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Poursharif S, Hamza S, Braam B. Changes in Proximal Tubular Reabsorption Modulate Microvascular Regulation via the TGF System. Int J Mol Sci 2022; 23:ijms231911203. [PMID: 36232506 PMCID: PMC9569689 DOI: 10.3390/ijms231911203] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/26/2022] Open
Abstract
This review paper considers the consequences of modulating tubular reabsorption proximal to the macula densa by sodium–glucose co-transporter 2 (SGLT2) inhibitors, acetazolamide, and furosemide in states of glomerular hyperfiltration. SGLT2 inhibitors improve renal function in early and advanced diabetic nephropathy by decreasing the glomerular filtration rate (GFR), presumably by activating the tubuloglomerular feedback (TGF) mechanism. Central in this paper is that the renoprotective effects of SGLT2 inhibitors in diabetic nephropathy can only be partially explained by TGF activation, and there are alternative explanations. The sustained activation of TGF leans on two prerequisites: no or only partial adaptation should occur in reabsorption proximal to macula densa, and no or only partial adaptation should occur in the TGF response. The main proximal tubular and loop of Henle sodium transporters are sodium–hydrogen exchanger 3 (NHE3), SGLT2, and the Na-K-2Cl co-transporter (NKCC2). SGLT2 inhibitors, acetazolamide, and furosemide are the most important compounds; inhibiting these transporters would decrease sodium reabsorption upstream of the macula densa and increase TGF activity. This could directly or indirectly affect TGF responsiveness, which could oppose sustained TGF activation. Only SGLT2 inhibitors can sustainably activate the TGF as there is only partial compensation in tubular reabsorption and TGF response. SGLT2 inhibitors have been shown to preserve GFR in both early and advanced diabetic nephropathy. Other than for early diabetic nephropathy, a solid physiological basis for these effects in advanced nephropathy is lacking. In addition, TGF has hardly been studied in humans, and therefore this role of TGF remains elusive. This review also considers alternative explanations for the renoprotective effects of SGLT2 inhibitors in diabetic patients such as the enhancement of microvascular network function. Furthermore, combination use of SGLT2 inhibitors and angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs). in diabetes can decrease inflammatory pathways, improve renal oxygenation, and delay the progression of diabetic nephropathy.
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Affiliation(s)
- Shayan Poursharif
- Department of Medicine, Division of Nephrology and Immunology, University of Alberta, Edmonton, AB T6G 2G3, Canada
| | - Shereen Hamza
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Branko Braam
- Department of Medicine, Division of Nephrology and Immunology, University of Alberta, Edmonton, AB T6G 2G3, Canada
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Correspondence: ; Tel.: +1-780-492-1867
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Mazaheri M, Assadi F, Sadeghi-Bojd S. Adjunctive acetazolamide therapy for the treatment of Bartter syndrome. Int Urol Nephrol 2019; 52:121-128. [PMID: 31820361 DOI: 10.1007/s11255-019-02351-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/24/2019] [Indexed: 12/17/2022]
Abstract
PURPOSE Bartter syndrome is a rare hereditary salt-losing tubulopathy caused by mutations of several genes in the thick ascending limb of Henle's loop, characterized by polyuria, hypokalemic metabolic alkalosis, growth retardation and normal blood pressure. Cyclooxygenase inhibitors, potassium-sparing diuretics and angiotensin-converting enzyme inhibitors are currently used to treat electrolyte derangements, but with poor response. Whether treatment with acetazolamide, a carbonic-anhydrase inhibitor, would result in better clinical outcomes is unknown. METHODS We randomly assigned children with Bartter syndrome in a 1:1 ratio to either receive indomethacin, enalapril, and spironolactone or indomethacin, enalapril, and spironolactone plus acetazolamide once daily in the morning for 4 weeks. After 2 days of washout, participants crossed over to receive the alternative intervention for 4 weeks. The present study examines the serum bicarbonate lowering effect of acetazolamide as an adjunctive therapy in children with Batter syndrome. RESULTS Of the 43 patients screened for eligibility, 22 (51%), between the ages 6 and 42 months, were randomized to intervention. Baseline characteristics were similar between the two groups. Addition of acetazolamide for a period of 4 weeks significantly reduced serum bicarbonate and increased serum potassium levels, parallel with a reduction in serum aldosterone and plasma renin concentration. The 24-h urine volume, sodium, potassium, and chloride decreased significantly. CONCLUSION Our data define a new physiologic and therapeutic role of acetazolamide for the management of children with Bartter syndrome.
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Affiliation(s)
- Mojgan Mazaheri
- Department of Pediatrics, Section of Nephrology, Semnan University of Medical Science, Semnan, Iran
| | - Farahnak Assadi
- Department of Pediatrics, Division of Nephrology, Rush University Medical Center, 445 East North Water Street, Chicago, IL, USA.
| | - Simin Sadeghi-Bojd
- Department of Pediatrics, Division of Nephrology, Zahedan University of Medical Sciences, Zahedan, Iran
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León Jiménez D, Cherney DZI, Bjornstad P, Castilla-Guerra L, Miramontes González JP. Antihyperglycemic agents as novel natriuretic therapies in diabetic kidney disease. Am J Physiol Renal Physiol 2018; 315:F1406-F1415. [PMID: 30066584 PMCID: PMC6293300 DOI: 10.1152/ajprenal.00384.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 07/11/2018] [Accepted: 07/26/2018] [Indexed: 02/07/2023] Open
Abstract
While sodium-glucose cotransporter-2 (SGLT2) inhibitors have been used for the routine management of type 2 diabetes for several years, it is perhaps their natriuretic effects that are most important clinically. This natriuresis activates tubuloglomerular feedback, resulting in reduced glomerular hypertension and proteinuria, leading to renal protective effects in the EMPA-REG OUTCOME and CANVAS Program trials. In the cardiovascular system, it is likely that plasma volume contraction due to natriuresis in response to SGLT2 inhibition is at least in part responsible for the reduction in the risk of heart failure observed in these trials. We compare this mechanism of action with other antidiabetics. Importantly, other diuretic classes, including thiazide and loop diuretics, have not resulted in such robust clinical benefits in patients with type 2 diabetes, possibly because these older agents do not influence intraglomerular pressure directly. In contrast, SGLT2 inhibitors do have important physiological similarities with carbonic anhydrase inhibitors, which also act proximally, and have been shown to activate tubuloglomerular feedback.
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Affiliation(s)
- David León Jiménez
- Vascular Risk Unit, Internal Medicine Clinical Management Unit, Hospital Universitario Virgen Macarena , Seville , Spain
| | - David Z I Cherney
- Department of Medicine, Division of Nephrology. Toronto General Hospital, University of Toronto , Toronto , Ontario, Canada
| | - Petter Bjornstad
- Department of Pediatrics, Division of Endocrinology and Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado , Aurora, Colorado
| | - Luis Castilla-Guerra
- Vascular Risk Unit, Internal Medicine Clinical Management Unit, Hospital Universitario Virgen Macarena , Seville , Spain
| | - José Pablo Miramontes González
- Service of Internal Medicine, Institute of Biomedical Research of Salamanca (IBSAL), Hospital Universitario de Salamanca , Salamanca , Spain
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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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Rajasekeran H, Reich HN, Hladunewich MA, Cattran D, Lovshin JA, Lytvyn Y, Bjornstad P, Lai V, Tse J, Cham L, Majumder S, Bowskill BB, Kabir MG, Advani SL, Gibson IW, Sood MM, Advani A, Cherney DZI. Dapagliflozin in focal segmental glomerulosclerosis: a combined human-rodent pilot study. Am J Physiol Renal Physiol 2017; 314:F412-F422. [PMID: 29141939 DOI: 10.1152/ajprenal.00445.2017] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is an important cause of nondiabetic chronic kidney disease (CKD). Sodium-glucose cotransporter 2 inhibition (SGLT2i) therapy attenuates the progression of diabetic nephropathy, but it remains unclear whether SGLT2i provides renoprotection in nondiabetic CKD such as FSGS. The primary aim of this pilot study was to determine the effect of 8 wk of dapagliflozin on glomerular filtration rate (GFR) in humans and in experimental FSGS. Secondary end points were related to changes in renal hemodynamic function, proteinuria, and blood pressure (BP). GFR (inulin) and renal plasma flow (para-aminohippurate), proteinuria, and BP were measured in patients with FSGS ( n = 10), and similar parameters were measured in subtotally nephrectomized (SNx) rats. In response to dapagliflozin, changes in GFR, renal plasma flow, and 24-h urine protein excretion were not statistically significant in humans or rats. Systolic BP (SBP) decreased in SNx rats (196 ± 26 vs. 165 ± 33 mmHg; P < 0.001), whereas changes were not statistically significant in humans (SBP 112.7 ± 8.5 to 112.8 ± 11.2 mmHg, diastolic BP 71.8 ± 6.5 to 69.6 ± 8.4 mmHg; P = not significant), although hematocrit increased (0.40 ± 0.05 to 0.42 ± 0.05%; P = 0.03). In archival kidney tissue from a separate patient cohort, renal parenchymal SGLT2 mRNA expression was decreased in individuals with FSGS compared with controls. Short-term treatment with the SGLT2i dapagliflozin did not modify renal hemodynamic function or attenuate proteinuria in humans or in experimental FSGS. This may be related to downregulation of renal SGLT2 expression. Studies examining the impact of SGLT2i on markers of kidney disease in patients with other causes of nondiabetic CKD are needed.
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Affiliation(s)
- Harindra Rajasekeran
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada.,Department of Physiology, University of Toronto , Toronto, Ontario , Canada
| | - Heather N Reich
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Michelle A Hladunewich
- Department of Medicine, Division of Nephrology, Sunnybrook Health Sciences Centre, University of Toronto , Toronto, Ontario , Canada
| | - Daniel Cattran
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Julie A Lovshin
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Yuliya Lytvyn
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Petter Bjornstad
- Department of Pediatric Endocrinology, University of Colorado School of Medicine , Aurora, Colorado.,Barbara Davis Center for Diabetes, University of Colorado Denver , Aurora, Colorado
| | - Vesta Lai
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Josephine Tse
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Leslie Cham
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada
| | - Syamantak Majumder
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, Ontario , Canada
| | - Bridgit B Bowskill
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, Ontario , Canada
| | - M Golam Kabir
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, Ontario , Canada
| | - Suzanne L Advani
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, Ontario , Canada
| | - Ian W Gibson
- Department of Pathology, University of Manitoba , Winnipeg, Manitoba , Canada
| | - Manish M Sood
- Ottawa Hospital Research Institute, University of Ottawa , Ottawa, Ontario , Canada
| | - Andrew Advani
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute, St. Michael's Hospital , Toronto, Ontario , Canada
| | - David Z I Cherney
- Department of Medicine, Division of Nephrology, University Health Network, University of Toronto , Toronto, Ontario , Canada.,Department of Physiology, University of Toronto , Toronto, Ontario , Canada
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6
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de Groot T, Doornebal J, Christensen BM, Cockx S, Sinke AP, Baumgarten R, Bedford JJ, Walker RJ, Wetzels JFM, Deen PMT. Lithium-induced NDI: acetazolamide reduces polyuria but does not improve urine concentrating ability. Am J Physiol Renal Physiol 2017; 313:F669-F676. [DOI: 10.1152/ajprenal.00147.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 06/07/2017] [Accepted: 06/09/2017] [Indexed: 01/07/2023] Open
Abstract
Lithium is the mainstay treatment for patients with bipolar disorder, but it generally causes nephrogenic diabetes insipidus (NDI), a disorder in which the renal urine concentrating ability has become vasopressin insensitive. Li-NDI is caused by lithium uptake by collecting duct principal cells and downregulation of aquaporin-2 (AQP2) water channels, which are essential for water uptake from tubular urine. Recently, we found that the prophylactic administration of acetazolamide to mice effectively attenuated Li-NDI. To evaluate whether acetazolamide might benefit lithium-treated patients, we administered acetazolamide to mice with established Li-NDI and six patients with a lithium-induced urinary concentrating defect. In mice, acetazolamide partially reversed lithium-induced polyuria and increased urine osmolality, which, however, did not coincide with increased AQP2 abundances. In patients, acetazolamide led to the withdrawal of two patients from the study due to side effects. In the four remaining patients acetazolamide did not lead to clinically relevant changes in maximal urine osmolality. Urine output was also not affected, although none of these patients demonstrated overt lithium-induced polyuria. In three out of four patients, acetazolamide treatment increased serum creatinine levels, indicating a decreased glomerular filtration rate (GFR). Strikingly, these three patients also showed a decrease in systemic blood pressure. All together, our data reveal that acetazolamide does not improve the urinary concentrating defect caused by lithium, but it lowers the GFR, likely explaining the reduced urine output in our mice and in a recently reported patient with lithium-induced polyuria. The reduced GFR in patients prone to chronic kidney disease development, however, warrants against application of acetazolamide in Li-NDI patients without long-term (pre)clinical studies.
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Affiliation(s)
- Theun de Groot
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joan Doornebal
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Nephrology, Isala Clinics, Zwolle, The Netherlands
| | | | - Simone Cockx
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | - Anne P. Sinke
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Robert J. Walker
- Department of Medicine, University of Otago, Dunedin, New Zealand
| | - Jack F. M. Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Peter M. T. Deen
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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7
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Zingerman B, Herman-Edelstein M, Erman A, Bar Sheshet Itach S, Ori Y, Rozen-Zvi B, Gafter U, Chagnac A. Effect of Acetazolamide on Obesity-Induced Glomerular Hyperfiltration: A Randomized Controlled Trial. PLoS One 2015; 10:e0137163. [PMID: 26367377 PMCID: PMC4569381 DOI: 10.1371/journal.pone.0137163] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 07/29/2015] [Indexed: 11/18/2022] Open
Abstract
AIMS Obesity is an important risk factor for the development of chronic kidney disease. One of the major factors involved in the pathogenesis of obesity-associated kidney disease is glomerular hyperfiltration. Increasing salt-delivery to the macula densa is expected to decrease glomerular filtration rate (GFR) by activating tubuloglomerular feedback. Acetazolamide, a carbonic anhydrase inhibitor which inhibits salt reabsorption in the proximal tubule, increases distal salt delivery. Its effects on obesity-related glomerular hyperfiltration have not previously been studied. The aim of this investigation was to evaluate whether administration of acetazolamide to obese non diabetic subjects reduces glomerular hyperfiltration. MATERIALS AND METHODS The study was performed using a randomized double-blind crossover design. Obese non-diabetic men with glomerular hyperfiltration were randomized to receive intravenously either acetazolamide or furosemide at equipotent doses. Twelve subjects received the allocated medications. Two weeks later, the same subjects received the drug which they had not received during the first study. Inulin clearance, p-aminohippuric acid clearance and fractional lithium excretion were measured before and after medications administration. The primary end point was a decrease in GFR, measured as inulin clearance. RESULTS GFR decreased by 21% following acetazolamide and did not decrease following furosemide. Renal vascular resistance increased by 12% following acetazolamide, while it remained unchanged following furosemide administration. Natriuresis increased similarly following acetazolamide and furosemide administration. Sodium balance was similar in both groups. CONCLUSIONS Intravenous acetazolamide decreased GFR in obese non-diabetic men with glomerular hyperfiltration. Furosemide, administered at equipotent dose, did not affect GFR, suggesting that acetazolamide reduced glomerular hyperfiltration by activating tubuloglomerular feedback. TRIAL REGISTRATION ClinicalTrials.gov NCT01146288.
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Affiliation(s)
- Boris Zingerman
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michal Herman-Edelstein
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Arie Erman
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | | | - Yaacov Ori
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Benaya Rozen-Zvi
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Uzi Gafter
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Avry Chagnac
- Department of Nephrology & Hypertension, Rabin Medical Center, Petah Tikva, Israel
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
- * E-mail:
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Braam B, Cupples WA, Joles JA, Gaillard C. Systemic arterial and venous determinants of renal hemodynamics in congestive heart failure. Heart Fail Rev 2013; 17:161-75. [PMID: 21553212 DOI: 10.1007/s10741-011-9246-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Heart and kidney interactions are fascinating, in the sense that failure of the one organ strongly affects the function of the other. In this review paper, we analyze how principal driving forces for glomerular filtration and renal blood flow are changed in heart failure. Moreover, renal autoregulation and modulation of neurohumoral factors, which can both have repercussions on renal function, are analyzed. Two paradigms seem to apply. One is that the renin-angiotensin system (RAS), the sympathetic nervous system (SNS), and extracellular volume control are the three main determinants of renal function in heart failure. The other is that the classical paradigm to analyze renal dysfunction that is widely applied in nephrology also applies to the pathophysiology of heart failure: pre-renal, intra-renal, and post-renal alterations together determine glomerular filtration. At variance with the classical paradigm is that the most important post-renal factor in heart failure seems renal venous hypertension that, by increasing renal tubular pressure, decreases GFR. When different pharmacological strategies to inhibit the RAS and SNS and to assist renal volume control are considered, there is a painful lack in knowledge about how widely applied drugs affect primary driving forces for ultrafiltration, renal autoregulation, and neurohumoral control. We call for more clinical physiological studies.
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Affiliation(s)
- Branko Braam
- Department of Medicine/Division of Nephrology and Immunology, University of Alberta Hospital, 11-132 CSB Clinical Sciences Building, Edmonton, AB T6G 2G3, Canada.
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Abstract
Elevated glomerular filtration rate (GFR) is a common observation in early diabetes mellitus and closely correlates with the progression of diabetic nephropathy. Hyperfiltration has been explained to be the result of a reduced load of sodium and chloride passing macula densa, secondarily to an increased proximal reabsorption of glucose and sodium by the sodium-glucose co-transporters. This results in an inactivation of the tubuloglomerular feedback (TGF), leading to a reduced afferent arteriolar vasoconstriction and subsequently an increase in GFR. This hypothesis has recently been questioned due to the observation that adenosine A(1)-receptor knockout mice, previously shown to lack a functional TGF mechanism, still display a pronounced hyperfiltration when diabetes is induced. Leyssac demonstrated in the 1960s (Acta Physiol Scand58, 1963:236) that GFR and proximal reabsorption can work independently of each other. Furthermore, by the use of micropuncture technique a reduced hydrostatic pressure in Bowman's space or in the proximal tubule of diabetic rats has been observed. A reduced pressure in Bowman's space will increase the pressure gradient over the filtration barrier and can contribute to the development of diabetic hyperfiltration. When inhibiting proximal reabsorption with a carbonic anhydrase inhibitor, GFR decreases and proximal tubular pressure increases. Measuring intratubular pressure allows a sufficient time resolution to reveal that net filtration pressure decreases before TGF is activated which highlights the importance of intratubular pressure as a regulator of GFR. Taken together, these results imply that the reduced intratubular pressure observed in diabetes might be crucial for the development of glomerular hyperfiltration.
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Affiliation(s)
- P Persson
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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10
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Sandson NB, Armstrong SC, Cozza KL. An overview of psychotropic drug-drug interactions. PSYCHOSOMATICS 2005; 46:464-94. [PMID: 16145193 DOI: 10.1176/appi.psy.46.5.464] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The psychotropic drug-drug interactions most likely to be relevant to psychiatrists' practices are examined. The metabolism and the enzymatic and P-glycoprotein inhibition/induction profiles of all antidepressants, antipsychotics, and mood stabilizers are described; all clinically meaningful drug-drug interactions between agents in these psychotropic classes, as well as with frequently encountered nonpsychotropic agents, are detailed; and information on the pharmacokinetic/pharmacodynamic results, mechanisms, and clinical consequences of these interactions is presented. Although the range of drug-drug interactions involving psychotropic agents is large, it is a finite and manageable subset of the much larger domain of all possible drug-drug interactions. Sophisticated computer programs will ultimately provide the best means of avoiding drug-drug interactions. Until these programs are developed, the best defense against drug-drug interactions is awareness and focused attention to this issue.
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Affiliation(s)
- Neil B Sandson
- Division of Education and Residency Training, Sheppard Pratt Health System, Towson, MD, USA
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11
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Gottlieb SS, Brater DC, Thomas I, Havranek E, Bourge R, Goldman S, Dyer F, Gomez M, Bennett D, Ticho B, Beckman E, Abraham WT. BG9719 (CVT-124), an A1 adenosine receptor antagonist, protects against the decline in renal function observed with diuretic therapy. Circulation 2002; 105:1348-53. [PMID: 11901047 DOI: 10.1161/hc1102.105264] [Citation(s) in RCA: 286] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Adenosine may adversely affect renal function via its effects on renal arterioles and tubuloglomerular feedback, but effects of adenosine blockade in humans receiving furosemide and ACE inhibitors is unknown. METHODS AND RESULTS This was a randomized, double-blind, ascending-dose, crossover study evaluating 3 doses of BG9719 in 63 patients with congestive heart failure. Patients received placebo or 1 of 3 doses of BG9719 on 1 day and the same medication plus furosemide on a separate day. Renal function and electrolyte and water excretion were assessed. BG9719 alone caused an increase in urine output and sodium excretion (P<0.05). Although administration of furosemide alone caused a large diuresis, addition of BG9719 to furosemide increased diuresis, which was significant at the 0.75-microg/mL concentration. BG9719 alone improved glomerular filtration rate (GFR) at the 2 lower doses. Furosemide alone caused a decline in GFR. When BG9719 was added to furosemide, however, creatinine clearance remained at baseline at the 2 lower doses. CONCLUSIONS In patients with congestive heart failure on standard therapy, including ACE inhibitors, BG9719 increased both urine output and GFR. In these same patients, furosemide increased urine output at the expense of decreased GFR. When BG9719 was given in addition to furosemide, urine volume additionally increased and there was no deterioration in GFR. A1 adenosine antagonism might preserve renal function while simultaneously promoting natriuresis during treatment for heart failure.
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Affiliation(s)
- Stephen S Gottlieb
- University of Maryland School of Medicine and the D.V.A. Medical Center, Baltimore, Md, USA.
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Abstract
Renal function is a very important prognostic indicator in patients with congestive heart failure. While some of the prognostic importance of poor renal function is related to the worse physiology associated with it, there are suggestions that the dysfunction itself is detrimental. Recently, it has been shown that adenosine may mediate much kidney activity. In addition to vasoconstrictive and vasodilatory effects, adenosine is intrinsic to the tubuloglomerular feedback which occurs when an acute increase in sodium levels in the proximal tubule feeds back to decrease glomerular filtration. Adenosine works via both adenosine A1 and A2 receptors. A1-receptor antagonists decrease afferent arteriolar pressure, and increase urine flow and sodium excretion. Studies suggest that A1-receptor antagonists cause a diuretic effect not by a change in the renal haemodynamics, but by the inhibition of water and sodium reabsorption in tubular sites secondary to direct tubuloglomerular feedback. Less consistent has been the occasional finding of increased glomerular filtration rate despite the lack of improved renal plasma flow. Clinically important questions are: what role adenosine plays in causing the poor renal function associated with heart failure and what A1-receptor antagonists do in such situations? If an A1-receptor antagonist could cause diuresis while maintaining or improving glomerular filtration, it would be a useful adjunct in the treatment of severe heart failure. We evaluated the effects of the A1-receptor antagonist CVT-124 (BG-9719) in heart failure patients. CVT-124 increased sodium excretion without decreasing glomerular filtration rate. These data suggest that adenosine might be an important determinant of renal function in patients with heart failure.
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Affiliation(s)
- S S Gottlieb
- Division of Cardiology, University of Maryland School of Medicine, Baltimore 21201, USA
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Swenson ER. Respiratory and renal roles of carbonic anhydrase in gas exchange and acid-base regulation. EXS 2001:281-341. [PMID: 11268521 DOI: 10.1007/978-3-0348-8446-4_15] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- E R Swenson
- VA Puget Sound Health Care System, 1660 S Columbian Way, Seattle, WA 98108, USA
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14
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Gottlieb SS, Skettino SL, Wolff A, Beckman E, Fisher ML, Freudenberger R, Gladwell T, Marshall J, Cines M, Bennett D, Liittschwager EB. Effects of BG9719 (CVT-124), an A1-adenosine receptor antagonist, and furosemide on glomerular filtration rate and natriuresis in patients with congestive heart failure. J Am Coll Cardiol 2000; 35:56-9. [PMID: 10636259 DOI: 10.1016/s0735-1097(99)00532-x] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES To determine the effects of furosemide and the selective A1 adenosine receptor BG9719 on renal function in patients with congestive heart failure (CHF). BACKGROUND Studies suggest that adenosine may affect renal function by various mechanisms, but the effects of blockade of this system in humans is unknown. In addition, the effects of a therapeutic dose of furosemide on glomerular filtration rate (GFR) and renal plasma flow (RPF) in heart failure patients are controversial. METHODS On different days, 12 patients received placebo, BG9719 and furosemide. Glomerular filtration rate, RPF and sodium and water excretion were assessed immediately following drug administration. RESULTS Glomerular filtration rate was 84 +/- 23 ml/min/1.73m2 after receiving placebo, 82 +/- 24 following BG9719 administration and a decreased (p < 0.005) 63 +/- 18 following furosemide. Renal plasma flow was unchanged at 293 +/- 124 ml/min/1.73m2 on placebo, 334 +/- 155 after receiving BG9719 and 374 +/- 231 after receiving furosemide. Sodium excretion increased from 8 +/- 8 mEq following placebo administration to 37 +/- 26 mEq following BG9719 administration. In the six patients in whom it was measured, sodium excretion was 104 +/- 78 mEq following furosemide administration. CONCLUSIONS Natriuresis is effectively induced by both furosemide and the adenosine A1 antagonist BG9719 in patients with CHF. Doses of the two drugs used in this study did not cause equivalent sodium and water excretion but only furosemide decreased GFR. These data suggest that adenosine is an important determinant of renal function in patients with heart failure.
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Affiliation(s)
- S S Gottlieb
- Department of Medicine, University of Maryland School of Medicine, Baltimore 21201, USA.
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15
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Atherton JC, Doyle A, Gee A, Green R, Gingell S, Nicholls F, Pempkowiak L, Plange-Rhule J. Lithium clearance: modification by the loop of Henle in man. J Physiol 1991; 437:377-91. [PMID: 1890640 PMCID: PMC1180053 DOI: 10.1113/jphysiol.1991.sp018601] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. The contribution of Li+ reabsorption in the loop of Henle to lithium clearance (CLi) and the possible mechanism(s) involved were assessed in healthy volunteers. Four mechanisms were considered: (a) passive reabsorption in the thin ascending limb, (b) solvent drag in the thin descending limb, (c) the Na+, K+, 2Cl- transporter in the thick ascending limb and (d) paracellular movement in the thick ascending limb. 2. Since alterations in the corticomedullary osmolal concentration gradient produced by fluid restriction (500 ml day-1) and subsequent water loading (15 ml kg-1) did not affect either CLi (28.5 +/- 2.1 vs. 28.2 +/- 1.9 ml min-1) or fractional lithium clearance (FELi; 23.5 +/- 2.0 vs. 23.0 +/- 1.9%), it is unlikely that substantial Li+ reabsorption occurs in the thin limbs by either passive movement or solvent drag. 3. Increasing plasma Li+ with unchanged plasma Na+ in salt-replete volunteers was associated with only small reductions in CLi (32.8 +/- 1.3 ml min-1, P less than 0.05) and FELi (27.3 +/- 1.8 vs. 25.3 +/- 2.0%, P less than 0.05). This suggests that substantial Li+ reabsorption on the Na+, K+, 2Cl- transporter does not occur. 4. Bumetanide increased FELi in salt-depleted (LS) and salt-replete (HS) volunteers and abolished the pre-diuretic difference in FELi between salt intakes (LS, 16.6 +/- 1.5 vs. 38.7 +/- 2.3%, P less than 0.001; HS, 30.1 +/- 1.5 vs. 40.5 +/- 2.0%, P less than 0.001). Changes in CPO4 and CHCO3 were not detected. Acetazolamide produced comparable increases in FELi (LS, 16.6 +/- 1.5 vs. 38.7 +/- 2.2%, P less than 0.001; HS, 30.1 +/- 1.5 vs. 43.1 +/- 2.4%, P less than 0.01); and CPO4 and CHCO3 were increased. When tubular flow to the loop of Henle was increased by acetazolamide, the bumetanide-induced increases in FELi were reduced (LS, 38.7 +/- 2.2 vs. 48.7 +/- 2.3%, P less than 0.001; HS, 43.1 +/- 2.4 vs. 48.1 +/- 2.6%, P less than 0.001). 5. These data are consistent with the view that (a) Li+ is reabsorbed by a bumetanide-sensitive mechanism in the loop of Henle, (b) approximately 20 and 10% of the filtered load, respectively, is reabsorbed in the loop in salt-depleted and salt-replete volunteers, (c) flow-dependent, voltage-driven paracellular movement in the thick ascending limb is the likely mechanism and (d) this mechanism could account for the difference in Li+ reabsorption between low and high salt intakes.
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Affiliation(s)
- J C Atherton
- Department of Physiological Sciences, Manchester University
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