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Edwards A, Kurtcuoglu V. Renal blood flow and oxygenation. Pflugers Arch 2022; 474:759-770. [PMID: 35438336 PMCID: PMC9338895 DOI: 10.1007/s00424-022-02690-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 03/19/2022] [Accepted: 03/21/2022] [Indexed: 02/07/2023]
Abstract
Our kidneys receive about one-fifth of the cardiac output at rest and have a low oxygen extraction ratio, but may sustain, under some conditions, hypoxic injuries that might lead to chronic kidney disease. This is due to large regional variations in renal blood flow and oxygenation, which are the prerequisite for some and the consequence of other kidney functions. The concurrent operation of these functions is reliant on a multitude of neuro-hormonal signaling cascades and feedback loops that also include the regulation of renal blood flow and tissue oxygenation. Starting with open questions on regulatory processes and disease mechanisms, we review herein the literature on renal blood flow and oxygenation. We assess the current understanding of renal blood flow regulation, reasons for disparities in oxygen delivery and consumption, and the consequences of disbalance between O2 delivery, consumption, and removal. We further consider methods for measuring and computing blood velocity, flow rate, oxygen partial pressure, and related parameters and point out how limitations of these methods constitute important hurdles in this area of research. We conclude that to obtain an integrated understanding of the relation between renal function and renal blood flow and oxygenation, combined experimental and computational modeling studies will be needed.
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Affiliation(s)
- Aurelie Edwards
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
| | - Vartan Kurtcuoglu
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- National Center of Competence in Research, Kidney.CH, University of Zurich, Zurich, Switzerland.
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland.
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2
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The role of nitric oxide in sepsis-associated kidney injury. Biosci Rep 2022; 42:231441. [PMID: 35722824 PMCID: PMC9274646 DOI: 10.1042/bsr20220093] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/07/2022] [Accepted: 06/17/2022] [Indexed: 01/09/2023] Open
Abstract
Sepsis is one of the leading causes of acute kidney injury (AKI), and several mechanisms including microcirculatory alterations, oxidative stress, and endothelial cell dysfunction are involved. Nitric oxide (NO) is one of the common elements to all these mechanisms. Although all three nitric oxide synthase (NOS) isoforms are constitutively expressed within the kidneys, they contribute in different ways to nitrergic signaling. While the endothelial (eNOS) and neuronal (nNOS) isoforms are likely to be the main sources of NO under basal conditions and participate in the regulation of renal hemodynamics, the inducible isoform (iNOS) is dramatically increased in conditions such as sepsis. The overexpression of iNOS in the renal cortex causes a shunting of blood to this region, with consequent medullary ischemia in sepsis. Differences in the vascular reactivity among different vascular beds may also help to explain renal failure in this condition. While most of the vessels present vasoplegia and do not respond to vasoconstrictors, renal microcirculation behaves differently from nonrenal vascular beds, displaying similar constrictor responses in control and septic conditions. The selective inhibition of iNOS, without affecting other isoforms, has been described as the ideal scenario. However, iNOS is also constitutively expressed in the kidneys and the NO produced by this isoform is important for immune defense. In this sense, instead of a direct iNOS inhibition, targeting the NO effectors such as guanylate cyclase, potassium channels, peroxynitrite, and S-nitrosothiols, may be a more interesting approach in sepsis-AKI and further investigation is warranted.
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Pravikova PD, Ivanova LN. Effect of NO Synthesis Blockade on Renal Osmoregulatory Function in Methimazole-Induced Hypothyroid Rats with Different Vasopressin Blood Level. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s0022093021060223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Dillon K, Shariffi B, Gillum T, Boyer W, Sullivan S, Kim JK. Effects of chronic dietary grape seed extract supplementation on aortic stiffness and hemodynamic responses in obese/overweight males during submaximal exercise. Eur J Sport Sci 2021; 22:1057-1064. [PMID: 33905304 DOI: 10.1080/17461391.2021.1923815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We investigated the effect of chronic grape seed extract (GSE) on blood pressure and aortic stiffness (AoS) among overweight and obese males. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), cardiac output (Q), total vascular conductance (TVC), and AoS were measured during two submaximal cycling exercises (40% and 60% VO2max), after 7 consecutive days of GSE or placebo (PL) ingestion with one week washout period. Compared with PL, GSE supplementation significantly decreased MAP at rest (85 ± 3 mmHg vs. 82 ± 3 mmHg), 40% (102 ± 3 mmHg vs. 99 ± 3 mmHg), and 60% workloads (109 ± 3 mmHg vs. 107 ± 3 mmHg) (P = 0.001, ES = 0.2). AoS was significantly reduced (13.0 ± 1.9 AU vs. 10.2 ± 1.0 AU) at rest (P = 0.002, ES = 0.6). Q was decreased at rest and across all workloads, but there were no significant differences (7.5 ± 0.4 L/min vs. 7.1 ± 0.4 L/min; 20.4 ± 1.2 L/min vs. 19.6 ± 0.9 L/min; 26.3 ± 1.1 L/min vs. 25.5 ± 1.6 L/min, respectively). GSE had no effect on HR, TVC, and SV. Our study indicates that chronic supplementation with GSE reduces arterial pressure at rest and during exercise primarily via the substantial reduction in AoS. Thus, GSE can be a dietary supplement to treat augmented blood pressure responses in obese and overweight males at rest and during exercise.Trial registration: ClinicalTrials.gov identifier: NCT04465110.
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Affiliation(s)
- Katherine Dillon
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
| | - Brian Shariffi
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
| | - Trevor Gillum
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
| | - William Boyer
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
| | - Sean Sullivan
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
| | - Jong-Kyung Kim
- Department of Kinesiology, California Baptist University, Riverside, CA, USA
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5
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Abstract
The prevalence of cardiovascular and metabolic disease coupled with kidney dysfunction is increasing worldwide. This triad of disorders is associated with considerable morbidity and mortality as well as a substantial economic burden. Further understanding of the underlying pathophysiological mechanisms is important to develop novel preventive or therapeutic approaches. Among the proposed mechanisms, compromised nitric oxide (NO) bioactivity associated with oxidative stress is considered to be important. NO is a short-lived diatomic signalling molecule that exerts numerous effects on the kidneys, heart and vasculature as well as on peripheral metabolically active organs. The enzymatic L-arginine-dependent NO synthase (NOS) pathway is classically viewed as the main source of endogenous NO formation. However, the function of the NOS system is often compromised in various pathologies including kidney, cardiovascular and metabolic diseases. An alternative pathway, the nitrate-nitrite-NO pathway, enables endogenous or dietary-derived inorganic nitrate and nitrite to be recycled via serial reduction to form bioactive nitrogen species, including NO, independent of the NOS system. Signalling via these nitrogen species is linked with cGMP-dependent and independent mechanisms. Novel approaches to restoring NO homeostasis during NOS deficiency and oxidative stress have potential therapeutic applications in kidney, cardiovascular and metabolic disorders.
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DILLON KN, SHARIFFI B, THOMPSON B, STEELE R, KIM JK. Effects of Acute Grape Seed Extract Supplementation on Hemodynamics in Normal Body Weight and Obese Males. J Nutr Sci Vitaminol (Tokyo) 2020; 66:427-431. [DOI: 10.3177/jnsv.66.427] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Brian SHARIFFI
- Department of Kinesiology, California Baptist University
| | | | - Richard STEELE
- Department of Kinesiology, California Baptist University
| | - Jong-Kyung KIM
- Department of Kinesiology, California Baptist University
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7
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Combination of Exercise Training and SOD Mimetic Tempol Enhances Upregulation of Nitric Oxide Synthase in the Kidney of Spontaneously Hypertensive Rats. Int J Hypertens 2020; 2020:2142740. [PMID: 33145105 PMCID: PMC7596428 DOI: 10.1155/2020/2142740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 08/12/2020] [Accepted: 09/30/2020] [Indexed: 12/02/2022] Open
Abstract
Both exercise training (Ex) and superoxide dismutase (SOD) mimetic tempol have antihypertensive and renal protective effects in rodent models of several hypertensions. We recently reported that Ex increases nitric oxide (NO) production and the expression levels of endothelial and neuronal NO synthase (eNOS and nNOS) in the kidney and aorta of the spontaneously hypertensive rats (SHR) and normotensive Wistar–Kyoto rats (WKY). We also found that endogenous hydrogen peroxide (H2O2) upregulates the expression levels of eNOS and nNOS in SHR. To elucidate the mechanism of the Ex-upregulated NO system in the kidney, we examined the additive effect of Ex and tempol on the renal NO system in SHR and WKY. Our data showed that, in SHR, both Ex and tempol increase the levels of H2O2 and nitrate/nitrite (NOx) in plasma and urine. We also observed an increased renal NOS activity and upregulated expression levels of eNOS and nNOS with decreased NADPH oxidase activity. The effects of the combination of Ex and tempol on these variables were cumulate in SHR. On the other hand, we found that Ex increases these variables with increased renal NADPH oxidase activity, but tempol did not change these variables or affect the Ex-induced upregulation in the activity and expression of NOS in WKY. The SOD activity in the kidney and aorta was activated by tempol only in SHR, but not in WKY; whereas Ex increased SOD activity only in the aorta in both SHR and WKY. These results indicate that Ex-induced endogenous H2O2 produced in the blood vessel and other organs outside of the kidney may be carried to the kidney by blood flow and stimulates the NO system in the kidney.
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Podkowińska A, Formanowicz D. Chronic Kidney Disease as Oxidative Stress- and Inflammatory-Mediated Cardiovascular Disease. Antioxidants (Basel) 2020; 9:E752. [PMID: 32823917 PMCID: PMC7463588 DOI: 10.3390/antiox9080752] [Citation(s) in RCA: 135] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 12/12/2022] Open
Abstract
Generating reactive oxygen species (ROS) is necessary for both physiology and pathology. An imbalance between endogenous oxidants and antioxidants causes oxidative stress, contributing to vascular dysfunction. The ROS-induced activation of transcription factors and proinflammatory genes increases inflammation. This phenomenon is of crucial importance in patients with chronic kidney disease (CKD), because atherosclerosis is one of the critical factors of their cardiovascular disease (CVD) and increased mortality. The effect of ROS disrupts the excretory function of each section of the nephron. It prevents the maintenance of intra-systemic homeostasis and leads to the accumulation of metabolic products. Renal regulatory mechanisms, such as tubular glomerular feedback, myogenic reflex in the supplying arteriole, and the renin-angiotensin-aldosterone system, are also affected. It makes it impossible for the kidney to compensate for water-electrolyte and acid-base disturbances, which progress further in the mechanism of positive feedback, leading to a further intensification of oxidative stress. As a result, the progression of CKD is observed, with a spectrum of complications such as malnutrition, calcium phosphate abnormalities, atherosclerosis, and anemia. This review aimed to show the role of oxidative stress and inflammation in renal impairment, with a particular emphasis on its influence on the most common disturbances that accompany CKD.
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Affiliation(s)
| | - Dorota Formanowicz
- Department of Clinical Biochemistry and Laboratory Medicine, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznan, Poland
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9
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The endothelial nitric oxide synthase gene G894T, glutathione S-transferase (GSTM1 and GSTT1) polymorphisms as a risk factor in the patient with nephrolithiasis. Int J Biol Macromol 2019; 140:719-726. [DOI: 10.1016/j.ijbiomac.2019.08.184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 08/20/2019] [Accepted: 08/20/2019] [Indexed: 11/24/2022]
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10
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Verma V, Gupta S, Kumar P, Yadav S, Dhanda RS, Gaind R, Arora R, Frimodt-Møller N, Yadav M. Involvement of NLRP3 and NLRC4 Inflammasome in Uropathogenic E. coli Mediated Urinary Tract Infections. Front Microbiol 2019; 10:2020. [PMID: 31551961 PMCID: PMC6734172 DOI: 10.3389/fmicb.2019.02020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/19/2019] [Indexed: 12/19/2022] Open
Abstract
Background Inflammatory response during urinary tract infection (UTI) is mediated by innate immune defense. Nod like receptors (NLRs) have been proposed to work simultaneously beside TLR pathways to mediate pro-inflammatory response and maintain tissue homeostasis. Some in vitro reports have showed the involvement of NLRP3 inflammasome during uropathogenic Escherichia coli (UPEC) mediated UTI. So we have sought to determine the status of various inflammasomes and their components in UPEC mediated UTI. Methods A total of 186 females experiencing the first episode of UTI were recruited for the study and forty were found to be positive for UPEC (≥105 CFU/ml) in their urine (N = 40). Further, we analyzed the expression of NLRP3, NLRC4, NAIP, AIM2, ASC, CASPASE-4, and CASPASE-1 gene at mRNA and protein level in the blood of UPEC confirmed study subjects through real time qPCR and immunoblotting. Healthy females (N = 40) visiting the OPD for health checkups, family planning advice and subjects undergoing routine medical examinations, were recruited as healthy control subjects. Pro-inflammatory cytokines (IL-6, IL-8, IFN-γ, TNF-α and MCP-1) were measured in the plasma of patients and controls through ELISA. For investigation of the involvement of NLRC4 and NLRP3 inflammasome, in vitro studies were performed using co-immunoprecipitation and confocal microscopy. Results Most of the inflammatory regulators studied (i.e., NLRP3, NAIP, NLRC4, ASC, and CASPASE-1) were found to be up-regulated at both mRNA and protein levels in the UPEC infected UTI patients. Also, pro-inflammatory cytokines (IL-6, IL-8, IFN-γ, TNF-α, and MCP-1) were found to be up-regulated in the patients group. However, no significant difference was observed in the expression of AIM2 and CASPASE-4 genes at both mRNA and protein levels. Further, in vitro studies have shown the involvement of NLRC4 inflammasome in UPEC infected THP1 derived macrophages. Conclusion Involvement of NLRP3 and NLRC4 inflammasomes in UPEC infected UTI is evident from our findings. This is the first report showing levels of inflammasome and its components in UTI patients suggesting a possible role during UPEC mediated UTI. We have also reported the involvement of NLRC4 inflammasome for the first time during UTI infection.
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Affiliation(s)
- Vivek Verma
- Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, New Delhi, India
| | - Surbhi Gupta
- Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, New Delhi, India
| | - Parveen Kumar
- Department of Urology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Sonal Yadav
- Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, New Delhi, India
| | | | - Rajni Gaind
- Department of Microbiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
| | - Renu Arora
- Department of Obstetrics and Gynecology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
| | | | - Manisha Yadav
- Dr. B.R. Ambedkar Center for Biomedical Research, University of Delhi, New Delhi, India.,Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
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Imafidon CE, Akomolafe RO, Eluwole OA, Adekunle IA, Agbaje RA. Aqueous garlic extract improves renal clearance via vasodilatory/antioxidant mechanisms and mitigated proteinuria via stabilization of glomerular filtration barrier. CLINICAL PHYTOSCIENCE 2019. [DOI: 10.1186/s40816-019-0118-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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12
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Effect of NO Synthesis Blockade on the Hydrouretic Function and Extracellular Matrix of the Kidneys in Rats with Different Blood Vasopressin Levels. Bull Exp Biol Med 2019; 167:233-236. [DOI: 10.1007/s10517-019-04498-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Indexed: 10/26/2022]
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13
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Melatonin therapy protects against renal injury before and after release of bilateral ureteral obstruction in rats. Life Sci 2019; 229:104-115. [PMID: 31100324 DOI: 10.1016/j.lfs.2019.05.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/06/2019] [Accepted: 05/13/2019] [Indexed: 01/31/2023]
Abstract
AIM Blockage of the urinary tract is often connected with renal function impediment, including reductions in glomerular filtration rate (GFR) and the power to control sodium as well as water elimination through urination. Melatonin, known to be the primary product of the pineal gland, prevents renal damage caused by ischemic reperfusion. However, the effects of melatonin on urinary obstruction, as well as release of obstruction induced kidney injury are still largely unknown. The aim of present study was to investigate the effect of melatonin on mediating protection against renal injury triggered from either bilateral ureteral obstruction (BUO) or BUO release (BUO-R). MAIN METHODS Adult male Sprague-Dawley rats (n = 60) were clustered into six treatment groups: sham treated-1; BUO-non-treated (24 h BUO only); BUO + melatonin; sham treated-2; BUO-48hR (24 h of BUO and then release for 2 days); and BUO-48hR + melatonin. Kidney tissues, blood and urine samples were obtained for further assessment. KEY FINDINGS It was found that melatonin treatment remarkably promoted the recovery of the handling capacity of urinary excretion of water as well as sodium in BUO and BUO-48hR models. Melatonin treatment partially inhibited inflammatory cytokine expression and the downregulation of aquaporin (AQPs, AQP-1, -2 and -3) expression in these two models. Moreover, the cytoarchitecture of BUO rats exposed to melatonin was well preserved. SIGNIFICANCE Melatonin treatment potently prevents BUO or BUO-R induced renal injury, which may be partially attributed to restoring the expression of AQPs and inhibition of inflammatory response, as well as preserving renal ultrastructural integrity.
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Rogers RT, Sun MA, Yue Q, Bao HF, Sands JM, Blount MA, Eaton DC. Lack of urea transporters, UT-A1 and UT-A3, increases nitric oxide accumulation to dampen medullary sodium reabsorption through ENaC. Am J Physiol Renal Physiol 2019; 316:F539-F549. [PMID: 30539654 PMCID: PMC6459308 DOI: 10.1152/ajprenal.00166.2018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 11/19/2018] [Accepted: 11/30/2018] [Indexed: 12/31/2022] Open
Abstract
Although the role of urea in urine concentration is known, the effect of urea handling by the urea transporters (UTs), UT-A1 and UT-A3, on sodium balance remains elusive. Serum and urinary sodium concentration is similar between wild-type mice (WT) and UT-A3 null (UT-A3 KO) mice; however, mice lacking both UT-A1 and UT-A3 (UT-A1/A3 KO) have significantly lower serum sodium and higher urinary sodium. Protein expression of renal sodium transporters is unchanged among all three genotypes. WT, UT-A3 KO, and UT-A1/A3 KO acutely respond to hydrochlorothiazide and furosemide; however, UT-A1/A3 KO fail to show a diuretic or natriuretic response following amiloride administration, indicating that baseline epithelial Na+ channel (ENaC) activity is impaired. UT-A1/A3 KO have more ENaC at the apical membrane than WT mice, and single-channel analysis of ENaC in split-open inner medullary collecting duct (IMCD) isolated in saline shows that ENaC channel density and open probability is higher in UT-A1/A3 KO than WT. UT-A1/A3 KO excrete more urinary nitric oxide (NO), a paracrine inhibitor of ENaC, and inner medullary nitric oxide synthase 1 mRNA expression is ~40-fold higher than WT. Because endogenous NO is unstable, ENaC activity was reassessed in split-open IMCD with the NO donor PAPA NONOate [1-propanamine-3-(2-hydroxy-2-nitroso-1-propylhydrazine)], and ENaC activity was almost abolished in UT-A1/A3 KO. In summary, loss of both UT-A1 and UT-A3 (but not UT-A3 alone) causes elevated medullary NO production and salt wasting. NO inhibition of ENaC, despite elevated apical accumulation of ENaC in UT-A1/A3 KO IMCD, appears to be the main contributor to natriuresis in UT-A1/A3 KO mice.
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Affiliation(s)
- Richard T Rogers
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Michael A Sun
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Hui-Fang Bao
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Jeff M Sands
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine , Atlanta, Georgia
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine , Atlanta, Georgia
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Rosenbaek JB, Pedersen EB, Bech JN. The effect of sodium nitrite infusion on renal function, brachial and central blood pressure during enzyme inhibition by allopurinol, enalapril or acetazolamide in healthy subjects: a randomized, double-blinded, placebo-controlled, crossover study. BMC Nephrol 2018; 19:244. [PMID: 30241504 PMCID: PMC6150994 DOI: 10.1186/s12882-018-1035-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 09/03/2018] [Indexed: 12/25/2022] Open
Abstract
Background Sodium nitrite (NaNO2) causes vasodilation, presumably by enzymatic conversion to nitric oxide (NO). Several enzymes with nitrite reducing capabilities have been discovered in vitro, but their relative importance in vivo has not been investigated. We aimed to examine the effects of NaNO2 on blood pressure, fractional sodium excretion (FENa), free water clearance (CH2O) and GFR, after pre-inhibition of xanthine oxidase, carbonic anhydrase, and angiotensin-converting enzyme. The latter as an approach to upregulate endothelial NO synthase activity. Methods In a double-blinded, placebo-controlled, crossover study, 16 healthy subjects were treated, in a randomized order, with placebo, allopurinol 150 mg twice daily (TD), enalapril 5 mg TD, or acetazolamide 250 mg TD. After 4 days of treatment and standardized diet, the subjects were examined at our lab. During intravenous infusion of 240 μg NaNO2/kg/hour for 2 h, we measured changes in brachial and central blood pressure (BP), plasma cyclic guanosine monophosphate (P-cGMP), plasma and urine osmolality, GFR by 51Cr-EDTA clearance, FENa and urinary excretion rate of cGMP (U-cGMP) and nitrite and nitrate (U-NOx). Subjects were supine and orally water-loaded throughout the examination day. Results Irrespective of pretreatment, we observed an increase in FENa, heart rate, U-NOx, and a decrease in CH2O and brachial systolic BP during NaNO2 infusion. P-cGMP and U-cGMP did not change during infusion. We observed a consistent trend towards a reduction in central systolic BP, which was only significant after allopurinol. Conclusion This study showed a robust BP lowering, natriuretic and anti-aquaretic effect of intravenous NaNO2 regardless of preceding enzyme inhibition. None of the three enzyme inhibitors used convincingly modified the pharmacological effects of NaNO2. The steady cGMP indicates little or no conversion of nitrite to NO. Thus the effect of NaNO2 may not be mediated by NO generation. Trial registration EU Clinical Trials Register, 2013-003404-39. Registered December 3 2013.
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Affiliation(s)
- Jeppe B Rosenbaek
- University Clinic in Nephrology and Hypertension, Regional Hospital West Jutland and Aarhus University, Laegaardvej 12J, DK-7500, Holstebro, Denmark.
| | - Erling B Pedersen
- University Clinic in Nephrology and Hypertension, Regional Hospital West Jutland and Aarhus University, Laegaardvej 12J, DK-7500, Holstebro, Denmark
| | - Jesper N Bech
- University Clinic in Nephrology and Hypertension, Regional Hospital West Jutland and Aarhus University, Laegaardvej 12J, DK-7500, Holstebro, Denmark
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16
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Abdulmahdi W, Rabadi MM, Jules E, Marghani Y, Marji N, Leung J, Zhang F, Siani A, Siskind T, Vedovino K, Chowdhury N, Sekulic M, Ratliff BB. Kidney dysfunction in the low-birth weight murine adult: implications of oxidative stress. Am J Physiol Renal Physiol 2018; 315:F583-F594. [DOI: 10.1152/ajprenal.00164.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Maternal undernutrition (MUN) during pregnancy leads to low-birth weight (LBW) neonates that have a reduced kidney nephron endowment and higher morbidity as adults. Using a severe combined caloric and protein-restricted mouse model of MUN to generate LBW mice, we examined the progression of renal insufficiency in LBW adults. Through 6 mo of age, LBW males experienced greater albuminuria (ELISA analysis), a more rapid onset of glomerular hypertrophy, and a worse survival rate than LBW females. In contrast, both sexes experienced a comparable progressive decline in renal vascular density (immunofluorescence analysis), renal blood flow (Laser-Doppler flowmetry analysis), glomerular filtration rate (FITC-sinistrin clearance analysis), and a progressive increase in systemic blood pressure (measured via tail-cuff method). Isolated aortas from both LBW sexes demonstrated reduced vasodilation in response to ACh, indicative of reduced nitric oxide bioavailability and endothelial dysfunction. ELISA and immunofluorescence analysis revealed a significant increase of circulating reactive oxygen species and NADPH oxidase type 4 (NOX4) expression in both LBW sexes, although these increases were more pronounced in males. Although more effective in males, chronic tempol treatment did improve all observed pathologies in both sexes of LBW mice. Chronic NOX4 inhibition with GKT137831 was more effective than tempol in preventing pathologies in LBW males. In conclusion, despite some minor differences, LBW female and male adults have a reduced nephron endowment comparable with progressive renal and vascular dysfunction, which is associated with increased oxidative stress and subsequent endothelial dysfunction. Tempol treatment and/or NOX4 inhibition attenuates renal and vascular dysfunction in LBW adults.
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Affiliation(s)
- Wasan Abdulmahdi
- Department of Physiology, Renal Research Institute, New York Medical College, Valhalla, New York
| | - May M. Rabadi
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Edson Jules
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Yara Marghani
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Noor Marji
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Jessica Leung
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Frank Zhang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Avi Siani
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Tamar Siskind
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Kiara Vedovino
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Nazrul Chowdhury
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
| | - Miroslav Sekulic
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Brian B. Ratliff
- Department of Medicine, Renal Research Institute, New York Medical College, Valhalla, New York
- Department of Physiology, Renal Research Institute, New York Medical College, Valhalla, New York
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17
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Nishimoto M, Mizuno R, Fujita T, Isshiki M. Stromal interaction molecule 1 modulates blood pressure via NO production in vascular endothelial cells. Hypertens Res 2018; 41:506-514. [DOI: 10.1038/s41440-018-0045-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/08/2018] [Accepted: 01/14/2018] [Indexed: 01/19/2023]
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18
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Olabiyi AA, Carvalho FB, Bottari NB, Morsch VM, Morel AF, Oboh G, Schetinger MR. Tiger nut and walnut extracts modulate extracellular metabolism of ATP and adenosine through the NOS/cGMP/PKG signalling pathway in kidney slices. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2018; 43:140-149. [PMID: 29747747 DOI: 10.1016/j.phymed.2018.04.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 02/19/2018] [Accepted: 04/15/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Tiger nut (Cyperus esculentus L.) and walnut (Tetracarpidium conophorum Müll. Arg.) have been reportedly used in the treatment of inflammatory diseases such as atherosclerosis, prevent heart attack and improve blood circulation, reduce serum cholesterol level as well as inhibit oxidation reactions. PURPOSE This study investigated the effect of tiger nut and walnut hydro-alcoholic extracts on extracellular metabolism of ATP through the NOS/cGMP/PKG signaling pathway induced by Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME) in kidney slices. METHODS The plants were extracted for 24 h in 10 ml of 70% ethanol and 30% distilled water per gram milled material on a mechanical shaker and filtered using Whatman filter paper. The effect of the extracts on ecto-nucleotidases (NTPDase and 5' nucleotidase) and adenosine deaminase activities, nitrites and nitrates levels (NO, markers of NO production) as well as lipid and protein oxidation reactions in kidney slices were evaluated. Also, the phenolic components of the nut samples were determined using High Performance Liquid Chromatography (HPLC). RESULTS The results revealed a protective effect of tiger nut and walnut on co-incubation with L-NAME of the enzyme activities, increased NO significantly (P < 0.05) when compared to the vehicle. L-NAME also increased the thiobabituric reactive substances but co-incubation with the extracts caused a significant reduction while protein oxidation across groups showed no significant difference when compared to the vehicle group. HPLC finger printing revealed the presence of quercetin and kaempferol as the most abundant phenolic compounds in tiger nut and walnut respectively. CONCLUSION Tiger nut and walnut extracts showed a protective effect on L-NAME induced kidney slices by reducing the activities of NTPDase (ATP as substrate) and adenosine deaminase, increased NO levels as well as prevent oxidative damage. The effect observed may be attributed to the phenolic compounds present in both nuts as depicted by HPLC finger printing.
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Affiliation(s)
- Ayodeji A Olabiyi
- Department of Biochemistry, Functional Foods and Nutraceuticals Unit, Federal University of Technology, P.M.B. 704, Akure 340001, Nigeria; Department of Medical Biochemistry, Afe Babalola University Ado-Ekiti, P.M.B. 5454, Nigeria; Department of Biochemistry and Molecular Biology, Center of Natural and Exacts Sciences, Federal University of Santa Maria, Santa Maria/RS 97105-900, Brazil.
| | - Fabiano B Carvalho
- Department of Biochemistry and Molecular Biology, Center of Natural and Exacts Sciences, Federal University of Santa Maria, Santa Maria/RS 97105-900, Brazil
| | - Nathieli B Bottari
- Department of Biochemistry and Molecular Biology, Center of Natural and Exacts Sciences, Federal University of Santa Maria, Santa Maria/RS 97105-900, Brazil
| | - Vera M Morsch
- Department of Biochemistry and Molecular Biology, Center of Natural and Exacts Sciences, Federal University of Santa Maria, Santa Maria/RS 97105-900, Brazil
| | - Ademir F Morel
- Department of Chemistry, Center of Natural and Exacts Sciences, Federal University of Santa Maria, RS 97105-900, Brazil
| | - Ganiyu Oboh
- Department of Biochemistry, Functional Foods and Nutraceuticals Unit, Federal University of Technology, P.M.B. 704, Akure 340001, Nigeria.
| | - Maria Rosa Schetinger
- Department of Biochemistry and Molecular Biology, Center of Natural and Exacts Sciences, Federal University of Santa Maria, Santa Maria/RS 97105-900, Brazil.
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Rezaei F, Mohhamadi R. Comparison of Saliva Nitric Oxide between Chronic Kidney Disease Before and After Dialysis and with Control Group. Open Dent J 2018; 12:213-218. [PMID: 29643947 PMCID: PMC5876925 DOI: 10.2174/1874210601812010213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 02/21/2018] [Accepted: 02/28/2018] [Indexed: 12/29/2022] Open
Abstract
Introduction: Chronic Kidney Disease (CKD) is a chronic progressive disorder and a major cause of death and disability in all countries. In the kidneys, Nitric Oxide (NO) has involved in several important cellular processes including glomerular and modular hemodynamics set-out, tubular - glomerular feedback reaction, renin releasing and extracellular fluid volume but NO can act as an inflammatory mediator and oxidative stress factor in high levels. Aim: The aim of this study was to evaluate salivary levels of NO in patients with chronic kidney disease on dialysis compared to the healthy subjects and evaluate the effect of dialysis on the level of NO in saliva. Materials & Methods: In this case-control study, 30 hemodialysis patients and 30 healthy controls that were matched for age and sex were selected. Unstimulated saliva samples were collected from all subjects. In the patient’s group, half an hour before starting dialysis first sampling and two hours after the completion of dialysis second sampling were collected. NO concentration in the samples was measured by using the Griess method. For data analysis, SPSS software version 16, Mann Whitney-U and Wilcoxon test were used. The level of significance was considered 0.05. Results: Mann-Whitney U test showed that the average concentration of salivary NO in patients with CKD (pre-dialysis and after dialysis) was higher than in the control group. The average concentration of salivary NO in patients with CKD was reduced after hemodialysis. Conclusion: Hemodialysis reduces salivary NO levels in CKD patients. It seems that hemodialysis has a role in decreasing the concentration of this inflammatory mediator and oxidative stress.
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Affiliation(s)
- Fatemeh Rezaei
- Department of Oral Medicine, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Reza Mohhamadi
- School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
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20
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Interaction between nitric oxide and renal α1-adrenoreceptors mediated vasoconstriction in rats with left ventricular hypertrophyin Wistar Kyoto rats. PLoS One 2018; 13:e0189386. [PMID: 29447158 PMCID: PMC5844246 DOI: 10.1371/journal.pone.0189386] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 11/26/2017] [Indexed: 01/19/2023] Open
Abstract
Left ventricular hypertrophy (LVH) is associated with decreased responsiveness of
renal α1-adrenoreceptors subtypes to adrenergic agonists. Nitric
oxide donors are known to have antihypertrophic effects however their impact on
responsiveness of renal α1-adrenoreceptors subtypes is unknown. This
study investigated the impact of nitric oxide (NO) and its potential interaction
with the responsiveness of renal α1-adrenoreceptors subtypes to
adrenergic stimulation in rats with left ventricular hypertrophy (LVH). This
study also explored the impact of NO donor on CSE expression in normal and LVH
kidney. LVH was induced using isoprenaline and caffeine in drinking water for 2
weeks while NO donor (L-arginine, 1.25g/Lin drinking water) was given for 5
weeks. Intrarenal noradrenaline, phenylephrine and methoxamine responses were
determined in the absence and presence of selective α1-adrenoceptor
antagonists, 5- methylurapidil (5-MeU), chloroethylclonidine (CeC) and BMY 7378.
Renal cortical endothelial nitric oxide synthase mRNA was upregulated 7 fold
while that of cystathione γ lyase was unaltered in the NO treated LVH rats
(LVH-NO) group compared to LVH group. The responsiveness of renal
α1A, α1B and α1D-adrenoceptors in the low dose
and high dose phases of 5-MeU, CEC and BMY7378 to adrenergic agonists was
increased along with cGMP in the kidney of LVH-NO group. These findings suggest
that exogenous NO precursor up-regulated the renal eNOS/NO/cGMP pathway in LVH
rats and resulted in augmented α1A, α1B and α1D
adrenoreceptors responsiveness to the adrenergic agonists. There is a positive
interaction between H2S and NO production in normal animals but this
interaction appears absent in LVH animals.
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21
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Effects of Nitric Oxide on Renal Proximal Tubular Na + Transport. BIOMED RESEARCH INTERNATIONAL 2017; 2017:6871081. [PMID: 29181400 PMCID: PMC5664255 DOI: 10.1155/2017/6871081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/14/2017] [Indexed: 12/28/2022]
Abstract
Nitric oxide (NO) has a wide variety of physiological functions in the kidney. Besides the regulatory effects in intrarenal haemodynamics and glomerular microcirculation, in vivo studies reported the diuretic and natriuretic effects of NO. However, opposite results showing the stimulatory effect of NO on Na+ reabsorption in the proximal tubule led to an intense debate on its physiological roles. Animal studies have showed the biphasic effect of angiotensin II (Ang II) and the overall inhibitory effect of NO on the activity of proximal tubular Na+ transporters, the apical Na+/H+ exchanger isoform 3, basolateral Na+/K+ ATPase, and the Na+/HCO3− cotransporter. However, whether these effects could be reproduced in humans remained unclear. Notably, our recent functional analysis of isolated proximal tubules demonstrated that Ang II dose-dependently stimulated human proximal tubular Na+ transport through the NO/guanosine 3′,5′-cyclic monophosphate (cGMP) pathway, confirming the human-specific regulation of proximal tubular transport via NO and Ang II. Of particular importance for this newly identified pathway is its possibility of being a human-specific therapeutic target for hypertension. In this review, we focus on NO-mediated regulation of proximal tubular Na+ transport, with emphasis on the interaction with individual Na+ transporters and the crosstalk with Ang II signalling.
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22
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Al Therwani S, Malmberg MES, Rosenbaek JB, Bech JN, Pedersen EB. Effect of tolvaptan on renal handling of water and sodium, GFR and central hemodynamics in autosomal dominant polycystic kidney disease during inhibition of the nitric oxide system: a randomized, placebo-controlled, double blind, crossover study. BMC Nephrol 2017; 18:268. [PMID: 28810844 PMCID: PMC5558668 DOI: 10.1186/s12882-017-0686-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 08/07/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Tolvaptan slows progression of autosomal dominant polycystic kidney disease (ADPKD) by antagonizing the vasopressin-cAMP axis. Nitric oxide (NO) stimulates natriuresis and diuresis, but its role is unknown during tolvaptan treatment in ADPKD. METHODS Eighteen patients with ADPKD received tolvaptan 60 mg or placebo in a randomized, placebo-controlled, double blind, crossover study. L-NMMA (L-NG-monomethyl-arginine) was given as a bolus followed by continuous infusion during 60 min. We measured: GFR, urine output (UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary excretion of aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma concentrations of vasopressin (p-AVP), renin (PRC), angiotensinII (p-AngII), aldosterone (p-Aldo), and central blood pressure (cBP). RESULTS During tolvaptan with NO-inhibition, a more pronounced decrease was measured in UO, CH2O (61% vs 43%) and FENa (46% vs 41%) after placebo than after tolvaptan; GFR and u-AQP2 decreased to the same extent; p-AVP increased three fold, whereas u-ENaCγ, PRC, p-AngII, and p-Aldo remained unchanged. After NO-inhibition, GFR increased after placebo and remained unchanged after tolvaptan (5% vs -6%). Central diastolic BP (CDBP) increased to a higher level after placebo than tolvaptan. Body weight fell during tolvaptan treatment. CONCLUSIONS During NO inhibition, tolvaptan antagonized both the antidiuretic and the antinatriuretic effect of L-NMMA, partly via an AVP-dependent mechanism. U-AQP2 was not changed by tolvaptan, presumeably due to a counteracting effect of elevated p-AVP. The reduced GFR during tolvaptan most likely is caused by the reduction in extracellular fluid volume and blood pressure. TRIAL REGISTRATION Clinical Trial no: NCT02527863 . Registered 18 February 2015.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark.
| | - My Emma Sofie Malmberg
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jeppe Bakkestroem Rosenbaek
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jesper Noergaard Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Erling Bjerregaard Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
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23
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Hunter RW, Moorhouse R, Farrah TE, MacIntyre IM, Asai T, Gallacher PJ, Kerr D, Melville V, Czopek A, Morrison EE, Ivy JR, Dear JW, Bailey MA, Goddard J, Webb DJ, Dhaun N. First-in-Man Demonstration of Direct Endothelin-Mediated Natriuresis and Diuresis. Hypertension 2017; 70:192-200. [PMID: 28507171 PMCID: PMC5739104 DOI: 10.1161/hypertensionaha.116.08832] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 12/19/2016] [Accepted: 04/19/2017] [Indexed: 01/23/2023]
Abstract
Endothelin (ET) receptor antagonists are potentially novel therapeutic agents in chronic kidney disease and resistant hypertension, but their use is complicated by sodium and water retention. In animal studies, this side effect arises from ETB receptor blockade in the renal tubule. Previous attempts to determine whether this mechanism operates in humans have been confounded by the hemodynamic consequences of ET receptor stimulation/blockade. We aimed to determine the effects of ET signaling on salt transport in the human nephron by administering subpressor doses of the ET-1 precursor, big ET-1. We conducted a 2-phase randomized, double-blind, placebo-controlled crossover study in 10 healthy volunteers. After sodium restriction, subjects received either intravenous placebo or big ET-1, in escalating dose (≤300 pmol/min). This increased plasma concentration and urinary excretion of ET-1. Big ET-1 reduced heart rate (≈8 beats/min) but did not otherwise affect systemic hemodynamics or glomerular filtration rate. Big ET-1 increased the fractional excretion of sodium (from 0.5 to 1.0%). It also increased free water clearance and tended to increase the abundance of the sodium-potassium-chloride cotransporter (NKCC2) in urinary extracellular vesicles. Our protocol induced modest increases in circulating and urinary ET-1. Sodium and water excretion increased in the absence of significant hemodynamic perturbation, supporting a direct action of ET-1 on the renal tubule. Our data also suggest that sodium reabsorption is stimulated by ET-1 in the thick ascending limb and suppressed in the distal renal tubule. Fluid retention associated with ET receptor antagonist therapy may be circumvented by coprescribing potassium-sparing diuretics.
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Affiliation(s)
- Robert W Hunter
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Rebecca Moorhouse
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Tariq E Farrah
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Iain M MacIntyre
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Takae Asai
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Peter J Gallacher
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Debbie Kerr
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Vanessa Melville
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Alicja Czopek
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Emma E Morrison
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Jess R Ivy
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - James W Dear
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Matthew A Bailey
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Jane Goddard
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - David J Webb
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom
| | - Neeraj Dhaun
- From the British Heart Foundation Centre of Research Excellence and The Queen's Medical Research Institute, University of Edinburgh, United Kingdom.
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24
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Gordish KL, Kassem KM, Ortiz PA, Beierwaltes WH. Moderate (20%) fructose-enriched diet stimulates salt-sensitive hypertension with increased salt retention and decreased renal nitric oxide. Physiol Rep 2017; 5:5/7/e13162. [PMID: 28408634 PMCID: PMC5392503 DOI: 10.14814/phy2.13162] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 12/25/2022] Open
Abstract
Previously, we reported that 20% fructose diet causes salt‐sensitive hypertension. In this study, we hypothesized that a high salt diet supplemented with 20% fructose (in drinking water) stimulates salt‐sensitive hypertension by increasing salt retention through decreasing renal nitric oxide. Rats in metabolic cages consumed normal rat chow for 5 days (baseline), then either: (1) normal salt for 2 weeks, (2) 20% fructose in drinking water for 2 weeks, (3) 20% fructose for 1 week, then fructose + high salt (4% NaCl) for 1 week, (4) normal chow for 1 week, then high salt for 1 week, (5) 20% glucose for 1 week, then glucose + high salt for 1 week. Blood pressure, sodium excretion, and cumulative sodium balance were measured. Systolic blood pressure was unchanged by 20% fructose or high salt diet. 20% fructose + high salt increased systolic blood pressure from 125 ± 1 to 140 ± 2 mmHg (P < 0.001). Cumulative sodium balance was greater in rats consuming fructose + high salt than either high salt, or glucose + high salt (114.2 ± 4.4 vs. 103.6 ± 2.2 and 98.6 ± 5.6 mEq/Day19; P < 0.05). Sodium excretion was lower in fructose + high salt group compared to high salt only: 5.33 ± 0.21 versus 7.67 ± 0.31 mmol/24 h; P < 0.001). Nitric oxide excretion was 2935 ± 256 μmol/24 h in high salt‐fed rats, but reduced by 40% in the 20% fructose + high salt group (2139 ± 178 μmol /24 hrs P < 0.01). Our results suggest that fructose predisposes rats to salt‐sensitivity and, combined with a high salt diet, leads to sodium retention, increased blood pressure, and impaired renal nitric oxide availability.
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Affiliation(s)
- Kevin L Gordish
- Department of Physiology, Wayne State School of Medicine, Detroit, Michigan
| | - Kamal M Kassem
- Department of Internal Medicine, Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, Michigan
| | - Pablo A Ortiz
- Department of Physiology, Wayne State School of Medicine, Detroit, Michigan.,Department of Internal Medicine, Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, Michigan
| | - William H Beierwaltes
- Department of Physiology, Wayne State School of Medicine, Detroit, Michigan .,Department of Internal Medicine, Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, Michigan
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25
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Al Therwani S, Rosenbæk JB, Mose FH, Bech JN, Pedersen EB. Effect of tolvaptan on renal water and sodium excretion and blood pressure during nitric oxide inhibition: a dose-response study in healthy subjects. BMC Nephrol 2017; 18:86. [PMID: 28288570 PMCID: PMC5347830 DOI: 10.1186/s12882-017-0501-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/07/2017] [Indexed: 01/17/2023] Open
Abstract
Background Tolvaptan is a selective vasopressin receptor antagonist. Nitric Oxide (NO) promotes renal water and sodium excretion, but the effect is unknown in the nephron’s principal cells. In a dose-response study, we measured the effect of tolvaptan on renal handling of water and sodium and systemic hemodynamics, during baseline and NO-inhibition with L-NMMA (L-NG-monomethyl-arginine). Methods In a randomized, placebo-controlled, double blind, cross over study, 15 healthy subjects received tolvaptan 15, 30 and 45 mg or placebo. L-NMMA was given as a bolus followed by continuous infusion during 60 min. We measured urine output (UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma vasopressin (p-AVP) and central blood pressure (cBP). Results During baseline, FENa was unchanged. Tolvaptan decreased u-ENaCγ dose-dependently and increased p-AVP threefold, whereas u-AQP2 was unchanged. During tolvaptan with NO-inhibition, UO and CH2O decreased dose-dependently. FENa decreased dose-independently and u-ENaCγ remained unchanged. Central BP increased equally after all treatments. Conclusions During baseline, fractional excretion of sodium was unchanged. During tolvaptan with NO-inhibition, renal water excretion was reduced dose dependently, and renal sodium excretion was reduced unrelated to the dose, partly via an AVP dependent mechanism. Thus, tolvaptan antagonized the reduction in renal water and sodium excretion during NO-inhibition. Most likely, the lack of decrease in AQP2 excretion by tolvaptan could be attributed to a counteracting effect of the high level of p-AVP. Trial registration Clinical Trial no: NCT02078973. Registered 1 March 2014. Electronic supplementary material The online version of this article (doi:10.1186/s12882-017-0501-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark.
| | - Jeppe Bakkestrøm Rosenbæk
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Frank Holden Mose
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Jesper Nørgaard Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
| | - Erling Bjerregaard Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital, Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500, Holstebro, Denmark
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26
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Monzon CM, Occhipinti R, Pignataro OP, Garvin JL. Nitric oxide reduces paracellular resistance in rat thick ascending limbs by increasing Na + and Cl - permeabilities. Am J Physiol Renal Physiol 2017; 312:F1035-F1043. [PMID: 28274930 DOI: 10.1152/ajprenal.00671.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 01/04/2023] Open
Abstract
About 50% of the Na+ reabsorbed in thick ascending limbs traverses the paracellular pathway. Nitric oxide (NO) reduces the permselectivity of this pathway via cGMP, but its effects on absolute Na+ ([Formula: see text]) and Cl- ([Formula: see text]) permeabilities are unknown. To address this, we measured the effect of l-arginine (0.5 mmol/l; NO synthase substrate) and cGMP (0.5 mmol/l) on [Formula: see text] and [Formula: see text] calculated from the transepithelial resistance (Rt) and [Formula: see text]/[Formula: see text] in medullary thick ascending limbs. Rt was 7,722 ± 1,554 ohm·cm in the control period and 6,318 ± 1,757 ohm·cm after l-arginine treatment (P < 0.05). [Formula: see text]/[Formula: see text] was 2.0 ± 0.2 in the control period and 1.7 ± 0.1 after l-arginine (P < 0.04). Calculated [Formula: see text] and [Formula: see text] were 3.52 ± 0.2 and 1.81 ± 0.10 × 10-5 cm/s, respectively, in the control period. After l-arginine they were 6.65 ± 0.69 (P < 0.0001 vs. control) and 3.97 ± 0.44 (P < 0.0001) × 10-5 cm/s, respectively. NOS inhibition with Nω-nitro-l-arginine methyl ester (5 mmol/l) prevented l-arginine's effect on Rt Next we tested the effect of cGMP. Rt in the control period was 7,592 ± 1,470 and 4,796 ± 847 ohm·cm after dibutyryl-cGMP (0.5 mmol/l; db-cGMP) treatment (P < 0.04). [Formula: see text]/[Formula: see text] was 1.8 ± 0.1 in the control period and 1.6 ± 0.1 after db-cGMP (P < 0.03). [Formula: see text] and [Formula: see text] were 4.58 ± 0.80 and 2.66 ± 0.57 × 10-5 cm/s, respectively, for the control period and 9.48 ± 1.63 (P < 0.007) and 6.01 ± 1.05 (P < 0.005) × 10-5 cm/s, respectively, after db-cGMP. We modeled NO's effect on luminal Na+ concentration along the thick ascending limb. We found that NO's effect on the paracellular pathway reduces net Na+ reabsorption and that the magnitude of this effect is similar to that due to NO's inhibition of transcellular transport.
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Affiliation(s)
- Casandra M Monzon
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio; .,Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires, Buenos Aires, Argentina; and
| | - Rossana Occhipinti
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
| | - Omar P Pignataro
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires, Buenos Aires, Argentina; and.,Laboratorio de Endocrinología Molecular y Transducción de Señales, Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
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Kouyoumdzian NM, Mikusic NR, Cao G, Choi MR, Penna SD, Fernández BE, Toblli JE, Rosón MI. Adverse effects of tempol on hidrosaline balance in rats with acute sodium overload. Biotech Histochem 2017; 91:510-521. [PMID: 27849390 DOI: 10.1080/10520295.2016.1249029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
We studied the effects of tempol, an oxygen radical scavenger, on hydrosaline balance in rats with acute sodium overload. Male rats with free access to water were injected with isotonic (control group) or hypertonic saline solution (0.80 mol/l NaCl) either alone (Na group) or with tempol (Na-T group). Hydrosaline balance was determined during a 90 min experimental period. Protein expressions of aquaporin 1 (AQP1), aquaporin 2 (AQP2), angiotensin II (Ang II) and endothelial nitric oxide synthase (eNOS) were measured in renal tissue. Water intake, creatinine clearance, diuresis and natriuresis increased in the Na group. Under conditions of sodium overload, tempol increased plasma sodium and protein levels and increased diuresis, natriuresis and sodium excretion. Tempol also decreased water intake without affecting creatinine clearance. AQP1 and eNOS were increased and Ang II decreased in the renal cortex of the Na group, whereas AQP2 was increased in the renal medulla. Nonglycosylated AQP1 and eNOS were increased further in the renal cortex of the Na-T group, whereas AQP2 was decreased in the renal medulla and was localized mainly in the cell membrane. Moreover, p47-phox immunostaining was increased in the hypothalamus of Na group, and this increase was prevented by tempol. Our findings suggest that tempol causes hypernatremia after acute sodium overload by inhibiting the thirst mechanism and facilitating diuresis, despite increasing renal eNOS expression and natriuresis.
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Affiliation(s)
- N M Kouyoumdzian
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - Nl Rukavina Mikusic
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - G Cao
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - M R Choi
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - Sl Della Penna
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - B E Fernández
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - J E Toblli
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
| | - M I Rosón
- a Cardiological Research Institute (ININCA), Scientific and Technological Research National Council (CONICET), University of Buenos Aires , Buenos Aires , Argentina
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Thieme M, Sivritas SH, Mergia E, Potthoff SA, Yang G, Hering L, Grave K, Hoch H, Rump LC, Stegbauer J. Phosphodiesterase 5 inhibition ameliorates angiotensin II-dependent hypertension and renal vascular dysfunction. Am J Physiol Renal Physiol 2017; 312:F474-F481. [PMID: 28052870 DOI: 10.1152/ajprenal.00376.2016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 12/23/2016] [Accepted: 01/03/2017] [Indexed: 01/24/2023] Open
Abstract
Changes in renal hemodynamics have a major impact on blood pressure (BP). Angiotensin (Ang) II has been shown to induce vascular dysfunction by interacting with phosphodiesterase (PDE)1 and PDE5. The predominant PDE isoform responsible for renal vascular dysfunction in hypertension is unknown. Here, we measured the effects of PDE5 (sildenafil) or PDE1 (vinpocetine) inhibition on renal blood flow (RBF), BP, and renal vascular function in normotensive and hypertensive mice. During acute short-term Ang II infusion, sildenafil decreased BP and increased RBF in C57BL/6 (WT) mice. In contrast, vinpocetine showed no effect on RBF and BP. Additionally, renal cGMP levels were significantly increased after acute sildenafil but not after vinpocetine infusion, indicating a predominant role of PDE5 in renal vasculature. Furthermore, chronic Ang II infusion (500 ng·kg-1·min-1) increased BP and led to impaired NO-dependent vasodilation in kidneys of WT mice. Additional treatment with sildenafil (100 mg·kg-1·day-1) attenuated Ang II-dependent hypertension and improved NO-mediated vasodilation. During chronic Ang II infusion, urinary nitrite excretion, a marker for renal NO generation, was increased in WT mice, whereas renal cGMP generation was decreased and restored after sildenafil treatment, suggesting a preserved cGMP signaling after PDE5 inhibition. To investigate the dependency of PDE5 effects on NO/cGMP signaling, we next analyzed eNOS-KO mice, a mouse model characterized by low vascular NO/cGMP levels. In eNOS-KO mice, chronic Ang II infusion increased BP but did not impair NO-mediated vasodilation. Moreover, sildenafil did not influence BP or vascular function in eNOS-KO mice. These results highlight PDE5 as a key regulator of renal hemodynamics in hypertension.
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Affiliation(s)
- Manuel Thieme
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Sema H Sivritas
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Evanthia Mergia
- Department of Pharmacology and Toxicology, Ruhr-University Bochum, Bochum, Germany
| | - Sebastian A Potthoff
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Guang Yang
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Lydia Hering
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Katharina Grave
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Henning Hoch
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Lars C Rump
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany; and
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Abstract
Cyclic GMP (cGMP) is a ubiquitous intracellular second messenger that mediates a wide spectrum of physiologic processes in multiple cell types within the cardiovascular and nervous systems. Synthesis of cGMP occurs either by NO-sensitive guanylyl cyclases in response to nitric oxide or by membrane-bound guanylyl cyclases in response to natriuretic peptides and has been shown to regulate blood pressure homeostasis by influencing vascular tone, sympathetic nervous system, and sodium and water handling in the kidney. Several cGMPs degrading phosphodiesterases (PDEs), including PDE1 and PDE5, play an important role in the regulation of cGMP signaling. Recent findings revealed that increased activity of cGMP-hydrolyzing PDEs contribute to the development of hypertension. In this review, we will summarize recent research findings regarding the cGMP/PDE signaling in the vasculature, the central nervous system, and the kidney which are associated with the development and maintenance of hypertension.
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Affiliation(s)
- Evanthia Mergia
- Department of Pharmacology and Toxicology, Ruhr-University Bochum, Bochum, Germany
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Moorenstr. 5, 40225, Düsseldorf, Germany.
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Gerber L, Madsen SS, Jensen FB. Cortisol regulates nitric oxide synthase in freshwater and seawater acclimated rainbow trout, Oncorhynchus mykiss. Comp Biochem Physiol A Mol Integr Physiol 2016; 204:1-8. [PMID: 27838356 DOI: 10.1016/j.cbpa.2016.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 11/02/2016] [Accepted: 11/07/2016] [Indexed: 12/16/2022]
Abstract
Cortisol and nitric oxide (NO) are regulators of ion transport and metabolic functions in fish. In the gill, they show opposite effects on Na+/K+-ATPase (NKA) activity: cortisol stimulates NKA activity while NO inhibits NKA activity. We hypothesized that cortisol may impact NO production in osmoregulatory tissues by regulating NO synthase (NOS) expression. We evaluated the influence of cortisol treatment on mRNA expression of Nos1 and Nos2 in gill, kidney and middle intestine of both freshwater (FW) and seawater (SW) acclimated rainbow trout and found both tissue- and salinity-dependent effects. Nos2 expression was down-regulated in the gill by cortisol injection in both FW and SW trout. This was substantiated by incubating gill tissue with cortisol ex vivo. Similarly, cortisol injection significantly down-regulated Nos2 expression in kidney of SW fish but not in FW fish. In the middle intestine, Nos2 expression was up-regulated by cortisol injection in FW but unchanged in SW fish. Nos1 expression was up-regulated by cortisol injection in FW kidney and down-regulated in SW kidney, whereas it was unaffected in gill and middle intestine of FW and SW fish. Our data provide the first evidence that cortisol may influence NO production in fish by regulating Nos expression. Indeed, the down-regulation of Nos2 expression by cortisol in the gill may prevent the inhibitory effect of NO on NKA activity thereby furthering the stimulatory effect of cortisol on ion-transport.
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Affiliation(s)
- Lucie Gerber
- Department of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Steffen S Madsen
- Department of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
| | - Frank B Jensen
- Department of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark
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31
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Ngo JP, Ow CP, Gardiner BS, Kar S, Pearson JT, Smith DW, Evans RG. Diffusive shunting of gases and other molecules in the renal vasculature: physiological and evolutionary significance. Am J Physiol Regul Integr Comp Physiol 2016; 311:R797-R810. [DOI: 10.1152/ajpregu.00246.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/27/2016] [Indexed: 01/22/2023]
Abstract
Countercurrent systems have evolved in a variety of biological systems that allow transfer of heat, gases, and solutes. For example, in the renal medulla, the countercurrent arrangement of vascular and tubular elements facilitates the trapping of urea and other solutes in the inner medulla, which in turn enables the formation of concentrated urine. Arteries and veins in the cortex are also arranged in a countercurrent fashion, as are descending and ascending vasa recta in the medulla. For countercurrent diffusion to occur, barriers to diffusion must be small. This appears to be characteristic of larger vessels in the renal cortex. There must also be gradients in the concentration of molecules between afferent and efferent vessels, with the transport of molecules possible in either direction. Such gradients exist for oxygen in both the cortex and medulla, but there is little evidence that large gradients exist for other molecules such as carbon dioxide, nitric oxide, superoxide, hydrogen sulfide, and ammonia. There is some experimental evidence for arterial-to-venous (AV) oxygen shunting. Mathematical models also provide evidence for oxygen shunting in both the cortex and medulla. However, the quantitative significance of AV oxygen shunting remains a matter of controversy. Thus, whereas the countercurrent arrangement of vasa recta in the medulla appears to have evolved as a consequence of the evolution of Henle’s loop, the evolutionary significance of the intimate countercurrent arrangement of blood vessels in the renal cortex remains an enigma.
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Affiliation(s)
- Jennifer P. Ngo
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology and
| | - Connie P.C. Ow
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology and
| | - Bruce S. Gardiner
- School of Engineering and Information Technology, Murdoch University, Perth, Western Australia
| | - Saptarshi Kar
- School of Computer Science and Software Engineering, The University of Western Australia, Perth, Australia; and
| | - James T. Pearson
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology and
- Monash Biomedical Imaging Facility, Monash University, Melbourne, Australia
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - David W. Smith
- School of Computer Science and Software Engineering, The University of Western Australia, Perth, Australia; and
| | - Roger G. Evans
- Cardiovascular Disease Program, Biosciences Discovery Institute and Department of Physiology and
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Gao Y, Stuart D, Pollock JS, Takahishi T, Kohan DE. Collecting duct-specific knockout of nitric oxide synthase 3 impairs water excretion in a sex-dependent manner. Am J Physiol Renal Physiol 2016; 311:F1074-F1083. [PMID: 27707708 DOI: 10.1152/ajprenal.00494.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 09/29/2016] [Indexed: 12/21/2022] Open
Abstract
Nitric oxide (NO) inhibits collecting duct (CD) Na+ and water reabsorption. Mice with CD-specific knockout (KO) of NO synthase 1 (NOS1) have salt-sensitive hypertension. In contrast, the role of NOS3 in CD salt and water reabsorption is unknown. Mice with CD NOS3 KO were generated with loxP-flanked exons 9-12 (encodes the calmodulin binding site) of the NOS3 gene and the aquaporin-2 promoter-Cre transgene. There were no differences between control and CD NOS3 KO mice, irrespective of sex, in food intake, water intake, urine volume, urinary Na+ or K+ excretion, plasma renin concentration, blood pressure, or pulse during 7 days of normal (0.3%), high (3.17%), or low (0.03%) Na+ intake. Blood pressure was similar between genotypes during DOCA-high salt. CD NOS3 KO did not alter urine volume or urine osmolality after water deprivation. In contrast, CD NOS3 KO male, but not female, mice had lower urine volume and higher urine osmolality over the course of 7 days of water loading compared with control mice. Male, but not female, CD NOS3 KO mice had reduced urinary nitrite+nitrate excretion compared with controls after 7 days of water loading. Urine AVP and AVP-stimulated cAMP accumulation in isolated inner medullary CD were similar between genotypes. Western analysis did not reveal a significant effect of CD NOS3 KO on renal aquaporin expression. In summary, these data suggest that CD NOS3 may be involved in the diuretic response to a water load in a sex-specific manner; the mechanism of this effect remains to be determined.
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Affiliation(s)
- Yang Gao
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Deborah Stuart
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Jennifer S Pollock
- Division of Nephrology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Takamune Takahishi
- Division of Nephrology, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah; .,George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, Utah
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Abstract
SIGNIFICANCE A common link between all forms of acute and chronic kidney injuries, regardless of species, is enhanced generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) during injury/disease progression. While low levels of ROS and RNS are required for prosurvival signaling, cell proliferation and growth, and vasoreactivity regulation, an imbalance of ROS and RNS generation and elimination leads to inflammation, cell death, tissue damage, and disease/injury progression. RECENT ADVANCES Many aspects of renal oxidative stress still require investigation, including clarification of the mechanisms which prompt ROS/RNS generation and subsequent renal damage. However, we currently have a basic understanding of the major features of oxidative stress pathology and its link to kidney injury/disease, which this review summarizes. CRITICAL ISSUES The review summarizes the critical sources of oxidative stress in the kidney during injury/disease, including generation of ROS and RNS from mitochondria, NADPH oxidase, and inducible nitric oxide synthase. The review next summarizes the renal antioxidant systems that protect against oxidative stress, including superoxide dismutase and catalase, the glutathione and thioredoxin systems, and others. Next, we describe how oxidative stress affects kidney function and promotes damage in every nephron segment, including the renal vessels, glomeruli, and tubules. FUTURE DIRECTIONS Despite the limited success associated with the application of antioxidants for treatment of kidney injury/disease thus far, preventing the generation and accumulation of ROS and RNS provides an ideal target for potential therapeutic treatments. The review discusses the shortcomings of antioxidant treatments previously used and the potential promise of new ones. Antioxid. Redox Signal. 25, 119-146.
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Affiliation(s)
- Brian B Ratliff
- 1 Department of Medicine, Renal Research Institute , New York Medical College, Valhalla, New York.,2 Department of Physiology, Renal Research Institute , New York Medical College, Valhalla, New York
| | - Wasan Abdulmahdi
- 2 Department of Physiology, Renal Research Institute , New York Medical College, Valhalla, New York
| | - Rahul Pawar
- 1 Department of Medicine, Renal Research Institute , New York Medical College, Valhalla, New York
| | - Michael S Wolin
- 2 Department of Physiology, Renal Research Institute , New York Medical College, Valhalla, New York
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34
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Hyponatremia in patients with systemic lupus erythematosus. Sci Rep 2016; 6:25566. [PMID: 27193532 PMCID: PMC4872139 DOI: 10.1038/srep25566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 04/19/2016] [Indexed: 01/06/2023] Open
Abstract
The aim of this study was to determine whether decreased serum sodium concentration could be associated with the disease activity in SLE. We retrospectively analyzed the data of the two independent cohorts of children and adults with SLE in two centers. Hyponatremia was associated with serum chloride (p = 0.004), albumin (p = 0.002) and SLE disease activity index (SLEDAI) (p = 0.026) in children with SLE. Serum sodium levels were correlated negatively with ESR (p =0.001) and positively with serum albumin levels (p < 0.0001) and C3 (p = 0.008) in children with SLE and those levels were correlated negatively with serum interleukin-6 levels (p = 0.003) in adults with SLE. Independent risk factors for the development of hyponatremia were the decreased serum C3 levels (OR 1.069, p = 0.031), the decreased serum chloride levels (OR 2.054, p = 0.006) and increased erythrocyte sedimentation rate (ESR) (OR 1.066, p = 0.03) in children with SLE and increased C-reactive protein (CRP) (OR 1.480, p = 0.023) in combined cohorts with SLE by multiple logistic regression analyses. Our study firstly showed that hyponatremia could reflect a disease activity and severe inflammation of SLE.
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35
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Absence of cytoglobin promotes multiple organ abnormalities in aged mice. Sci Rep 2016; 6:24990. [PMID: 27146058 PMCID: PMC4857093 DOI: 10.1038/srep24990] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/04/2016] [Indexed: 01/10/2023] Open
Abstract
Cytoglobin (Cygb) was identified in hepatic stellate cells (HSCs) and pericytes of all organs; however, the effects of Cygb on cellular functions remain unclear. Here, we report spontaneous and age-dependent malformations in multiple organs of Cygb(-/-) mice. Twenty-six percent of young Cygb(-/-) mice (<1 year old) showed heart hypertrophy, cystic disease in the kidney or ovary, loss of balance, liver fibrosis and lymphoma. Furthermore, 71.3% (82/115) of aged Cygb(-/-) mice (1-2 years old) exhibited abnormalities, such as heart hypertrophy and cancer development in multiple organs; by contrast, 5.8% (4/68) of aged wild-type (WT) mice had abnormalities (p < 0.0001). Interestingly, serum and urine analysis demonstrated that the concentration of nitric oxide metabolites increased significantly in Cygb(-/-) mice, resulting in an imbalance in the oxidative stress and antioxidant defence system that was reversed by N(G)-monomethyl-L-arginine treatment. A senescent phenotype and evidence of DNA damage were found in primary HSCs and the liver of aged Cygb(-/-) mice. Moreover, compared with HSC(+/+), HSC(-/-) showed high expression of Il-6 and chemokine mRNA when cocultured with mouse Hepa 1-6 cells. Thus, the absence of Cygb in pericytes provokes organ abnormalities, possibly via derangement of the nitric oxide and antioxidant defence system and through accelerated cellular senescence.
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Nagy K, Nagaraju SP, Rhee CM, Mathe Z, Molnar MZ. Adipocytokines in renal transplant recipients. Clin Kidney J 2016; 9:359-73. [PMID: 27274819 PMCID: PMC4886901 DOI: 10.1093/ckj/sfv156] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/18/2015] [Indexed: 02/07/2023] Open
Abstract
In the last two decades, perceptions about the role of body fat have changed. Adipocytes modulate endocrine and immune homeostasis by synthesizing hundreds of hormones, known as adipocytokines. Many studies have been investigating the influences and effects of these adipocytokines and suggest that they are modulated by the nutritional and immunologic milieu. Kidney transplant recipients (KTRs) are a unique and relevant population in which the function of adipocytokines can be examined, given their altered nutritional and immune status and subsequent dysregulation of adipocytokine metabolism. In this review, we summarize the recent findings about four specific adipocytokines and their respective roles in KTRs. We decided to evaluate the most widely described adipocytokines, including leptin, adiponectin, visfatin and resistin. Increasing evidence suggests that these adipocytokines may lead to cardiovascular events and metabolic changes in the general population and may also increase mortality and graft loss rate in KTRs. In addition, we present findings on the interrelationship between serum adipocytokine levels and nutritional and immunologic status, and mechanisms by which adipocytokines modulate morbidity and outcomes in KTRs.
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Affiliation(s)
- Kristof Nagy
- Department of Transplantation and Surgery , Semmelweis University , Budapest , Hungary
| | | | - Connie M Rhee
- Harold Simmons Center for Chronic Disease Research and Epidemiology, Division of Nephrology and Hypertension , University of California Irvine , Orange, CA , USA
| | - Zoltan Mathe
- Department of Transplantation and Surgery , Semmelweis University , Budapest , Hungary
| | - Miklos Z Molnar
- Division of Nephrology, Department of Medicine , University of Tennessee Health Science Center , Memphis, TN , USA
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37
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Gordish KL, Beierwaltes WH. Chronic resveratrol reverses a mild angiotensin II-induced pressor effect in a rat model. Integr Blood Press Control 2016; 9:23-31. [PMID: 26869812 PMCID: PMC4734803 DOI: 10.2147/ibpc.s96092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Resveratrol is reported to reduce blood pressure in animal models of hypertension, but the mechanisms are unknown. We have shown that resveratrol infusion increases sodium excretion. We hypothesized that chronic ingestion of resveratrol would reduce angiotensin II (Ang II)-induced increases in blood pressure by decreasing oxidative stress and by also decreasing sodium reabsorption through a nitric oxide-dependent mechanism. We infused rats with vehicle or 80 μg Ang II/d over 4 weeks. Vehicle or Ang II-infused rats were individually housed, pair fed, and placed on a diet of normal chow or normal chow plus 146 mg resveratrol/d. Groups included 1) control, 2) resveratrol-fed, 3) Ang II-treated, and 4) Ang II plus resveratrol. Systolic blood pressure was measured by tail cuff. During the 4th week, rats were placed in metabolic caging for urine collection. NO2/NO3 and 8-isoprostane excretion were measured. Ang II increased systolic blood pressure in the 1st week by +14±5 mmHg (P<0.05) in Group 3 and +10±3 mmHg (P<0.05) in Group 4, respectively. Blood pressure was unchanged in Groups 1 and 2. After 4 weeks, blood pressure remained elevated in Group 3 rats with Ang II (+9±3 mmHg, P<0.05), but in Group 4, blood pressure was no longer elevated (+2±2 mmHg). We found no significant differences between the groups in sodium excretion or cumulative sodium balance (18.49±0.12, 17.75±0.16, 17.97±0.17, 18.46±0.18 μEq Na+/7 d in Groups 1-4, respectively). Urinary excretion of NO2/NO3 in the four groups was 1) 1631±207 μmol/24 h, 2) 1045±236 μmol/24 h, 3) 1490±161 μmol/24 h, and 4) 609±17 μmol/24 h. 8-Isoprostane excretion was 1) 63.85±19.39 nmol/24 h, 2) 73.57±22.02 nmol/24 h, 3) 100.69±37.62 nmol/24 h, and 4) 103.00±38.88 nmol/24 h. We conclude that chronic resveratrol supplementation does not blunt Ang II-increased blood pressure, and while resveratrol has mild depressor effects, these do not seem to be due to natriuresis or enhanced renal nitric oxide synthesis.
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Affiliation(s)
- Kevin L Gordish
- Department of Physiology, Wayne State School of Medicine, Henry Ford Hospital, Detroit, MI, USA
| | - William H Beierwaltes
- Department of Physiology, Wayne State School of Medicine, Henry Ford Hospital, Detroit, MI, USA
- Department of Internal Medicine, Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, MI, USA
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38
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Lynch IJ, Welch AK, Gumz ML, Kohan DE, Cain BD, Wingo CS. Effect of mineralocorticoid treatment in mice with collecting duct-specific knockout of endothelin-1. Am J Physiol Renal Physiol 2015; 309:F1026-34. [PMID: 26400543 DOI: 10.1152/ajprenal.00220.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/16/2015] [Indexed: 02/02/2023] Open
Abstract
Aldosterone increases blood pressure (BP) by stimulating sodium (Na) reabsorption within the distal nephron and collecting duct (CD). Aldosterone also stimulates endothelin-1 (ET-1) production that acts within the CD to inhibit Na reabsorption via a negative feedback mechanism. We tested the hypothesis that this renal aldosterone-endothelin feedback system regulates electrolyte balance and BP by comparing the effect of a high-salt (NaCl) diet and mineralocorticoid stimulation in control and CD-specific ET-1 knockout (CD ET-1 KO) mice. Metabolic balance and radiotelemetric BP were measured before and after treatment with desoxycorticosterone pivalate (DOCP) in mice fed a high-salt diet with saline to drink. CD ET-1 KO mice consumed more high-salt diet and saline and had greater urine output than controls. CD ET-1 KO mice exhibited increased BP and greater fluid retention and body weight than controls on a high-salt diet. DOCP with high-salt feeding further increased BP in CD ET-1 KO mice, and by the end of the study the CD ET-1 KO mice were substantially hypernatremic. Unlike controls, CD ET-1 KO mice failed to respond acutely or escape from DOCP treatment. We conclude that local ET-1 production in the CD is required for the appropriate renal response to Na loading and that lack of local ET-1 results in abnormal fluid and electrolyte handling when challenged with a high-salt diet and with DOCP treatment. Additionally, local ET-1 production is necessary, under these experimental conditions, for renal compensation to and escape from the chronic effects of mineralocorticoids.
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Affiliation(s)
- I Jeanette Lynch
- Research Service, North Florida/South Georgia Veterans Health System, Gainesville, Florida; Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida
| | - Amanda K Welch
- Research Service, North Florida/South Georgia Veterans Health System, Gainesville, Florida; Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida; Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida
| | - Michelle L Gumz
- Research Service, North Florida/South Georgia Veterans Health System, Gainesville, Florida; Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida; Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida; and
| | - Donald E Kohan
- Division of Nephrology, University of Utah Health Sciences Center and Salt Lake City Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Brian D Cain
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida; and
| | - Charles S Wingo
- Research Service, North Florida/South Georgia Veterans Health System, Gainesville, Florida; Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida; Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida;
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Mose FH, Larsen T, Jensen JM, Hansen AB, Bech JN, Pedersen EB. Effects of atorvastatin on systemic and renal NO dependency in patients with non-diabetic stage II-III chronic kidney disease. Br J Clin Pharmacol 2015; 78:789-99. [PMID: 24697877 DOI: 10.1111/bcp.12390] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/25/2014] [Indexed: 12/20/2022] Open
Abstract
AIMS Clinical trials suggest that statins have beneficial effects on the cardiovascular system independent from their cholesterol lowering properties. In patients with chronic kidney disease stage II-III, we tested the hypothesis that atorvastatin increased systemic and renal nitric oxide (NO) availability using L-N(G) -monomethyl arginine (L-NMMA) as an inhibitor of NO production. METHODS In a randomized, placebo-controlled, crossover study patients were treated with atorvastatin for 5 days with standardized diet and fluid intake. Glomerular filtration reate (GFR), fractional excretions of sodium (FENa ), urinary excretion of aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaCγ ), vasoactive hormones (renin, angiotensin II, aldosterone, arginine vasopressin, endothelin-1 and brain natriuretic peptide) and central blood pressure (BP) estimated by applanation tonometry were measured before and after systemic administration of the NO inhibitor L-NMMA. RESULTS Atorvastatin caused a significant reduction in U-ENaCγ , but sodium excretion, C H 2 O , FENa and u-AQP2 were not changed by atorvastatin. L-NMMA reduced renal effect variables, including GFR, FENa and u-ENaCγ and increased brachial BP and central BP to a similar extent during both treatments. Vasoactive hormones were changed in the same way by L-NMMA during atorvastatin and placebo treatment. CONCLUSION During, atorvastatin and placebo treatment, inhibition of nitric oxide synthesis induced the same response in brachial and central blood pressure, GFR, renal tubular function and vasoactive hormones. Thus, the data do not support that atorvastatin changes nitric oxide availability in patients with mild nephropathy. The reduced u-ENaC may reflect changes in sodium absorption in the nephron induced by atorvastatin.
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Affiliation(s)
- Frank Holden Mose
- Department of Medical Research, University Clinic in Hypertension and Nephrology, Holstebro Hospital, Holstebro, Denmark
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Mose FH, Jensen JM, Therwani S, Mortensen J, Hansen AB, Bech JN, Pedersen EB. Effect of nebivolol on renal nitric oxide availability and tubular function in patients with essential hypertension. Br J Clin Pharmacol 2015; 80:425-35. [PMID: 25778445 DOI: 10.1111/bcp.12627] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 03/02/2015] [Accepted: 03/04/2015] [Indexed: 12/18/2022] Open
Abstract
AIMS Nebivolol is a selective β1 -receptor antagonist with vasodilating properties. In patients with essential hypertension, we tested the hypothesis that nebivolol increases systemic and renal nitric oxide (NO) availability using L-N(G) -monomethyl arginine (L-NMMA) as an inhibitor of NO production. METHODS In a randomized, placebo-controlled, crossover study, patients with essential hypertension were treated with nebivolol for five days, along with a standardized diet and fluid intake. We examined the acute effects of systemic NO synthase inhibition with L-NMMA on brachial blood pressure (bBP), pulse wave velocity (PWV) and central blood pressure (cBP) estimated by applanation tonometry, glomerular filtration rate (GFR), fractional excretion of sodium (FENa ), urinary excretion of both aquaporin-2 (u-AQP2) and epithelial sodium channels (u-ENaCγ ), and plasma concentrations of nitrate/nitrite (p-NOx ) and vasoactive hormones after five days' treatment with placebo and nebivolol. RESULTS Nebivolol significantly reduced PWV, bBP, cBP and plasma renin, angiotensin II and aldosterone concentrations. The renal parameters, p-NOx and plasma arginine vasopressin concentration were not changed by nebivolol. There was no difference between nebivolol and placebo in the response to L-NMMA, with LMMA inducing a similar increase in PWV, bBP and cBP and a similar decrease in GFR, uAQP2 and u-ENaCγ and FENa [mean change -0.62% (95% confidence interval {CI} -0.40 to -0.84) during placebo vs. -0.57% (95% CI -0.46 to -0.68; P = 0.564) during nebivolol treatment]. Vasoactive hormones were changed to a similar extend by L-NMMA during administration of nebivolol and placebo. CONCLUSIONS Nebivolol did not change p-NOx , and inhibition of NO synthesis induced the same response in blood pressure, GFR, renal tubular function and vasoactive hormones during nebivolol and placebo. Thus, the data did not support the hypothesis that nebivolol changes vascular and renal NO availability in patients with essential hypertension.
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Affiliation(s)
- Frank H Mose
- University Clinic in Nephrology and Hypertension, Department of Medical Research and University of Aarhus
| | - Janni M Jensen
- University Clinic in Nephrology and Hypertension, Department of Medical Research and University of Aarhus
| | - Safa Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research and University of Aarhus
| | | | | | - Jesper N Bech
- University Clinic in Nephrology and Hypertension, Department of Medical Research and University of Aarhus
| | - Erling B Pedersen
- University Clinic in Nephrology and Hypertension, Department of Medical Research and University of Aarhus
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Monzon CM, Garvin JL. Nitric oxide decreases the permselectivity of the paracellular pathway in thick ascending limbs. Hypertension 2015; 65:1245-50. [PMID: 25895589 DOI: 10.1161/hypertensionaha.115.05356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 03/19/2015] [Indexed: 12/22/2022]
Abstract
Thick ascending limbs reabsorb 25% to 30% of the filtered NaCl. About 50% to 70% is reabsorbed via the transcellular pathway and 30% to 50% is reabsorbed through the Na-selective paracellular pathway. Nitric oxide (NO) inhibits transepithelial Na reabsorption, but its effects on the paracellular pathway are unknown. We hypothesized that NO decreases the selectivity of the paracellular pathway in thick ascending limbs via cGMP-dependent protein kinase. To assess relative Na/Cl permeability ratios (PNa/PCl), we perfused rat thick ascending limbs and measured the effect of reducing bath NaCl on transepithelial voltage, creating dilution potentials, with vehicle, NO donors, and endogenous NO. PNa/PCl was calculated using the Goldman-Hodgkin-Katz equation. Reducing bath Na/Cl to 16/8, 32/24, and 64/56 mmol/L created dilution potentials of -13.6±2.2, -10.8±3.0, and -6.1±0.9 mV, respectively. Calculated PNa/PCls were 2.0±0.2, 2.2±0.5, and 1.9±0.2. The NO donor spermine NONOate (200 µmol/L) blunted the dilution potential caused by 32/24 mmol/L Na/Cl from -11.1±2.1 to -6.5±1.6 mV (P<0.004) and PNa/PCl from 2.2±0.4 to 1.5±0.2. Nitroglycerin (200 µmol/L), another NO donor, also reduced PNa/PCl. Controls showed no significant changes. Dibutyryl-cGMP decreased dilution potentials from -13.4±2.9 to -7.5±1.8 mV (n=6; P<0.01). cGMP-dependent protein kinase inhibition with KT5823 (4 µmol/L) blocked the effect of spermine NONOate, whereas phosphodiesterase 2 inhibition did not. Endogenously produced NO mimicked the effect of the NO donors. In conclusion, NO reduces the selectivity of the paracellular pathway in thick ascending limbs via cGMP and cGMP-dependent protein kinase.
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Affiliation(s)
- Casandra M Monzon
- From the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH
| | - Jeffrey L Garvin
- From the Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH.
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Tomlinson JAP, Caplin B, Boruc O, Bruce-Cobbold C, Cutillas P, Dormann D, Faull P, Grossman RC, Khadayate S, Mas VR, Nitsch DD, Wang Z, Norman JT, Wilcox CS, Wheeler DC, Leiper J. Reduced Renal Methylarginine Metabolism Protects against Progressive Kidney Damage. J Am Soc Nephrol 2015; 26:3045-59. [PMID: 25855779 DOI: 10.1681/asn.2014030280] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 02/16/2015] [Indexed: 01/10/2023] Open
Abstract
Nitric oxide (NO) production is diminished in many patients with cardiovascular and renal disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis, and elevated plasma levels of ADMA are associated with poor outcomes. Dimethylarginine dimethylaminohydrolase-1 (DDAH1) is a methylarginine-metabolizing enzyme that reduces ADMA levels. We reported previously that a DDAH1 gene variant associated with increased renal DDAH1 mRNA transcription and lower plasma ADMA levels, but counterintuitively, a steeper rate of renal function decline. Here, we test the hypothesis that reduced renal-specific ADMA metabolism protects against progressive renal damage. Renal DDAH1 is expressed predominately within the proximal tubule. A novel proximal tubule-specific Ddah1 knockout (Ddah1(PT-/-)) mouse demonstrated tubular cell accumulation of ADMA and lower NO concentrations, but unaltered plasma ADMA concentrations. Ddah1(PT-/-) mice were protected from reduced kidney tissue mass, collagen deposition, and profibrotic cytokine expression in two independent renal injury models: folate nephropathy and unilateral ureteric obstruction. Furthermore, a study of two independent kidney transplant cohorts revealed higher levels of human renal allograft methylarginine-metabolizing enzyme gene expression associated with steeper function decline. We also report an association among DDAH1 expression, NO activity, and uromodulin expression supported by data from both animal and human studies, raising the possibility that kidney DDAH1 expression exacerbates renal injury through uromodulin-related mechanisms. Together, these data demonstrate that reduced renal tubular ADMA metabolism protects against progressive kidney function decline. Thus, circulating ADMA may be an imprecise marker of renal methylarginine metabolism, and therapeutic ADMA reduction may even be deleterious to kidney function.
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Affiliation(s)
- James A P Tomlinson
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom;
| | - Ben Caplin
- Centre for Nephrology, UCL Medical School Royal Free, London, United Kingdom
| | - Olga Boruc
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Claire Bruce-Cobbold
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Pedro Cutillas
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Dirk Dormann
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Peter Faull
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Rebecca C Grossman
- Centre for Nephrology, UCL Medical School Royal Free, London, United Kingdom
| | - Sanjay Khadayate
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Valeria R Mas
- Translational Genomics Transplant Laboratory, Transplant Division, Department of Surgery, University of Virginia, Charlottesville, Virginia
| | - Dorothea D Nitsch
- Department of Non-communicable Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom; and
| | - Zhen Wang
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
| | - Jill T Norman
- Centre for Nephrology, UCL Medical School Royal Free, London, United Kingdom
| | - Christopher S Wilcox
- Hypertension, Kidney and Vascular Research Center, Georgetown University, Washington, DC
| | - David C Wheeler
- Centre for Nephrology, UCL Medical School Royal Free, London, United Kingdom
| | - James Leiper
- Medical Research Council Clinical Sciences Centre, Imperial College, London, United Kingdom
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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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Fry BC, Edwards A, Layton AT. Impacts of nitric oxide and superoxide on renal medullary oxygen transport and urine concentration. Am J Physiol Renal Physiol 2015; 308:F967-80. [PMID: 25651567 DOI: 10.1152/ajprenal.00600.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 01/20/2015] [Indexed: 12/17/2022] Open
Abstract
The goal of this study was to investigate the reciprocal interactions among oxygen (O2), nitric oxide (NO), and superoxide (O2 (-)) and their effects on medullary oxygenation and urinary output. To accomplish that goal, we developed a detailed mathematical model of solute transport in the renal medulla of the rat kidney. The model represents the radial organization of the renal tubules and vessels, which centers around the vascular bundles in the outer medulla and around clusters of collecting ducts in the inner medulla. Model simulations yield significant radial gradients in interstitial fluid oxygen tension (Po2) and NO and O2 (-) concentration in the OM and upper IM. In the deep inner medulla, interstitial fluid concentrations become much more homogeneous, as the radial organization of tubules and vessels is not distinguishable. The model further predicts that due to the nonlinear interactions among O2, NO, and O2 (-), the effects of NO and O2 (-) on sodium transport, osmolality, and medullary oxygenation cannot be gleaned by considering each solute's effect in isolation. An additional simulation suggests that a sufficiently large reduction in tubular transport efficiency may be the key contributing factor, more so than oxidative stress alone, to hypertension-induced medullary hypoxia. Moreover, model predictions suggest that urine Po2 could serve as a biomarker for medullary hypoxia and a predictor of the risk for hospital-acquired acute kidney injury.
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Affiliation(s)
- Brendan C Fry
- Department of Mathematics, Duke University, Durham, North Carolina; and
| | - Aurélie Edwards
- University of Paris 6, University of Paris 5, Institut National de la Santé et de la Recherche Médicale UMRS 1138, Centre National de la Recherche Scientifique ERL 8228, Centre de Recherche des Cordeliers, Paris, France
| | - Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina; and
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Pearce D, Soundararajan R, Trimpert C, Kashlan OB, Deen PM, Kohan DE. Collecting duct principal cell transport processes and their regulation. Clin J Am Soc Nephrol 2015; 10:135-46. [PMID: 24875192 PMCID: PMC4284417 DOI: 10.2215/cjn.05760513] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The principal cell of the kidney collecting duct is one of the most highly regulated epithelial cell types in vertebrates. The effects of hormonal, autocrine, and paracrine factors to regulate principal cell transport processes are central to the maintenance of fluid and electrolyte balance in the face of wide variations in food and water intake. In marked contrast with the epithelial cells lining the proximal tubule, the collecting duct is electrically tight, and ion and osmotic gradients can be very high. The central role of principal cells in salt and water transport is reflected by their defining transporters-the epithelial Na(+) channel (ENaC), the renal outer medullary K(+) channel, and the aquaporin 2 (AQP2) water channel. The coordinated regulation of ENaC by aldosterone, and AQP2 by arginine vasopressin (AVP) in principal cells is essential for the control of plasma Na(+) and K(+) concentrations, extracellular fluid volume, and BP. In addition to these essential hormones, additional neuronal, physical, and chemical factors influence Na(+), K(+), and water homeostasis. Notably, a variety of secreted paracrine and autocrine agents such as bradykinin, ATP, endothelin, nitric oxide, and prostaglandin E2 counterbalance and limit the natriferic effects of aldosterone and the water-retaining effects of AVP. Considerable recent progress has improved our understanding of the transporters, receptors, second messengers, and signaling events that mediate principal cell responses to changing environments in health and disease. This review primarily addresses the structure and function of the key transporters and the complex interplay of regulatory factors that modulate principal cell ion and water transport.
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Affiliation(s)
- David Pearce
- Division of Nephrology, Department of Medicine, University of California, San Francisco, California
| | - Rama Soundararajan
- Department of Translational Molecular Pathology, MD Anderson Cancer Center, Houston, Texas
| | - Christiane Trimpert
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ossama B. Kashlan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Peter M.T. Deen
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Donald E. Kohan
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah
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Ghasemi A, Khalifi S, Jedi S. Streptozotocin-nicotinamide-induced rat model of type 2 diabetes (review). ACTA ACUST UNITED AC 2014; 101:408-20. [DOI: 10.1556/aphysiol.101.2014.4.2] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Horita S, Nakamura M, Shirai A, Yamazaki O, Satoh N, Suzuki M, Seki G. Regulatory roles of nitric oxide and angiotensin II on renal tubular transport. World J Nephrol 2014; 3:295-301. [PMID: 25374825 PMCID: PMC4220364 DOI: 10.5527/wjn.v3.i4.295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 09/05/2014] [Accepted: 10/10/2014] [Indexed: 02/06/2023] Open
Abstract
Renal tubules regulate blood pressure and humoral homeostasis. Mediators that play a significant role in regulating the transport of solutes and water include angiotensin II (AngII) and nitric oxide (NO). AngIIcan significantly raise blood pressure via effects on the heart, vasculature, and renal tubules. AngII generally stimulates sodium reabsorption by triggering sodium and fluid retention in almost all segments of renal tubules. Stimulation of renal proximal tubule (PT) transport is thought to be essential for AngII-mediated hypertension. However, AngII has a biphasic effect on in vitro PT transport in mice, rats, and rabbits: stimulation at low concentrations and inhibition at high concentrations. On the other hand, NO is generally thought to inhibit renal tubular transport. In PTs, NO seems to be involved in the inhibitory effect of AngII. A recent study reports a surprising finding: AngII has a monophasic stimulatory effect on human PT transport. Detailed analysis of signalling mechanisms indicates that in contrast to other species, the human NO/guanosine 3’,5’-cyclic monophosphate/extracellular signal-regulated kinase pathway seems to mediate this effect of Ang II on PT transport. In this review we will discuss recent progress in understanding the effects of AngII and NO on renal tubular transport.
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Gordish KL, Beierwaltes WH. Sustained resveratrol infusion increases natriuresis independent of renal vasodilation. Physiol Rep 2014; 2:2/9/e12144. [PMID: 25214522 PMCID: PMC4270224 DOI: 10.14814/phy2.12144] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Resveratrol is reported to exert cardio‐renal protective effects in animal models of pathology, yet the mechanisms underlying these effects are poorly understood. Previously, we reported an i.v. bolus of resveratrol induces renal vasodilation by increasing nitric oxide bioavailability and inhibiting reactive oxygen species. Thus, we hypothesized a sustained infusion of resveratrol would also increase renal blood flow (RBF), and additionally glomerular filtration rate (GFR). We infused vehicle for 30 min followed by 30 min resveratrol at either: 0, 0.5, 1.0, 1.5 mg/min, and measured RBF, renal vascular resistance (RVR), GFR, and urinary sodium excretion. At all three doses, blood pressure and GFR remained unchanged. Control RBF was 7.69 ± 0.84 mL/min/gkw and remained unchanged by 0.5 mg/min resveratrol (7.88 ± 0.94 mL/min/gkw, n = 9), but urinary sodium excretion increased from 2.19 ± 1.1 to 5.07 ± 0.92 μmol/min/gkw (n = 7, P < 0.01). In separate experiments, 1.0 mg/min resveratrol increased RBF by 17%, from 7.16 ± 0.29 to 8.35 ± 0.42 mL/min/gkw (P < 0.01, n = 10), decreased RVR 16% from 13.63 ± 0.65 to 11.36 ± 0.75 ARU (P < 0.003) and increased sodium excretion from 1.57 ± 0.46 to 3.10 ± 0.80 μmol/min/gkw (n = 7, P < 0.04). At the 1.5 mg/min dose, resveratrol increased RBF 12% from 6.76 ± 0.57 to 7.58 ± 0.60 mL/min/gkw (n = 8, P < 0.003), decreased RVR 15% (15.58 ± 1.35 to 13.27 ± 1.14 ARU, P < 0.003) and increased sodium excretion (3.99 ± 1.71 to 7.80 ± 1.51 μmol/min/gkw, n = 8, P < 0.04). We conclude that a constant infusion of resveratrol can induce significant renal vasodilation while not altering GFR or blood pressure. Also, resveratrol infusion produced significant natriuresis at all doses, suggesting it may have a direct effect on renal tubular sodium handling independent of renal perfusion pressure or flow. We have previously documented that resveratrol causes a nitric oxide‐dependent acute renal vasodilation. We now report that sustained resveratrol has no effect on GFR but induced a remarkable natriuresis which is independent from the hemodynamic effects, suggesting resveratrol acts directly on nephron sodium reabsorption.
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Affiliation(s)
- Kevin L Gordish
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - William H Beierwaltes
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan Department Internal Medicine, Hypertension and Vascular Research Div., Henry Ford Hospital, Detroit, Michigan
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Al Therwani S, Mose FH, Jensen JM, Bech JN, Pedersen EB. Effect of vasopressin antagonism on renal handling of sodium and water and central and brachial blood pressure during inhibition of the nitric oxide system in healthy subjects. BMC Nephrol 2014; 15:100. [PMID: 24965902 PMCID: PMC4079642 DOI: 10.1186/1471-2369-15-100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 06/19/2014] [Indexed: 11/10/2022] Open
Abstract
Background Tolvaptan is a selective vasopressin receptor antagonist (V2R) that increases free water excretion. We wanted to test the hypotheses that tolvaptan changes both renal handling of water and sodium and systemic hemodynamics during basal conditions and during nitric oxide (NO)-inhibition with L-NG-monomethyl-arginine (L-NMMA). Methods Nineteen healthy subjects were enrolled in a randomized, placebo-controlled, double-blind, crossover study of two examination days. Tolvaptan 15 mg or placebo was given in the morning. L-NMMA was given as a bolus followed by continuous infusion during 60 minutes. We measured urine output(UO), free water clearance (CH2O), fractional excretion of sodium (FENa), urinary aquaporin-2 channels (u-AQP2) and epithelial sodium channels (u-ENaCγ), plasma vasopressin (p-AVP), central and brachial blood pressure(cBP, bBP). Results During baseline conditions, tolvaptan caused a significant increase in UO, CH2O and p-AVP, and FENa was unchanged. During L-NMMA infusion, UO and CH2O decreased more pronounced after tolvaptan than after placebo (-54 vs.-42% and -34 vs.-9% respectively). U-AQP2 decreased during both treatments, whereas u-ENaCγ decreased after placebo and increased after tolvaptan. CBP and bBP were unchanged. Conclusion During baseline conditions, tolvaptan increased renal water excretion. During NO-inhibition, the more pronounced reduction in renal water excretion after tolvaptan indicates that NO promotes water excretion in the principal cells, at least partly, via an AVP-dependent mechanism. The lack of decrease in u-AQP2 by tolvaptan could be explained by a counteracting effect of increased plasma vasopressin. The antagonizing effect of NO-inhibition on u-ENaC suggests that NO interferes with the transport via ENaC by an AVP-dependent mechanism.
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Affiliation(s)
- Safa Al Therwani
- University Clinic in Nephrology and Hypertension, Department of Medical Research, Holstebro Hospital and Aarhus University, Hospital Unit Jutland West, Laegaardvej 12, 7500 Holstebro, Denmark.
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Dobrowolski L, Kuczeriszka M, Castillo A, Majid DS, Navar LG. Role of atrial natriuretic peptide in mediating the blood pressure-independent natriuresis elicited by systemic inhibition of nitric oxide. Pflugers Arch 2014; 467:833-41. [PMID: 24953240 PMCID: PMC4276550 DOI: 10.1007/s00424-014-1557-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 06/05/2014] [Accepted: 06/11/2014] [Indexed: 01/23/2023]
Abstract
While it is clearly recognized that increased intrarenal nitric oxide (NO) levels elicit natriuresis, confounding data showing that systemic nitric oxide synthase inhibition (NOSi) also increases sodium excretion (UNaV) poses a conundrum. This response has been attributed to the associated increases in arterial pressure (AP); however, the increases in AP and in UNaV are temporally dissociated. The changes in regional renal haemodynamics induced by NOSi could also contribute to the alterations of UNaV. To evaluate the roles of AP and non-AP mechanisms mediating the natriuresis, Nω-nitro-l-arginine methyl ester hydrochloride (L-NAME) was infused i.v. at doses ranging from 5 to 50 μg/kg/min in anaesthetized rats. UNaV, perfusion of the cortex (cortical blood flow, CBF) and medulla (medullary blood flow, MBF) with laser-Doppler flowmetry and glomerular filtration rate (GFR) were measured. UNaV increased from 0.6 ± 0.2 to 1.6 ± 0.1 μmol/kg/min (P < 0.05) with the lower nonpressor doses. With the higher doses, AP increased from 116 ± 4 to 122 ± 4 mmHg and UNaV increased from 1.1 ± 0.3 to 3.3 ± 0.7 μmol/min/g (P < 0.002). UNaV increased similarly in a group where renal AP was maintained at baseline levels. The associated reductions in CBF (17 ± 5 and 38 ± 5 %) and MBF (27 ± 6 and 52 ± 6 %) would be expected to attenuate rather than contribute to the natriuresis. Plasma atrial natriuretic peptide (ANP) concentrations increased significantly following NOSi. Anantin, a natriuretic peptide receptor-A blocker, prevented or reversed the L-NAME-induced natriuresis without altering the L-NAME-induced changes in AP or CBF. The results indicate that increased ANP and related natriuretic peptides mediate the AP-independent natriuresis, at least partly, elicited by systemic L-NAME infusion and help resolve the conundrum of natriuresis during systemic NOSi.
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Affiliation(s)
- Leszek Dobrowolski
- Department of Physiology, Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, LA, USA
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