Effects of oral adsorbent in the rat model of chronic renal failure.

The effects of oral adsorbent, AST-120 (Kureha Chemical Ind. Co., Tokyo), were studied in the rat model of subtotal nephrectomy. In 34 female Sprague-Dawley rats, three quarters of the renal mass were removed from the left kidney by ligation of 3 branches of the left renal artery. One week later, the right kidney was removed. Two days after right nephrectomy, control rats were fed standard rat chow ad libitum, while AST-120-treated rats were fed standard rat chow containing AST-120 ad libitum. The animals were observed for 9 weeks. Of the control rats, some became severely ill and appeared to be almost dying before 9 weeks, while paired AST-120-treated rats appeared well. Body weight was maintained better in AST-120-treated rats than in control rats. At completion of the study, levels of BUN and serum creatinine were lower and glomerular filtration rate and renal plasma flow rate were higher in AST-120-treated than in control rats (p < 0.05), although there was no statistically significant difference in proteinuria. Serum uremic peak 2a measured by high-performance liquid chromatography, which is considered to correspond to uremic toxins, was statistically lower in AST-120-treated rats (p < 0.05). Finally, a marked reduction in the degree of glomerular sclerosis was noted in AST-120-treated versus control rats (p < 0.05). The results indicate that AST-120 is effective in the treatment of chronic renal failure in terms of reducing uremic symptoms as well as preserving renal function and glomerular architecture. The data also indicate that a reduction in uremic toxins could delay the progressive damage of renal function and glomerular architecture in chronic renal failure.     

Effects of oral adsorbent AST-120 (Kremezin) on renal function and glomerular injury in early-stage renal failure of subtotal nephrectomized rats

The aim of the present study was to determine if treatment with an oral adsorbent (AST-120, Kremezin) might decrease the urinary albumin excretion and serum indoxyl sulfate (s-IS), and prevent glomerular sclerosis in early-stage renal failure, i.e. 0.9-1.2 mg/dl of serum creatinine (s-Cr) and 60-95 mg/dl of blood urea nitrogen (BUN), in subtotal (3/4) nephrectomized rats. Levels of s-Cr and s-IS in the AST-120-treated rats were significantly lower than those in the untreated control rats. The AST-120-treated rats showed an increase of creatinine clearance. Urinary protein and indoxyl sulfate excretion in the AST-120-treated rats were also significantly lower than those in the untreated control rats. The ratio of glomerular tuft area to the area of Bowman's capsules (GT/BC) in the AST-120-treated rats was significantly lower than that in the untreated control rats. The degree of glomerular sclerosis and tubulointerstitial fibrosis in the AST-120-treated rats was significantly lower than that in the untreated control rats. Furthermore, there was a significant relationship among the degree of GT/BC, glomerular sclerosis, tubulointerstitial fibrosis and the levels of urinary protein excretion. It appears that AST-120 might decrease the accumulation of s-Cr and s-IS, and prevent glomerular sclerosis in early stage renal failure in the subtotal nephrectomized rats.     

Correction by oral adsorbent of abnormal digestive tract milieu in rats with chronic renal failure

In order to examine the mechanism by which the oral carbonaceousadsorbent, AST-120 delays the appearance of glomerular sclerosis,experiments were carried out in 120 male Sprague-Dawley ratsweighing 285–320 g. The rats were first subjected to 2/3,3/4, and 4/5 nephrectomy (n=40). The experiments were begunat 2 weeks after the surgery, and were performed over an 8-weekperiod. Half of each group (n=20) was administered 1 g/day ofliquid AST-120, and the other half received liquid vehicle solutionwith pair feeding in each group. In the 2/3 nephrectomized groupthe administration of AST-120 delayed the occurrence of glomerularhypertrophy and prevented the appearance of glomerular sclerosiswithout any significant differences in renal function, systemicblood pressure (SBP), and urinary protein excretion (U-P). Inthe 3/4 nephrectomized group the administration of AST-120 delayedthe appearance of glomerular hypertrophy and sclerosis withsignificant decreases in SBP and U-P. In the 4/5 nephrectomizedgroup the administration of AST-120 delayed the appearance ofglomerular sclerosis and prevented a decrease in renal function.It is concluded that administration of the oral adsorbent AST-120delays the occurrence of glomerular sclerosis by delaying theappearance of glomerular hypertrophy, systemic hypertension,and the increase in proteinuria. It can be therefore mentionedthat the accumulating substances in the digestive tract worsenthe abnormal milieu of chronic renal failure.     

Effect of an oral adsorbent (AST-120) in rats with daunomycin-induced chronic renal failure

The effect of an oral adsorbent (AST-120) was examined in rats with daunomycin-induced chronic renal failure. Sixteen pairs of daunomycin rats which had similar levels of proteinuria at 4 weeks after being injected with daunomycin were selected. One rat of each pair served as a control and was fed on a standard diet, while the other rats were fed on a diet containing AST-120. The blood creatinine and blood urea nitrogen (BUN) were significantly lower in the rats fed with AST-120 than in the controls. Moreover, the life span of the rats fed with AST-120 was significantly prolonged as compared to that of the control rats. These findings suggest that oral administration of AST-120 may help to prevent rapid deterioration of renal function in experimental chronic renal failure induced by daunomycin in rats.     

Oral sorbent AST-120 increases renal NO synthesis in uremic rats.

OBJECTIVE: The urine level of nitric oxide (NO) metabolites, i.e., nitrates/nitrites (NOx), in chronic renal failure (CRF) is decreased because of reduced renal synthesis of NO. We determined whether the administration of an oral sorbent, AST-120, increases the urine level of NOx and the renal expression of nitric oxide synthase (NOS) isoforms in CRF rats. METHODS: Chronic renal failure rats were produced by 4/5 nephrectomy. Rats were randomized into two groups: CRF control rats, and AST-120-treated CRF rats. The AST-120 was administered to the rats at a dose of 4 g/kg with powder chow for 16 weeks, whereas powder chow alone was administered to control rats. The urine levels of NOx were measured by using a NOx colorimetric assay kit. The expression of endothelial NOS (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) in the kidney was determined by immunohistochemistry. Serum and urine levels of indoxyl sulfate were determined by high-performance liquid chromatography. RESULTS: Urine levels of NOx and the expression of glomerular eNOS and tubulointerstitial nNOS were significantly decreased in CRF rats compared with normal rats. The administration of AST-120 to CRF rats significantly increased urine levels of NOx and the expression of glomerular eNOS and tubulointerstitial nNOS. The administration of AST-120 to CRF rats significantly decreased urine and serum levels of indoxyl sulfate. CONCLUSIONS: The oral sorbent AST-120 increases NO synthesis in the kidneys of uremic rats by increasing the renal expression of eNOS and nNOS, through alleviation of indoxyl sulfate overload on the kidney.     

Effects of antihypertensive drugs on glomerular morphology

We quantitated the glomerular size and the degree of sclerosis simultaneously in individual glomeruli with the use of three-dimensional histological analysis on serial sections obtained from remnant kidneys with highly heterogeneous glomerular lesions after subtotal nephrectomy (sNPX). Four to six weeks after sNPX (Group I, N = 7), 90% of glomeruli had mild sclerosis (sclerosis index, SI; less than 1.5 on a 0 to 4 scale) with a strong positive correlation between the maximum planar area of glomerulus (PAmax) versus SI. Twelve weeks after sNPX (Group II, N = 6) more than 50% of glomeruli had advanced sclerosis (average SI:1.88), and a significant positive correlation was again found between PAmax and SI in glomeruli with mild to modest sclerosis (SI less than 1.5), whereas these two variables were correlated inversely in glomeruli with advanced sclerosis. Administration of enalapril (50 mg/liter drinking water) or hydralazine (200 mg/liter) + hydrochlorothiazide (50 mg/liter) for 12 weeks (Group III, N = 12) markedly attenuated the sclerosis to comparable degrees (average SI: 0.15 vs. 0.22). The former antihypertensive therapy decreased glomerular capillary hydraulic pressure (PGC) to normal range, whereas the latter triple drug therapy was largely without effect on PGC. Of note, the positive correlation between SI and PAmax remained unaffected by these anti-hypertensive drugs. SI of the glomeruli from both treated groups was expressed as a first-order function of PAmax. The correlation coefficient is identical to that found in non-treated Group II remnant glomeruli, so that the degree of sclerosis is mathematically uniquely correlated with the glomerular size, regardless of drug treatment. Thus, within a given remnant kidney, the magnitude of glomerular hypertrophy has a direct correlation with the degree of sclerosis, while the altered glomerular hemodynamic pattern has little modulatory role in determining the magnitude of this hypertrophy. Enalapril and triple drug therapy, at equi-depressor doses in regard to systemic blood pressure, had identical potency in sparing glomerular structure. The primary determinant for this antisclerotic potency appears to be related to the drugs' potency to inhibit glomerular growth rather than an effect on the abnormal hemodynamics which develop in the glomerulus.     

Effect of oral adsorbent (AST-120) in the rat model of chronic renal failure induced by adriamycin]

The effect of AST-120 was examined in the rat model of CRF induced by adriamycin (ADM), which is known to induce focal glomerular sclerosis (GS). ADM (2mg/kg) was injected intravenously twice at a 3-wk interval. After 14 wks, rats were paired with control (C) and AST-120 (A) groups according to levels of BUN and proteinuria. Then, the rats were fed regular rat chow with (A, n = 10) or without (C, n = 10) AST-120. After 28 wks, there were more GS in C. Averaged sclerosis index (SI, 0-4 scale) in C was 1.97 (0.94-3.22), while 1.61 (0.60-2.97) in A. When GS was advanced in C (SI > 2.0), largely ameliorated SI was noted in A (2.61 vs. 1.97, C vs. A, p < 0.05 by paired W-test, n = 5 each). Also, in these rats, BUN, serum creatinine and Ht were all improved in A (p < 0.05). Thus, AST-120 was effective in CRF rats induced by ADM when uremia was advanced. The data also indicates that a reduction of uremic toxins could improve glomerular histology and renal function in CRF.     

Combination therapy with angiotensin-converting enzyme inhibitor and oral adsorbent of uremic toxins can delay the appearance of glomerular sclerosis and interstitial fibrosis in established renal failure

BACKGROUND/AIM: Angiotensin II plays a central role in the progression of chronic renal failure (CRF), and administration of angiotensin-converting enzyme inhibitor (ACEI) in rats delays the progression of CRF. However, ACEI has little effect on CRF progression in rats with established CRF. We therefore examined whether combination therapy with ACEI and oral adsorbent for uremic toxins in the gastrointestinal tract has the desired effect. METHODS: Rats subjected to subtotal nephrectomy were given enalapril at 20 mg/kg (n = 10, group E), AST-120 at 5 g (n = 10, group A), enalapril and AST-120 together at the same doses (n = 10, group EA), or no treatment (n = 10, group C) 8 weeks after the operation. The substances were administered in 100 g rat chow. All animals were pair-fed, and all were killed after 8 weeks of pair-feeding. RESULTS: Body weight did not differ between groups during the study. Blood pressure at week 8 was significantly lower in groups E and EA than in groups C and A (p < 0.05). Urinary protein excretion level and renal plasma flow rate at week 8 were significantly less in groups E and EA than in group C (p < 0.05, p < 0.01). The glomerular filtration rate at week 8 was significantly higher in group EA than in group C (p < 0.05). The glomerular sclerosis index and interstitial fibrosis area at week 8 were significantly less in group EA than in group C (p < 0.01). CONCLUSION: ACEI and AST-120 in combination can delay progression of established CRF in rats by inhibiting the appearance of glomerular sclerosis and interstitial fibrosis.     

Ameliorated glomerular injury in mice overexpressing brain natriuretic peptide with renal ablation

Brain natriuretic peptide (BNP) is a cardiac hormone produced by the ventricle, and its secretion is markedly increased in heart failure, hypertension, and renal failure. Transgenic mice that overexpress BNP in the liver (BNP-Tg) were recently generated, resulting in low BP. To elucidate the role of BNP in renal pathophysiology, the effect of chronic excess of BNP in transgenic mice on glomerular injury after subtotal nephrectomy induced by resection of the renal poles was examined. After nephrectomy, glomerular cross-sectional areas in control nontransgenic mice markedly increased as compared with those in sham-operated mice (+81 +/- 7%), whereas there was only a modest increase in BNP-Tg (+10 +/- 6%). Expansion of the mesangial area and increase in the intraglomerular cell number were also inhibited in BNP-Tg. Glomerular expressions of transforming growth factor-beta and fibronectin were increased with hypertrophy and were significantly suppressed in BNP-Tg. Furthermore, increases in the urinary albumin excretion and BP were significantly ameliorated in BNP-Tg. Chronic hydralazine treatment in nephrectomized nontransgenic mice failed to inhibit glomerular hypertrophy. These findings indicate that the chronic excess of BNP in mice ameliorates glomerular hypertrophy and mesangial expansion after renal ablation. The results also suggest that the observed effects of natriuretic peptides under reduced renal mass are not due merely to systemic BP reduction and may be therapeutically applicable in various renal diseases.     

Effect of oral adsorbent (AST-120) on renal function,acquired renal cysts and aortic calcification in rats with adriamycin nephropathy

AIMS: The effect of oral adsorbent, AST-120, on the experimental renal disease induced by adriamycin, uninephrectomy and high protein diet proposed as a model of acquired cystic disease of the kidney was investigated. METHODS: 3 mg of adriamycin was injected into the tail vein of rats and 4 weeks later right-side nephrectomy was performed, 2 weeks thereafter 26 rats with urinary protein excretion between 100 and 358 mg/day were selected from 60 rats. Two groups, 13 rats in each group, namely the AST-120-treated group and control group, both of which had equal renal damage before the administration of AST-120 or placebo. AST-120 (0.4 g/100 g BW/day) was administered for 19 weeks. RESULTS: Serum creatinine and BUN in the AST-120-treated group were significantly lower (serum creatinine: 3.3 +/- 2.1 vs. 7.1 +/- 2.7 mg/dl, p < 0.003) and creatinine clearance was higher (0.62 +/- 0.49 vs. 0.29 +/- 0.30 ml/min, p < 0.05) at the final examination than in the control group. Survival rate which was examined using another set of 9 rats was higher in AST-120-treated rats than in AST-120-untreated rats. Serum indoxyl sulfate was significantly lower at all times after using AST-120 in the AST-120-treated group than in contrast to the control group. Histological examination revealed less severe interstitial and cystic changes in the AST-120-treated group. This suggests that AST-120 can prevent or retard the development of acquired renal cystic disease in this model. Aortic calcification tended to be less severe in the AST-120-treated group because of less serum Ca x P products. CONCLUSION: The AST-120-treated group significantly decreased serum creatinine and increased creatinine clearance with less severe renal cystic changes in this model during the later weeks of administration of AST-120 or at death, accompanied with the tendency of less severe aortic calcification.     

An oral sorbent reduces overload of indoxyl sulphate and gene expression of TGF-beta1 in uraemic rat kidneys.

BACKGROUND: An oral adsorbent (AST-120) delays the progression of chronic renal failure (CRF). The aims of the present study are to determine the effects of AST-120 on the localization of indoxyl sulphate in uraemic rat kidneys, and to examine whether AST-120 reduces the renal cortical gene expression of transforming growth factor (TGF)-beta1, tissue inhibitor of metalloproteinase (TIMP)-1 and pro-alpha1(I)collagen, and ameliorates glomerular and tubulointerstitial injuries in uraemic rats. METHODS: Two weeks after 5/6-nephrectomy, 10 rats were divided into pairs such that both rats in each pair exhibited almost the same levels of serum creatinine, blood urea nitrogen and creatinine clearance. One rat from each pair was assigned to a control uraemic group, the other to a uraemic group which received AST-120 everyday for 11 weeks. The localization of indoxyl sulphate was studied by immunohistochemistry using a monoclonal anti-indoxyl sulphate antibody we had developed. The renal cortical gene expression was studied by using northern blotting. RESULTS: Rats treated with AST-120 showed decreased levels of serum creatinine, blood urea nitrogen and urinary protein as well as increased levels of creatinine clearance as compared with control uraemic rats. AST-120 markedly decreased indoxyl sulphate levels in both serum and urine. Immunohistochemistry demonstrated that indoxyl sulphate was localized in the renal proximal tubular epithelial cells, especially of dilated tubules, and that AST-120 markedly reduced the tubular staining of indoxyl sulphate. AST-120 attenuated interstitial fibrosis, tubular injury as well as glomerular sclerosis, and reduced the renal gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen. CONCLUSIONS: AST-120 reduces the gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen in the kidneys, and delays the progression of CRF, at least in part, by alleviating the overload of indoxyl sulphate on remnant proximal tubular epithelial cells.     

Pathological study on the effect of oral adsorbent AST-120 on chronic renal failure in rats]

In order to evaluate the direct or indirect effect of AST-120 on chronic renal failure (CRF) in rats, histological and electron microscopical examinations were performed. A total of 30 Sprague-Dawley rats (aged 11 weeks and weighing 226 to 229 gm) with CRF induced by 5/6 nephrectomy were prepared. Rats were fed by a commercial diet (CE-2, Japan Kurea) and were divided into two groups: A (16 rats) and B (14 rats). AST-120 (5% content) was only administered to group B. After two months, kidneys were removed and prepared for the histological and electron microscopical examinations. On histological examination, group A kidneys showed severe glomerular hyalinization (more than 80%) and frequent crescents, as well as tubulo-interstitial fibrosis and many protein casts. In contrast, segmental glomerular lesions were identified in group B kidneys. Tubulo-interstitium were also well preserved. Furthermore, the ultrastructural findings of group B were milder than that of group A. The preservation of renal tissue in group B revealed the beneficial effect of AST-120 on CRF rats' kidneys. In conclusion, this beneficial effect is provided by the removal of the serum toxic metabolite (uremic toxin) and the precursor substance of the toxin by orally administered AST-120.     

Role for "uremic toxin" in the progressive loss of intact nephrons in chronic renal failure.

We studied the effect on the progression of glomerular sclerosis of two different experimental maneuvers, peritoneal dialysis and oral adsorbent, which remove circulating substances in different fashions. Munich-Wistar rats with established glomerular sclerosis, verified by renal biopsy analysis at seven weeks after subtotal nephrectomy, were treated for four weeks with either peritoneal dialysis (PD) or oral charcoal adsorbent (AST-120). Treatment was initiated at eight weeks. Rats were paired in treatment and control groups according to the similarity in the degree of sclerosis determined at biopsy with a minimum of 50 glomeruli analyzed. Systolic blood pressure and BUN and creatinine clearance, measured at seven to eight weeks, were not different among groups. In Group 2 rats, PD was performed with 1.5% dextrose for eight one-hour cycles, six days per week, while Group 1 control rats had zero indwelling time of the dialysate. Group 4 rats received AST-120, an oral adsorbent charcoal, mixed 5% by weight with standard rat chow and given ad libitum from 8 to 12 weeks after subtotal nephrectomy, while control Group 3 rats received only rat chow. Whole kidney GFR at 12 weeks was significantly higher in Group 2 PD versus Group 1 control (0.50 +/- 0.08 vs. 0.30 +/- 0.05 ml/min, P less than 0.05). There was no statistical difference for BUN and whole kidney creatinine or inulin clearance in Group 4 AST-120 treated versus Group 3 control rats. Light microscopic studies in autopsy specimens revealed that both PD and AST-120 attenuated progression of glomerular sclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of oral adsorbent AST-120 in rats with chronic renal failure--mechanism of progression of renal failure by dietary protein]

Progression of renal insufficiency was evaluated in partially nephrectomized Sprague-Dawley rats at the age of 10 weeks, fed on the low (6%), usual (20%), and high (36%) protein diet (group 6C, 20C, and 36C). Effects of oral adsorbent AST-120 on these experimental uremic models were also examined (group 6A, 20A, 36A). All the rats underwent paired feeding, and survived during the experimental period of 3 weeks. GFR (inulin clearance) and RPF (para-amino hippurate clearance), as well as Ccr was measured before the sacrifice. Initial serum creatinine and Ccr were 1.7 mg/dl and 0.27 ml/min. The rats of group 36C showed progressive elevation of serum creatinine level and decrease in Ccr. At the end of the study, GFR was significantly lower in group 36C than in group 6C and 20C (0.19, 0.68, 0.87 ml/min respectively). Significant elevation of filtration fraction in group 36C suggested that the decrease in GFR mainly resulted from low RPF. Even in group 36C, no glomerular sclerosis was histologically demonstrated in the remnant kidney, and the mean planar area of the remnant glomeruli was significantly small, which might reflect low RPF. Tubulo-interstitial changes like dilatation of the urinary space and tubular epithelial flattening were prominent in group 36C. Beneficial effect of AST-120 was obvious in high protein diet groups. GFR and RPF were rather well preserved in group 36A (0.36 and 0.78 ml/min) with normal filtration fraction. Tubulo-interstitial damage was evidently mild in group 36A. These data suggested the presence of some humoral factors, which can be adsorbed by AST-120 in gastrointestinal tract, and responsible for the deterioration of renal function and tubulo-interstitial damage induced by high protein diet in the uremic condition. Besides hyperfiltration and glomerular hypertrophy, such humoral factors as suggested in this study may contribute to the progression of chronic renal failure to some extent.     

Oral ADSORBENT AST-120 decreases carotid intima-media thickness and arterial stiffness in patients with chronic renal failure

BACKGROUND/AIM: Intima media thickness (IMT) and stiffness of the carotid arteries is related to coronary artery disease, and chronic renal failure patients are at high risk for such diseases. An oral adsorbent, AST-120 (Kremezin; Kureha Chemical Industry, Tokyo, Japan), can delay the progression of chronic renal failure in undialyzed uremic patients. The aim of the present study was to determine whether AST-120 affects carotid artery IMT and pulse wave velocity (PWV) in patients with chronic renal failure not undergoing dialysis. METHODS: Fifty patients with non-diabetic chronic renal failure were randomly divided into two groups: 30 patients (18 men and 12 women; mean age 53.5 years; mean serum creatinine 3.2 mg/dl) who were given AST-120 (6.0 g/day) and 20 patients (12 men and 8 women; mean age 52.0 years; mean serum creatinine 3.5 mg/dl) who were not given AST-120. Thirty healthy age-matched subjects (18 men and 12 women; mean age 51.5 years; mean serum creatinine 0.9 mg/dl) were also included. The treatment period was 24 months. IMT and arterial stiffness were measured before and after treatment. RESULTS: The slope of the reciprocal serum creatinine concentration over time became significantly less steep in the AST-120 group than in the non-AST-120 group (p < 0.001). Before treatment, carotid artery IMT differed little between the AST-120 group (0.90 +/- 0.22 mm) and the non-AST-120 group (0.88 +/- 0.20 mm). IMT in these two groups was significantly greater than IMT in the control group (0.64 +/- 0.14 mm) (p < 0.01). Carotid IMT in the AST-120 group decreased slightly but not significantly to 0.84 +/- 0.20 mm after 12 months and then significantly after 24 months to 0.78 +/- 0.18 mm (p < 0.05). Carotid IMT in the non-AST group showed little change throughout the experimental period. PWV differed little between the AST-120 group (1,980 +/- 330 cm/s) and the non-AST group (1,940 +/- 360 cm/s) before treatment. PWV values in these two groups were significantly greater than PWV in the control group (1,280 +/- 240 cm/s) (p < 0.01). After 12 and 24 months, PWV in the AST-120 group decreased significantly to 1,840 +/- 280 cm/s (p < 0.05) and to 1,780 +/- 260 cm/s (p < 0.05), respectively; however, PWV in the non-AST group showed a slight increase during the experimental period. CONCLUSION: The data suggest that AST-120 may reduce arterial stiffness and IMT in non-diabetic chronic renal failure patients before dialysis.     

Glomerular hemodynamic changes vs. hypertrophy in experimental glomerular sclerosis

In a variety of recent studies in animals with chronic renal diseases, investigators have found a tight correlation between the elevation in glomerular pressures and flows versus glomerular hypertrophy. To investigate a possible causal link between the glomerular hyperfunction and hypertrophy, we studied the functional and morphological sequelae of nephrectomy and those of unilateral ureteral diversion (UD) into the peritoneal cavity (that is, removal of renal clearance function while keeping the kidney tissue in situ). In all nine experimental groups of 54 Munich-Wistar rats, 2/3 of the renal mass was removed from the left kidney by ligation of two or three branches of the left renal artery. In addition, right nephrectomy (NPX) was performed in Groups 1B, 2B and 3B or UD in Groups 1C, 2C and 3C. The right kidney was left untouched in control groups, Groups 1A, 2A and 3A. Micropuncture measurements and histological studies were performed at four days (Groups 1A, 1B and 1C), two weeks (Groups 2A, 2B and 2C) or four weeks (Groups 3A, 3B and 3C). At both four days and two weeks, NPX and UD groups had marked and comparable degrees of glomerular hypertension, hyperperfusion and hyperfiltration compared to the control group in the left kidney.(ABSTRACT TRUNCATED AT 250 WORDS)     

Combination therapy with benazepril and oral adsorbent ameliorates progressive renal fibrosis in uremic rats

BACKGROUND/AIMS: The administration of an angiotensin-converting enzyme (ACE) inhibitor or an oral adsorbent, AST-120 (Kremezin), prevents the progression of renal failure. This study was designed to determine the additional effects of AST-120 combined with an ACE inhibitor, benazepril, on the progression of renal fibrosis in uremic rats. METHODS: 5/6-nephrectomized uremic rats were divided into control uremic rats (CRF group), benazepril-treated uremic rats (CRF+B group) and uremic rats receiving benazepril and AST-120 (CRF+BK group). After 14 weeks of treatment renal function and pathological changes were investigated. RESULTS: The progression of renal dysfunction was delayed in both the CRF+B and CRF+BK groups as compared with the CRF group. In the CRF+BK group, the level of serum and urinary indoxyl sulfate and the tubular accumulation of indoxyl sulfate decreased. Both the CRF+B and CRF+BK groups showed lower glomerular sclerosis indices than the CRF group. In the CRF+BK group, but not the CRF+B group, the interstitial fibrosis area and the expression of transforming growth factor (TGF) beta1 and tissue inhibitor of metalloproteinases (TIMP) 1 were decreased as compared with the CRF group. Furthermore, the CRF+BK group showed a smaller interstitial fibrosis area and a lower renal osteopontin expression than the CRF+B group. CONCLUSION: Combination therapy of benazepril and AST-120 is more effective than benazepril alone in retarding the progression of interstitial fibrosis by reducing the expression of TGF-beta 1, TIMP-1 and osteopontin.     

An oral adsorbent, AST-120, suppresses oxidative stress in uremic rats

BACKGROUND: The production of reactive oxygen species (ROS) has been suggested to play an important role in the progression of chronic kidney disease (CKD). An oral adsorbent, AST-120, removes uremic toxins such as indoxyl sulfate (IS) and delays the progression of CKD, but the effect on ROS production is unknown. The present study aimed to determine whether AST-120 reduces oxidative stress in uremic rat kidneys using markers of ROS production such as acrolein and 8-hydroxy-2'-deoxyguanosine (8-OHdG). METHODS: Daily administration of AST-120 was started 6 weeks after 5/6 nephrectomy and continued for 18 weeks. The changes in metabolic data, serum and urine IS levels, urinary excretion of markers of oxidative stress, and renal histological findings were investigated in uremic rats with or without AST-120 treatment. RESULTS: In parallel with the increase in serum and urine IS, the serum creatinine, urinary protein and acrolein levels started to increase at 6 weeks, but urinary 8-OHdG remained unchanged and significantly increased at 18 weeks in uremic rats. AST-120 markedly and significantly attenuated increases in uremic toxins and oxidative stress levels as well as the histological changes in glomerular sclerosis, interstitial fibrosis, and the tubular staining of 8-OHdG. CONCLUSION: AST-120 suppressed the progression of CKD, at least in part, via attenuation of oxidative stress induced by uremic toxin.     

Oral adsorbent AST-120 ameliorates interstitial fibrosis and transforming growth factor-beta(1) expression in spontaneously diabetic (OLETF) rats

Diabetic nephropathy is a common cause of end-stage renal disease. The administration of an oral adsorbent, AST-120, prevents the progression of chronic renal failure in uremic rats and undialyzed uremic patients. This study was designed to determine if AST-120 slows the progression of diabetic nephropathy using Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of non-insulin-dependent diabetic mellitus. At 21 weeks of age the OLETF rats were divided into 2 groups: AST-120-administered OLETF rats (n = 7), and control OLETF rats (n = 7). LETO rats, which are genetically similar to the OLETF rats but not diabetic, were also included. After the oral administration of AST-120 for 65 weeks, renal function and pathological changes were investigated in the 3 groups. The administration of AST-120 to the OLETF rats attenuated the progression of glomerular sclerosis, interstitial fibrosis, tubular injury as well as renal dysfunction, and reduced the serum and urinary levels of indoxyl sulfate. Furthermore, AST-120 administration reduced the interstitial expression of transforming growth factor (TGF)-beta(1) and tissue inhibitor of metalloproteinase (TIMP)-1, as well as interstitial infiltration of macrophages. The TGF-beta(1)-stained interstitial area showed positive correlations with the interstitial fibrosis area, the number of TIMP-1-positive cells, and the number of macrophages, and showed a negative correlation with creatinine clearance. In conclusion, AST-120 reduced the interstitial expression of TGF-beta(1) and TIMP-1, and the interstitial infiltration of macrophages, and ameliorates the progression of diabetic nephropathy in OLETF rats.     

红细胞生成素对慢性肾衰竭大鼠肾小球内皮细胞功能的影响

目的 探讨红细胞生成素（EPO）对慢性肾衰竭（CRF）大鼠肾小球内皮细胞功能的影响。 方法 采用分阶段5/6肾切除术制备大鼠慢性肾衰竭动物模型。实验动物按数字随机法分为4组：假手术组（对照组）、慢性肾衰竭组（模型组）及EPO干预的两个剂量组（小剂量组EPO用量30 U/kg,大剂量组EPO用量50 U/kg）。慢性肾衰竭大鼠皮下注射EPO 6周后处死。检测各组大鼠血肌酐（Scr）、血尿素氮（BUN）、尿蛋白、血红蛋白（Hb）和血压的变化,并观察肾组织病理改变。免疫组化法检测肾小球CD34、CD31表达;RT-PCR检测肾组织内皮素1（ET-1）、内皮细胞一氧化氮合酶（eNOS）和血管内皮细胞生长因子（VEGF） mRNA的表达。 结果 与模型组比较,EPO治疗能显著增加大鼠肾小球CD34、CD31的表达（均P < 0.05）;下调肾组织ET-1 mRNA的表达（P < 0.05）;上调肾组织eNOS和 VEGF mRNA的表达（均P < 0.05）。此外,EPO治疗还能使大鼠Scr、BUN、尿蛋白和血压水平显著降低（均P < 0.05）,Hb水平显著增高（P < 0.05）,肾组织病理损害明显减轻。 结论 EPO能减轻慢性肾衰竭大鼠肾脏的病理损害,改善肾功能。这种作用可能与其促进肾小球内皮细胞的修复和改善内皮功能有关。