Effects of rosuvastatin on glomerular capillary size-selectivity function in rats with renal mass ablation

BACKGROUND

Evidence is accumulating that statins can reduce proteinuria and disease progression in chronic kidney disease. However, some safety concerns have been recently raised on the use of these agents, mainly due to transient episodes of proteinuria observed in patients receiving high doses of rosuvastatin.

METHODS

We investigated in rats with renal mass ablation (RMR) whether rosuvastatin (5 or 20 mg/day) worsens proteinuria as compared to untreated RMR animals. Moreover, we also examined whether rosuvastatin-induced changes in proteinuria would be due to the effect of the drug on permselective properties of glomerular capillary barrier, measured by the fractional clearance of graded-size Ficoll molecules and/or by proximal tubular mechanisms, by assessing urinary excretion of beta(2)-microglobulin.

RESULTS

RMR rats given rosuvastatin for 28 days showed a progressive increase in proteinuria, with values numerically but not significantly higher than those in RMR animals given the vehicle. In RMR rats, rosuvastatin did not significantly affect the fractional clearance of Ficoll as compared to vehicle-treated RMR animals. A significant correlation was found between urinary protein and beta(2)-microglobulin excretion in rats treated with rosuvastatin (r = 0.936, p < 0.001), but not in those given vehicle. Renal function, glomerular and tubulointerstitial injury were comparable in rosuvastatin-treated and untreated RMR rats at the end of the 28-day follow-up.

CONCLUSION

In rats with RMR, rosuvastatin mildly enhances urinary protein excretion rate. This, however, was not the result of further changes in the size-permselective function of glomerular capillary barrier.

Vitamin D, insulin resistance, and renal disease

Chonchol and Scragg report the results of a population study on levels of 25-hydroxyvitamin D in patients with renal dysfunction. They demonstrate that these patients do not show vitamin D deficiency unless renal function is severely affected (GFR<29 mL/min/1.73m2), while vitamin D and renal function loss are independently associated with insulin resistance. These data provide more solid evidence than previous available studies on small patient groups, and pose new questions about the mechanisms responsible for progressive renal disease as well as potential effects of vitamin D supplementation.

ACE inhibition reduces glomerulosclerosis and regenerates glomerular tissue in a model of progressive renal disease

Today angiotensin II inhibition is primarily used to slow the rate of progression of kidney diseases. There is evidence that these therapies can induce a partial regression of glomerular lesions. However, we do not know yet the extent of sclerotic lesion regression and whether new glomerular tissue is formed to help support the renal function. We used male Munich Wistar Fromter (MWF) rats, an experimental model for progressive kidney disease, to quantify kidney structural lesions upon angiotensin-converting enzyme (ACE) inhibition therapy. Animals were studied at 50 weeks of age, when renal function and structure are severely altered, and after a 10-week observation period, without or with treatment with lisinopril (80 mg/l in drinking water). A group of untreated Wistar rats was used as controls. With age, proteinuria, and serum creatinine worsen, but lisinopril almost normalized proteinuria and stabilized serum creatinine. Serial section analysis of whole glomerular tufts showed that at baseline, glomerulosclerosis affected the entire glomerular population, and that these changes further increased with age. Lisinopril significantly reduced incidence and extent of glomerulosclerosis, with the presence of glomerular tufts not affected by sclerosis (23% of glomeruli). Glomerular volume was not significantly affected by treatment, and glomerular mass spared from sclerosis increased from 46.9 to 65.5% upon treatment, indicating consistent regeneration of glomerular tissue. Lisinopril normalized baseline glomerular transforming growth factor-beta and alpha-smooth muscle actin overexpression, and prevented worsening of interstitial changes. Hence, ACE inhibition, which is widely used in human kidney disease, may not only halt the progression of renal failure, but also actually induce the regeneration of new renal tissue.

Vascular tissue engineering

Reconstructive surgery using autologous vessels is the conventional approach for substitution of diseased vessels or for generation of bypass to improve blood supply downstream of stenosed vessels. In some circumstances the use of autologous material is not possible due to concomitant diseases or previous use, and artificial grafts must be used. Unfortunately, these grafts cannot substitute small-caliber arterial vessels because of thrombotic complications. The objective of tissue engineering at the vascular level is then to generate biological substitutes of arterial conduits with functional characteristics of native vessels, combining cellular components with biodegradable scaffolds. These research projects started in several laboratories, in the late 1990s, and have expanded in different directions using a number of experimental approaches. The objective of this review is to give an overview of the results so far obtained in this area of research, and to discuss the problems related to these investigations, at the experimental and clinical level. The article provides an overview of different biodegradable scaffolds used, experimental techniques for vessels maturation in vitro under mechanical stimulation, and of differentiated as well as precursors of vascular cells, which opens new opportunities for further development of this form of cell transplantation. Finally, the current available results in clinical research will be discussed.

Computed tomography evaluation of autosomal dominant polycystic kidney disease progression: a progress report

At the moment, there are no effective therapies to prevent or slow the progression of autosomal dominant polycystic kidney disease (ADPKD). Radiologic evaluations are used to monitor volume of renal cysts and parenchyma during disease evolution. Volumetric quantifications based on computed tomography were used to investigate the relation between structural and functional changes in patients with advanced-stage ADPKD. By use of image-processing techniques, volume of kidneys, renal cysts, fully enhanced parenchyma, and faintly contrast-enhanced parenchyma, referred to as intermediate, was estimated. GFR measurements and computed tomography evaluations were repeated 6 mo later. No statistically significant correlations were found between volumes of cysts and parenchyma and intermediate volume and GFR. However, the ratio of intermediate over parenchymal volume strongly correlated with GFR (r = -0.81, P < 0.001). In addition, there were significant correlations between percentage changes in intermediate volume (absolute or relative to parenchyma) and GFR changes during the observation period (r = -0.70 and r = -0.75, P < 0.01). These data support the hypothesis of a significant relation between radiologic appearance of renal structure and functional changes and suggest new ways that renal dysfunction in ADPKD may be predicted. Further work is necessary to determine the nature of faintly contrast-enhanced parenchyma and its role in renal functional loss.

Permselective dysfunction of podocyte-podocyte contact upon angiotensin II unravels the molecular target for renoprotective intervention

Ameliorating the function of the glomerular barrier to circulating proteins by blocking angiotensin II (Ang II) translates into less risk of progression toward end-stage renal failure in diabetic and nondiabetic nephropathies. However, the mechanisms underlying this barrier protection are not clear. Specialized contacts between adjacent podocytes are major candidate targets, and the actin cytoskeleton is emerging as a regulatory element. Here, we present data demonstrating that Ang II induced reorganization of F-actin fibers and redistribution of zonula occludens-1 (ZO-1) that is physically associated with actin in murine podocytes. These effects were paralleled by increased albumin permeability across podocyte monolayers. The F-actin stabilizer jasplakinolide prevented both ZO-1 redistribution and albumin leakage, suggesting that actin cytoskeleton rearrangement is instrumental to podocyte permselective dysfunction induced by Ang II. Changes in both F-actin and ZO-1 patterns were confirmed in glomeruli of rat isolated perfused kidneys on short infusion of Ang II, leading to increased protein excretion. Podocyte dysfunction was mediated by Ang II type 1 receptor and was partly dependent on Src kinase-phospholipase C activation. These data demonstrate that strategies aimed at stabilizing podocyte-podocyte contacts and targeting the relevant intracellular signal transduction are crucial to renoprotection.

Pathophysiologic implications of reduced podocyte number in a rat model of progressive glomerular injury

Changes in podocyte number or density have been suggested to play an important role in renal disease progression. Here, we investigated the temporal relationship between glomerular podocyte number and development of proteinuria and glomerulosclerosis in the male Munich Wistar Fromter (MWF) rat. We also assessed whether changes in podocyte number affect podocyte function and focused specifically on the slit diaphragm-associated protein nephrin. Age-matched Wistar rats were used as controls. Estimation of podocyte number per glomerulus was determined by digital morphometry of WT1-positive cells. MWF rats developed moderate hypertension, massive proteinuria, and glomerulosclerosis with age. Glomerular hypertrophy was already observed at 10 weeks of age and progressively increased thereafter. By contrast, mean podocyte number per glomerulus was lower than normal in young animals and further decreased with time. As a consequence, the capillary tuft volume per podocyte was more than threefold increased in older rats. Electron microscopy showed important changes in podocyte structure of MWF rats, with expansion of podocyte bodies surrounding glomerular filtration membrane. Glomerular nephrin expression was markedly altered in MWF rats and inversely correlated with both podocyte loss and proteinuria. Our findings suggest that reduction in podocyte number is an important determinant of podocyte dysfunction and progressive impairment of the glomerular permselectivity that lead to the development of massive proteinuria and ultimately to renal scarring.

Biocompatibility and function of microencapsulated pancreatic islets

Encapsulation of pancreatic islets in alginate is used to protect against xenogenic rejection in different animal models. In this study, several factors, including differences in alginate composition, the presence or absence of xenogenic islet tissue and a transient immunosuppression, were investigated in a model of bovine islet transplantation in rats. A pure alginate with predominantly guluronic acid (Manugel) and an ultrapure low viscosity guluronic acid alginate (UP-LVG) were used. When microcapsules of Manugel or UP-LVG containing 16,000 bovine islet equivalents were transplanted in diabetic rats, we observed normoglycemia for 8.3+/-0.7 (range 6-12 days) and 7.5+/-0.2 days (range 7-8 days) on average, respectively. To ameliorate immunoprotection of alginate microcapsules we repeated the same experiments using transient immunosuppressive therapy. Low doses of cyclosporin A (CyA) administered for 18 days after implantation increased the time in normoglycemia, which averaged 27+/-3 days (range 8-55 days) in Manugel capsules while in UP-LVG capsules it averaged 18+/-8 days (range 3-39 days). The surface of recovered capsules showed less capsules free of overgrowth in Manugel with respect to UP-LVG alginate. These data were comparable with those observed in empty microcapsules similarly implanted, indicating that the capsular overgrowth was not promoted by the presence of xenogenic islet tissue. In recovered Manugel capsules the percentage of capsules without fibrotic overgrowth was higher than that observed without CyA. The same observation was made in empty capsules. These observations indicate that a combination of a highly purified alginate and short-term immunosuppression prolong islet function in a model of xenotransplantation.

Mechanisms of progression and regression of renal lesions of chronic nephropathies and diabetes

The incidence of chronic kidney diseases is increasing worldwide, and these conditions are emerging as a major public health problem. While genetic factors contribute to susceptibility and progression of renal disease, proteinuria has been claimed as an independent predictor of outcome. Reduction of urinary protein levels by various medications and a low-protein diet limits renal function decline in individuals with nondiabetic and diabetic nephropathies to the point that remission of the disease and regression of renal lesions have been observed in experimental animals and even in humans. In animal models, regression of glomerular structural changes is associated with remodeling of the glomerular architecture. Instrumental to this discovery were 3D reconstruction studies of the glomerular capillary tuft, which allowed the quantification of sclerosis volume reduction and capillary regeneration upon treatment. Regeneration of capillary segments might result from the contribution of resident cells, but progenitor cells of renal or extrarenal origin may also have a role. This review describes recent advances in our understanding of the mechanisms and mediators underlying renal tissue repair ultimately responsible for regression of renal injury.

Subcutaneous xenotransplantation of bovine pancreatic islets

Transplantation of pancreatic islets in diabetes is currently limited by the need of immunosuppressive therapy. The present study was designed to test an immunoprotection planar device for subcutaneous xenotransplantation of pancreatic islets in the diabetic rat. We tested three different devices made of polyethersulfone hollow fibers. In all diabetic rats, implantation of islet-containing devices promptly normalized hyperglycemia. In vitro membrane permeability to glucose was correlated with implant function duration. These data confirm that bovine islets contained within devices and implanted subcutaneously remain functional for several days. Strategies to prolong islet function may allow achieving successful long-term islet implantation in this attractive site.

Safety and efficacy of long-acting somatostatin treatment in autosomal-dominant polycystic kidney disease

BACKGROUND

The fluid filling renal cysts in human polycystic kidneys is secreted chiefly by the tubular epithelium lining the cysts via secondary chloride transport. Inhibiting this process by somatostatin therapy should induce shrinking of renal cysts.

METHODS

In this randomized, cross-over, placebo-controlled trial we compared the risk/benefit profile of 6-month treatment with long-acting somatostatin (octreotide-LAR, 40 mg intramuscularly every 28 days) or placebo in autosomal-dominant polycystic kidney disease (ADPKD) patients with mild-to-moderate renal insufficiency and no evidence of other kidney disease. Volumes of kidney structures were evaluated by a two-slice computed tomography (CT) scanner; while glomerular filtration rate (GFR) was estimated by iohexol plasma clearance.

RESULTS

One patient on somatostatin and one on placebo were prematurely withdrawn because of nonsymptomatic, reversible colelithiasis and asthenia, respectively. In the remaining 12 patients somatostatin was well tolerated. Kidney volume increased by 71 +/- 107 mL (P < 0.05) on somatostatin and by 162 +/- 114 mL (P < 0.01) on placebo. The percent increase was significantly lower on somatostatin (2.2 +/- 3.7% vs. 5.9 +/- 5.4%) (P < 0.05). Cystic volume tended to increase less on somatostatin than on placebo (3.0 +/- 6.5% vs. 5.6 +/- 5.8%). The "parenchymal" volume nonsignificantly increased by 2.5 +/- 8.4% on placebo and slightly decreased by 4.4 +/- 8.9% on somatostatin. The GFR did not change significantly during both treatment periods.

CONCLUSION

In ADPKD patients, 6-month somatostatin therapy is safe and may slow renal volume expansion. This may reflect an inhibited growth in particular of smallest cysts beyond the detection threshold of CT scan evaluation. Whether this effect may prove renoprotective in the long term should be tested in additional trials of longer duration.

The effect of sodium ascorbate on the mechanical properties of hyaluronan-based vascular constructs

Esterified hyaluronic acid (HYAFF) is routinely used for clinical tissue engineering applications such as skin and cartilage. In a previous study we developed a technique for in vitro generation of cylindrical constructs from cellularized HYAFF flat sheets. In the present investigation we studied the possibility to improve mechanical properties of this vascular construct by the addition of sodium ascorbate (SA). Non-woven HYAFF flat sheets were seeded with porcine aortic smooth muscle cells (SMCs) and cultured for 14 or 28 days with standard medium or medium added with SA. In selected experiments HYAFF sheets seeded with SMCs were wrapped to obtain cylindrical shape and then cultured in control medium or SA added medium for up to 28 days. We estimated cell viability for flat sheets, and performed histological examination, analysis of extracellular matrix (ECM) deposition and mechanical tests on tubular constructs. The number of viable cells and ECM deposition increased with time in constructs cultured in the presence of SA, as compared to control group. Moreover, SA improved mechanical properties of the vascular construct lowering material stiffness and increasing tensile strength as compared to untreated controls. The addition of SA to the medium improved cell proliferation and ECM synthesis on this biodegradable material, which leads to the formation of well organized, mechanical resistant tissue-engineered structure.

Vascular Smooth Muscle Cells on Hyaluronic Acid: Culture and Mechanical Characterization of an Engineered Vascular Construct

Esterified hyaluronic acid (HYAFF) is routinely used for clinical tissue-engineering applications such as skin and cartilage. The material is degraded by neotissue formation and degradation products are highly biocompatible. In the present article we investigate the possibility to culture vascular smooth muscle cells on this biodegradable material for the generation of tubular constructs to be used for vascular tissue engineering. We have evaluated cell attachment and growth, and the possibility to obtain a three-dimensional tubular shape culture from flat HYAFF sheets. We also evaluated the mechanical properties of the cell constructs, using a specific testing protocol, and compared them with the properties of segments of porcine coronary artery. Morphology and viability tests demonstrated that vascular cells, either from porcine or human origin, adhere and grow on nonwoven meshes of HYAFF, and that precoating of the material with fibronectin or collagen had a modest effect on cell growth and extracellular matrix production. Cell growth reached a maximum 7 days after seeding. Simple wrapping of flat sheets of nonwoven meshes containing vascular cells around a cylindrical mandrel, and culture under static conditions for 14 days, yielded tubular constructs suitable for mechanical tests. Despite cell colonization, constructs showed lower mechanical resistance as compared with porcine coronary arteries. The material used and the technique developed result in highly cellularized tubular constructs. Whether the mechanical properties may be improved by dynamic culture conditions is worthy of investigation.

A comparative evaluation of chondrocyte/scaffold constructs for cartilage tissue engineering

This study aimed to evaluate three biodegradable scaffolds as cell carriers for in vitro cartilage regeneration using mature human chondrocyte cells. We compared cell distribution, viability and morphology and we evaluated the mechanical properties of the constructs after 2 weeks of in vitro culture. The materials used as scaffolds were fibrin glue, a collagen sponge and a polyurethane foam (DegraPol(R)). Fibrin glue was found unsuitable as a chondrocyte carrier vehicle after culture times longer than a few days, probably due to significant barriers to nutrients and oxygen diffusion, and the material weakened rapidly. The collagen-based sponge was found to be unsuitable to support chondrocyte survival in vitro, although the presence of newly synthesized collagen was observed in these constructs. The synthetic biodegradable scaffold was more adequate in supporting cell survival and mechanical properties. After 2 weeks of static culture, the storage modulus obtained by dynamic shear testing was in the order of 0.7 kPa in fibrin constructs, 3.7 kPa in collagen constructs and 105 kPa in DegraPol(R) constructs. The better mechanical stability of the synthetic foam supports further investigation in the possible use of synthetic biomaterials as biodegradable scaffolds for in vitro cartilage regeneration. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 55-64).

The effect of media perfusion on three-dimensional cultures of human chondrocytes: integration of experimental and computational approaches

This work examines the effect of perfusion on human mature articular chondrocytes cultured on synthetic biodegradable scaffolds (DegraPol). Human chondrocytes were isolated, seeded on the scaffolds and subjected to perfused culture at a flow rate of 0.5 ml/min, corresponding to an average inlet fluid velocity of 44 microm/s, with flow inversion every 1 minute. The flow was imposed at the construct surface in some constructs, it was forced through the construct thickness in other constructs and was absent in the static controls. We compared cell viability and morphology and we evaluated material properties of the constructs at 1 month of culture. Thickness-perfused constructs showed significantly higher material properties and roughly a two-fold cell viability, when compared both to surface-perfused constructs and to static controls. Chondrocytes maintained a phenotypic morphology in all experiments, probably favoured by a limited cell-scaffold interaction. Biosynthetic activity could be demonstrated only in the bioreactor-cultured constructs. In this experimental model, a bi-directional flow of culture medium was applied to the cells at a macroscopic level and computational modelling was used to quantify the fluid-dynamic environment induced on the cells at a microscopic level. This method may be used to quantify the effects of fluid-dynamic shear on the growth modulation of tissue-engineered cartilage constructs, to potentially enhance tissue growth in vitro.

Radial artery remodeling in response to shear stress increase within arteriovenous fistula for hemodialysis access

It is known that changes in blood flow induce vascular remodeling and that shear stress, the tractive force acting on the vessel wall due to blood flowing, influences endothelial cell function. The aim of the present study was to investigate the relation between changes in pulsatile shear forces and arterial remodeling in response to chronic elevation in blood flow within the radial artery. The authors studied vessel diameter, flow rate, and shear stress in the radial artery of uremic patients before and after surgical creation of a native arteriovenous fistula for hemodialysis access. For this purpose, the authors used echo-color-Doppler ultrasound to perform diameter and blood velocity measurements. Time-function blood flow rate and wall shear stress were calculated based on arterial diameter, center-line velocity wave-form, and blood viscosity, using a numerical method developed according to Womersley's theory for unsteady flow in tubes. The results confirmed that the radial artery diameter increases in response to a chronic increase in blood flow in uremic patients. Moreover, it seems that the radial artery dilates in such a way as to maintain the peak wall shear stress constant, suggesting that endothelial cells sense the maximum rather than the time-averaged wall shear stress. This finding may lead to further understanding of the mechanisms responsible for endothelial response to physical stimulation by flowing blood.

The response of endothelial cells to fluid shear stress using a co-culture model of the arterial wall

An endothelial cell (EC) smooth muscle cell (SMC) co-culture model of the arterial wall was used to study the effect of fluid shear stress on EC behavior. This model, in addition to being a more realistic tissue analogue, is a valuable research tool for studying the effects of mechanical stimulation upon the behavior of both SMCs and ECs. In the present study, a 10% cyclic strain was used to alter the characteristics of an SMC-seeded collagen gel. This form of strain preconditioning resulted in a rearrangement of the vessel wall that yielded circumferentially oriented cells and collagen fibrils. The preconditioned collagen gel was subsequently seeded with ECs and exposed to fluid-induced shear stress (10 dynes/cm2) for 48 hr. In the absence of flow, ECs seeded on slab constructs were oriented with the underlying collagen fibrils. Sheared constructs exhibited ECs oriented in the flow direction. Shear stress also affected EC proliferation, reducing the total number of dividing ECs by as much as 48 percent compared to unsheared constructs. The shear-induced reduction in proliferation was further enhanced when constructs were first strain-preconditioned (64% reduction). Moreover, conditioned media from shear stress experiments inhibited proliferation of ECs seeded on tissue culture plastic. These results suggest that EC response to fluid shear stress in a collagen co-culture model is influenced by the underlying substrate, and one that in this study is modified by strain preconditioning.

Computational geometry for patient-specific reconstruction and meshing of blood vessels from MR and CT angiography

Investigation of three-dimensional (3-D) geometry and fluid-dynamics in human arteries is an important issue in vascular disease characterization and assessment. Thanks to recent advances in magnetic resonance (MR) and computed tomography (CT), it is now possible to address the problem of patient-specific modeling of blood vessels, in order to take into account interindividual anatomic variability of vasculature. Generation of models suitable for computational fluid dynamics is still commonly performed by semiautomatic procedures, in general based on operator-dependent tasks, which cannot be easily extended to a significant number of clinical cases. In this paper, we overcome these limitations making use of computational geometry techniques. In particular, 3-D modeling was carried out by means of 3-D level sets approach. Model editing was also implemented ensuring harmonic mean curvature vectors distribution on the surface, and model geometric analysis was performed with a novel approach, based on solving Eikonal equation on Voronoi diagram. This approach provides calculation of central paths, maximum inscribed sphere estimation and geometric characterization of the surface. Generation of adaptive-thickness boundary layer finite elements is finally presented. The use of the techniques presented here makes it possible to introduce patient-specific modeling of blood vessels at clinical level.

Radial artery wall shear stress evaluation in patients with arteriovenous fistula for hemodialysis access

It has been extensively documented that changes in blood flow induce vascular remodeling and this phenomenon seems to be correlated to the shear forces imposed on the vessel wall by motion of blood. Wall shear stress, the tractive force that acts on the endothelium, has been shown to influence endothelial cell function. To study changes in wall shear stress that develop on the vessel wall upon changes of blood flow, we set up a technique that allows estimation of shear stress in the radial artery of patients on chronic hemodialysis therapy. The technique is based on color-flow Doppler examination of the radial artery before and after surgical creation of radiocephalic fistula for hemodialysis. Calculation of time function wall shear stress and blood flow rate in the radial artery is performed on the basis of arterial diameter, center-line velocity waveform and blood viscosity, using a numerical method developed according to Womersley's theory for pulsatile flow in tubes. The results presented confirm that the model developed is suitable for calculation of the wall shear stress that develops in the radial artery of patients before and after surgical creation of an arteriovenous fistula for hemodialysis. This methodology was developed for characterization of wall shear stress in the radial artery but may be well applied to other vessels that can be examined by echo-Doppler technique.

Effects of combined ACE inhibitor and angiotensin II antagonist treatment in human chronic nephropathies

BACKGROUND

Proteinuria predicts renal disease progression, and its reduction by angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II receptor antagonists (ARA) is renoprotective.

METHODS

In this prospective, randomized, cross-over study of 24 patients with nondiabetic, chronic nephropathies, we compared the effects on proteinuria, renal hemodynamics, and glomerular permselectivity of 8 weeks with comparable blood pressure control achieved by benazepril (10 mg/day) and valsartan (80 mg/day) combined therapy with those achieved by benazepril (20 mg/day) or valsartan (160 mg/day) alone.

RESULTS

Despite comparable changes in blood pressure and glomerular filtration rate (GFR), combined therapy decreased proteinuria more than benazepril (-56% vs. -45.9%, P=0.02) and valsartan (-41.5%, P=0.002). Changes in urinary protein to creatinine ratio followed the same trend. Filtration fraction and renal vascular resistances (RVR) decreased more with combined (-14.7%,-23.7%) or benazepril (-12.4%, -20.5%) than with valsartan (-2.7%, -12.5%, P < 0.05 vs. both). RVR changes, adjusted for GFR changes, were associated with those in proteinuria (P < 0.05). Changes in glomerular permeability were comparable and did not predict different changes in proteinuria in the three groups.

CONCLUSION

At comparable blood pressure, combined ACEi and ARA decreased proteinuria better than ACEi and ARA. The greater antiproteinuric effect most likely depended on an ACEi-related hemodynamic effect, in addition to glomerular size selectivity amelioration. Long-term combined ACEi and ARA therapy may be more renoprotective than treatment with each agent alone.