1
|
Lidberg KA, Muthusamy S, Adil M, Mahadeo A, Yang J, Patel RS, Wang L, Bammler TK, Reichel J, Yeung CK, Himmelfarb J, Kelly EJ, Akilesh S. Serum Protein Exposure Activates a Core Regulatory Program Driving Human Proximal Tubule Injury. J Am Soc Nephrol 2022; 33:949-965. [PMID: 35197326 PMCID: PMC9063895 DOI: 10.1681/asn.2021060751] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 02/06/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The kidneys efficiently filter waste products while retaining serum proteins in the circulation. However, numerous diseases compromise this barrier function, resulting in spillage of serum proteins into the urine (proteinuria). Some studies of glomerular filtration suggest that tubules may be physiologically exposed to nephrotic-range protein levels. Therefore, whether serum components can directly injure the downstream tubular portions of the kidney, which in turn can lead to inflammation and fibrosis, remains controversial. METHODS We tested the effects of serum protein exposure in human kidney tubule microphysiologic systems and with orthogonal epigenomic approaches since animal models cannot directly assess the effect of serum components on tubules. RESULTS Serum, but not its major protein component albumin, induced tubular injury and secretion of proinflammatory cytokines. Epigenomic comparison of serum-injured tubules and intact kidney tissue revealed canonical stress-inducible regulation of injury-induced genes. Concordant transcriptional changes in microdissected tubulointerstitium were also observed in an independent cohort of patients with proteinuric kidney disease. CONCLUSIONS Our results demonstrate a causal role for serum proteins in tubular injury and identify regulatory mechanisms and novel pathways for intervention.
Collapse
Affiliation(s)
- Kevin A. Lidberg
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Selvaraj Muthusamy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Mohamed Adil
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Anish Mahadeo
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | - Jade Yang
- Department of Pharmaceutics, University of Washington, Seattle, Washington
| | | | - Lu Wang
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington
| | - Theo K. Bammler
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington
| | - Jonathan Reichel
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - Catherine K. Yeung
- Department of Pharmacy, University of Washington, Seattle, Washington
- Kidney Research Institute, Seattle, Washington
| | - Jonathan Himmelfarb
- Kidney Research Institute, Seattle, Washington
- Nephrology Division, Department of Medicine, University of Washington, Seattle, Washington
| | - Edward J. Kelly
- Department of Pharmaceutics, University of Washington, Seattle, Washington
- Kidney Research Institute, Seattle, Washington
| | - Shreeram Akilesh
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Kidney Research Institute, Seattle, Washington
| |
Collapse
|
2
|
Ziegler V, Fremter K, Helmchen J, Witzgall R, Castrop H. Mesangial cells regulate the single nephron GFR and preserve the integrity of the glomerular filtration barrier: An intravital multiphoton microscopy study. Acta Physiol (Oxf) 2021; 231:e13592. [PMID: 33269519 DOI: 10.1111/apha.13592] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/25/2022]
Abstract
AIM The intraglomerular mesangial cells are located between the glomerular capillaries. Here we hypothesized that mesangial cells regulate the single nephron glomerular filtration rate (snGFR) and that mesangial cells support the integrity of the glomerular filtration barrier. METHODS We assessed the function of mesangial cells in vivo by multiphoton microscopy. Mesangial cells were depleted in Munich Wistar Froemter rats using the Thy1.1 antibody model. RESULTS The Thy1.1 antibody caused the cell-specific loss of 82 ± 3% of mesangial cells. After mesangial cell depletion, the baseline snGFR was reduced to 12.0 ± 1.2 vs 32.4 ± 3.2 nL/min in controls. In control rats, the snGFR decreased after angiotensin II infusion by 61 ± 3% (P = .004), whereas it remained unchanged in Thy1.1-treated rats. The changes in the snGFR after angiotensin II infusion in control rats were accompanied by the marked rotation of the capillary loops within Bowman's space. This phenomenon was absent in anti-Thy1.1-treated rats. The glomerular sieving coefficient (GSCA ) for albumin, used as a measure of the integrity of the glomerular filtration barrier, was low in control rats (0.00061 ± 0.00004) and increased after angiotensin II infusion (0.00121 ± 0.00015). In Thy1.1-treated rats, the GSC was elevated (0.0032 ± 0.00059) and did not change in response to angiotensin II. Electron microscopy revealed the increased thickness of the glomerular basement membrane after mesangial cell depletion. CONCLUSION Our data suggest that mesangial cells actively contribute to the regulation of the snGFR. Furthermore, mesangial cells are crucially involved in maintaining the integrity of the glomerular filtration barrier, in part by modulating the thickness of the glomerular basement membrane.
Collapse
Affiliation(s)
- Vera Ziegler
- Institute of Physiology University of Regensburg Regensburg Germany
| | | | - Julia Helmchen
- Institute of Physiology University of Regensburg Regensburg Germany
| | - Ralph Witzgall
- Institute of Molecular and Cellular Anatomy University of Regensburg Regensburg Germany
| | - Hayo Castrop
- Institute of Physiology University of Regensburg Regensburg Germany
| |
Collapse
|
3
|
Gianesello L, Del Prete D, Ceol M, Priante G, Calò LA, Anglani F. From protein uptake to Dent disease: An overview of the CLCN5 gene. Gene 2020; 747:144662. [PMID: 32289351 DOI: 10.1016/j.gene.2020.144662] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/07/2020] [Indexed: 12/12/2022]
Abstract
Proteinuria is a well-known risk factor, not only for renal disorders, but also for several other problems such as cardiovascular diseases and overall mortality. In the kidney, the chloride channel Cl-/H+ exchanger ClC-5 encoded by the CLCN5 gene is actively involved in preventing protein loss. This action becomes evident in patients suffering from the rare proximal tubulopathy Dent disease because they carry a defective ClC-5 due to CLCN5 mutations. In fact, proteinuria is the distinctive clinical sign of Dent disease, and mainly involves the loss of low-molecular-weight proteins. The identification of CLCN5 disease-causing mutations has greatly improved our understanding of ClC-5 function and of the ClC-5-related physiological processes in the kidney. This review outlines current knowledge regarding the CLCN5 gene and its protein product, providing an update on ClC-5 function in tubular and glomerular cells, and focusing on its relationship with proteinuria and Dent disease.
Collapse
Affiliation(s)
- Lisa Gianesello
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Dorella Del Prete
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Monica Ceol
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Giovanna Priante
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Lorenzo Arcangelo Calò
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| | - Franca Anglani
- Kidney Histomorphology and Molecular Biology Laboratory, Clinical Nephrology Unit, Department of Medicine - DIMED, University of Padua, Padua, Italy.
| |
Collapse
|
4
|
Desideri S, Onions KL, Qiu Y, Ramnath RD, Butler MJ, Neal CR, King MLR, Salmon AE, Saleem MA, Welsh GI, Michel CC, Satchell SC, Salmon AHJ, Foster RR. A novel assay provides sensitive measurement of physiologically relevant changes in albumin permeability in isolated human and rodent glomeruli. Kidney Int 2018; 93:1086-1097. [PMID: 29433915 PMCID: PMC5912930 DOI: 10.1016/j.kint.2017.12.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/05/2017] [Accepted: 12/13/2017] [Indexed: 01/06/2023]
Abstract
Increased urinary albumin excretion is a key feature of glomerular disease but has limitations as a measure of glomerular permeability. Here we describe a novel assay to measure the apparent albumin permeability of single capillaries in glomeruli, isolated from perfused kidneys cleared of red blood cells. The rate of decline of the albumin concentration within the capillary lumen was quantified using confocal microscopy and used to calculate apparent permeability. The assay was extensively validated and provided robust, reproducible estimates of glomerular albumin permeability. These values were comparable with previous in vivo data, showing this assay could be applied to human as well as rodent glomeruli. To confirm this, we showed that targeted endothelial glycocalyx disruption resulted in increased glomerular albumin permeability in mice. Furthermore, incubation with plasma from patients with post-transplant recurrence of nephrotic syndrome increased albumin permeability in rat glomeruli compared to remission plasma. Finally, in glomeruli isolated from rats with early diabetes there was a significant increase in albumin permeability and loss of endothelial glycocalyx, both of which were ameliorated by angiopoietin-1. Thus, a glomerular permeability assay, producing physiologically relevant values with sufficient sensitivity to measure changes in glomerular permeability and independent of tubular function, was developed and validated. This assay significantly advances the ability to study biology and disease in rodent and human glomeruli.
Collapse
Affiliation(s)
- Sara Desideri
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Karen L Onions
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Yan Qiu
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Raina D Ramnath
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Matthew J Butler
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Christopher R Neal
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Matthew L R King
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Andrew E Salmon
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Moin A Saleem
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Gavin I Welsh
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | | | - Simon C Satchell
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Andrew H J Salmon
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK
| | - Rebecca R Foster
- Bristol Renal, Bristol Medical School, University of Bristol, Bristol, UK.
| |
Collapse
|
5
|
Castrop H, Schießl IM. Novel routes of albumin passage across the glomerular filtration barrier. Acta Physiol (Oxf) 2017; 219:544-553. [PMID: 27452481 DOI: 10.1111/apha.12760] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/13/2016] [Accepted: 07/20/2016] [Indexed: 12/20/2022]
Abstract
Albuminuria is a hallmark of kidney diseases of various aetiologies and an unambiguous symptom of the compromised integrity of the glomerular filtration barrier. Furthermore, there is increasing evidence that albuminuria per se aggravates the development and progression of chronic kidney disease. This review covers new aspects of the movement of large plasma proteins across the glomerular filtration barrier in health and disease. Specifically, this review focuses on the role of endocytosis and transcytosis of albumin by podocytes, which constitutes a new pathway of plasma proteins across the filtration barrier. Thus, we summarize what is known about the mechanisms of albumin endocytosis by podocytes and address the fate of the endocytosed albumin, which is directed to lysosomal degradation or transcellular movement with subsequent vesicular release into the urinary space. We also address the functional consequences of overt albumin endocytosis by podocytes, such as the formation of pro-inflammatory cytokines, which might eventually result in a deterioration of podocyte function. Finally, we consider the diagnostic potential of podocyte-derived albumin-containing vesicles in the urine as an early marker of a compromised glomerular barrier function. In terms of new technical approaches, the review covers how our knowledge of the movement of albumin across the glomerular filtration barrier has expanded by the use of new intravital imaging techniques.
Collapse
Affiliation(s)
- H. Castrop
- Institute of Physiology; University of Regensburg; Regensburg Germany
| | - I. M. Schießl
- Institute of Physiology; University of Regensburg; Regensburg Germany
| |
Collapse
|
6
|
Abstract
The mouse isolated perfused kidney (MIPK) is a technique for keeping a mouse kidney under ex vivo conditions perfused and functional for 1 hr. This is a prerequisite for studying the physiology of the isolated organ and for many innovative applications that may be possible in the future, including perfusion decellularization for kidney bioengineering or the administration of anti-rejection or genome-editing drugs in high doses to prime the kidney for transplantation. During the time of the perfusion, the kidney can be manipulated, renal function can be assessed, and various pharmaceuticals administered. After the procedure, the kidney can be transplanted or processed for molecular biology, biochemical analysis, or microscopy. This paper describes the perfusate and the surgical technique needed for the ex vivo perfusion of mouse kidneys. Details of the perfusion apparatus are given and data are presented showing the viability of the kidney's preparation: renal blood flow, vascular resistance, and urine data as functional, transmission electron micrographs of different nephron segments as morphological readouts, and western blots of transport proteins of different nephron segments as molecular readout.
Collapse
Affiliation(s)
- Jan Czogalla
- Institute of Anatomy, Swiss National Centre of Competence in Research Kidney, University of Zürich;
| | | | - Johannes Loffing
- Institute of Anatomy, Swiss National Centre of Competence in Research Kidney, University of Zürich
| |
Collapse
|
7
|
Schießl IM, Kattler V, Castrop H. In Vivo Visualization of the Antialbuminuric Effects of the Angiotensin-Converting Enzyme Inhibitor Enalapril. J Pharmacol Exp Ther 2015; 353:299-306. [DOI: 10.1124/jpet.114.222125] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
8
|
Burwick RM, Easter SR, Dawood HY, Yamamoto HS, Fichorova RN, Feinberg BB. Complement Activation and Kidney Injury Molecule-1–Associated Proximal Tubule Injury in Severe Preeclampsia. Hypertension 2014; 64:833-8. [DOI: 10.1161/hypertensionaha.114.03456] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Richard M. Burwick
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Sarah Rae Easter
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Hassan Y. Dawood
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Hidemi S. Yamamoto
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Raina N. Fichorova
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Bruce B. Feinberg
- From the Division of Maternal Fetal Medicine and Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland (R.M.B.); and Division of Maternal Fetal Medicine (B.B.F.), Laboratory of Genital Tract Biology (H.Y.D., H.S.Y., R.N.F.), and Department of Obstetrics, Gynecology, and Reproductive Biology (S.R.E.), Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| |
Collapse
|
9
|
Castrop H. Reply to "Letter to the editor: 'Quantifying albumin permeability with multiphoton microscopy: why the difference?'". Am J Physiol Renal Physiol 2014; 306:F1101-3. [PMID: 24785958 DOI: 10.1152/ajprenal.00038.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Hayo Castrop
- Institute of Physiology, Univ. of Regensburg, Universitätsstr. 31, 93040 Regensburg, Germany.
| |
Collapse
|
10
|
Schießl IM, Castrop H. Angiotensin II AT2 receptor activation attenuates AT1 receptor-induced increases in the glomerular filtration of albumin: a multiphoton microscopy study. Am J Physiol Renal Physiol 2013; 305:F1189-200. [PMID: 23946289 DOI: 10.1152/ajprenal.00377.2013] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this study, we assessed the acute effects of angiotensin II on the albumin glomerular sieving coefficient (GSC) using intravital microscopy. The experiments were performed on Munich Wistar Froemter (MWF) rats. Alexa-Fluor-594 albumin was injected intravenously, and the fluorescence intensity in the glomerular capillaries and Bowman's space was determined to calculate the albumin GSC. The GSC was measured before and during the constant infusion of angiotensin II (10 ng·min(-1)·kg(-1) body wt). Baseline mean arterial pressure (MAP) was 99 ± 5 mmHg and stabilized at 137 ± 5 mmHg during angiotensin II infusion. The baseline GSC averaged 0.00044 ± 4.8 × 10(-5) and increased by 286 ± 44% after angiotensin II infusion (P < 0.0001). The proximal tubular Alexa-Fluor-594 albumin uptake was enhanced during angiotensin II infusion (518% of the baseline value during angiotensin II vs. 218% in controls; P < 0.0001). No change in GSC was observed when the AT1 antagonist losartan was injected before the start of angiotensin II infusion. The AT2 antagonist PD123319 increased the baseline GSC from 0.00052 ± 3.6 × 10(-5) to 0.00074 ± 8.2 × 10(-5) (P = 0.02) without altering the MAP. During angiotensin II infusion with losartan, PD123319 increased the albumin GSC from 0.00037 ± 5.8 × 10(-5) to 0.00115 ± 0.00015 (P = 0.001). When the renal perfusion pressure was mechanically controlled, the GSC increased from 0.0007 ± 0.00019 to 0.0025 ± 0.00063 during angiotensin II infusion (P = 0.047), similar to what was observed when the renal perfusion pressure was allowed to increase. In summary, AT1 activation acutely increases the albumin GSC. This effect appears to be largely independent of changes in the renal perfusion pressure. The AT2 receptor partially attenuates the proteinuric effects of the AT1 receptor.
Collapse
Affiliation(s)
- Ina Maria Schießl
- Institute of Physiology, Univ. of Regensburg, Universitätsstr. 31, 93040 Regensburg, Germany.
| | | |
Collapse
|
11
|
|
12
|
Zandi-Nejad K, Eddy AA, Glassock RJ, Brenner BM. Why is proteinuria an ominous biomarker of progressive kidney disease? Kidney Int 2005:S76-89. [PMID: 15485426 DOI: 10.1111/j.1523-1755.2004.09220.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Progressive tubule injury and interstitial fibrosis frequently accompany glomerulopathies associated with proteinuria. Clinical experience indicates that higher levels of proteinuria prior to, as well as after initiation of treatment predict more rapid decline in renal function and more pronounced tubulointerstitial injury. It has been proposed that filtration of potentially tubulotoxic plasma proteins is responsible for the observed correlations between proteinuria and progression (i.e., proteinuria is a cause and not only a consequence of progressive renal injury). Numerous attempts have been made to identify the species of putative tubulotoxic proteins in this progressive injury process, but much uncertainty persists. These uncertainties stem from nonphysiologic exposure of apical cell surfaces to proteins in vitro, the extremely high concentrations of various proteins tested in vitro, and the nonuniformity of end points measured. Furthermore, there is often a lack of correlation between in vitro and in vivo findings, and a lack of uniformity of results even for seemingly similar in vitro experiments. Less controversy is evident in the potential pathways whereby injured tubules evoke a tubulointerstitial inflammatory and fibrotic response, with many in vivo models serving to incriminate excessive cytokine and chemokine production, infiltration of various inflammatory cells, and the balance between apoptosis and cell proliferation. Despite many years of concerted efforts, we believe it is still unclear whether proteinuria is a cause (and if so, which species of protein), or only a consequence of progressive renal injury. Nevertheless, pending the resolution of these uncertainties by more decisive and unambiguous experimentation, the strongly predictive inverse relationship between level of proteinuria and long-term renal survival currently justifies aggressive antiproteinuric treatment strategies, with a goal of reducing protein excretion rate to the lowest level possible without the induction of symptoms or undue risk.
Collapse
Affiliation(s)
- Kambiz Zandi-Nejad
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | | | | |
Collapse
|
13
|
Neumann KH, Kellner C, Kühn K, Stolte H, Schurek HJ. Age-dependent thickening of glomerular basement membrane has no major effect on glomerular hydraulic conductivity. Nephrol Dial Transplant 2004; 19:805-11. [PMID: 15031333 DOI: 10.1093/ndt/gfh067] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The effect of the increasing thickness of the glomerular basement membrane (GBM), which is seen in ageing rats, on the effective hydraulic conductivity (k) of the glomerular capillary wall was studied in Wistar rats aged 2 and 18 months. METHODS With the use of micropuncture techniques, ultrafiltration characteristics of cortical glomeruli were determined in isolated cell-free perfused kidneys. Because the filtration fraction in this preparation is low (3%) as a consequence of high perfusion rates at glomerular filtration rates comparable with in vivo conditions, uniform ultrafiltration conditions are provided over the whole filtering surface. After fixation at a defined perfusion pressure, the surface of glomerular capillaries (S) was obtained morphometrically on light microscopic sections of the glomeruli studied previously. RESULTS The glomerular ultrafiltration coefficient (K(f)) was 0.025 nl/s.mmHg in young rats and 0.038 nl/s.mmHg in old rats (P<0.0005) and S was 0.140 mm(2) in young and 0.244 mm(2) in old rats (P<0.0005). However, k was not significantly different (18.0 nl/s.mmHg.cm(2) in young and 15.8 nl/s.mmHg.cm(2) in old rats) despite a 2.4-fold increase of GBM thickness as estimated from electron microscopic sections. CONCLUSIONS These findings indicate that the age-dependent increase of GBM thickness in rat kidneys did not substantially increase hydraulic resistance of the glomerular capillary wall.
Collapse
Affiliation(s)
- Klaus H Neumann
- Klinik für Nephrologie, Universitätsklinikum, Leipziger Strasse 44, D-39120 Magdeburg, Germany.
| | | | | | | | | |
Collapse
|
14
|
Ciarimboli G, Hjalmarsson C, Bökenkamp A, Schurek HJ, Haraldsson B. Dynamic alterations of glomerular charge density in fixed rat kidneys suggest involvement of endothelial cell coat. Am J Physiol Renal Physiol 2003; 285:F722-30. [PMID: 12812917 DOI: 10.1152/ajprenal.00227.2001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In a previous paper, we found that low ionic strength (I) reversibly reduced the glomerular charge density, suggesting increased volume of the charge-selective barrier. Because glutaraldehyde makes most structures rigid, we considered the isolated, perfusion-fixed rat kidney to be an ideal model for further analysis. The fixed kidneys were perfused with albumin solutions containing FITC-Ficoll at two different Is (I = 151 and 34 mM). At normal I, the fractional clearance () for albumin was 0.0049 (SE -0.0017, +0.0027, n = 6), whereas for neutral Ficoll35.5A of similar size was significantly higher 0.104 (SE 0.010, n = 5, P < 0.001). At low I, for albumin was 0.0030 (SE -0.0011, +0.0018, n = 6, not significant from albumin at normal I) and for Ficoll35.5A was identical to that at normal I, 0.104 (SE 0.015, n = 6, P < 0.01 compared with albumin at low I). According to a heterogeneous charged fiber model, low I reduced the fiber density from 0.056 to 0.0315, suggesting a 78% gel volume expansion. We conclude that 1) there is a significant glomerular charge barrier. 2) Solutions with low I increase the volume of the charge barrier even in kidneys fixed with glutaraldehyde. Our findings suggest that polysaccharide-rich structures, such as the endothelial cell coat, are key components in the glomerular barrier.
Collapse
|
15
|
Jeansson M, Haraldsson B. Glomerular size and charge selectivity in the mouse after exposure to glucosaminoglycan-degrading enzymes. J Am Soc Nephrol 2003; 14:1756-65. [PMID: 12819235 DOI: 10.1097/01.asn.0000072742.02714.6e] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
This is the first functional study of glomerular size and charge selectivity in mice. The aim was to investigate the controversial issue of glomerular permselectivity in animals exposed to glucosaminoglycan-degrading enzymes, hyaluronidase, and heparinase. Fractional clearances (theta) for FITC-Ficoll and albumin were estimated in isoflurane anesthetized mice in vivo and in cooled isolated perfused kidneys (cIPK). In cIPK, a significant increase of theta(albumin) from 0.0023 (95% confidence interval, 0.0014 to 0.0033) in controls to 0.0130 (95% confidence interval, 0.0055 to 0.0206) was seen after hyaluronidase treatment. The theta for neutral Ficoll of similar size as albumin was 0.063 to 0.093 in all groups. According to a heterogeneous charged fiber model, the fiber volume fraction of negatively charged fibers decreased by 10% after enzyme treatments. It is concluded that glomerular size and charge selectivity in mice is similar to that previously shown for rats. Moreover, hyaluronic acid, chondroitin sulfate, and heparan sulfate are of importance for charge selectivity.
Collapse
Affiliation(s)
- Marie Jeansson
- Department of Physiology, Göteborg University, Box 432, SE-405 30 Göteborg, Sweden.
| | | |
Collapse
|
16
|
Russo LM, Bakris GL, Comper WD. Renal handling of albumin: a critical review of basic concepts and perspective. Am J Kidney Dis 2002; 39:899-919. [PMID: 11979334 DOI: 10.1053/ajkd.2002.32764] [Citation(s) in RCA: 159] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Biochemical and physiological processes that underlie the mechanism of albuminuria are completely reassessed in this article in view of recent discoveries that filtered proteins undergo rapid degradation during renal passage and the resulting excreted peptide fragments are not detected by conventional urine protein assays. This means that filtered protein and/or albumin levels in urine have been seriously underestimated. The concept that albuminuria is a result of changes in glomerular permeability is questioned in light of these findings and also in terms of a critical examination of charge selectivity, shunts, or large-pore formation and hemodynamic effects. The glomerulus appears to function merely in terms of size selectivity alone, and for albumin, this does not change significantly in disease states. Intensive albumin processing by a living kidney occurs through cellular processes distal to the glomerular basement membrane. Failure of this cellular processing primarily leads to albuminuria. This review brings together recent data about urinary albumin clearance and current knowledge of receptors known to process albumin in both health and disease states. We conclude with a discussion of topical and controversial issues associated with the proposed new understanding of renal handling of albumin.
Collapse
Affiliation(s)
- Leileata M Russo
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | | | | |
Collapse
|
17
|
Hjalmarsson C, Ohlson M, Haraldsson B. Puromycin aminonucleoside damages the glomerular size barrier with minimal effects on charge density. Am J Physiol Renal Physiol 2001; 281:F503-12. [PMID: 11502599 DOI: 10.1152/ajprenal.2001.281.3.f503] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Puromycin aminonucleoside (PAN) has been suggested to reduce glomerular charge density, to create large glomerular "leaks," or not to affect the glomerular barrier. Therefore, we analyzed glomerular charge and size selectivity in vivo and in isolated kidneys perfused at 8 degrees C (cIPK) in control and PAN-treated rats. The fractional clearances (theta) for albumin and Ficoll of similar hydrodynamic size were 0.0017 +/- 0.0004 and 0.15 +/- 0.02, respectively, in control cIPKs. Two-pore analysis gave similar results in vivo and in vitro, with small- and large-pore radii of 47-52 and 85-105 A, respectively, in controls. Puromycin increased the number of large pores 40-50 times, the total pore area over diffusion distance decreased by a factor of 25-30, and the small-pore radius increased by 33% (P < 0.001 for all comparisons of size selectivity and theta). The effect of PAN was less dramatic on the estimated wall charge density, which was 73% of that of controls. We conclude that puromycin effectively destroys the glomerular size barrier with minimal effects on charge density.
Collapse
Affiliation(s)
- C Hjalmarsson
- Department of Physiology, Göteborg University, SE-405 30 Göteborg, Sweden
| | | | | |
Collapse
|
18
|
Ciarimboli G, Bökenkamp A, Schurek HJ, Fels LM, Kilian I, Maess B, Stolte H. The "fixed" charge of glomerular capillary wall as determinant of permselectivity. Ren Fail 2001; 23:365-76. [PMID: 11499552 DOI: 10.1081/jdi-100104720] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The determinants of glomerular capillary wall (GCW) permeability to proteins have been subject of controversial discussion. To study this question we have developed a modified isolated perfused rat kidney model in which tubular transport processes are completely blocked by perfusion fixation with glutaraldehyde. This model allows to directly titrate the charge density of the GCW using albumin solutions buffered over a wide pH-range, a manipulation that cannot be performed in the intact kidney. Analyzing the results of these experiments helped to determine a fixed charge density of the GCW of 43 mEq/L. In the present work, we used the isolated perfused fixed rat kidney model to study the influence of this fixed charge on the transglomerular passage of proteins. To do this, the fixed kidney was perfused with albumin solutions containing different isoforms of horseradish peroxidase. The lowest sieving coefficient was obtained with the acidic isoform (0.035+/-0.008, n = 7), while the isoforms at pI 6.85 and 8.45 showed higher sieving coefficients (0.059+/-0.008, n = 7 and 0.090+/-0.008, n = 4, respectively). The highest sieving coefficient (0.59+/-0.031, n = 6) was observed in perfusion experiments of the fixed kidney with cationic HRP (pI > or = 9.30). However, when comparing the sieving coefficients, the highly cationic isoform was excluded because it has a lower molecular weight than the other isoforms. The sieving coefficients of the other isoforms were significantly different (p < 0.05. ANOVA, Scheffé test). In conclusion, the presence of a discrete (even if lower than previously thought) "fixed" charge on the GCW of 43 mEq/L restricts the transglomerular passage of isoforms of horseradish peroxidase by a factor 2-3. These results imply that the influence of charge selectivity has been overstated in the literature.
Collapse
Affiliation(s)
- G Ciarimboli
- Division of Nephrology, Hannover Medical School, Germany.
| | | | | | | | | | | | | |
Collapse
|
19
|
Lindström KE, Rönnstedt L, Jaremko G, Haraldsson B. Physiological and morphological effects of perfusing isolated rat kidneys with hyperosmolal mannitol solutions. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 166:231-8. [PMID: 10468660 DOI: 10.1046/j.1365-201x.1999.00559.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recently, we were able to modify the glomerular charge barrier using perfusates with low and normal ionic strengths keeping the osmolality unchanged. The concentration of fixed charges was reversibly reduced from 35 to 12 mEq L-1 as the solution with low content of NaCl was introduced with no apparent effect on the size selectivity. It can be argued however, that the mannitol used for maintenance of osmolality may induce changes in glomerular permeability per se. To explore this possibility, isolated kidneys were perfused at 8 degrees with hyperosmolal mannitol solutions (560 mOsm) and compared with those perfused with standard albumin solutions (295 mOsm). The vascular resistance (PRU100) fell from 0. 14 +/- 0.01 to 0.11 +/- 0.01 mmHg min 100 g mL-1 as the mannitol solution was introduced (P < 0.001). As the blood pressure should remain unchanged, the flow was increased from 8 to 11 mL min-1. The glomerular filtration rate (GFR) increased by 50% from 320 +/- 40 to 490 +/- 20 microL min-1 g-1 (P < 0.001). Despite these changes in haemodynamical parameters, there was no significant change in the fractional clearance for albumin. Kidneys perfused with the mannitol solution showed well-preserved histology, while there was a conspicuous collapse of the cortical tissue and signs of tubular epithelial swelling with the standard perfusate. Moreover, all glomeruli were perfused in the mannitol group, as revealed by fluorescence of FITC dextran, while the distribution was uneven in the control kidneys. We conclude that perfusion of isolated kidneys with a hyperosmolal mannitol solution increased GFR by increasing the number of functionally active nephrons with no apparent effect on the glomerular barrier, a pattern differing from alteration of ionic strength.
Collapse
Affiliation(s)
- K E Lindström
- Department of Physiology, Göteborg University, Sweden
| | | | | | | |
Collapse
|
20
|
Osicka TM, Comper WD. Tubular inhibition destroys charge selectivity for anionic and neutral horseradish peroxidase. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1381:170-8. [PMID: 9685630 DOI: 10.1016/s0304-4165(98)00025-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The fractional clearance of [3H]anionic HRP and [3H]neutral HRP in the isolated perfused kidney as determined by radioactivity analysis was 0.0160+/-0.0028 (n=6) and 0.0388+/-0.0076 (n=8) respectively. The apparent charge selectivity for both the anionic and neutral forms of HRP observed was destroyed with the inclusion of the tubular uptake inhibitors, 150 mM lysine and 10 mM NH4Cl, in the perfusate. In the presence of 150 mM lysine, the clearances of [3H]anionic HRP and [3H]neutral HRP were 0.0645+/-0.0110 (n=4) and 0. 0784+/-0.0120 (n=4) respectively, and 0.0564+/-0.0035 (n=4) and 0. 0694+/-0.0054 (n=4) respectively in the presence of 10 mM NH4Cl. The clearance for both the anionic and neutral HRP probes in these tubular uptake inhibited systems fits precisely the size selective characteristics of the glomerular capillary wall as determined by transport probes calibrated for hydrodynamic size by size exclusion chromatography. The tubular uptake inhibitors were observed not to alter glomerular permselectivity as determined using polydisperse dextran fractions and the behaviour of neutral HRP. This study demonstrates that charge selectivity for differently charged proteins is not as great as originally thought and suggests that the clearance differences between anionic and neutral forms may be due to differential handling by the tubules.
Collapse
Affiliation(s)
- T M Osicka
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168, Australia
| | | |
Collapse
|
21
|
Lindström KE, Blom A, Johnsson E, Haraldsson B, Fries E. High glomerular permeability of bikunin despite similarity in charge and hydrodynamic size to serum albumin. Kidney Int 1997; 51:1053-8. [PMID: 9083270 DOI: 10.1038/ki.1997.147] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Bikunin is a chondroitin-sulphate containing serum protein with a Stokes-Einstein radius and a negative net charge close to those of serum albumin. The plasma half life of bikunin is about 10 minutes, and approximately half of its clearance occurs in the kidneys. The quantitative role of glomerular filtration in the renal clearance of this protein has not been determined. To assess the glomerular permeability of bikunin we used isolated rat kidneys that were perfused with an albumin solution. The metabolic activities of the tubuli were inhibited by low temperature (8 degrees C). The clearances of radiolabeled bikunin and albumin were repeatedly determined under identical conditions. The fractional clearance of bikunin was found to be 80 times higher than that of albumin: 15% +/- 1% versus 0.18% +/- 0.02%. This value for bikunin can fully account for its renal clearance in vivo. It has previously been shown that uncharged flexible solutes, such as dextrans, have higher renal clearances than globular molecules with similar radii. The high glomerular permeability of bikunin is therefore probably due to its elongated and flexible configuration. Moreover, the observed clearance value of the anionic molecule bikunin is close to that of a neutral flexible dextran of similar size, indicating that the charge of bikunin is of little importance for its glomerular permeability.
Collapse
Affiliation(s)
- K E Lindström
- Department of Physiology, Göteborg University, Sweden
| | | | | | | | | |
Collapse
|
22
|
OSICKA TM, PRATT LM, COMPER WD. Glomerular capillary wall permeability to albumin and horseradish peroxidase. Nephrology (Carlton) 1996. [DOI: 10.1111/j.1440-1797.1996.tb00088.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
23
|
Johnsson E, Rippe B, Haraldsson B. Reduced permselectivity in isolated perfused rat kidneys following small elevations of glomerular capillary pressure. ACTA PHYSIOLOGICA SCANDINAVICA 1994; 150:201-9. [PMID: 8191899 DOI: 10.1111/j.1748-1716.1994.tb09677.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A modified rat kidney preparation was used to explore how changes in hydrostatic pressure affect the permselective properties of the glomerular capillary bed. The maximally vasodilated kidneys of 18 rats were perfused with albumin solutions (16.7 g l-1) at different flow rates and hence arterial pressures (PA). One kidney in each rat was exposed to pressure elevations with the other kidney serving as a control perfused at constant PA of about 100 mmHg. Both the vascular resistance to flow and the glomerular filtration rate (GFR 34.6 +/- 2.9 ml min-1 100 g-1) were similar in the two kidneys at equal PA and remained constant throughout the experiment. The ratio of albumin clearance over GFR (theta) was initially around 0.4% at constant PA and gradually increased during 1.5 h to reach 0.7% at the end of the experiment. A direct increase of PA from 100 to 200 mmHg for 15 min resulted in a calculated increase of the effective glomerular filtration pressure gradient of 10-15 mmHg and in a two-fold increase of theta when measured at an identical PA of 100 mmHg. Albumin clearance was almost fully normalized within 20 min similar to that observed in e.g. skeletal muscle. However, the glomerular capillary barrier seemed to be far more sensitive to elevations of hydrostatic pressure than other capillary walls which require capillary pressure increments of 60 mmHg in order to induce similar reversible changes in permeability. Therefore, we conclude that an elevated PGC per se induces changes of glomerular permselectivity, which may have important pathophysiological implications during conditions of proteinuria.
Collapse
Affiliation(s)
- E Johnsson
- Department of Physiology, University of Göteborg, Sweden
| | | | | |
Collapse
|
24
|
Johnsson E, Haraldsson B. Addition of purified orosomucoid preserves the glomerular permeability for albumin in isolated perfused rat kidneys. ACTA PHYSIOLOGICA SCANDINAVICA 1993; 147:1-8. [PMID: 8452035 DOI: 10.1111/j.1748-1716.1993.tb09466.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The serum protein, orosomucoid has been shown to be essential for the maintenance of normal capillary permeability in several different organs, including the kidney. Thus, the clearance of albumin was found to be almost fivefold higher in the absence of orosomucoid in a previous study on isolated rat kidneys, perfused with either of two commercially available human albumin solutions of similar composition, but differing in their content of orosomucoid (0.21 g l-1 vs. < 0.005 g l-1). The following experiments were performed in order to verify the hypothesis that this effect on glomerular permselectivity was due to orosomucoid per se and not to other ingredients in the two solutions. Both kidneys of 12 rats were isolated and perfused with identical albumin solutions without orosomucoid, but with the addition of purified orosomucoid (0.25 g l-1) to one of the kidneys. No significant differences in vascular resistance, urine flow or glomerular filtration rate (GFR), which was found to be 27 +/- 2 ml min-1 100 g-1, were observed between the two groups of kidneys. The fractional clearance of albumin (theta) was initially similar for both kidneys (0.0022 +/- 0.0002). In the absence of orosomucoid, theta gradually increased to 0.0076 +/- 0.0013 after 1 h of perfusion compared to 0.0040 +/- 0.0006 for the kidneys with orosomucoid added to the perfusate (P < 0.001, n = 12). We conclude that the plasma glycoprotein orosomucoid indeed plays an important role in regulating the dynamic properties of the glomerular capillary wall by reducing the permeability towards macromolecules such as albumin.
Collapse
Affiliation(s)
- E Johnsson
- Department of Physiology, University of Göteborg, Sweden
| | | |
Collapse
|
25
|
Haraldsson BS, Johnsson EK, Rippe B. Glomerular permselectivity is dependent on adequate serum concentrations of orosomucoid. Kidney Int 1992; 41:310-6. [PMID: 1552704 DOI: 10.1038/ki.1992.43] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Orosomucoid, or alpha 1-acid glycoprotein, a serum protein known to be an "acute phase reactant" has recently been shown to be needed for the maintenance of normal capillary permeability in skeletal muscle and mesentery. Therefore, we were interested in studying whether the glomerular capillary wall is affected by orosomucoid as well. For this purpose, left and right kidneys from nine rats (group A) were isolated and perfused in situ and in parallel using separate solutions of human albumin (1.8% in Tyrode), differing in their content of orosomucoid, one containing 0.21 g/liter, the other less than 0.005 g/liter. The temperature was kept at 8 degrees C in order to minimize tubular reabsorption of fluid and albumin. The two kidneys showed identical and stable vascular resistances during the experiments. Also the glomerular filtration rates (GFR) were stable between 30 and 33 ml/min/100 g kidney. Initially, the two kidneys showed similar fractional albumin clearance (theta) values of approximately 0.003. However, in the "absence" of orosomucoid theta increased to become four- to fivefold higher in the test kidney than in the control kidney at the end of the 1 1/2 hour experiment. This difference was observed in all rats, suggesting that orosomucoid is needed also for the maintenance of the glomerular permselectivity. In a separate group of eight animals (group B), orosomucoid-containing albumin solutions were used in parallel with horse serum solutions to perfuse the two kidneys of each rat, at 8 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- B S Haraldsson
- Department of Physiology and Nephrology, University of Göteborg, Sweden
| | | | | |
Collapse
|
26
|
Johnsson E, Haraldsson B. An isolated perfused rat kidney preparation designed for assessment of glomerular permeability characteristics. ACTA PHYSIOLOGICA SCANDINAVICA 1992; 144:65-73. [PMID: 1595354 DOI: 10.1111/j.1748-1716.1992.tb09268.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The aim of the present investigation was to modify the widely used isolated perfused rat kidney preparation to make it more suitable for studies of glomerular permeability to macromolecules. Both kidneys were perfused in situ using separate pumps in two of each other independent systems with Tyrode-solution containing human serum albumin (18.2 g l-1). Sodium nitroprusside was administered to induce dilatation and to maintain constant vascular resistance (PRU100) during the experiments. The addition of sodium nitroprusside decreased vascular resistance from 0.17 +/- 0.05 to 0.09 +/- 0.02 mmHg min-1 100 g-1 ml-1 and increased urine flow and glomerular filtration rate. The temperature of the perfusate was reduced from 37 degrees C to 8 degrees C to inhibit tubular reabsorption of protein and fluid, resulting in a urine to plasma concentration ratio of [51Cr]EDTA of 1.26 +/- 0.07. Furosemide reduced the urine to plasma concentration ratio for [51Cr]EDTA further to 1.15 +/- 0.02 and increased glomerular filtration rate. Moreover, by performing the studies at low temperatures (8 degrees C) in the presence of sodium nitroprusside and furosemide it was possible to achieve low and stable albumin fractional clearance values close to those prevailing in vivo. Thus, the described technique, allowing simultaneous perfusions of both kidneys with different solutions, pressures and flows, seem to be well suited for studies of macromolecular transport across glomerular capillaries.
Collapse
Affiliation(s)
- E Johnsson
- Department of Physiology, University of Göteborg, Sweden
| | | |
Collapse
|
27
|
Glomerular function, basic knowledge. Clin Chem Lab Med 1992. [DOI: 10.1515/cclm.1992.30.10.627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
28
|
Jonas E, Alt JM, Schurek HJ, Brunkhorst R, Stolte H. Study on the renal handling of sex dependent proteins in male rats studied by micropuncture techniques and by the isolated perfused rat kidney. Pflugers Arch 1989; 414:634-9. [PMID: 2478957 DOI: 10.1007/bf00582128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The separation of sex dependent urinary proteins of the rat (SDP) by micro-disc electrophoresis results in at least eight well defined protein bands with differing molecular weights. The hepatic origin of a sex dependent urinary protein, named alpha 2u-globulin, has been demonstrated before by other authors applying immunological methods. In the present study, it could been shown that SDP circulate in the plasma at a concentration of 23.8 mg/l. The origin of those protein bands which appear typically upon electrophoresis was still under dispute because they could not been demonstrated in proximal tubular fluid. The present study confirms the extrarenal source of SDP and suggests identity with alpha 2u-globulin. The attempt to track down SDP from plasma to excreted urine demonstrated that, in contrast to proximal fluid, samples from nephron parts distal to the loop of Henle contain large amounts of SDP. An isolated kidney model was used to determine the sieving coefficient and tubular reabsorption of SDP, obtained from male rat urine. We have found a correlation between the sieving coefficient and the molecular weight of SDP. The sieving coefficient ranged from 0.375 to 0.834. The tubular reabsorption which has been determined with an isolated kidney perfused with albumin and erythrocytes also showed variation with regard to molecular weight and was 61.7%, on average.
Collapse
Affiliation(s)
- E Jonas
- Department of Internal Medicine, Medical School Hannover, Federal Republic of Germany
| | | | | | | | | |
Collapse
|
29
|
Abstract
The ultrafiltration properties of isolated glomerular basement membrane were studied in vitro by forming membrane fragments into thin films for use as ultrafiltration membranes. The filtration properties of the films were examined using cytochrome c, myoglobin, lysozyme, ovalbumin, lactoglobulin, and serum albumin. The films behaved as compressible filters showing size-dependent rejection of the proteins. The behavior of the films was modelled using the fiber matrix hypothesis which gave good prediction of film behavior. The membrane behaved as a random fiber matrix composed of fibers of 0.8-1.0 nm in radius.
Collapse
Affiliation(s)
- G B Robinson
- Department of Biochemistry, Oxford, United Kingdom
| | | |
Collapse
|
30
|
Migasena P, Areekul S. Capillary permeability function in malaria. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 1987; 81:549-60. [PMID: 3331244 DOI: 10.1080/00034983.1987.11812156] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- P Migasena
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | |
Collapse
|
31
|
Boyce NW, Holdsworth SR. Direct antiGBM antibody induced alterations in glomerular permselectivity. Kidney Int 1986; 30:666-72. [PMID: 3537458 DOI: 10.1038/ki.1986.238] [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: 01/06/2023]
Abstract
The glomerular fixation of anti-glomerular-basement-membrane (antiGBM) antibody is associated with complement activation, neutrophil accumulation, and renal injury. This injury manifests both as an increase in the rate of urinary protein excretion and altered renal hemodynamic characteristics. We have utilized an isolated perfused kidney system (IPK) to assess the capacity of antiGBM antibody to alter glomerular permselectivity in the absence of both glomerular complement activation and neutrophil infiltration. Control perfusions with Krebs-Henseleit buffered 5% albumin solutions containing normal sheep globulin had a protein excretion rate of 0.223 +/- 0.044 mg/min (mean +/- SEM). Assessment of glomerular permselectivity using fractional dextran clearances demonstrated an intact negative charge barrier in control preparations. AntiGBM antibody bound in a dose related fashion to the kidney and was localized to the glomerular basement membrane on immunofluorescence. Antibody induced a significant increase in mean protein excretion (2.009 +/- 0.681 mg/min, P less than 0.01) in association with a loss of the glomerular filter's negative charge barrier. These IPK studies demonstrate that antiGBM antibody can itself produce proteinuria, in association with loss of the glomerular capillary negative charge barrier, in the absence of all circulating humoral and cellular inflammatory mediator systems.
Collapse
|
32
|
Abstract
Increased glomerular permeability to protein occurs during isolated rat kidney perfusion in the absence of ultrastructural changes in the glomerular capillary wall. The increase is greater with age, varies with strain and is reduced by amino acid supplementation of the perfusate. Glomerular permeability to protein is thus perceptibly influenced by non-pathogenic stimuli. Such phenomena, in turn, may influence glomerular function in disease or after experimental damage.
Collapse
|
33
|
Cybulsky AV, Rennke HG, Feintzeig ID, Salant DJ. Complement-induced glomerular epithelial cell injury. Role of the membrane attack complex in rat membranous nephropathy. J Clin Invest 1986; 77:1096-107. [PMID: 3514672 PMCID: PMC424443 DOI: 10.1172/jci112408] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
In passive Heymann nephritis (PHN) in rats, antibody (anti-Fx1A) reacts in situ with a glomerular epithelial antigen and induces complement (C)-mediated cell-independent proteinuria. To assess the role of the membrane attack complex (MAC), we determined the need for C8 in the pathogenesis of proteinuria in an autologous-phase model of PHN. Isolated rat kidneys, containing nonnephritogenic, non-C-fixing gamma 2 sheep anti-Fx1A (planted antigen), when perfused in vitro with C-fixing guinea pig anti-sheep IgG and a source of C (fresh human plasma 50% vol/vol in buffer containing bovine serum albumin), developed marked proteinuria after 20 min (0.58 +/- 0.08 mg/min X g, n = 8) that increased further to 3.20 +/- 0.93 mg/min X g after 80 min. In contrast, identical kidneys perfused with antibody and heat-inactivated or C8-deficient human plasma and normal kidneys perfused with antibody and fresh plasma excreted only 0.27 +/- 0.03 (n = 6), 0.27 +/- 0.04 (n = 5), and 0.40 +/- 0.05 mg/min X g (n = 6) after 20 min, and 0.13 +/- 0.02, 0.22 +/- 0.03, and 0.32 +/- 0.05 mg/min X g after 80 min, respectively. When C8-deficient plasma was reconstituted with sources of C8 (n = 3), proteinuria was restored to the level observed with fresh normal plasma. Differences in protein excretion could not be explained by quantitative differences in glomerular antigen or antibody content. Extensive ultrastructural damage to glomerular visceral epithelial cells was exclusively seen in antigen-containing kidneys perfused with antibody and C8-replete plasma. Thus, glomerular injury in this model results from an antigen-specific, antibody-directed, C8-dependent reaction involving assembly of the MAC. The ultrastructural findings argue in favor of MAC-induced cytotoxicity of the glomerular visceral epithelial cells.
Collapse
|
34
|
Abstract
Alterations in glomerular permeability were studied in Adriamycin-induced proteinuria in rats by measuring fractional clearances (C/GFR) of uncharged labeled dextrans of varying molecular radii (ae) and of anionic, native, and cationic horseradish peroxidases (HRP) in experimental and control animals. Experimental animals were studied between days 14 and 55 after a single intravenous dose of Adriamycin (doxorubicin), 7.5 mg/kg. Mean proteinuria in the experimental animals was 98 mg/24 hr. Glomerular morphology showed few changes except for epithelial cell swelling, vacuolization, and foot process obliteration, and a significant reduction of glomerular colloidal iron staining. Polyethyleneimine staining revealed a similar distribution of anionic sites in the laminae rarae interna and externa in proteinuric rats as compared with controls. Inulin clearances revealed reduction in GFR and RPF of 20 and 15%, respectively. Dextran C/GFR values showed in experimental animals a size defect for molecules with an ae exceeding 40 A, with a four- to fivefold increase over the values found in control animals for dextrans with ae of 58 and 60 A. The peroxidase clearances showed a slight increase in C/GFR of anionic HRP in experimental animals, as could be expected on the basis of the sieving defect, whereas the C/GFR values for native and cationic HRP were virtually unchanged, indicating an intact functional charge barrier in the proteinuric animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
|
35
|
Brink HM, Moons WM, Slegers JF. Glomerular filtration in the isolated perfused kidney. I. Sieving of macromolecules. Pflugers Arch 1983; 397:42-7. [PMID: 6191276 DOI: 10.1007/bf00585166] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The permeability of the glomerular capillary wall to neutral macromolecules was studied in isolated perfused rat kidneys. Pluronic F108 (BASF, Wyandotte, MI, USA), a polyoxyethylene-polyoxypropylene block copolymer of mol weight approximately 14,000, was used as plasma expander. Pore theory was applied to the fractional clearances of Pluronic F108 and dextran (mol weight 19,400) molecules measured both as a function of glomerular filtration rate. Using the pore model of Verniory et al. [30] the effective pore radius (60.9 A) and the ratio of total pore area and pore length (4.0 cm/nephron) were estimated, and a hydraulic permeability coefficient KF (0.036 nl/s . mm Hg) was calculated. There was no significant difference between the fractional clearance of Pluronic F108 obtained with different Pluronic F108 concentrations over the range 15-35 g/l, hence with largely differing osmotic pressures. It was concluded that the sieving properties of the glomerular membrane of the isolated perfused rat kidney are not detectably different from those in the intact rat, at least in the case of uncharged macromolecules.
Collapse
|
36
|
|
37
|
|
38
|
Schlatter E, Schurek HJ, Zick R. Renal handling of homologous and heterologous insulin in the isolated perfused rat kidney. Pflugers Arch 1982; 393:227-31. [PMID: 7048243 DOI: 10.1007/bf00584074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. Renal handling of pig- and rat-insulin was studied in the isolated perfused rat kidney. 2. Metabolic clearance rates of both pig- and rat-insulin exceeded GFR. 3. Peritubular uptake of pig-insulin accounted for 13% of rat-insulin for 31% of the total metabolic clearance. 4. The nonfiltering kidney does not remove insulin from the peritubular circulation. 5. Metabolic clearance rates of pig- and rat-insulin are directly related to GFR. 6. The filtration process seems to be necessary for the uptake of insulin at the peritubular site.
Collapse
|
39
|
|
40
|
|
41
|
Schurek HJ, Schlatter E, Meier W, Zick R, Dorn G, Hehrmann R, Stolte H. Renal handling of polypeptide hormones (insulin, C-peptide, h-PTH) as studied in the isolated perfused rat kidney. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1980; 12:237-42. [PMID: 6995196 DOI: 10.1016/0020-711x(80)90077-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
|
42
|
Stolte H, Alt J, Schurek HJ. [Experimental and clinical studies on the differential diagnosis of proteinuria]. KLINISCHE WOCHENSCHRIFT 1979; 57:1069-79. [PMID: 392181 DOI: 10.1007/bf01479993] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|