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Structural and Functional Changes in Aging Kidneys. Int J Mol Sci 2022; 23:ijms232315435. [PMID: 36499760 PMCID: PMC9737118 DOI: 10.3390/ijms232315435] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 11/30/2022] [Accepted: 12/04/2022] [Indexed: 12/12/2022] Open
Abstract
The renal condition is one of the crucial predictors of longevity; therefore, early diagnosis of any dysfunction plays an important role. Kidneys are highly susceptible to the aging process. Unfavorable conditions may lead to a significant disturbance of the body's homeostasis. Apart from physiological changes, there are some conditions such as hypertension, diabetes or obesity which contribute to the acceleration of the aging process. A determination of macroscopic and microscopic changes is essential for assessing the progression of aging. With age, we observe a decrease in the volume of renal parenchyma and an increase in adipose tissue in the renal sinuses. Senescence may also be manifested by the roughness of the kidney surface or simple renal cysts. The main microscopic changes are a thickening of the glomerular basement membrane, nephrosclerosis, an accumulation of extracellular matrix, and mesangial widening. The principal aspect of stopping unfavorable changes is to maintain health. Studies have shown many useful ways to mitigate renal aging. This review is focused especially on medications such as renin-angiotensin-aldosterone system blockers or resveratrol, but even eating habits and lifestyle.
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Wang M, Wu J, Jiao H, Oluwabiyi C, Li H, Zhao J, Zhou Y, Wang X, Lin H. Enterocyte synthesizes and secrets uric acid as antioxidant to protect against oxidative stress via the involvement of Nrf pathway. Free Radic Biol Med 2022; 179:95-108. [PMID: 34954337 DOI: 10.1016/j.freeradbiomed.2021.12.307] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/14/2021] [Accepted: 12/20/2021] [Indexed: 12/22/2022]
Abstract
The gut is an important site to excreting uric acid (UA) in addition to the kidney. The gastrointestinal tract is constantly exposed to various potentially harmful substances, triggering intestinal oxidative damage. In the present study, the hypothesis that UA is can be synthesized to function as an antioxidant in the gut is evaluated. The synthesis and secretion of UA by enterocytes were analyzed in the presence of inosine, a precursor of UA, febuxostat (Fx), an inhibitor of xanthine oxidase (XOR), and H2O2. The regulation of Nrf2 pathway on UA secretion and transport were evaluated in the present of agonist (TBHQ) and inhibitor (ML385) of Nrf2. The in vivo result showed that UA and its oxidation product allantoin were presented in gut contents along the gastrointestinal tract and the highest level of UA and allantoin were detected in duodenum and jejunum respectively. The genes in the de novo purine nucleotide synthesis and salvage-catabolism pathways, and UA transporters were expressed in the intestinal tract. In the in vitro cultured enterocytes and everted gut sacs, inosine stimulated UA synthesis and secretion. H2O2 stimulated UA synthesis and secretion and meanwhile induced oxidative damage. UA attenuated H2O2-induced oxidative damage by Nrf2 pathway. UA secretion and transport were reduced by blocking Nrf2 with ML385, while increased by activating Nrf2 with TBHQ. This study provides new insights into the antioxidant effects if UA on intestinal lumen. The result suggests that activation of Nrf2 pathway is involved in the transportation and secretion of UA.
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Affiliation(s)
- Minghui Wang
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Jianmin Wu
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Hongchao Jiao
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Cecilia Oluwabiyi
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Haifang Li
- College of Life Sciences, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Jingpeng Zhao
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Yunlei Zhou
- College of Chemistry and Material Science, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China
| | - Xiaojuan Wang
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China.
| | - Hai Lin
- Department of Animal Science & Technology, Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong Agricultural University, No. 61, Daizong Street, Taian, Shandong, 271018, PR China.
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Fang Y, Gong AY, Haller ST, Dworkin LD, Liu Z, Gong R. The ageing kidney: Molecular mechanisms and clinical implications. Ageing Res Rev 2020; 63:101151. [PMID: 32835891 PMCID: PMC7595250 DOI: 10.1016/j.arr.2020.101151] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 08/07/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022]
Abstract
As human life expectancy keeps increasing, ageing populations present a growing challenge for clinical practices. Human ageing is associated with molecular, structural, and functional changes in a variety of organ systems, including the kidney. During the ageing process, the kidney experiences progressive functional decline as well as macroscopic and microscopic histological alterations, which are accentuated by systemic comorbidities like hypertension and diabetes mellitus, or by preexisting or underlying kidney diseases. Although ageing per se does not cause kidney injury, physiologic changes associated with normal ageing processes are likely to impair the reparative capacity of the kidney and thus predispose older people to acute kidney disease, chronic kidney disease and other renal diseases. Mechanistically, cell senescence plays a key role in renal ageing, involving a number of cellular signaling mechanisms, many of which may be harnessed as international targets for slowing or even reversing kidney ageing. This review summarizes the clinical characteristics of renal ageing, highlights the latest progresses in deciphering the role of cell senescence in renal ageing, and envisages potential interventional strategies and novel therapeutic targets for preventing or improving renal ageing in the hope of maintaining long-term kidney health and function across the life course.
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Affiliation(s)
- Yudong Fang
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China; Division of Nephrology, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Athena Y Gong
- Division of Nephrology, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Steven T Haller
- Division of Cardiology, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Lance D Dworkin
- Department of Medicine, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Zhangsuo Liu
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
| | - Rujun Gong
- Division of Nephrology, University of Toledo College of Medicine, Toledo, Ohio, USA; Department of Medicine, University of Toledo College of Medicine, Toledo, Ohio, USA; Department of Physiology and Pharmacology, University of Toledo College of Medicine, Toledo, Ohio, USA.
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Li M, Li X, Liu Y, Liu X, Song Y, Zhao J, Mohan C, Wu T, Peng A, Qin L. Relationship between serum bilirubin levels s and the progression of renal function in patients with chronic kidney disease and hyperuricemia. Clin Chim Acta 2018; 486:156-161. [PMID: 30076802 DOI: 10.1016/j.cca.2018.07.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/12/2018] [Accepted: 07/30/2018] [Indexed: 12/11/2022]
Abstract
It is known that inflammation and oxidative stress have strong influences on chronic kidney disease (CKD). As an antioxidant, bilirubin is currently under extensive scrutiny. However, there are disagreements with regard to the oxidative and antioxidative roles of serum uric acid (SUA). This study aimed to investigate the relationship between serum bilirubin and the progression of renal function in CKD patients with hyperuricemia (HUA). This retrospective longitudinal study included 427 CKD patients. The endpoint was renal replacement therapy or death. Patients were divided into the following two groups according to the SUA level: HUA group (SUA ≥ 420 μmol/L for men; SUA ≥ 360 μmol/L for women) and normal uric acid level (NUA) group. A Cox proportional hazards model was used to evaluate the risk factors for renal outcomes in the two patient groups. The median follow-up time was 36 months. In the Cox regression analysis, the risk of renal outcomes in patients with serum indirect bilirubin (IBIL) levels >4.55 μmol/L was 0.15 times the risk in patients with serum IBIL levels ≤4.55 μmol/L (hazard ratio = 0.15, p = .013). Our findings suggest that a high serum IBIL level might be a protective factor for the progression of renal function in CKD patients with HUA.
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Affiliation(s)
- Mengyuan Li
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Xinhua Li
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Yan Liu
- Department of Nephrology, Heze Municipal Hospital, 2888, West Caozhou Road, Shandong 274031, China
| | - Xinying Liu
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Yaxiang Song
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Jian Zhao
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Chandra Mohan
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, USA
| | - Tianfu Wu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, USA
| | - Ai Peng
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China
| | - Ling Qin
- Department of Nephrology & Rheumatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301, Middle Yanchang Road, Shanghai 200072, China.
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Calvo‐Rubio M, Burón MI, López‐Lluch G, Navas P, de Cabo R, Ramsey JJ, Villalba JM, González‐Reyes JA. Dietary fat composition influences glomerular and proximal convoluted tubule cell structure and autophagic processes in kidneys from calorie-restricted mice. Aging Cell 2016; 15:477-87. [PMID: 26853994 PMCID: PMC4854917 DOI: 10.1111/acel.12451] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/10/2016] [Indexed: 01/09/2023] Open
Abstract
Calorie restriction (CR) has been repeatedly shown to prevent cancer, diabetes, hypertension, and other age-related diseases in a wide range of animals, including non-human primates and humans. In rodents, CR also increases lifespan and is a powerful tool for studying the aging process. Recently, it has been reported in mice that dietary fat plays an important role in determining lifespan extension with 40% CR. In these conditions, animals fed lard as dietary fat showed an increased longevity compared with mice fed soybean or fish oils. In this paper, we study the effect of these dietary fats on structural and physiological parameters of kidney from mice maintained on 40% CR for 6 and 18 months. Analyses were performed using quantitative electron microcopy techniques and protein expression in Western blots. CR mitigated most of the analyzed age-related parameters in kidney, such as glomerular basement membrane thickness, mitochondrial mass in convoluted proximal tubules and autophagic markers in renal homogenates. The lard group showed improved preservation of several renal structures with aging when compared to the other CR diet groups. These results indicate that dietary fat modulates renal structure and function in CR mice and plays an essential role in the determination of health span in rodents.
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Affiliation(s)
- Miguel Calvo‐Rubio
- Departamento de Biología Celular, Fisiología e InmunologíaCampus de Excelencia Internacional AgroalimentarioceiA3Universidad de CórdobaCórdobaSpain
| | - Mª Isabel Burón
- Departamento de Biología Celular, Fisiología e InmunologíaCampus de Excelencia Internacional AgroalimentarioceiA3Universidad de CórdobaCórdobaSpain
| | - Guillermo López‐Lluch
- Centro Andaluz de Biología del DesarrolloCIBERERInstituto de Salud Carlos IIIUniversidad Pablo de Olavide‐CSICSevillaSpain
| | - Plácido Navas
- Centro Andaluz de Biología del DesarrolloCIBERERInstituto de Salud Carlos IIIUniversidad Pablo de Olavide‐CSICSevillaSpain
| | - Rafael de Cabo
- Translational Gerontology BranchNational Institute of AgingNational Institutes of HealthBaltimoreMDUSA
| | - Jon J. Ramsey
- VM Molecular BiosciencesUniversity of CaliforniaDavisCAUSA
| | - José M. Villalba
- Departamento de Biología Celular, Fisiología e InmunologíaCampus de Excelencia Internacional AgroalimentarioceiA3Universidad de CórdobaCórdobaSpain
| | - José A. González‐Reyes
- Departamento de Biología Celular, Fisiología e InmunologíaCampus de Excelencia Internacional AgroalimentarioceiA3Universidad de CórdobaCórdobaSpain
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Affiliation(s)
| | - Ishaya Chuwang Pam
- Department of Obstetrics and Gynaecology Jos University Teaching Hospital, Jos, Nigeria
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Costa E, Fernandes J, Ribeiro S, Sereno J, Garrido P, Rocha-Pereira P, Coimbra S, Catarino C, Belo L, Bronze-da-Rocha E, Vala H, Alves R, Reis F, Santos-Silva A. Aging is Associated with Impaired Renal Function, INF-gamma Induced Inflammation and with Alterations in Iron Regulatory Proteins Gene Expression. Aging Dis 2013; 5:356-65. [PMID: 25489488 DOI: 10.14366/ad.2014.0500356] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/04/2013] [Accepted: 12/07/2013] [Indexed: 12/21/2022] Open
Abstract
Our aim was to contribute to a better understanding of the pathophysiology of anemia in elderly, by studying how aging affects renal function, iron metabolism, erythropoiesis and the inflammatory response, using an experimental animal model. The study was performed in male Wistar, a group of young rats with 2 months age and an old one with 18 months age. Old rats presented a significant higher urea, creatinine, interferon (INF)-gamma, ferritin and soluble transferrin receptor serum levels, as well as increased counts of reticulocytes and RDW. In addition, these rats showed significant lower erythropoietin (EPO) and iron serum levels. Concerning gene expression of iron regulatory proteins, old rats presented significantly higher mRNA levels of hepcidin (Hamp), transferrin (TF), transferrin receptor 2 (TfR2) and hemojuvelin (HJV); divalent metal transporter 1 (DMT1) mRNA levels were significantly higher in duodenal tissue; EPO gene expression was significantly higher in liver and lower in kidney, and the expression of the EPOR was significantly higher in both liver and kidney. Our results showed that aging is associated with impaired renal function, which could be in turn related with the inflammatory process and with a decline in EPO renal production. Moreover, we also propose that aging may be associated with INF-gamma-induced inflammation and with alterations upon iron regulatory proteins gene expression.
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Affiliation(s)
- Elísio Costa
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - João Fernandes
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal ; Laboratório de Farmacologia e Terapêutica Experimental, Instituto de Imagem Biomédica e Ciências da Vida, Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal
| | - Sandra Ribeiro
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - José Sereno
- Laboratório de Farmacologia e Terapêutica Experimental, Instituto de Imagem Biomédica e Ciências da Vida, Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal
| | - Patrícia Garrido
- Laboratório de Farmacologia e Terapêutica Experimental, Instituto de Imagem Biomédica e Ciências da Vida, Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal
| | - Petronila Rocha-Pereira
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal ; Centro Investigação Ciências da Saúde, Universidade Beira Interior, Covilhã, Portugal
| | - Susana Coimbra
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal ; CESPU, Institute for Research and Advanced Training in Health Sciences and Technologies, Gandhinagar-PRD, Portugal
| | - Cristina Catarino
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Luís Belo
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Elsa Bronze-da-Rocha
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Helena Vala
- Escola Superior Agrária de Viseu, Instituto Politécnico de Viseu, Viseu, Portugal ; Centro de Estudos em Educação, Tecnologias e Saúde, Instituto Politécnico de Viseu, Viseu, Portugal
| | - Rui Alves
- Departamento de Nefrologia, CHUC, Coimbra, Portugal ; Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal
| | - Flávio Reis
- Laboratório de Farmacologia e Terapêutica Experimental, Instituto de Imagem Biomédica e Ciências da Vida, Faculdade de Medicina, Universidade de Coimbra, Coimbra, Portugal
| | - Alice Santos-Silva
- Laboratório de Bioquímica, Departamento de Ciências Biológicas, Faculdade de Farmácia, Universidade do Porto, Porto, Portugal ; Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
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Ljubisavljevic S, Stojanovic I, Vojinovic S, Milojkovic M, Dunjic O, Stojanov D, Pavlovic D. Association of serum bilirubin and uric acid levels changes during neuroinflammation in patients with initial and relapsed demyelination attacks. Metab Brain Dis 2013; 28:629-38. [PMID: 23606133 DOI: 10.1007/s11011-013-9409-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 04/11/2013] [Indexed: 11/27/2022]
Abstract
In order to examine the endogenous antioxidants values in the earliest phase of demyelination, we have determined bilirubin and uric acid (UA) serum values in the patients with clinically isolated syndrome (CIS) and relapsing remitting multiple sclerosis (RRMS), regarding their clinical disability, measured by Extended Disability Status Scale (EDSS), Magnetic Resonance Imaging (MRI), disease duration, gender and other parameters. The bilirubin and UA levels were lower in CIS and RRMS patients than in control group, whether male or female (p < 0.05). The bilirubin and UA levels were decreased in RRMS compared to CIS patients (p < 0.05). Regarding EDSS, MRI and disease duration, obtained values of bilirubin and UA were higher in both study groups in patients with lower EDSS, lower MRI lesion number and shorter disease duration (p < 0.05). The greatest significance in decreased bilirubin and UA levels was observed in female compared to male patients, in both study groups (p < 0.05). The results suggest negative linear correlation between bilirubin and UA levels and disease duration, EDSS and MRI in CIS (p < 0.01), with the same correlation between bilirubin and UA levels and disease duration in RRMS patients (p < 0.01). There was also significant correlation between bilirubin level and MRI findings and UA levels and EDSS in RRMS patients (p < 0.01). The obtained results point to the importance of endogenous antioxidants in the outbreak and course of neuroinflammation. This could be favorable for the new pathogenetically conditioned neuroinflammatory therapy concepts which do not initially rely only on immunomodulatory, but also on the antioxidative effects.
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Affiliation(s)
- Srdjan Ljubisavljevic
- Clinic of Neurology, Clinical Centre Nis, Bul. Dr Zorana Djindjica 48, 18000, Nis, Serbia,
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Abstract
It has been known for many years that the kidney plays a major role in uric acid homeostasis, as more than 70% of urate excretion is renal. Furthermore, hyperuricemia in gout is most commonly the result of relative urate underexcretion, as the kidney has enormous capacity for urate reabsorption. A clear understanding of the mechanisms of renal handling of urate has been hampered by the differences between humans and animal models. The power of human genetics and genome-wide association studies has now provided new insight into the molecular mechanisms of urate transport by identifying the transporters that have critical roles in urate transport. This review surveys the new evidence for a molecular model of urate transport in the renal proximal tubule and uses these data to refute the popular four-component model for urate transport that has long been in vogue. It also discusses data that help us understand the relation of diuretics to hyperuricemia, losartan-induced uricosuria, variations in uric acid levels in hyperglycemia, and the effects of dairy diets on serum urate levels. In the end, several of these clinical findings are explained, and the remaining gaps in our knowledge will become evident.
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Fujiwara Y, Kawakami Y, Shinohara Y, Ichida K. A case of hereditary xanthinuria type 1 accompanied by bilateral renal calculi. Intern Med 2012; 51:1879-84. [PMID: 22821105 DOI: 10.2169/internalmedicine.51.6891] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hereditary xanthinuria is an extremely rare purine metabolism disorder caused by a genetic abnormality in xanthine dehydrogenase. A new case of hereditary xanthinuria type 1 accompanied by bilateral renal calculi was encountered. We performed an allopurinol loading test and diagnosed classical type 1 xanthinuria. Through genetic diagnosis, we identified a mutation site in the xanthine dehydrogenase gene. Genetic analysis revealed a homozygous deletion of cytosine 2,567 in the xanthine dehydrogenase gene, and as a result, a stop codon was formed at position 928. Renal failure caused by the deposition of xanthine crystals is a known complication because xanthine is poorly soluble in water. With high fluid intake and low purine diet, no significant increase in calculi has been observed in this patient for 2 years.
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Affiliation(s)
- Yutaka Fujiwara
- Department of Endocrinology and Metabolism, KKR Sapporo Medical Center, Japan.
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11
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Gava AL, Freitas FPS, Meyrelles SS, Silva IV, Graceli JB. Gender-dependent effects of aging on the kidney. Braz J Med Biol Res 2011; 44:905-13. [PMID: 21956533 DOI: 10.1590/s0100-879x2011007500101] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 08/05/2011] [Indexed: 11/22/2022] Open
Abstract
It is well known that the kidney plays an important role in the development of cardiovascular diseases such as hypertension. The normal aging process leads to changes in kidney morphology, hemodynamics and function, which increase the incidence of cardiovascular events in the elderly population. These disturbances are influenced by several factors, including gender. In general, females are protected by the effects of estrogens on the cardiorenal system. Several studies have demonstrated the beneficial effects of estrogens on renal function in the elderly; however, the relationships between androgens and kidney health during one's lifetime are not well understood. Sex steroids have many complex actions, and the decline in their levels during aging clearly influences kidney function, decreases the renal reserve and facilitates the development of cardiovascular disorders. Therefore, in this review, we discuss the cellular, biochemical, and molecular mechanisms by which sex hormones may influence renal function during the aging process.
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Affiliation(s)
- A L Gava
- Laboratório de Transgenes e Controle Cardiovascular, Programa de Pós-Graduação em Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, ES, Brasil
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12
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Bataille AM, Maffeo CL, Renfro JL. Avian renal proximal tubule urate secretion is inhibited by cellular stress-induced AMP-activated protein kinase. Am J Physiol Renal Physiol 2011; 300:F1327-38. [DOI: 10.1152/ajprenal.00680.2010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Urate is a potent antioxidant at high concentrations but it has also been associated with a wide variety of health risks. Plasma urate concentration is determined by ingestion, production, and urinary excretion; however, factors that regulate urate excretion remain uncertain. The objective of this study was to determine whether cellular stress, which has been shown to affect other renal transport properties, modulates urate secretion in the avian renal proximal tubule. Chick kidney proximal tubule epithelial cell primary culture monolayers were used to study the transepithelial transport of radiolabeled urate. This model allowed examination of the processes, such as multidrug resistance protein 4 (Mrp4, Abcc4), which subserve urate secretion in a functional, intact, homologous system. Our results show that the recently implicated urate efflux transporter, breast cancer resistance protein ( ABCG2), does not significantly contribute to urate secretion in this system. Exposure to a high concentration of zinc for 6 h induced a cellular stress response and a striking decrease in transepithelial urate secretion. Acute exposure to zinc had no effect on transepithelial urate secretion or isolated membrane vesicle urate transport, suggesting involvement of a cellular stress adaptation. Activation of AMP-activated protein kinase (AMPK), a candidate modulator of ATP-dependent urate efflux, by 5′-aminoimidazole-4-carboxamide 1-β-d-ribo-furanoside caused a decrease in urate secretion similar to that seen with zinc-induced cellular stress. This effect was prevented with the AMPK inhibitor compound C. Notably, the decrease in urate secretion seen with zinc-induced cellular stress was also prevented by compound C, implicating AMPK in regulation of renal uric acid excretion.
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Affiliation(s)
- Amy M. Bataille
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Carla L. Maffeo
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - J. Larry Renfro
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
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Hollman PCH, Cassidy A, Comte B, Heinonen M, Richelle M, Richling E, Serafini M, Scalbert A, Sies H, Vidry S. The biological relevance of direct antioxidant effects of polyphenols for cardiovascular health in humans is not established. J Nutr 2011; 141:989S-1009S. [PMID: 21451125 DOI: 10.3945/jn.110.131490] [Citation(s) in RCA: 269] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Human studies provide evidence for beneficial effects of polyphenol-rich foods on cardiovascular health. The antioxidant activity of polyphenols potentially explains these effects, but is the antioxidant activity a reliable predictor for these effects? An International Life Sciences Institute Europe working group addressed this question and explored the potential of antioxidant claims for polyphenols in relation to cardiovascular health by using the so-called Process for the Assessment of Scientific Support for Claims on Foods project criteria. In this process, analytical aspects of polyphenols, their occurrence in foods, dietary intake, and bioavailability were reviewed. Human studies on polyphenols and cardiovascular health were reviewed together with methods for biomarkers of oxidative damage and total antioxidant capacity (TAC). In retrospective studies, F2-isoprostanes and oxidized LDL, the most reliable biomarkers of lipid peroxidation, and measures for TAC showed the expected differences between cardiovascular disease patients and healthy controls, but prospective studies are lacking, and a causal relationship between these biomarkers and cardiovascular health could not be established. Therefore, the physiological relevance of a potential change in these biomarkers is unclear. We found limited evidence that some types of polyphenol-rich products modify these biomarkers in humans. A direct antioxidant effect of polyphenols in vivo is questionable, however, because concentrations in blood are low compared with other antioxidants and extensive metabolism following ingestion lowers their antioxidant activity. Therefore, the biological relevance of direct antioxidant effects of polyphenols for cardiovascular health could not be established. Overall, although some polyphenol-rich foods exert beneficial effects on some biomarkers of cardiovascular health, there is no evidence that this is caused by improvements in antioxidant function biomarkers (oxidative damage or antioxidant capacity).
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Affiliation(s)
- Peter C H Hollman
- RIKILT-Institute of Food Safety and Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
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14
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Lauretani F, Maggio M, Pizzarelli F, Michelassi S, Ruggiero C, Ceda GP, Bandinelli S, Ferrucci L. Omega-3 and renal function in older adults. Curr Pharm Des 2010; 15:4149-56. [PMID: 20041816 DOI: 10.2174/138161209789909719] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic kidney disease (CKD) is a major public health problem and can result in end-stage renal disease with need for dialysis or transplantation. In Europe up to 12% of the adult population had some renal impairment, while in the United States the end stage of CKD has increased dramatically from 209.000 in 1991 to 472.000 in 2004. Diabetes and hypertension are major causes of kidney pathology. Infection, particularly ascending infection, is more common with increasing age, as both immune function declines and associated pathology predisposing to infection, such as obstructive uropathy, becomes more common. Most pathological changes in the kidney appear to be initiated by oxidative stress, followed by an inflammatory reaction. Oxidative stress results from an imbalance between free radicals and their detoxification by endogenous and exogenous scavengers, including polyunsaturated fatty acids (PUFA). Recent studies showed that PUFA supplementation slowed the rate of loss of renal function in patients with IgA nephropathy. Then, studies of omega-3 supplementation in dialysis patients describe salutary effects on triglyceride levels and dialysis access patency. We examined the relationship between total plasma PUFA levels and change in creatinine clearance over a three-year follow-up in the older persons enrolled in the InCHIANTI study, a population-based epidemiology study conducted in Tuscany, Italy. This study showed that older adults with low total plasma PUFA levels have a greater decline in creatinine clearance over three years of follow-up. These findings suggest that a higher dietary intake of PUFA may be protective against progression to chronic kidney disease.
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Affiliation(s)
- F Lauretani
- Geriatric Unit, Geriatric-Rehabilitation Department, University Hospital of Parma, Parma, Italy.
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15
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Smith A, Benkel BF. Novel avian leukosis virus-related endogenous proviruses from layer chickens: characterization and development of locus-specific assays. Poult Sci 2009; 88:1580-5. [PMID: 19590071 DOI: 10.3382/ps.2009-00148] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the course of evolution, vertebrate genomes have been invaded and colonized by retroviruses. In humans, for example, endogenous retroviruses (long terminal repeat elements) occupy roughly twice as much sequence space as essential genes. There are numerous reports in the literature implicating endogenous proviruses in the modulation of host physiology. The fact that many of these host-virus interactions take place in a proviral locus-specific manner speaks to the need for rapid assays for element profiling. This report deals with the identification of novel elements belonging to a family of endogenous retroviruses, designated ALVE, that reside in the genome of the chicken and that are closely related to exogenous avian leukosis viruses. The study of ALVE elements in the chicken genome serves as a model system for understanding the interplay between endogenous viruses and their vertebrate hosts in general, including humans. In this report, we present locus-specific, diagnostic PCR-based assays for 2 novel ALVE elements. In addition, we characterize the proviral structures and examine the genomic environments of both novel elements along with a previously described element known as ALVE-NSAC-3.
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Affiliation(s)
- A Smith
- Nova Scotia Agricultural College, Department of Plant and Animal Sciences, Truro, Nova Scotia, B2N 5E3, Canada
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16
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Mirshafiey A, Mohsenzadegan M. Antioxidant therapy in multiple sclerosis. Immunopharmacol Immunotoxicol 2009; 31:13-29. [PMID: 18763202 DOI: 10.1080/08923970802331943] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Reactive oxygen species (ROS) play an important role in various events underlying multiple sclerosis pathology. In the initial phase of lesion formation, ROS are known to mediate the transendothelial migration of monocytes and induce a dysfunction in the blood-brain barrier. Although the pathogenesis of MS is not completely understood, various studies suggest that reactive oxygen species contribute to the formation and persistence of multiple sclerosis lesions by acting on distinct pathological processes. The detrimental effects of ROS in the central nervous system are endowed with a protective mechanism consisting of enzymatic and non-enzymatic antioxidant. Antioxidant therapy may therefore represent an attractive treatment of MS. Several studies have shown that antioxidant therapy is beneficial in vitro and in vivo in animal models for MS. Since oxidative damage has been known to be involved in inflammatory and autoimmune-mediated tissue destruction in which, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory and autoimmune diseases. Several experimental studies have been performed to see whether dietary intake of several antioxidants can prevent and or reduce the progression of EAE or not. Although a few antioxidants showed some efficacy in these studies, little information is available on the effect of treatments with such compounds in patients with MS. In this review, our aim is to clarify the therapeutic efficacy of antioxidants in MS disease.
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Affiliation(s)
- Abbas Mirshafiey
- Department of Immunology, Tehran University of Medical Sciences, Iran.
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17
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Bataille AM, Goldmeyer J, Renfro JL. Avian renal proximal tubule epithelium urate secretion is mediated by Mrp4. Am J Physiol Regul Integr Comp Physiol 2008; 295:R2024-33. [DOI: 10.1152/ajpregu.90471.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Birds are uricotelic and, like humans, maintain high plasma urate concentrations (∼300 μM). The majority of their urate waste, as in humans, is eliminated by renal proximal tubular secretion; however, the mechanism of urate transport across the brush-border membrane of the intact proximal tubule epithelium during secretion is uncertain. The dominance of secretory urate transport in the bird provides a convenient model for examining this process. The present study shows that short hairpin RNA interference (shRNAi) effectively knocked down gene expression of multidrug resistance protein 4 (Mrp4; 25% of control) in primary monolayer cultures of isolated chicken proximal tubule epithelial cells (cPTCs). Control and Mrp4-shRNAi-treated cPTCs were mounted in Ussing chambers and unidirectional transepithelial fluxes of urate were measured. To detect nonspecific effects, transepithelial electrical resistance (TER) and sodium-dependent glucose transport (Iglu) were monitored throughout experiments. Knocking down Mrp4 expression resulted in a reduction of transepithelial urate secretion to 35% of control with no effects on TER or Iglu. Although electrical gradient-driven urate transport in isolated brush-border membrane vesicles was confirmed, potassium-induced depolarization of the plasma membrane in intact cPTCs failed to inhibit active transepithelial urate secretion. However, electrical gradient-dependent vesicular urate transport was inhibited by the MRP4 inhibitor MK-571 also known to inhibit active transepithelial urate transport by cPTCs. Based on these data, direct measure of active transepithelial urate secretion in functional avian proximal tubule epithelium indicates that Mrp4 is the dominant apical membrane exit pathway from cell to lumen.
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18
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Gersch C, Palii SP, Kim KM, Angerhofer A, Johnson RJ, Henderson GN. Inactivation of nitric oxide by uric acid. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 27:967-78. [PMID: 18696365 DOI: 10.1080/15257770802257952] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The 1980 identification of nitric oxide (NO) as an endothelial cell-derived relaxing factor resulted in an unprecedented biomedical research of NO and established NO as one of the most important cardiovascular, nervous and immune system regulatory molecule. A reduction in endothelial cell NO levels leading to "endothelial dysfunction" has been identified as a key pathogenic event preceding the development of hypertension, metabolic syndrome, and cardiovascular disease. The reduction in endothelial NO in cardiovascular disease has been attributed to the action of oxidants that either directly react with NO or uncouple its substrate enzyme. In this report, we demonstrate that uric acid (UA), the most abundant antioxidant in plasma, reacts directly with NO in a rapid irreversible reaction resulting in the formation of 6-aminouracil and depletion of NO. We further show that this reaction occurs preferentially with NO even in the presence of oxidants peroxynitrite and hydrogen peroxide and that the reaction is at least partially blocked by glutathione. This study shows a potential mechanism by which UA may deplete NO and cause endothelial dysfunction, particularly under conditions of oxidative stress in which UA is elevated and intracellular glutathione is depleted.
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Affiliation(s)
- Christine Gersch
- Department of Medicine, Division of Nephrology and Hypertension, University of Florida, Gainesville, Florida 32610, USA
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19
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Unger S, Tausche AK, Kopprasch S, Bornstein SR, Aringer M, Grässler J. [Molecular basis of primary renal hyperuricemia : role of the human urate transporter hURAT1]. Z Rheumatol 2008; 66:556, 58-61. [PMID: 17891408 DOI: 10.1007/s00393-007-0208-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In highly industrialized countries hyperuricemia is one of the most common metabolic disorders. High uric acid blood levels may lead to the manifestation of gout owing to the precipitation of urate crystals in connective tissue, the skeletal system and kidneys. A primary reduction of renal uric acid excretion can be detected in more than 90% of all cases of hyperuricemia. Despite the identification of several uric acid transporting proteins their pathogenetic role for the induction of primary reduced renal uric acid excretion has not yet been verified. As a result of a case-control study on individuals with normal and reduced renal uric acid excretion, an association of polymorphisms in the human urate transporter 1 gene (hURAT1) with primary reduced urate excretion has been demonstrated for the first time. The hURAT1 gene is an organic anion transporter (SLC22A12), which is preferentially expressed in the apical membrane of proximal renal tubule cells. Functioning as an antiporter, hURAT1 mediates the uptake of urate from the lumen into proximal tubule cells in exchange for organic and inorganic anions. Loss-of-function mutations in the hURAT1 gene are a cause of hereditary renal hypouricemia. The precisely regulated hURAT1 is a candidate gene for hyperuricemia and an important target for the development and optimization of new diagnostic approaches and pharmacological interventions of primary reduced renal uric acid excretion.
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Affiliation(s)
- S Unger
- Bereich Pathologische Biochemie, Medizinische Klinik und Poliklinik III, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Dresden, Deutschland
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20
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Eraly SA, Vallon V, Rieg T, Gangoiti JA, Wikoff WR, Siuzdak G, Barshop BA, Nigam SK. Multiple organic anion transporters contribute to net renal excretion of uric acid. Physiol Genomics 2008; 33:180-92. [PMID: 18270321 DOI: 10.1152/physiolgenomics.00207.2007] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Excretion of uric acid, a compound of considerable medical importance, is largely determined by the balance between renal secretion and reabsorption. The latter process has been suggested to be principally mediated by urate transporter 1 (URAT1; slc22a12), but the role of various putative urate transporters has been much debated. We have characterized urate handling in mice null for RST, the murine ortholog of URAT1, as well as in those null for the related organic anion transporters Oat1 and Oat3. Expression of mRNA of other putative urate transporters (UAT, MRP2, MRP4, Oatv1) was unaffected in the knockouts, as were general indexes of renal function (glomerular filtration rate, fractional excretion of fluid and electrolytes). While mass spectrometric analyses of urine and plasma revealed significantly diminished renal reabsorption of urate in RST-null mice, the bulk of reabsorption, surprisingly, was preserved. Oat1- and Oat3-null mice manifested decreased secretion rather than reabsorption, indicating that these related transporters transport urate in the "opposite" direction to RST. Moreover, metabolomic analyses revealed significant alteration in the concentration of several molecules in the plasma and urine of RST knockouts, some of which may represent additional substrates of RST. The results suggest that RST, Oat1, and Oat3 each contribute to urate handling, but, at least in mice, the bulk of reabsorption is mediated by a transporter(s) that remains to be identified. We discuss the data in the context of recent human genetic studies that suggest that the magnitude of the contribution of URAT1 to urate reabsorption might vary with ethnic background.
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Affiliation(s)
- Satish A Eraly
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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21
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Abstract
The function of the kidney, as well as its morphology, changes markedly with age. The glomerular filtration rate falls progressively, independent of overt pathology. Glomerular, vascular and accompanying parenchymal changes occur and other disorders associated with ageing, such as diabetes and hypertension, have a stochastic deleterious effect on both form and function. Declining renal function with age has important implications, not only for individual homeostasis but also for the use of drug therapy and for the receipt and donation of organs for transplantation. Molecular mechanisms and cellular changes underlying some of the functional and structural changes associated with ageing are becoming clearer, as are some of the ways in which genetic background, age and disease can combine to produce functional damage.
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Affiliation(s)
- J E Martin
- Pathology Group, Institute of Cell and Molecular Sciences, St Bartholomew's and the London Hospital School of Medicine and Dentistry, London, UK.
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22
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Mizuno N, Takahashi T, Iwase Y, Kusuhara H, Niwa T, Sugiyama Y. Human Organic Anion Transporters 1 (hOAT1/SLC22A6) and 3 (hOAT3/SLC22A8) Transport Edaravone (MCI-186; 3-methyl-1-phenyl-2-pyrazolin-5-one) and Its Sulfate Conjugate. Drug Metab Dispos 2007; 35:1429-34. [PMID: 17502342 DOI: 10.1124/dmd.106.013912] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
3-Methyl-1-phenyl-2-pyrazolin-5-one (MCI-186; edaravone), a novel free radical scavenger, is used for the treatment of acute cerebral infarction. After marketing, a few cases of acute renal failure were reported in patients following treatment with this drug. Because edaravone is mainly excreted into the urine following conjugation to glucuronide or sulfate, the renal excretion mechanisms of edaravone should help provide important information when considering the clinical cases. We examined the transport of edaravone and its sulfate and glucuronide conjugates via human organic anion transporter 1 (hOAT1) and 3 (hOAT3), expressed on the basolateral membranes of proximal tubules. The hOAT1- and hOAT3-transfected human embryonic kidney (HEK)-293 cells exhibited a markedly higher uptake of edaravone sulfate and a slightly higher uptake of edaravone than vector-transfected cells. The K(m) values of edaravone sulfate uptake by hOAT1 and hOAT3 were 11 and 15 microM, respectively. Estimation of the relative contribution of hOAT1 and hOAT3 using reference compounds suggested that hOAT1 and hOAT3 might contribute to the renal uptake of edaravone sulfate to the same extent. However, edaravone and its sulfate showed no cytotoxicity toward both hOAT1-HEK and control cells, suggesting that higher uptake in hOAT1-HEK did not associate with cytotoxicity of these compounds. In conclusion, our results suggest that both hOAT1 and hOAT3 are responsible for the basolateral uptake of edaravone sulfate in the kidney.
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Affiliation(s)
- Naomi Mizuno
- Pharmacokinetics Laboratory, Mitsubishi Pharma Corporation, Chiba, Japan
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23
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24
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Xu G, Chen X, Wu D, Shi S, Wang J, Ding R, Hong Q, Feng Z, Lin S, Lu Y. Development of High-specificity Antibodies against Renal Urate Transporters Using Genetic Immunization. BMB Rep 2006; 39:696-702. [PMID: 17129404 DOI: 10.5483/bmbrep.2006.39.6.696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recently three proteins, playing central roles in the bidirectional transport of urate in renal proximal tubules, were identified: two members of the organic anion transporter (OAT) family, OAT1 and OAT3, and a protein that designated renal urate-anion exchanger (URAT1). Antibodies against these transporters are very important for investigating their expressions and functions. With the cytokine gene as a molecular adjuvant, genetic immunization-based antibody production offers several advantages including high specificity and high recognition to the native protein compared with current methods. We fused high antigenicity fragments of the three transporters to the plasmids pBQAP-TT containing T-cell epitopes and flanking regions from tetanus toxin, respectively. Gene gun immunization with these recombinant plasmids and two other adjuvant plasmids, which express granulocyte/ macrophage colony-stimulating factor and FMS-like tyrosine kinase 3 ligand, induced high level immunoglobulin G antibodies, respectively. The native corresponding proteins of URAT1, OAT1 and OAT3, in human kidney can be recognized by their specific antibodies, respectively, with Western blot analysis and immunohistochemistry. Besides, URAT1 expression in Xenopus oocytes can also be recognized by its corresponding antibody with immuno-fluorescence. The successful production of the antibodies has provided an important tool for the study of UA transporters.
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Affiliation(s)
- Guoshuang Xu
- Department of Nephrology, Institute of Nephrology & Key Lab of PLA, General Hospital of PLA, Beijing 100853, P. R. China
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25
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Tsahar E, Arad Z, Izhaki I, Guglielmo CG. The relationship between uric acid and its oxidative product allantoin: a potential indicator for the evaluation of oxidative stress in birds. J Comp Physiol B 2006; 176:653-61. [PMID: 16705445 DOI: 10.1007/s00360-006-0088-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 04/17/2006] [Accepted: 04/18/2006] [Indexed: 01/23/2023]
Abstract
Uric acid is the main nitrogenous waste product in birds but it is also known to be a potent antioxidant. Hominoid primates and birds lack the enzyme urate oxidase, which oxidizes uric acid to allantoin. Consequently, the presence of allantoin in their plasma results from non-enzymatic oxidation. In humans, the allantoin to uric acid ratio in plasma increases during oxidative stress, thus this ratio has been suggested to be an in vivo marker for oxidative stress in humans. We measured the concentrations of uric acid and allantoin in the plasma and ureteral urine of white-crowned sparrows (Zonotrichia leucophrys gambelii) at rest, immediately after 30 min of exercise in a hop/hover wheel, and after 1 h of recovery. The plasma allantoin concentration and the allantoin to uric acid ratio did not increase during exercise but we found a positive relationship between the concentrations of uric acid and allantoin in the plasma and in the ureteral urine in the three activity phases. In the plasma, the slope of the regression describing the above positive relationships was significantly higher immediately after activity. We suggest that the slope indicates the rate of uric acid oxidation and that during activity this rate increases as a result of higher production of free radicals. The present study demonstrates that allantoin is present in the plasma and in the ureteral urine of white-crowned sparrows and therefore might be useful as an indicator of oxidative stress in birds.
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Affiliation(s)
- Ella Tsahar
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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26
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Abstract
Serum uric acid is determined by a balance between production and renal excretion. Luminal reabsorption of urate by the proximal tubule from the glomerular ultrafiltrate involves coupling between sodium-anion cotransport and urate-anion exchange. Apical sodium-coupled cotransport of lactate, ketoacids, nicotinate, and pyrazinoate increases intracellular levels of these anions in proximal tubular cells, stimulating the apical absorption of luminal urate via anion exchange. Hyperuricemia occurs when plasma levels of these anions increase; for example, hyperuricemia is a well-recognized concomitant of lactic acidosis and ketoacidosis. Relevant developments in the molecular and renal physiology of urate homeostasis are reviewed.
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Affiliation(s)
- Fred G Silva
- The United States and Canadian Academy of Pathology, Emory University and the Medical college of Georgia, Augusta, GA 30909, USA.
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28
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Enomoto A, Endou H. Roles of organic anion transporters (OATs) and a urate transporter (URAT1) in the pathophysiology of human disease. Clin Exp Nephrol 2005; 9:195-205. [PMID: 16189627 DOI: 10.1007/s10157-005-0368-5] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2004] [Accepted: 05/13/2005] [Indexed: 12/22/2022]
Abstract
Renal proximal and distal tubules are highly polarized epithelial cells that carry out the specialized directional transport of various solutes. This renal function, which is essential for homeostasis in the body, is achieved through the close pairing of apical and basolateral carriers expressed in the renal epithelial cells. The family of organic anion transporters (OATs), which belong to the major facilitator superfamily (SLC22A), are expressed in the renal epithelial cells to regulate the excretion and reabsorption of endogenous and exogenous organic anions. We now understand that these OATs are crucial components in the renal handling of drugs and their metabolites, and they are implicated in various clinically important drug interactions, and their adverse reactions. In recent years, the molecular entities of these transporters have been identified, and their function and regulatory mechanisms have been partially clarified. Workers in this field have identified URAT1 (urate transporter 1), a novel member of the OAT family that displays unique and selective substrate specificity compared with other multispecific OATs. In the OAT family, URAT1 is the main transporster responsible for human genetic diseases. In this review, we introduce and discuss some novel aspects of OATs, with special emphasis on URAT1, in the context of their biological significance, functional regulation, and roles in human disease.
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Affiliation(s)
- Atsushi Enomoto
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, 181-8611, Japan
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29
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Weinman EJ, Mohanlal V, Stoycheff N, Wang F, Steplock D, Shenolikar S, Cunningham R. Longitudinal study of urinary excretion of phosphate, calcium, and uric acid in mutant NHERF-1 null mice. Am J Physiol Renal Physiol 2005; 290:F838-43. [PMID: 16249272 DOI: 10.1152/ajprenal.00374.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
NHERF-1 binds numerous renal protein targets, including the proximal tubule transporters Na(+)/H(+) exchanger 3 (NHE3) and Na(+)-phosphate cotransporter 2a (Npt2a). Young NHERF-1(-/-) male mice display defective targeting of Npt2a to apical membranes in the renal proximal tubule and manifest hypophosphatemia and increased urinary excretion of phosphate. The present studies describe the changes in the urinary excretion of phosphate, calcium, uric acid, and sodium in male and female wild-type and NHERF-1 null mice over a time period from 12 to 54 wk of age. Young male and female NHERF-1(-/-) mice demonstrated increased urinary excretion of phosphate and urine phosphate/creatinine ratios. There was an age-related decline in the phosphate/creatinine ratio in mutant mice such that there were no differences between wild-type and NHERF-1(-/-) by 24 to 30 wk of age despite the continued presence of hypophosphatemia. Male and female NHERF-1 null mice also demonstrate increased urine calcium/creatinine and uric acid/creatinine ratios compared with wild-type controls. These studies indicate defects in the renal tubule transport of phosphate, calcium, and uric acid in NHERF-1(-/-) male and female mice that could account for the increased deposition of calcium in the papilla of null mice.
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Affiliation(s)
- Edward J Weinman
- Department of Medicine, University of Maryland School of Medicine, Baltimore 21202, USA.
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30
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Taniguchi A, Urano W, Yamanaka M, Yamanaka H, Hosoyamada M, Endou H, Kamatani N. A common mutation in an organic anion transporter gene, SLC22A12, is a suppressing factor for the development of gout. ACTA ACUST UNITED AC 2005; 52:2576-7. [PMID: 16059895 DOI: 10.1002/art.21242] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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31
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Li T, Walsh JR, Ghishan FK, Bai L. Molecular cloning and characterization of a human urate transporter (hURAT1) gene promoter. ACTA ACUST UNITED AC 2004; 1681:53-8. [PMID: 15566944 DOI: 10.1016/j.bbaexp.2004.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2004] [Revised: 09/22/2004] [Accepted: 10/01/2004] [Indexed: 11/21/2022]
Abstract
We report the novel cloning and preliminary characterization of a human urate transporter (hURAT1) gene promoter. The transcription initiation site was mapped to a base 337 bp upstream of the ATG start codon by primer extension and 5'-RACE. The minimal functional promoter region is within 253 bp when the promoter/luciferase constructs were transfected into OK cells. The sex hormone testosterone significantly increases promoter activity, suggesting that hormonal regulation of hURAT1 is the root cause of observed differences in urate levels between males and females.
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Affiliation(s)
- Tao Li
- Department of Pediatrics, Steele Memorial Children's Research Center, University of Arizona Health Sciences Center, Room 3325, 1501 North Campbell Avenue, Tucson, AZ 85724, USA
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Zhang X, Groves CE, Bahn A, Barendt WM, Prado MD, Rödiger M, Chatsudthipong V, Burckhardt G, Wright SH. Relative contribution of OAT and OCT transporters to organic electrolyte transport in rabbit proximal tubule. Am J Physiol Renal Physiol 2004; 287:F999-1010. [PMID: 15251863 DOI: 10.1152/ajprenal.00156.2004] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We compared the characteristics of several cloned rabbit organic electrolyte (OE) transporters expressed in cultured cells with their behavior in intact rabbit renal proximal tubules (RPT) to determine the contribution of each to basolateral uptake of the weak acid ochratoxin A (OTA) and the weak base cimetidine (CIM). The activity of organic anion transporters OAT1 and OAT3 proved to be distinguishable because OAT1 had a high affinity for PAH ( Ktof 20 μM) and did not support estrone sulfate (ES) transport, whereas OAT3 had a high affinity for ES ( Ktof 4.5 μM) and a weak interaction with PAH (IC50> 1 mM). In contrast, both transporters robustly accumulated OTA. Intact RPT also accumulated OTA, with OAT1 and OAT3 each responsible for ∼50%: ES and PAH each reduced uptake by ∼50%, and the combination of the two eliminated mediated OTA uptake. The weak base CIM was transported by OAT3 ( Ktof 80 μM) and OCT2 ( Ktof 2 μM); OCT1 had a comparatively low affinity for CIM, and CIM uptake by OAT1 was equivocal. Intact RPT accumulated CIM, with TEA and ES reducing CIM uptake by 20 and 75%, respectively, suggesting that OAT3 plays a quantitatively more significant role in CIM uptake in the early proximal tubule than OCT1/2. In single S2 segments of RPT, ES and TEA each blocked ∼50% of CIM uptake. Thus the fractional contribution of different OE transporters to renal secretion is influenced by their affinity for substrate and relative expression level in RPT.
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Affiliation(s)
- Xiaohong Zhang
- Dept. of Physiology, College of Medicine, University of Arizona, Tucson, AZ 85724, USA
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Van Aubel RAMH, Smeets PHE, van den Heuvel JJMW, Russel FGM. Human organic anion transporter MRP4 (ABCC4) is an efflux pump for the purine end metabolite urate with multiple allosteric substrate binding sites. Am J Physiol Renal Physiol 2004; 288:F327-33. [PMID: 15454390 DOI: 10.1152/ajprenal.00133.2004] [Citation(s) in RCA: 171] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The end product of human purine metabolism is urate, which is produced primarily in the liver and excreted by the kidney through a well-defined basolateral blood-to-cell uptake step. However, the apical cell-to-urine efflux mechanism is as yet unidentified. Here, we show that the renal apical organic anion efflux transporter human multidrug resistance protein 4 (MRP4), but not apical MRP2, mediates ATP-dependent urate transport via a positive cooperative mechanism (K(m) of 1.5 +/- 0.3 mM, V(max) of 47 +/- 7 pmol x mg(-1) x min(-1), and Hill coefficient of 1.7 +/- 0.2). In HEK293 cells overexpressing MRP4, intracellular urate levels were lower than in control cells. Urate inhibited methotrexate transport (IC50 of 235 +/- 8 microM) by MRP4, did not affect cAMP transport, whereas cGMP transport was stimulated. Urate shifted cGMP transport by MRP4 from positive cooperativity (K(m) and V(max) value of 180 +/- 20 microM and 58 +/- 4 pmol x mg(-1) x min(-1), respectively, Hill coefficient of 1.4 +/- 0.1) to single binding site kinetics (K(m) and V(max) value of 2.2 +/- 0.9 mM and 280 +/- 50 pmol x mg(-1) x min(-1), respectively). Finally, MRP4 could transport urate simultaneously with cAMP or cGMP. We conclude that human MRP4 is a unidirectional efflux pump for urate with multiple allosteric substrate binding sites. We propose MRP4 as a candidate transporter for urinary urate excretion and suggest that MRP4 may also mediate hepatic export of urate into the circulation, because of its basolateral expression in the liver.
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Affiliation(s)
- Rémon A M H Van Aubel
- Department of Pharmacology-Toxicology, Radboud University Nijmegen Medical Center, Nijmegen Center for Molecular Life Sciences, Nijmegen, The Netherlands
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Mousavizadeh K, Dehpour AR, Minagar A, Ghafourifar P. Uric acid: a novel treatment strategy for multiple sclerosis. Trends Pharmacol Sci 2003; 24:563-4; author reply 564-5. [PMID: 14607077 DOI: 10.1016/j.tips.2003.09.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Braun EJ. Regulation of renal and lower gastrointestinal function: role in fluid and electrolyte balance. Comp Biochem Physiol A Mol Integr Physiol 2003; 136:499-505. [PMID: 14613780 DOI: 10.1016/s1095-6433(03)00170-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
For the majority of vertebrates, the kidneys are not the sole organs that function to maintain homeostasis of body fluid and electrolytes. Mammals are unusual in this respect, as the kidneys are the organs that fill this role. For non-mammalian vertebrates, other organs such as gills, skin, salt glands, urinary bladders and the gastrointestinal (GI) system function in concert with the kidneys in the control of fluid and ion balance. Birds are of particular interest and unique as they do not possess a urinary bladder and the renal output enters the lower GI tract. The physiology of the interaction of avian kidneys and lower GI tract is an excellent example of integrative physiology and several aspects of it have been examined, for example, the role of the avian antidiuretic hormone (arginine vasotocin, AVT) in controlling renal output. AVT produces both a tubular and glomerular antidiuresis. The glomerular antidiuresis is important, as the fluid from the kidneys that enters the GI should not be highly concentrated. Another hormone, aldosterone, has been shown to play an important role in regulating the transport of sodium by the GI epithelium. In addition, the lower GI tract plays a significant role in recycling a portion of the nitrogen that leaves the kidneys as uric acid. Furthermore, the output of avian kidneys contains large amount of protein that is conserved by the lower GI tract.
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Affiliation(s)
- Eldon J Braun
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
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Eraly SA, Blantz RC, Bhatnagar V, Nigam SK. Novel aspects of renal organic anion transporters. Curr Opin Nephrol Hypertens 2003; 12:551-8. [PMID: 12920404 DOI: 10.1097/00041552-200309000-00011] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Organic anion transporters, transmembrane proteins present in the renal proximal tubule, are a critical component of the human drug excretion machinery. Recent advances have clarified the function of these transporters, with broad clinical implications for pharmacogenetics, drug interactions and adverse reactions. Here, we discuss these issues in the context of the basic biology of the transporters. RECENT FINDINGS Understanding of organic anion transporter function has proceeded on several fronts. The continued cataloging of organic anion transporter substrates has revealed that the transporters' activity likely underlies many common drug interactions and nephrotoxic adverse reactions. Meanwhile, immunohistochemical and physiological studies suggest their potential involvement in the apical as well as basolateral steps of renal organic anion secretion. In addition, studies of the genomic organization of these transporters reveal that they are found in pairs of similar and similarly expressed genes, suggesting that pair members are coordinately regulated. Finally, we hypothesize here that organic anion transporters might impact renal susceptibility to ischemia and toxic injury, because their uptake of substrates can result in the efflux of Krebs cycle intermediates, an important nutrient source for the proximal tubule. SUMMARY The study of these transporters will likely have a significant impact on renal pharmacology and pharmacogenetics. In this regard, the generation of organic anion transporter gene knockout mice could provide invaluable models for defects in renal drug-handling. Ultimately, detailed knowledge of organic anion transporter function will assist in the choice of optimum pharmacological therapies.
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Affiliation(s)
- Satish A Eraly
- Department of Medicine1, University of California, San Diego, 9500 Gilman Drive, La Jolla, Californian 92093-0693, USA.
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Metabolism of Aromatic Compounds and Nucleic Acid Bases. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50028-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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