from differential expression of their receptors within the vasculature. P2X1 receptors mediate the vasocontractile actions of ATP released as a neurotransmitter with noradrenaline (NA) from sympathetic perivascular nerves, and are located on the vascular smooth muscle adjacent to the nerve varicosities, the sites of neurotransmitter release. The relative contribution of ATP and NA as functional cotransmitters varies with species, type and size of blood vessel, neuronal firing pattern, the tone/pressure of the blood vessel, and in ageing and disease. ATP is also a neurotransmitter in non-adrenergic non-cholinergic perivascular nerves and mediates vasorelaxation via smooth muscle P2Y-like receptors. ATP and adenosine can act as neuromodulators, with the most robust evidence being for prejunctional inhibition of neurotransmission via A1 adenosine receptors, but also prejunctional excitation and inhibition of neurotransmission via P2X and P2Y receptors, respectively. P2Y2, P2Y4 and P2Y6 receptors expressed on the vascular smooth muscle are coupled to vasocontraction, and may have a role in pathophysiological conditions, when purines are released from damaged cells, or when there is damage to the protective barrier that is the endothelium. Adenosine is released during hypoxia to increase blood flow via vasodilator A2A and A2B receptors expressed on the endothelium and smooth muscle. ATP is released from endothelial cells during hypoxia and shear stress and can act at P2Y and P2X4 receptors expressed on the endothelium to increase local blood flow. Activation of endothelial purine receptors leads to the release of nitric oxide, hyperpolarising factors and prostacyclin, which inhibits platelet aggregation and thus ensures patent blood flow. Vascular purine receptors also regulate endothelial and smooth muscle growth, and inflammation, and thus are involved in the underlying processes of a number of cardiovascular diseases.
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Affiliation(s)
- Vera Ralevic
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
| | - William R Dunn
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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24
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Abstract
Intrarenal autoregulatory mechanisms maintain renal blood flow (RBF) and glomerular filtration rate (GFR) independent of renal perfusion pressure (RPP) over a defined range (80-180 mmHg). Such autoregulation is mediated largely by the myogenic and the macula densa-tubuloglomerular feedback (MD-TGF) responses that regulate preglomerular vasomotor tone primarily of the afferent arteriole. Differences in response times allow separation of these mechanisms in the time and frequency domains. Mechanotransduction initiating the myogenic response requires a sensing mechanism activated by stretch of vascular smooth muscle cells (VSMCs) and coupled to intracellular signaling pathways eliciting plasma membrane depolarization and a rise in cytosolic free calcium concentration ([Ca(2+)]i). Proposed mechanosensors include epithelial sodium channels (ENaC), integrins, and/or transient receptor potential (TRP) channels. Increased [Ca(2+)]i occurs predominantly by Ca(2+) influx through L-type voltage-operated Ca(2+) channels (VOCC). Increased [Ca(2+)]i activates inositol trisphosphate receptors (IP3R) and ryanodine receptors (RyR) to mobilize Ca(2+) from sarcoplasmic reticular stores. Myogenic vasoconstriction is sustained by increased Ca(2+) sensitivity, mediated by protein kinase C and Rho/Rho-kinase that favors a positive balance between myosin light-chain kinase and phosphatase. Increased RPP activates MD-TGF by transducing a signal of epithelial MD salt reabsorption to adjust afferent arteriolar vasoconstriction. A combination of vascular and tubular mechanisms, novel to the kidney, provides for high autoregulatory efficiency that maintains RBF and GFR, stabilizes sodium excretion, and buffers transmission of RPP to sensitive glomerular capillaries, thereby protecting against hypertensive barotrauma. A unique aspect of the myogenic response in the renal vasculature is modulation of its strength and speed by the MD-TGF and by a connecting tubule glomerular feedback (CT-GF) mechanism. Reactive oxygen species and nitric oxide are modulators of myogenic and MD-TGF mechanisms. Attenuated renal autoregulation contributes to renal damage in many, but not all, models of renal, diabetic, and hypertensive diseases. This review provides a summary of our current knowledge regarding underlying mechanisms enabling renal autoregulation in health and disease and methods used for its study.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Christopher S Wilcox
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - William J Arendshorst
- Department of Medicine, Division of Nephrology and Hypertension and Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, District of Columbia; Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; and Department of Cell Biology and Physiology, UNC Kidney Center, and McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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Song J, Lu Y, Lai EY, Wei J, Wang L, Chandrashekar K, Wang S, Shen C, Juncos LA, Liu R. Oxidative status in the macula densa modulates tubuloglomerular feedback responsiveness in angiotensin II-induced hypertension. Acta Physiol (Oxf) 2015; 213:249-58. [PMID: 25089004 DOI: 10.1111/apha.12358] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 06/27/2014] [Accepted: 07/28/2014] [Indexed: 12/20/2022]
Abstract
AIM Tubuloglomerular feedback (TGF) is an important mechanism in control of signal nephron glomerular filtration rate. The oxidative stress in the macula densa, primarily determined by the interactions between nitric oxide (NO) and superoxide (O2-), is essential in maintaining the TGF responsiveness. However, few studies examining the interactions between and amount of NO and O2- generated by the macula densa during normal and hypertensive states. METHODS In this study, we used isolated perfused juxtaglomerular apparatus to directly measure the amount and also studied the interactions between NO and O2- in macula densa in both physiological and slow pressor Angiotensin II (Ang II)-induced hypertensive mice. RESULTS We found that slow pressor Ang II at a dose of 600 ng kg(-1) min(-1) for two weeks increased mean arterial pressure by 26.1 ± 5.7 mmHg. TGF response increased from 3.4 ± 0.2 μm in control to 5.2 ± 0.2 μm in hypertensive mice. We first measured O2- generation by the macula densa and found it was undetectable in control mice. However, O2- generation by the macula densa increased to 21.4 ± 2.5 unit min(-1) in Ang II-induced hypertensive mice. We then measured NO generation and found that NO generation by the macula densa was 138.5 ± 9.3 unit min(-1) in control mice. The NO was undetectable in the macula densa in hypertensive mice infused with Ang II. CONCLUSIONS Under physiological conditions, TGF response is mainly controlled by the NO generated in the macula densa; in Ang II induced hypertension, the TGF response is mainly controlled by the O2- generated by the macula densa.
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Affiliation(s)
- J. Song
- State Key Laboratory of Cardiovascular Disease; Fuwai Hospital; National Center for Cardiovascular Diseases; Chinese Academy of Medical Sciences and Peking Union Medical College; Beijing China
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - Y. Lu
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
- Division of Nephrology; Department of Medicine; University of Mississippi Medical Center; Jackson MS USA
| | - E. Y. Lai
- Department of Physiology; Zhejiang University; Hanzhou China
| | - J. Wei
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - L. Wang
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - K. Chandrashekar
- Division of Nephrology; Department of Medicine; University of Mississippi Medical Center; Jackson MS USA
| | - S. Wang
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - C. Shen
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
| | - L. A. Juncos
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
- Division of Nephrology; Department of Medicine; University of Mississippi Medical Center; Jackson MS USA
| | - R. Liu
- Department of Physiology & Biophysics; University of Mississippi Medical Center; Jackson MS USA
- Division of Nephrology; Department of Medicine; University of Mississippi Medical Center; Jackson MS USA
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Jönsson S, Agic MB, Narfström F, Melville JM, Hultström M. Renal neurohormonal regulation in heart failure decompensation. Am J Physiol Regul Integr Comp Physiol 2014; 307:R493-7. [PMID: 24920735 DOI: 10.1152/ajpregu.00178.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Decompensation in heart failure occurs when the heart fails to balance venous return with cardiac output, leading to fluid congestion and contributing to mortality. Decompensated heart failure can cause acute kidney injury (AKI), which further increases mortality. Heart failure activates signaling systems that are deleterious to kidneys such as renal sympathetic nerve activity (RSNA), renin-angiotensin-aldosterone system, and vasopressin secretion. All three reduce renal blood flow (RBF) and increase tubular sodium reabsorption, which may increase renal oxygen consumption causing AKI through renal tissue hypoxia. Vasopressin contributes to venous congestion through aquaporin-mediated water retention. Additional water retention may be mediated through vasopressin-induced medullary urea transport and hyaluronan but needs further study. In addition, there are several systems that could protect the kidneys and reduce fluid retention such as natriuretic peptides, prostaglandins, and nitric oxide. However, the effect of natriuretic peptides and nitric oxide are blunted in decompensation, partly due to oxidative stress. This review considers how neurohormonal signaling in heart failure drives fluid retention by the kidneys and thus exacerbates decompensation. It further identifies areas where there is limited data, such as signaling systems 20-HETE, purines, endothelin, the role of renal water retention mechanisms for congestion, and renal hypoxia in AKI during heart failure.
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Affiliation(s)
- Sofia Jönsson
- Unit for Integrative Physiology, Department of Medical Cellbiology, Uppsala University, Uppsala, Sweden; and
| | - Mediha Becirovic Agic
- Unit for Integrative Physiology, Department of Medical Cellbiology, Uppsala University, Uppsala, Sweden; and
| | - Fredrik Narfström
- Unit for Anaesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Jacqueline M Melville
- Unit for Integrative Physiology, Department of Medical Cellbiology, Uppsala University, Uppsala, Sweden; and
| | - Michael Hultström
- Unit for Integrative Physiology, Department of Medical Cellbiology, Uppsala University, Uppsala, Sweden; and Unit for Anaesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
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27
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A randomized, controlled, double-blind crossover study on the effects of 1-L infusions of 6% hydroxyethyl starch suspended in 0.9% saline (voluven) and a balanced solution (Plasma Volume Redibag) on blood volume, renal blood flow velocity, and renal cortical tissue perfusion in healthy volunteers. Ann Surg 2014; 259:881-7. [PMID: 24253140 DOI: 10.1097/sla.0000000000000324] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE We compared the effects of intravenous administration of 6% hydroxyethyl starch (maize-derived) in 0.9% saline (Voluven; Fresenius Kabi, Runcorn, United Kingdom) and a "balanced" preparation of 6% hydroxyethyl starch (potato-derived) [Plasma Volume Redibag (PVR); Baxter Healthcare, Thetford, United Kingdom] on renal blood flow velocity and renal cortical tissue perfusion in humans using magnetic resonance imaging. BACKGROUND Hyperchloremia resulting from 0.9% saline infusion may adversely affect renal hemodynamics when compared with balanced crystalloids. This phenomenon has not been studied with colloids. METHODS Twelve healthy adult male subjects received 1-L intravenous infusions of Voluven or PVR over 30 minutes in a randomized, double-blind manner, with crossover studies 7 to 10 days later. Magnetic resonance imaging proceeded for 60 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled, and weight was recorded at 0, 30, 60, 120, 180, and 240 minutes. RESULTS Mean peak serum chloride concentrations were 108 and 106 mmol/L, respectively, after Voluven and PVR infusion (P = 0.032). Changes in blood volume (P = 0.867), strong ion difference (P = 0.219), and mean renal artery flow velocity (P = 0.319) were similar. However, there was a significant increase in mean renal cortical tissue perfusion after PVR when compared with Voluven (P = 0.033). There was no difference in urinary neutrophil gelatinase-associated liopcalin to creatinine ratios after the infusion (P = 0.164). CONCLUSIONS There was no difference in the blood volume-expanding properties of the 2 preparations of 6% hydroxyethyl starch. The balanced starch produced an increase in renal cortical tissue perfusion, a phenomenon not seen with starch in 0.9% saline.
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Lobo DN, Awad S. Should chloride-rich crystalloids remain the mainstay of fluid resuscitation to prevent 'pre-renal' acute kidney injury?: con. Kidney Int 2014; 86:1096-105. [PMID: 24717302 PMCID: PMC4255073 DOI: 10.1038/ki.2014.105] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 02/07/2023]
Abstract
The high chloride content of 0.9% saline leads to adverse pathophysiological effects in both animals and healthy human volunteers, changes not seen after balanced crystalloids. Small randomized trials confirm that the hyperchloremic acidosis induced by saline also occurs in patients, but no clinical outcome benefit was demonstrable when compared with balanced crystalloids, perhaps due to a type II error. A strong signal is emerging from recent large propensity-matched and cohort studies for the adverse effects that 0.9% saline has on the clinical outcome in surgical and critically ill patients when compared with balanced crystalloids. Major complications are the increased incidence of acute kidney injury and the need for renal replacement therapy, and that pathological hyperchloremia may increase postoperative mortality. However, there are no large-scale randomized trials comparing 0.9% saline with balanced crystalloids. Some balanced crystalloids are hypo-osmolar and may not be suitable for neurosurgical patients because of their propensity to cause brain edema. Saline may be the solution of choice used for the resuscitation of patients with alkalosis and hypochloremia. Nevertheless, there is evidence to suggest that balanced crystalloids cause less detriment to renal function than 0.9% saline, with perhaps better clinical outcome. Hence, we argue that chloride-rich crystalloids such as 0.9% saline should be replaced with balanced crystalloids as the mainstay of fluid resuscitation to prevent ‘pre-renal' acute kidney injury.
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Affiliation(s)
- Dileep N Lobo
- Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre, National Institute of Health Research Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham, UK
| | - Sherif Awad
- Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre, National Institute of Health Research Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham, UK
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Persson AEG, Lai EY, Gao X, Carlström M, Patzak A. Interactions between adenosine, angiotensin II and nitric oxide on the afferent arteriole influence sensitivity of the tubuloglomerular feedback. Front Physiol 2013; 4:187. [PMID: 23882224 PMCID: PMC3714451 DOI: 10.3389/fphys.2013.00187] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 06/28/2013] [Indexed: 11/13/2022] Open
Abstract
Adenosine, via activation of A1 receptors on the afferent arteriole (AA), mediates the tubuloglomerular feedback (TGF) mechanism. Angiotensin II and nitric oxide (NO) can modulate the sensitivity of the TGF mechanism. However, the interaction among these substances in regulating the TGF resetting phenomenon has been debated. Studies in isolated perfused AA have shown a biphasic response to accumulating doses of adenosine alone. In the nanomolar range adenosine has a weak contractile effect (7%), whereas vasodilatation is observed at high concentrations. However, a synergistic interaction between the contractile response by adenosine and that of angiotensin II has been demonstrated. Adenosine in low concentrations strongly enhances the response to angiotensin II. At the same time, angiotensin II in physiological concentrations increases significantly the contractile response to adenosine. Moreover, addition of a NO donor (spermine NONOate) to increase NO bioavailability abolished the contractile response from combined application of angiotensin II and adenosine. These mutual modulating effects of adenosine and angiotensin II, and the effect of NO on the response of AA can contribute to the resetting of the TGF sensitivity.
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Affiliation(s)
- A E G Persson
- Department of Medical Cell Biology, Uppsala University Uppsala, Sweden
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30
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Oppermann M, Carota I, Schiessl I, Eisner C, Castrop H, Schnermann J. Direct assessment of tubuloglomerular feedback responsiveness in connexin 40-deficient mice. Am J Physiol Renal Physiol 2013; 304:F1181-6. [PMID: 23445620 PMCID: PMC3651628 DOI: 10.1152/ajprenal.00721.2012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 02/26/2013] [Indexed: 11/22/2022] Open
Abstract
Participation of connexin 40 (Cx40) in the regulation of renin secretion and in the tubuloglomerular feedback (TGF) component of renal autoregulation suggests that gap junctional coupling through Cx40 contributes to the function of the juxtaglomerular apparatus. In the present experiments, we determined the effect of targeted Cx40 deletion in C57BL/6 and FVB mice on TGF responsiveness. In C57BL/6 mice, stop-flow pressure (PSF) fell from 40.3 ± 2 to 34.5 ± 2 mmHg in wild-type (WT) and from 31 ± 1.06 to 26.6 ± 0.98 mmHg in Cx40-/- mice. PSF changes of 5.85 ± 0.67 mmHg in WT and of 4.3 ± 0.55 mmHg in Cx40-/- mice were not significantly different (P = 0.08). In FVB mice, PSF fell from 37.4 ± 1.5 to 31.6 ± 1.5 mmHg in WT and from 28.1 ± 1.6 to 25.4 ± 1.7 mmHg in Cx40-/-, with mean TGF responses being significantly greater in WT than Cx40-/- (5.5 ± 0.55 vs. 2.7 ± 0.84 mmHg; P = 0.002). In both genetic backgrounds, PSF values were significantly lower in Cx40-/- than WT mice at all flow rates. Arterial blood pressure in the animals prepared for micropuncture was not different between WT and Cx40-/- mice. We conclude that the TGF response magnitude in superficial cortical nephrons is reduced by 30-50% in mice without Cx40, but that with the exception of a small number of nephrons, residual TGF activity is maintained. Thus gap junctional coupling appears to modulate TGF, perhaps by determining the kinetics of signal transmission.
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Affiliation(s)
- Mona Oppermann
- Institute of Physiology, University of Regensburg, Regensburg, Germany
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31
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Zhang Q, Lin L, Lu Y, Liu H, Duan Y, Zhu X, Zou C, Manning RD, Liu R. Interaction between nitric oxide and superoxide in the macula densa in aldosterone-induced alterations of tubuloglomerular feedback. Am J Physiol Renal Physiol 2012; 304:F326-32. [PMID: 23220724 DOI: 10.1152/ajprenal.00501.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Tubuloglomerular feedback (TGF)-mediated constriction of the afferent arteriole is modulated by a balance between release of superoxide (O(2)(-)) and nitric oxide (NO) in macula densa (MD) cells. Aldosterone activates mineralocorticoid receptors that are expressed in the MD and induces both NO and O(2)(-) generation. We hypothesize that aldosterone enhances O(2)(-) production in the MD mediated by protein kinase C (PKC), which buffers the effect of NO in control of TGF response. Studies were performed in microdissected and perfused MD and in a MD cell line, MMDD1 cells. Aldosterone significantly enhanced O(2)(-) generation both in perfused MD and in MMDD1 cells. When aldosterone (10(-7) mol/l) was added in the tubular perfusate, TGF response was reduced from 2.4 ± 0.3 μm to 1.4 ± 0.2 μm in isolated perfused MD. In the presence of tempol, a O(2)(-) scavenger, TGF response was 1.5 ± 0.2 μm. In the presence of both tempol and aldosterone in the tubular perfusate, TGF response was further reduced to 0.4 ± 0.2 μm. To determine if PKC is involved in aldosterone-induced O(2)(-) production, we exposed the O(2)(-) cells to a nonselective PKC inhibitor chelerythrine chloride, a specific PKCα inhibitor Go6976, or a PKCα siRNA, and the aldosterone-induced increase in O(2)(-) production was blocked. These data indicate that aldosterone-stimulated O(2)(-) production in the MD buffers the effect of NO in control of TGF response, an effect that was mediated by PKCα.
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Affiliation(s)
- Qian Zhang
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
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32
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A Randomized, Controlled, Double-Blind Crossover Study on the Effects of 2-L Infusions of 0.9% Saline and Plasma-Lyte® 148 on Renal Blood Flow Velocity and Renal Cortical Tissue Perfusion in Healthy Volunteers. Ann Surg 2012; 256:18-24. [DOI: 10.1097/sla.0b013e318256be72] [Citation(s) in RCA: 537] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Riksen NP, Rongen GA. Targeting adenosine receptors in the development of cardiovascular therapeutics. Expert Rev Clin Pharmacol 2012; 5:199-218. [PMID: 22390562 DOI: 10.1586/ecp.12.8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine receptor stimulation has negative inotropic and dromotropic actions, reduces cardiac ischemia-reperfusion injury and remodeling, and prevents cardiac arrhythmias. In the vasculature, adenosine modulates vascular tone, reduces infiltration of inflammatory cells and generation of foam cells, and may prevent the development of atherosclerosis as a result. Modulation of insulin sensitivity may further add to the anti-atherosclerotic properties of adenosine signaling. In the kidney, adenosine plays an important role in tubuloglomerular feedback and modulates tubular sodium reabsorption. The challenge is to take advantage of the beneficial actions of adenosine signaling while preventing its potential adverse effects, such as salt retention and sympathoexcitation. Drugs that interfere with adenosine formation and elimination or drugs that allosterically enhance specific adenosine receptors seem to be most promising to meet this challenge.
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Affiliation(s)
- Niels P Riksen
- Department of Pharmacology-Toxicology 149 and Internal Medicine 463, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Cabral PD, Hong NJ, Garvin JL. ATP mediates flow-induced NO production in thick ascending limbs. Am J Physiol Renal Physiol 2012; 303:F194-200. [PMID: 22496412 DOI: 10.1152/ajprenal.00504.2011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical stimulation caused by increasing flow induces nucleotide release from many cells. Luminal flow and extracellular ATP stimulate production of nitric oxide (NO) in thick ascending limbs. However, the factors that mediate flow-induced NO production are unknown. We hypothesized that luminal flow stimulates thick ascending limb NO production via ATP. We measured NO in isolated, perfused rat thick ascending limbs using the fluorescent dye DAF FM. The rate of increase in dye fluorescence reflects NO accumulation. Increasing luminal flow from 0 to 20 nl/min stimulated NO production from 17 ± 16 to 130 ± 37 arbitrary units (AU)/min (P < 0.02). Increasing flow from 0 to 20 nl/min raised ATP release from 4 ± 1 to 21 ± 6 AU/min (P < 0.04). Hexokinase (10 U/ml) plus glucose, which consumes ATP, completely prevented the measured increase in ATP. Luminal flow did not increase NO production in the presence of luminal and basolateral hexokinase (10 U/ml). When flow was increased with the ATPase apyrase in both luminal and basolateral solutions (5 U/ml), NO levels did not change significantly. The P2 receptor antagonist suramin (300 μmol/l) reduced flow-induced NO production by 83 ± 25% (P < 0.03) when added to both and basolateral sides. Luminal hexokinase decreased flow-induced NO production from 205.6 ± 85.6 to 36.6 ± 118.6 AU/min (P < 0.02). Basolateral hexokinase also reduced flow-induced NO production. The P2X receptor-selective antagonist NF023 (200 μmol/l) prevented flow-induced NO production when added to the basolateral side but not the luminal side. We conclude that ATP mediates flow-induced NO production in the thick ascending limb likely via activation of P2Y receptors in the luminal and P2X receptors in the basolateral membrane.
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Affiliation(s)
- Pablo D Cabral
- Hypertension and Vascular Research Div., Dept. of Internal Medicine, Henry Ford Hospital, 2799 West Grand Blvd., Detroit, MI 48202, USA.
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35
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Guan Z, Inscho EW. Role of adenosine 5'-triphosphate in regulating renal microvascular function and in hypertension. Hypertension 2011; 58:333-40. [PMID: 21768526 DOI: 10.1161/hypertensionaha.110.155952] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
ATP is an essential energy substrate for cellular metabolism, but it can also influence many biological processes when released into the extracellular milieu. Research has established that extracellular ATP acts as an autocrine/paracrine factor that regulates many physiological functions. Alternatively, excessive extracellular ATP levels contribute to pathophysiological processes, such as inflammation, cell proliferation and apoptosis, and atherosclerosis. Renal P2 receptors are widely distributed throughout glomeruli, vasculature, and tubular segments and participate in controlling renal vascular resistance, mediating renal autoregulation, and regulating tubular transport function. This review will focus on the role of ATP-P2 receptor signaling in regulating renal microvascular function and autoregulation, recent advances on the role of ATP-P2 signaling in hypertension-associated renal vascular injury, and emerging new directions.
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Affiliation(s)
- Zhengrong Guan
- Department of Physiology CA3137, Georgia Health Sciences University, 1120 15th St, Augusta, GA 30912, USA
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36
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Lai EY, Wang Y, Persson AEG, Manning RD, Liu R. Pressure induces intracellular calcium changes in juxtaglomerular cells in perfused afferent arterioles. Hypertens Res 2011; 34:942-8. [PMID: 21633358 DOI: 10.1038/hr.2011.65] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Calcium (Ca(2+)) has an important role in nearly all types of cellular secretion, with a particularly novel role in the juxtaglomerular (JG) cells in the kidney. In JG cells, Ca(2+) inhibits renin secretion, which is a major regulator of blood pressure and renal hemodynamics. However, whether alterations in afferent arteriolar (Af-Art) pressure change intracellular Ca(2+) concentration ([Ca(2+)](i)) in JG cells and whether [Ca(2+)](i) comes from extracellular or intracellular sources remains unknown. We hypothesize that increases in perfusion pressure in the Af-Art result in elevations in [Ca(2+)](i) in JG cells. We isolated and perfused Af-Art of C57BL6 mice and measured changes in [Ca(2+)](i) in JG cells in response to perfusion pressure changes. The JG cells' [Ca(2+)](i) was 93.3±2.2 nM at 60 mm Hg perfusion pressure and increased to 111.3±13.4, 119.6±7.3, 130.3±2.9 and 140.8±12.1 nM at 80, 100, 120 and 140 mm Hg, respectively. At 120 mm Hg, increases in [Ca(2+)](i) were reduced in mice receiving the following treatments: (1) the mechanosensitive cation channel blocker, gadolinium (94.6±7.5 nM); (2) L-type calcium channel blocker, nifedipine (105.8±7.5 nM); and (3) calcium-free solution plus ethylene glycol tetraacetic acid (96.0±5.8 nM). Meanwhile, the phospholipase C inhibitor, inositol triphosphate receptor inhibitor, T-type calcium channel blocker, N-type calcium channel blocker and Ca(2+)-ATPase inhibitor did not influence changes in [Ca(2+)](i) in JG cells. In summary, JG cell [Ca(2+)](i) rise as perfusion pressure increases; furthermore, the calcium comes from extracellular sources, specifically mechanosensitive cation channels and L-type calcium channels.
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Affiliation(s)
- En Yin Lai
- Department of Medical Cell Biology, Division of Integrative Physiology, Uppsala University, Uppsala, Sweden
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Morris C, Plumb J. Mobilising Oedema in the Oedematous Critically Ill Patient with ARDS: Do We Seek Natriuresis Not Diuresis? J Intensive Care Soc 2011. [DOI: 10.1177/175114371101200204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In the treatment of the acute respiratory distress syndrome in the intensive care unit, one of the aims is to achieve a negative fluid balance. Traditional use of sole-agent loop diuretics such as furosemide often results in the loss of free water, dehydration, hypernatraemia and metabolic alkalosis, with therapeutic failure once water is replaced. A more rational approach is to induce natriuresis with loss of sodium in the urine to reduce extracellular and interstitial fluid volume, not total body water. Polypharmacy with a loop diuretic combined with other weak diuretics to prevent tubules modifying glomerular filtrate, promotes natriuresis with large volume urinary losses and minimal electrolyte disturbance, and the excretion of urine with a composition comparable to plasma.
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Affiliation(s)
- Craig Morris
- Consultant Intensivist and Anaesthetist
- Royal Derby Hospital
| | - James Plumb
- CT3 in Anaesthesia and Intensive Care Medicine
- Royal Derby Hospital
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38
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Schnermann J. Maintained tubuloglomerular feedback responses during acute inhibition of P2 purinergic receptors in mice. Am J Physiol Renal Physiol 2010; 300:F339-44. [PMID: 21147842 DOI: 10.1152/ajprenal.00637.2010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tubuloglomerular feedback (TGF), the change of afferent arteriolar resistance initiated by changes of luminal NaCl concentration, is thought to be related to NaCl-dependent release of ATP by macula densa cells. In the present study, we have explored the possibility that the released ATP may directly interact with vasoconstrictor P2 purinergic receptors in the vicinity of the glomerular vascular pole. In two different strains of wild-type mice (SWR/J and FVB), TGF responses were determined in vivo by measuring the stop flow pressure (P(SF)) change caused by a saturating increase in loop of Henle flow rate before and during the administration of the P2 receptor inhibitors PPADS (12 mg/kg + 35 mg·kg(-1)·h(-1) iv) or suramin (50 mg/kg + 150 mg·kg(-1)·h(-1)). Both agents significantly reduced the blood pressure response to the P2X agonist α,β-methylene ATP. In SWR/J and FVB mice, elevating flow to 30 nl/min reduced P(SF) by 16.4 ± 2.2 and 17.1 ± 1.8%. During infusion of PPADS, P(SF) fell by 18.8 ± 2 (P = 0.4) and 16.5 ± 1.5% (P = 0.82) in the two strains of mice. During suramin infusion, P(SF) decreased by 14.7 ± 2.4 (P = 0.62) and 15 ± 1.3% (P = 0.4) in SWR/J and FVB mice, respectively. Including PPADS (10(-4) M) in the loop perfusate did not significantly alter the P(SF) response (18.9 ± 1.8%; P = 0.54). Arterial blood pressure was not systematically affected by the P2 inhibitors. As measured by free-flow micropuncture, PPADS significantly reduced proximal tubular fluid reabsorption in both fractional and absolute terms. These results indicate that the direct activation of P2 purinergic receptors by ATP is not a major cause of TGF-induced vasoconstriction in vivo.
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Affiliation(s)
- Jurgen Schnermann
- Kidney Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Carlström M, Wilcox CS, Welch WJ. Adenosine A(2) receptors modulate tubuloglomerular feedback. Am J Physiol Renal Physiol 2010; 299:F412-7. [PMID: 20519378 DOI: 10.1152/ajprenal.00211.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adenosine can mediate the tubuloglomerular (TGF) response via activation of A(1) receptors on the afferent arteriole, but both adenosine A(1) and A(2) receptors can regulate preglomerular resistance. We tested the hypothesis that adenosine A(2) receptors offset the effect of A(1) receptors and modulate the TGF. Maximal TGF responses were measured in male Sprague-Dawley rats as changes in proximal stop-flow pressure (DeltaP(SF)) in response to increased perfusion of the loop of Henle (0 to 40 nl/min) with artificial tubular fluid (ATF). The maximal TGF response was studied after 5 min of intratubular perfusion (10 nl/min) with ATF alone, or with ATF plus the A(2A) receptor antagonist (ZM-241385; 10(-7) or 10(-5) mol/l), A(1) receptor antagonist (PSB-36; 10(-8) mol/l), or with a combination of A(1) (PSB-36; 10(-8) mol/l) and A(2A) (ZM-241385; 10(-7) mol/l) antagonists. The maximal TGF response (DeltaP(SF)) with ATF alone was 11.7 +/- 1.0 mmHg. Specific A(2) inhibition (low dose) enhanced the maximal TGF response (15.7 +/- 0.8 mmHg; P < 0.01), whereas a high dose (unspecific inhibition) attenuated the response (5.0 +/- 0.4 mmHg; P < 0.001). A(1) inhibition alone led to a paradoxical TGF response, with an increase in P(SF) of 3.1 +/- 0.5 mmHg (P < 0.05). Simultaneous application of A(1) and A(2) antagonists abolished the TGF response (DeltaP(SF): 0.4 +/- 0.3 mmHg). In conclusion, adenosine A(2) receptors modulate the TGF response by counteracting the effects of adenosine A(1) receptors.
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Affiliation(s)
- Mattias Carlström
- Department of Medicine, Georgetown University Medical Center, Washington, District of Columbia, USA
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Abstract
P2X receptors are membrane cation channels gated by extracellular ATP. Seven P2X receptor subunits (P2X(1-7)) are widely distributed in excitable and nonexcitable cells of vertebrates. They play key roles in inter alia afferent signaling (including pain), regulation of renal blood flow, vascular endothelium, and inflammatory responses. We summarize the evidence for these and other roles, emphasizing experimental work with selective receptor antagonists or with knockout mice. The receptors are trimeric membrane proteins: Studies of the biophysical properties of mutated subunits expressed in heterologous cells have indicated parts of the subunits involved in ATP binding, ion permeation (including calcium permeability), and membrane trafficking. We review our current understanding of the molecular properties of P2X receptors, including how this understanding is informed by the identification of distantly related P2X receptors in simple eukaryotes.
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Affiliation(s)
- Annmarie Surprenant
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
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Peti-Peterdi J, Toma I, Sipos A, Vargas SL. Multiphoton imaging of renal regulatory mechanisms. Physiology (Bethesda) 2009; 24:88-96. [PMID: 19364911 DOI: 10.1152/physiol.00001.2009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and previously inaccessible structures in many organ parts that have been difficult to study. Multiphoton fluorescence microscopy offers a state-of-the-art imaging technique for deep optical sectioning of living tissues and organs with minimal deleterious effects. Dynamic regulatory processes and multiple functions in the intact kidney can be quantitatively visualized in real time, noninvasively, and with submicron resolution. This article reviews innovative multiphoton imaging technologies and their applications that provided the most complex, immediate, and dynamic portrayal of renal function-clearly depicting as well as analyzing the components and mechanisms involved in renal (patho)physiology.
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Affiliation(s)
- János Peti-Peterdi
- Departments of Physiology and Biophysics and Medicine, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA.
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Cook N, Fraser SA, Katerelos M, Katsis F, Gleich K, Mount PF, Steinberg GR, Levidiotis V, Kemp BE, Power DA. Low salt concentrations activate AMP-activated protein kinase in mouse macula densa cells. Am J Physiol Renal Physiol 2009; 296:F801-9. [PMID: 19176702 DOI: 10.1152/ajprenal.90372.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The energy-sensing kinase AMP-activated protein kinase (AMPK) is associated with the sodium-potassium-chloride cotransporter NKCC2 in the kidney and phosphorylates it on a regulatory site in vitro. To identify a potential role for AMPK in salt sensing at the macula densa, we have used the murine macula densa cell line MMDD1. In this cell line, AMPK was rapidly activated by isosmolar low-salt conditions. In contrast to the known salt-sensing pathway in the macula densa, AMPK activation occurred in the presence of either low sodium or low chloride and was unaffected by inhibition of NKCC2 with bumetanide. Assays using recombinant AMPK demonstrated activation of an upstream kinase by isosmolar low salt. The specific calcium/calmodulin-dependent kinase kinase inhibitor STO-609 failed to suppress AMPK activation, suggesting that it was not part of the signal pathway. AMPK activation was associated with increased phosphorylation of the specific substrate acetyl-CoA carboxylase (ACC) at Ser(79), as well as increased NKCC2 phosphorylation at Ser(126). AMPK activation due to low salt concentrations was inhibited by an adenovirus construct encoding a kinase dead mutant of AMPK, leading to reduced ACC Ser(79) and NKCC2 Ser(126) phosphorylation. This work demonstrates that AMPK activation in macula densa-like cells occurs via isosmolar changes in sodium or chloride concentration, leading to phosphorylation of ACC and NKCC2. Phosphorylation of these substrates in vivo is predicted to increase intracellular chloride and so reduce the effect of salt restriction on tubuloglomerular feedback and renin secretion.
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Affiliation(s)
- Natasha Cook
- Dept. of Nephrology, Austin Health, Studley Rd., Heidelberg 3084, Victoria, Australia.
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Current concepts of neurohormonal activation in heart failure: mediators and mechanisms. AACN Adv Crit Care 2009; 19:364-85; quiz 386-7. [PMID: 18981739 DOI: 10.1097/01.aacn.0000340718.93742.c4] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Neurohormonal activation is a commonly cited array of phenomena in the body's physiologic response to heart failure. Although various neurohormones and pharmacologic agents that moderate their pathophysiologic effects have been reviewed in the nursing literature, both the mechanisms of neurohormonal system activation and cellular and organ system effects have been described only in brief. Accordingly, this article reviews mechanisms of neurohormonal activation and describes cellular and cardiovascular effects of the (1) sympathetic nervous system, (2) renin-angiotensin-aldosterone system, (3) kallikrein-kininogen-kinin system, (4) vasopressinergic system, (5) natriuretic peptide systems, and (6) endothelin in the context of heart failure. This article implicitly details the physiologic basis for numerous current and potential future pharmacologic agents used in the management of heart failure. It is intended that this article be used as a reference for advanced clinical nursing practice, research, and education.
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Abstract
The autacoid, adenosine, is present in the normoxic kidney and generated in the cytosol as well as at extracellular sites. The rate of adenosine formation is enhanced when the rate of ATP hydrolysis prevails over the rate of ATP synthesis during increased tubular transport work or during oxygen deficiency. Extracellular adenosine acts on adenosine receptor subtypes (A(1), A(2A), A(2B), and A(3)) in the cell membranes to affect vascular and tubular functions. Adenosine lowers glomerular filtration rate by constricting afferent arterioles, especially in superficial nephrons, and thus lowers the salt load and transport work of the kidney consistent with the concept of metabolic control of organ function. In contrast, it leads to vasodilation in the deep cortex and the semihypoxic medulla, and exerts differential effects on NaCl transport along the tubular and collecting duct system. These vascular and tubular effects point to a prominent role of adenosine and its receptors in the intrarenal metabolic regulation of kidney function, and, together with its role in inflammatory processes, form the basis for potential therapeutic approaches in radiocontrast media-induced acute renal failure, ischemia reperfusion injury, and in patients with cardiorenal failure.
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Affiliation(s)
- Volker Vallon
- Department of Medicine, University of California San Diego and VA San Diego Healthcare System, San Diego, CA 92161, USA.
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Cross-talk between arterioles and tubules in the kidney. Pediatr Nephrol 2009; 24:31-5. [PMID: 18488254 PMCID: PMC2697568 DOI: 10.1007/s00467-008-0852-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 03/03/2008] [Accepted: 03/06/2008] [Indexed: 10/22/2022]
Abstract
In hypertension the pressure natriuresis set point is shifted to a higher pressure due to an increase in both renal vascular resistance and sodium (Na) reabsorption. The afferent arterioles (Af-Arts) and efferent arterioles (Ef-Arts) account for most renal vascular resistance; they control glomerular filtration rate (GFR) and peritubular pressure, and, consequently, renal function. Af-Art and Ef-Art resistance is regulated by factors similar to those in other arterioles and also by tubuloglomerular feedback (TGF). TGF operates via the macula densa, which senses increases in sodium chloride (NaCl) and sends a signal that constricts the Af-Art and dilates the Ef-Art. In the outer renal cortex, the connecting tubule (CNT) returns to the glomerular hilus and contacts the Af-Art. This morphology is compatible with cross-talk between the CNT and Af-Art, so-called connecting tubule glomerular feedback (CTGF). Our studies show that increasing NaCl delivery to the CNT results in Af-Art dilatation that can be blocked by inhibitors of Na transport. We believe cross-talk between the CNT and Af-Art is a novel mechanism that may contribute to regulation of renal blood flow and GFR.
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Navar LG, Arendshorst WJ, Pallone TL, Inscho EW, Imig JD, Bell PD. The Renal Microcirculation. Compr Physiol 2008. [DOI: 10.1002/cphy.cp020413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Aoyagi T, Izumi Y, Hiroyama M, Matsuzaki T, Yasuoka Y, Sanbe A, Miyazaki H, Fujiwara Y, Nakayama Y, Kohda Y, Yamauchi J, Inoue T, Kawahara K, Saito H, Tomita K, Nonoguchi H, Tanoue A. Vasopressin regulates the renin-angiotensin-aldosterone system via V1a receptors in macula densa cells. Am J Physiol Renal Physiol 2008; 295:F100-7. [PMID: 18448596 DOI: 10.1152/ajprenal.00088.2008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The neuropeptide hormone arginine-vasopressin (AVP) is well known to exert its antidiuretic effect via the vasopressin V2 receptor (V2R), whereas the role of the vasopressin V1a receptor (V1aR) in the kidney remains to be clarified. Previously, we reported decreased plasma volume and blood pressure in V1a receptor-deficient (V1aR-/-) mice (Koshimizu T, Nasa Y, Tanoue A, Oikawa R, Kawahara Y, Kiyono Y, Adachi T, Tanaka T, Kuwaki T, Mori T. Proc Natl Acad Sci USA 103: 7807-7812, 2006). In this study, we investigated the role of V1aR in urine concentration, renal function, and the renin-angiotensin system (RAS) using V1aR-/- mice. Urine volume of V1aR-/- mice was greater than that of wild-type mice, particularly when water was loaded, while the glomerular filtration rate (GFR), urinary NaCl excretion, AVP-dependent cAMP generation, V2R, and aquaporin 2 (AQP2) expression in the kidney were lower, indicating that the diminished GFR and V2R-AQP2 system led to impaired urinary concentration in V1aR-/- mice. Since the GFR and V2R-AQP2 system are regulated by RAS, we analyzed renin and angiotensin II in V1aR-/- mice and found that the plasma renin and angiotensin II were decreased. The expression of renin in granule cells was decreased in V1aR-/- mice, which led to a decreased level of plasma renin. In addition, the expression of renin stimulators such as neuronal nitric oxide synthase and cyclooxygenase-2 in macula densa (MD) cells, where V1aR was specifically expressed, was decreased in V1aR-/- mice. These data indicate that AVP regulates body fluid homeostasis and GFR via the V1aR in MD cells by activating RAS and subsequently the V2R-AQP2 system.
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Affiliation(s)
- Toshinori Aoyagi
- Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan
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Purinergic signaling in the lumen of a normal nephron and in remodeled PKD encapsulated cysts. Purinergic Signal 2008; 4:109-24. [PMID: 18438719 DOI: 10.1007/s11302-008-9102-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Accepted: 04/08/2008] [Indexed: 01/10/2023] Open
Abstract
The nephron is the functional unit of the kidney. Blood and plasma are continually filtered within the glomeruli that begin each nephron. Adenosine 5' triphosphate (ATP) and its metabolites are freely filtered by each glomerulus and enter the lumen of each nephron beginning at the proximal convoluted tubule (PCT). Flow rate, osmolality, and other mechanical or chemical stimuli for ATP secretion are present in each nephron segment. These ATP-release stimuli are also different in each nephron segment due to water or salt permeability or impermeability along different luminal membranes of the cells that line each nephron segment. Each of the above stimuli can trigger additional ATP release into the lumen of a nephron segment. Each nephron-lining epithelial cell is a potential source of secreted ATP. Together with filtered ATP and its metabolites derived from the glomerulus, secreted ATP and adenosine derived from cells along the nephron are likely the principal two of several nucleotide and nucleoside candidates for renal autocrine and paracrine ligands within the tubular fluid of the nephron. This minireview discusses the first principles of purinergic signaling as they relate to the nephron and the urinary bladder. The review discusses how the lumen of a renal tubule presents an ideal purinergic signaling microenvironment. The review also illustrates how remodeled and encapsulated cysts in autosomal dominant polycystic kidney disease (ADPKD) and remodeled pseudocysts in autosomal recessive PKD (ARPKD) of the renal collecting duct likely create an even more ideal microenvironment for purinergic signaling. Once trapped in these closed microenvironments, purinergic signaling becomes chronic and likely plays a significant epigenetic and detrimental role in the secondary progression of PKD, once the remodeling of the renal tissue has begun. In PKD cystic microenvironments, we argue that normal purinergic signaling within the lumen of the nephron provides detrimental acceleration of ADPKD once remodeling is complete.
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Oppermann M, Friedman DJ, Faulhaber-Walter R, Mizel D, Castrop H, Enjyoji K, Robson SC, Schnermann J. Tubuloglomerular feedback and renin secretion in NTPDase1/CD39-deficient mice. Am J Physiol Renal Physiol 2008; 294:F965-70. [PMID: 18256308 DOI: 10.1152/ajprenal.00603.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Studies in mice with null mutations of adenosine 1 receptor or ecto-5'-nucleotidase genes suggest a critical role of adenosine and its precursor 5'-AMP in tubulovascular signaling. To assess whether the source of juxtaglomerular nucleotides can be traced back to ATP dephosphorylation, experiments were performed in mice with a deficiency in NTPDase1/CD39, an ecto-ATPase catalyzing the formation of AMP from ATP and ADP. Urine osmolarity and glomerular filtration rate (GFR) were indistinguishable between NTPDase1/CD39(-/-) and wild-type (WT) mice. Maximum tubuloglomerular feedback (TGF) responses, as determined by proximal tubular stop flow pressure measurements, were reduced in NTPDase1/CD39(-/-) mice compared with controls (4.2 +/- 0.9 vs. 10.5 +/- 1.2 mmHg, respectively; P = 0.0002). Residual TGF responses gradually diminished after repeated changes in tubular perfusion flow averaging 2.9 +/- 0.9 (on response) and 3.5 +/- 1.1 (off response) mmHg after the second and 2.2 +/- 0.5 (on response) and 1.5 +/- 0.8 (off response) mmHg after the third challenge, whereas no fading of TGF responsiveness was observed in WT mice. Macula densa-dependent and pressure-dependent inhibition of renin secretion, as assessed by acute salt loading and phenylephrine injection, respectively, were intact in NTPDase1/CD39-deficient mice. In summary, NTPDase1/CD39-deficient mice showed a markedly compromised TGF regulation of GFR. These data support the concept of an extracellular dephosphorylation cascade during tubular-vascular signal transmission in the juxtaglomerular apparatus that is initiated by a regulated release of ATP from macula densa cells and results in adenosine-mediated afferent arteriole constriction.
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Affiliation(s)
- Mona Oppermann
- National Institute of Digestive and Diabetes and Kidney Diseases, National Institute of Health, 10 Center Drive-MSC 1370, Bethesda, MD 20892, USA
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Vallon V, Miracle C, Thomson S. Adenosine and kidney function: potential implications in patients with heart failure. Eur J Heart Fail 2008; 10:176-87. [PMID: 18242127 DOI: 10.1016/j.ejheart.2008.01.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 01/07/2008] [Accepted: 01/15/2008] [Indexed: 02/06/2023] Open
Abstract
Therapy of heart failure is more difficult when renal function is impaired. Here, we outline the effects on kidney function of the autacoid, adenosine, which forms the basis for adenosine A(1) receptor (A(1)R) antagonists as treatment for decompensated heart failure. A(1)R antagonists induce a eukaliuretic natriuresis and diuresis by blocking A(1)R-mediated NaCl reabsorption in the proximal tubule and the collecting duct. Normally, suppressing proximal reabsorption will lower glomerular filtration rate (GFR) through the tubuloglomerular feedback mechanism (TGF). But the TGF response, itself, is mediated by A(1)R in the preglomerular arteriole, so blocking A(1)R allows natriuresis to proceed while GFR remains constant or increases. The influence of A(1)R over vascular resistance in the kidney is augmented by angiotensin II while A(1)R activation directly suppresses renin secretion. These interactions could modulate the overall impact of A(1)R blockade on kidney function in patients taking angiotensin II blockers. A(1)R blockers may increase the energy utilized for transport in the semi-hypoxic medullary thick ascending limb, an effect that could be prevented with loop diuretics. Finally, while the vasodilatory effect of A(1)R blockade could protect against renal ischaemia, A(1)R blockade may act on non-resident cells to exacerbate reperfusion injury, where ischaemia to occur. Despite these uncertainties, the available data on A(1)R antagonist therapy in patients with decompensated heart failure are promising and warrant confirmation in further studies.
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Affiliation(s)
- Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego & VASDHCS, San Diego, CA 92161, USA.
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