Unaltered size selectivity of the glomerular filtration barrier in caveolin-1 knockout mice

2009 ◽  
Vol 297 (2) ◽  
pp. F257-F262 ◽  
Author(s):  
Gustaf Grände ◽  
Catarina Rippe ◽  
Anna Rippe ◽  
Awahan Rahman ◽  
Karl Swärd ◽  
...  
Keyword(s):  
Glomerular Filtration ◽  
High Performance ◽  
Microvascular Permeability ◽  
Size Exclusion ◽  
No Production ◽  
Glomerular Permeability ◽  
Caveolin 1 ◽  
Filtration Barrier ◽  
Transcapillary Escape Rate ◽  
Exclusion Chromatography

The transfer of albumin from blood to tissue has been found to be increased in caveolin-1 knockout (KO) mice. This has been considered to reflect increased microvascular permeability, conceivably caused by an increased endothelial production of nitric oxide (NO) in these mice. To investigate whether such an increase in NO production would also affect glomerular barrier characteristics, the glomerular sieving coefficients (θ) to neutral FITC-Ficoll 70/400 (molecular radius 13–90 Å) were determined in caveolin-1 KO mice vs. their wild-type counterparts. The θ for Ficoll were assessed using high-performance size-exclusion chromatography on blood and urine samples. Furthermore, the transcapillary escape rate (TER) of 125I-labeled albumin and plasma volume (PV) were determined in both types of mice. The kidney expressed low levels of caveolin-1 compared with the lung and bladder, but immunofluorescence associated with vascular structures was evident. Staining was lost in the caveolin-1 KO kidney, as was caveolin-1 expression in the lung and bladder. Despite an increase in the glomerular filtration rate in caveolin-1 KO mice (0.23 ± 0.04 vs. 0.10 ± 0.02 ml/min; both n = 7; P < 0.05), the glomerular Ficoll sieving curves were nearly identical. Furthermore, caveolin-1 KO mice showed an increased PV (6.59 ± 0.42 vs. 5.18 ± 0.13 ml/100 g; P < 0.01) but only a tendency toward an increased TER (14.69 ± 1.59 vs. 11.62 ± 1.62%/h; not significant). It is concluded that in caveolin-1 KO mice the glomerular permeability was not increased, despite the presence of glomerular hyperfiltration. The present data are in line with the concept that the increased transvascular albumin leakage previously found in mice lacking caveolin-1 may be due to an elevation in systemic microvascular pressure due to precapillary vasodilatation, rather than being a consequence of increased microvascular permeability per se.

Loss of size selectivity of the glomerular filtration barrier in rats following laparotomy and muscle trauma

2009 ◽  
Vol 297 (3) ◽  
pp. F577-F582 ◽  
Author(s):  
Josefin Axelsson ◽  
Irma Mahmutovic ◽  
Anna Rippe ◽  
Bengt Rippe
Keyword(s):  
Glomerular Filtration ◽  
High Performance ◽  
Size Exclusion ◽  
Blunt Injury ◽  
Abdominal Muscles ◽  
Glomerular Filtration Barrier ◽  
Glomerular Permeability ◽  
Filtration Barrier ◽  
Muscle Trauma ◽  
Exclusion Chromatography

Posttraumatic microalbuminuria may be caused by either charge- or size-selective alterations in the glomerular filtration barrier, or both, and/or to a reduction in proximal tubular protein reabsorption. This study was performed to elucidate the pathophysiology of the increases in glomerular permeability occurring in rats exposed to a laparotomy or to a laparotomy and muscle trauma. In anesthetized Wistar rats (250–280 g), the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Rats were exposed to trauma by a laparotomy (L; n = 8), or by a combination of L and muscle trauma (MT; L+MT) induced by topical blunt injury of the abdominal muscles bilaterally. After L, muscles were crushed using hemostatic forceps at either 2 × 2 sites (“small” MT; n = 9), or at 2 × 5 sites (“large” MT; n = 9). Sham groups ( n = 16), not exposed to a laparotomy, were used as controls. The glomerular sieving coefficients (θ) to polydisperse FITC-Ficoll-70/400 (molecular radius 13–80 Å) were determined at 5 or 60 min after L and L+MT, respectively, from plasma and urine samples, and analyzed by high-performance size-exclusion chromatography. A tissue-uptake technique was used to assess θ for 125I-labeled serum albumin. L, with or without MT, increased θ for Ficoll55–80Å and albumin rapidly and markedly. θ-Ficoll70Å thus increased approximately threefold, and θ for albumin significantly, for all trauma groups. According to the “two-pore model” of glomerular permeability, these changes mainly reflect an increase in the number of large pores in the glomerular filter without any primary changes in the charge-selective properties of the filter.

Reduced diffusion of charge-modified, conformationally intact anionic Ficoll relative to neutral Ficoll across the rat glomerular filtration barrier in vivo

2011 ◽  
Vol 301 (4) ◽  
pp. F708-F712 ◽  
Author(s):  
Josefin Axelsson ◽  
Kristinn Sverrisson ◽  
Anna Rippe ◽  
William Fissell ◽  
Bengt Rippe
Keyword(s):  
Glomerular Filtration ◽  
High Performance ◽  
Size Exclusion ◽  
Glomerular Filtration Barrier ◽  
Glomerular Permeability ◽  
Charge Effects ◽  
Filtration Barrier ◽  
A Charge

The glomerular filtration barrier (GFB) is commonly conceived as a negatively charged sieve to proteins. Recent studies, however, indicate that glomerular charge effects are small for anionic, carboxymethylated (CM) dextran vs. neutral dextran. Furthermore, two studies assessing the glomerular sieving coefficients (θ) for negative CM-Ficoll vs. native Ficoll have demonstrated an increased glomerular permeability for CM-Ficoll (Asgeirsson D, Venturoli D, Rippe B, Rippe C. Am J Physiol Renal Physiol 291: F1083–F1089, 2006; Guimarães M, Nikolovski J, Pratt L, Greive K, Comper W. Am Physiol Renal Physiol 285: F1118–F1124, 2003.). The CM-Ficoll used, however, showed a larger Stokes-Einstein radius ( ae) than neutral Ficoll, and it was proposed that the introduction of negative charges in the Ficoll molecule had made it more flexible and permeable. Recently, a negative FITC-labeled CM-Ficoll (CMI-Ficoll) was produced with a conformation identical to that of neutral FITC-Ficoll. Using these probes, we determined their θ:s in anesthetized Wistar rats (259 ± 2.5 g). After blood access had been achieved, the left ureter was cannulated for urine sampling. Either polysaccharide was infused (iv) together with a filtration marker, and urine and plasma were collected. Assessment of θ FITC-Ficoll was achieved by high-performance size-exclusion chromatography (HPSEC). CMI-Ficoll and native Ficoll had identical elugrams on the HPSEC. Diffusion of anionic Ficoll was significantly reduced compared with that of neutral Ficoll across the GFB for molecules of ae ∼20–35 Å, while there were no charge effects for Ficoll of ae = 35–80 Å. The data are consistent with a charge effect present in “small pores,” but not in “large pores,” of the GFB and mimicked those obtained for anionic membranes in vitro for the same probes.

Effects of early endotoxemia and dextran-induced anaphylaxis on the size selectivity of the glomerular filtration barrier in rats

2009 ◽  
Vol 296 (2) ◽  
pp. F242-F248 ◽  
Author(s):  
Josefin Axelsson ◽  
Anna Rippe ◽  
Daniele Venturoli ◽  
Per Swärd ◽  
Bengt Rippe
Keyword(s):  
Fluorescein Isothiocyanate ◽  
Size Exclusion ◽  
Glomerular Permeability ◽  
Left Ureter ◽  
Filtration Barrier ◽  
Dextran 70 ◽  
Exclusion Chromatography ◽  
Plasma And Urine Samples ◽  
Permeability Alterations ◽  
Molecular Radius

This study was performed to investigate the glomerular permeability alterations responsible for the microalbuminuria occurring in endotoxemia and during anaphylactic shock. In anesthetized Wistar rats, the left ureter was catheterized for urine collection while, simultaneously, blood access was achieved. Endotoxemia was induced by lipopolysaccharide (LPS) from Escherichia coli, and glomerular permeability was assessed at 60 and 90 ( n = 7) and 120 ( n = 7) min. Anaphylaxis was induced by a bolus dose of Dextran-70, and glomerular permeability assessed at 5 min ( n = 8) and 40 min ( n = 9). Sham animals were followed for either 5 or 120 min. The glomerular sieving coefficients (θ) to fluorescein isothiocyanate-Ficoll (70/400) were determined from plasma and urine samples and assessed using size-exclusion chromatography (HPLC). After start of the LPS infusion (2 h), but not at 60 or 90 min, θ for Ficoll70Å had increased markedly [from 2.91 × 10−5 ± 6.33 × 10−6 to 7.78 × 10−5 ± 6.21 × 10−6 ( P < 0.001)]. In anaphylaxis, there was a large increase in θ for Ficolls >60 Å in molecular radius already at 5 min, but the glomerular permeability was completely restored at 40 min. In conclusion, there was a transient, immediate increment of glomerular permeability in dextran-induced anaphylaxis, which was completely reversible within 40 min. By contrast, endotoxemia caused an increase in glomerular permeability that was manifest first after 2 h. In both cases, θ to large Ficoll molecules were markedly increased, reflecting an increase in the number of large pores in the glomerular filter.

Extracellular fetal hemoglobin induces increases in glomerular permeability: inhibition with α1-microglobulin and tempol

2014 ◽  
Vol 306 (4) ◽  
pp. F442-F448 ◽  
Author(s):  
Kristinn Sverrisson ◽  
Josefin Axelsson ◽  
Anna Rippe ◽  
Magnus Gram ◽  
Bo Åkerström ◽  
...  
Keyword(s):  
High Performance ◽  
Fetal Hemoglobin ◽  
Size Exclusion ◽  
Radical Scavenger ◽  
Glomerular Permeability ◽  
Exclusion Chromatography ◽  
Ros Scavenger ◽  
Adult Hemoglobin ◽  
Heme Binding Protein

Extracellular fetal hemoglobin (HbF) and adult hemoglobin (HbA) are proinflammatory and generate ROS. Increased plasma levels of extracellular HbF have recently been reported to occur in early preeclampsia. α1-Microglobulin (A1M) is a physiological heme-binding protein and radical scavenger that has been shown to counteract vascular permeability increases induced by HbA in the perfused placenta. The present study was performed to investigate whether HbF and HbA will increase glomerular permeability in vivo and to test whether A1M and tempol, a ROS scavenger, can prevent their effects. Anesthetized Wistar rats were continuously infused intravenously with either HbA, HbF, or cyano-inactivated HbF together with FITC-Ficoll-70/400, inulin, and 51Cr-labeled EDTA for 2 h. Plasma samples and urine samples (left ureter) were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients for Ficoll of radius 10–80 Å. In separate experiments, A1M or tempol was given before and during Hb infusions. Extracellular HbF caused rapid, transient increases in glomerular permeability to large Ficoll molecules (50–80Å), contrary to the effects of HbA and cyano-inactivated HbF. For HbF, glomerular sieving coefficients for Ficoll of radius 60Å increased from 3.85 ± 0.85 × 10−5 to 2.60 ± 0.96 × 10−4 at 15 min, changes that were abrogated by tempol and reduced by A1M. In conclusion, our data demonstrate that extracellular HbF, infused systemically, can acutely increase glomerular permeability through inducing oxidative stress.

Transient and sustained increases in glomerular permeability following ANP infusion in rats

2011 ◽  
Vol 300 (1) ◽  
pp. F24-F30 ◽  
Author(s):  
Josefin Axelsson ◽  
Anna Rippe ◽  
Bengt Rippe
Keyword(s):  
High Performance ◽  
Initial Permeability ◽  
Size Exclusion ◽  
Glomerular Permeability ◽  
Exclusion Chromatography ◽  
Plasma And Urine Samples ◽  
Reversible Permeability ◽  
Molecular Radius ◽  
Sustained Increase

The present study was performed to investigate the effects of systemic atrial natriuretic peptide (ANP) infusion on the glomerular permeability to macromolecules in rats. In anesthetized Wistar rats (250–280 g), the left urether was cannulated for urine collection while simultaneously blood access was achieved. Rats were continuously infused intravenously with ANP [30 ng·kg−1·min−1 (Lo-ANP; n = 8) or 800 ng·kg−1·min−1 (Hi-ANP; n = 10)] or 0.9% NaCl (SHAM; n = 16), respectively, and with polydisperse FITC-Ficoll-70/400 (molecular radius 13–90 Å) and 51Cr-EDTA for 2 h. Plasma and urine samples were taken at 5, 15, 30, 60, and 120 min of ANP infusion and analyzed by high-performance size-exclusion chromatography (HPLC) for determination of glomerular sieving coefficients (θ) for Ficoll. GFR was also assessed (51Cr-EDTA). In Hi-ANP, there was a rapid (within 5 min), but bimodal, increase in glomerular permeability. θ to high-molecular-weight Ficoll thus reached a maximum at 15 min, after which θ returned to near control at 30 min, to again increase moderately at 60 and 120 min. In Lo-ANP, there was also a rapid, reversible increase in glomerular θ, returning to near control at 30 min, followed by just a tendency of a sustained increase in permeability, but with a significant increase in “large-pore” radius. In conclusion, in Hi-ANP there was a rapid increase in glomerular permeability, with an early, partly reversible permeability peak, followed by a (moderate) sustained increase in permeability. In Lo-ANP animals, only the initial permeability peak was evident. In both Lo-ANP and Hi-ANP, the glomerular sieving pattern observed was found to mainly reflect an increase in the number and radius of large pores in the glomerular filter.

scholarly journals Acute reactive oxygen species (ROS)-dependent effects of IL-1β, TNF-α, and IL-6 on the glomerular filtration barrier (GFB) in vivo

2015 ◽  
Vol 309 (9) ◽  
pp. F800-F806 ◽  
Author(s):  
Kristinn Sverrisson ◽  
Josefin Axelsson ◽  
Anna Rippe ◽  
Daniel Asgeirsson ◽  
Bengt Rippe
Keyword(s):  
Reactive Oxygen Species ◽  
Glomerular Filtration ◽  
Reactive Oxygen ◽  
Size Exclusion ◽  
Oxygen Species ◽  
Glomerular Filtration Barrier ◽  
Glomerular Permeability ◽  
Filtration Barrier ◽  
Tnf Α ◽  
Superoxide Scavenger

This study was performed to investigate the immediate actions of the proinflammatory cytokines IL-1β, TNF-α, and IL-6 on the permeability of the glomerular filtration barrier (GFB) in rats and to test whether these actions are dependent upon the release of reactive oxygen species (ROS). In anesthetized rats, blood access was achieved and the left ureter was cannulated for urine collection. Rats were continuously infused intravenously with either IL-1β (0.4 and 2 μg·kg−1·h−1), TNF-α (0.4 and 2 μg·kg−1·h−1), or IL-6 (4 and 8 μg·kg−1·h−1), together with polydisperse FITC-Ficoll-70/400 and inulin for 1 h. Plasma and urine samples were analyzed by high performance size exclusion chromatography (HPSEC) for determination of glomerular sieving coefficients (θ). The glomerular filtration rate (GFR) was also assessed (51Cr-EDTA). In separate experiments, the superoxide scavenger tempol (30 mg·kg−1·h−1) was given before and during cytokine infusions. IL-1β and TNF-α caused rapid, partly reversible increases in glomerular permeability to large molecules (Ficoll50–80Å), peaking at 5–30 min, while IL-6 caused a more gradual increase in permeability, leveling off at 60 min. Tempol almost completely abrogated the glomerular permeability effects of the cytokines infused. In conclusion IL-1β, TNF-α, and IL-6, when infused systemically, caused immediate and partly reversible increases in glomerular permeability, which could be inhibited by the superoxide scavenger tempol, suggesting an important role of ROS in acute cytokine-induced permeability changes in the GFB.

Dynamic, size-selective effects of protamine sulfate and hyaluronidase on the rat glomerular filtration barrier in vivo

2014 ◽  
Vol 307 (10) ◽  
pp. F1136-F1143 ◽  
Author(s):  
Kristinn Sverrisson ◽  
Josefin Axelsson ◽  
Anna Rippe ◽  
Daniel Asgeirsson ◽  
Bengt Rippe
Keyword(s):  
Glomerular Filtration ◽  
High Performance ◽  
Protamine Sulfate ◽  
Size Exclusion ◽  
Endothelial Glycocalyx ◽  
Glomerular Filtration Barrier ◽  
Filtration Barrier ◽  
Charge Selectivity ◽  
The Impact

The proteinuric actions of protamine sulfate (PS) have classically been, at least partly, attributed to alterations of the negatively charged glomerular endothelial glycocalyx. To investigate whether the charge-selective properties of the glomerular filtration barrier (GFB) would be altered by PS, we assessed the glomerular sieving of conventional, uncharged, polydispersed Ficoll (n-Ficoll) compared with charge modified, conformationally intact, anionic (carboxymethylated) Ficoll (a-Ficoll) before and after systemic infusions of PS in rats. For comparison, we also investigated the impact of hyaluronidase (hyase), which partially degrades the glycocalyx, on GFB permeability. In anaesthetized Wistar rats, blood access was achieved, and the left ureter was cannulated for urine collection. Rats were infused with either n-Ficoll or a-Ficoll before and during systemic infusions with either PS or hyase. Plasma and urine samples were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients (θ) for Ficoll (radius 10–80 Å). The GFB showed a significant glomerular charge selectivity for Ficoll molecules of radius 20–35 Å. PS and hyase infusions reversibly increased θ for large Ficoll molecules (Ficoll molecules of radius 50–80 Å). Thus, for PS, θ for a-Ficoll molecules of radius 70 Å increased from 2.47 × 10−5± 1.1−5to 7.25 × 10−5± 1.1−5( P < 0.05) at 15 min. For hyase, changes in a-Ficoll molecules of radius 50–80 Å were, however, not statistically significant. Neither PS nor hyase had any effect on θ for n-Ficoll molecules of radius 20–45 Å or a-Ficoll molecules of radius 20–45 Å. It is concluded that systemically administered PS and hyase in moderate doses dynamically decreased the size selectivity of the rat GFB without affecting its charge selective properties.

Rapid, dynamic changes in glomerular permeability to macromolecules during systemic angiotensin II (ANG II) infusion in rats

2012 ◽  
Vol 303 (6) ◽  
pp. F790-F799 ◽  
Author(s):  
Josefin Axelsson ◽  
Anna Rippe ◽  
Carl M. Öberg ◽  
Bengt Rippe
Keyword(s):  
Angiotensin Ii ◽  
High Performance ◽  
Size Exclusion ◽  
Ang Ii ◽  
Glomerular Permeability ◽  
Small Pore ◽  
Exclusion Chromatography ◽  
Plasma And Urine Samples ◽  
Log Normal

The actions of systemic angiotensin II (ANG II) infusions on glomerular permeability were investigated in vivo. In anesthetized Wistar rats (250–280 g), the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Rats were continuously infused intravenously with either of four doses of ANG II ranging from 16 ng·kg−1·min−1 (Lo-ANG II) to 1.82 μg·kg−1·min−1 (Hi-ANG II), and in separate experiments with aldosterone (Aldo; 0.22 mg·kg−1·min−1), or with the calcium channel blocker nimodipine, or with the Aldo antagonist spironolactone together with a high ANG II dose (910 ng·kg−1·min−1; Hi-Int-ANG II), respectively, and with polydisperse FITC-Ficoll-70/400 (molecular radius 10–80 Å) and 51Cr-EDTA. Plasma and urine samples were taken at 5, 15, 30, 60, and 120 min and analyzed by high performance size-exclusion chromatography for determination of glomerular sieving coefficients (θ) to Ficoll. Mean arterial pressure (MAP) and glomerular filtration rate (GFR) were also assessed. For ANG II, there was a rapid, marked, partly reversible increase in glomerular permeability (θ) for Ficoll molecules >34 Å in radius, peaking at 5–15 min, which was completely abrogated by the ANG II blocker candesartan but not affected by spironolactone at 15 and 30 min. For Aldo, the response was similar to that found for the lowest dose of ANG II infused. For the two highest ANG II doses given (Hi-Int-ANG II and Hi-ANG II), GFR decreased transiently, concomitant with marked, sustained increases in MAP. Nimodipine completely blocked all hemodynamic ANG II actions, whereas the glomerular permeability response remained unchanged. Thus ANG II directly increased glomerular permeability independently of its hemodynamic actions and largely independently of the concomitant Aldo response. The ANG II-induced increases in glomerular permeability were, according to a two-pore and a log-normal distributed pore model, compatible with an increased number of “large pores” in the glomerular filter, and, to some extent, an increase in the dispersity of the small-pore radius.

Size and charge selectivity of the glomerular filter in early experimental diabetes in rats

2007 ◽  
Vol 293 (5) ◽  
pp. F1533-F1538 ◽  
Author(s):  
Catarina Rippe ◽  
Anna Rippe ◽  
Ole Torffvit ◽  
Bengt Rippe
Keyword(s):  
Glomerular Filtration ◽  
Experimental Diabetes ◽  
Renal Plasma Flow ◽  
Size Exclusion ◽  
Glomerular Filtration Barrier ◽  
Functional Changes ◽  
Filtration Barrier ◽  
Charge Selectivity ◽  
Exclusion Chromatography ◽  
Proximal Tubular

Microalbuminuria is an early sign of diabetic nephropathy. The aim of the present study was to investigate whether the changes of the glomerular filtration barrier in early experimental diabetes are due to size- or charge-selective alterations. Wistar rats, made diabetic by streptozotocin (STZ) and having their blood glucose maintained at ∼20 mM for 3 or 9 wk, were compared with age-matched controls. Glomerular clearances of native albumin (Cl-HSA) and neutralized albumin (Cl-nHSA) were assessed using a renal uptake technique. Glomerular filtration rate and renal plasma flow were assessed using 51Cr-EDTA and [125I]iodohippurate, respectively. In a separate set of animals, diabetic for 9 wk, and in controls, glomerular sieving coefficients (θ) for neutral FITC-Ficoll (molecular radius: 15–90 Å) were assessed using size exclusion chromatography. At 3 wk of diabetes, Cl-HSA and Cl-nHSA remained unchanged, indicating no alteration in either size or charge selectivity. By contrast, at 9 wk of diabetes, there was a twofold increase of Cl-HSA, whereas Cl-nHSA remained largely unchanged, at first suggesting a glomerular charge defect. However, according to a two-pore model, the number of large pores, assessed from both Ficoll and Cl-HSA, increased twofold. In addition, a small reduction in proximal tubular reabsorption was observed at 3 wk, which was further reduced at 9 wk. In conclusion, no functional changes were observed in the glomerular filtration barrier at 3 wk of STZ-induced diabetes, whereas at 9 wk there was a decrease in size selectivity due to an increased number of large glomerular pores.

scholarly journals Nitric oxide synthase inhibition causes acute increases in glomerular permeability in vivo, dependent upon reactive oxygen species

2016 ◽  
Vol 311 (5) ◽  
pp. F984-F990 ◽  
Author(s):  
Julia Dolinina ◽  
Kristinn Sverrisson ◽  
Anna Rippe ◽  
Carl M. Öberg ◽  
Bengt Rippe
Keyword(s):  
Nitric Oxide ◽  
Reactive Oxygen Species ◽  
High Performance ◽  
Reactive Oxygen ◽  
Size Exclusion ◽  
Oxygen Species ◽  
Glomerular Permeability ◽  
No Donor ◽  
Filtration Barrier

There is increasing evidence that the permeability of the glomerular filtration barrier (GFB) is partly regulated by a balance between the bioavailability of nitric oxide (NO) and that of reactive oxygen species (ROS). It has been postulated that normal or moderately elevated NO levels protect the GFB from permeability increases, whereas ROS, through reducing the bioavailability of NO, have the opposite effect. We tested the tentative antagonism between NO and ROS on glomerular permeability in anaesthetized Wistar rats, in which the left ureter was cannulated for urine collection while simultaneously blood access was achieved. Rats were systemically infused with either l-NAME or l-NAME together with the superoxide scavenger Tempol, or together with l-arginine or the NO-donor DEA-NONOate, or the cGMP agonist 8-bromo-cGMP. To measure glomerular sieving coefficients (theta, θ) to Ficoll, rats were infused with FITC-Ficoll 70/400 (mol/radius 10–80 Å). Plasma and urine samples were analyzed by high-performance size-exclusion chromatography (HPSEC) for determination of θ for Ficoll repeatedly during up to 2 h. l-NAME increased θ for Ficoll70Å from 2.27 ± 1.30 × 10−5 to 8.46 ± 2.06 × 10−5 ( n = 6, P < 0.001) in 15 min. Tempol abrogated these increases in glomerular permeability and an inhibition was also observed with l-arginine and with 8-bromo-cGMP. In conclusion, acute NO synthase inhibition in vivo by l-NAME caused rapid increases in glomerular permeability, which could be reversed by either an ROS antagonist or by activating the guanylyl cyclase-cGMP pathway. The data strongly suggest a protective effect of NO in maintaining normal glomerular permeability in vivo.

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