[Experimental study of the effect of benzidinsulfon, included in the group of diaminodifenils, with potential carcinogenic effects]

There was performed a study of carcinogenicity of benzidinsulfon (4.4'-diaminodiphenil sulfone) in rats and mice. Experimental animals (99 mice and 99 rats, approximately equally divided by sex) received the drug throughout the life by subcutaneous injections (once a week) or addition to food (5 times a week). A single dose per animal in rats was: subcutaneous administration--50 mg (in females it was reduced due to the toxicity after beginning of the experiment to 25 mg) in 0.5 ml of oil, while feeding--20 mg in 0 5 ml of oil; in mice--respectively 5 mg in 0.2 ml of oil, and 2 mg in 0, 2 ml of oil. The maximum amount of a substance when administered subcutaneously to male rats was 5.65 g, to female rats--2, 68 g, when fed to rats 12.44 g, when injected subcutaneously in mice--380 mg, when fed--737 mg. The survival of experimental animals was significantly reduced as compared to the intact control because of the toxic effect of the drug, preferably chronic nephrosis with nephritic component and secondary nephrosclerosis and as well as miocardiosclerosis and aortic sclerosis. Frequency and timing of detection of tumors in experimental animals was not significantly different from that observed in the control that indicated the absence of carcinogenic features of benzidinsulfon.

Inhibitory effect of pravastatin on transforming growth factor beta1-inducible gene h3 expression in a rat model of chronic cyclosporine nephropathy

BACKGROUND/AIMS

Overexpression of transforming growth factor beta1-inducible gene h3 (betaig-h3) is associated with renal scarring in several models of renal disease. We investigated the inhibitory effect of pravastatin on betaig-h3 expression in a rat model of chronic cyclosporin A (CsA)-induced nephropathy.

METHODS

Adult Sprague Dawley rats kept on a low salt diet (0.05% sodium) were treated daily for 4 weeks with vehicle (olive oil, 1 ml/kg), CsA (15 mg/kg) or both CsA and pravastatin (20 mg/kg in drinking water). The effect of pravastatin on betaig-h3 expression was evaluated using in situ hybridization, immunohistochemistry, and immunoblotting. Functional parameters, histopathology (tubulointerstitial fibrosis, TIF, and arteriolopathy), and levels of transforming growth factor beta1 (TGF-beta1) and endothelial nitric oxide synthase were compared for the different treatment groups.

RESULTS

Co-administration of pravastatin significantly inhibited betaig-h3 mRNA production and gene expression within the tubulointerstitium of the CsA-treated kidneys, and this paralleled an attenuation of TIF (12.7 +/- 2.2 vs. 35.9 +/- 5.4%, p < 0.01 vs. CsA) and the expression of TGF-beta1 mRNA (279 +/- 40 vs. 719 +/- 85%, p < 0.01 vs. CsA). Pravastatin treatment reduced endothelial nitric oxide synthase protein levels and reversed the renal dysfunction caused by CsA. Neither CsA nor pravastatin affected total serum cholesterol or triglyceride levels in the treatment groups.

CONCLUSION

Pravastatin thus effectively abrogated the upregulation of betaig-h3 gene expression and associated TGF-beta1 production, and this was associated with attenuated TIF in this model of chronic CsA-induced nephropathy.

Imidapril improves l-NAME-exacerbated nephrosclerosis with TGF-β1 inhibition in spontaneously hypertensive rats

OBJECTIVE

This study was designed to investigate whether chronic angiotensin-converting enzyme (ACE) inhibition prevents hypertensive glomerular injury and inhibits increases in the mRNA levels and immunohistological expression of the apoptosis inducer caspase-3, and transforming growth factor (TGF)-beta 1 during prolonged nitric oxide synthase (NOS) inhibition with N-nitro-L-arginine methyl ester (L-NAME) in spontaneously hypertensive rats (SHR).

METHODS AND RESULTS

For 3 weeks, we studied three groups of 20-week-old male SHR: a control group, a l-NAME group, and a group treated with L-NAME and the ACE inhibitor imidapril. L-NAME rats developed severe hypertensive nephrosclerosis with significantly elevated blood pressure, markedly increased urinary protein excretion and serum creatinine levels, and more severe glomerulosclerosis and tubulo-interstitial changes. Levels of TGF-beta 1 mRNA in the renal tissue was also significantly increased in L-NAME rats compared with control SHR. Addition of imidapril significantly lowered blood pressure, inhibited nephrosclerosis and attenuated the mRNA level of TGF-beta 1 in comparison with L-NAME/SHR. Histologically, the glomerular cell apoptosis labeling index, terminal doxynucleotidil transferase-mediated dUTP nick-end labeling of fragmented DNA (TUNEL) and active caspase-3, and TGF-beta 1 positive areas were also reduced by imidapril.

CONCLUSION

These data suggest that imidapril prevents glomerular and arteriolar damages and renal functions, through inhibiting both TGF-beta 1 production and apoptosis induction.

[Effect of astragalus-angelica mixture on osteopontin expression in rats with chronic nephrosclerosis]

OBJECTIVE

To observe the effect of Astragalus-Angelica Mixture (AAM) on osteopontin (OPN) expression in rats with chronic nephrosclerosis.

METHODS

Chronic nephrosclerosis model rats induced by repeated intraperitoneal injection of puromycin were randomly divided into the model group, AAM group and Irbesartan (an antagonist of angiotensin) group. The experimental course lasted 12 weeks. Blood and urine samples were examined by biochemical method. Kidney tissue was taken for pathological stain and immunohistochemical method and was applied to examine OPN expression, mononuclear macrophage, laminin in extracellular matrix and decorin expressions.

RESULTS

AAM showed the effects of decreasing urinary protein and improving renal function similar to that of Irbesartan. It also could alleviate the pathological damage of kidney tissue, especially in decreasing renal tubular mesenchymal damage index. The accumulation of decorin and laminin in the mesenchymal extracellular matrix significantly decreased. Renal tubular OPN expression and mesenchymal infiltration of mononuclear macrophage decreased significantly and in a positive correlated manner (r = 0.885, P < 0.01).

CONCLUSION

AAM has similar renal protective action to that of Irbesartan, this action may be related to the inhibition of up-regulated OPN expression.

N- and L-type calcium channel antagonist improves glomerular dynamics, reverses severe nephrosclerosis, and inhibits apoptosis and proliferation in an l-NAME/SHR model

OBJECTIVE

To determine the responses of the new dihydropyridine N- and L-type calcium antagonist, cilnidipine, on systemic and renal hemodynamics, glomerular dynamics, renal function, and histopathology in an Nomega-nitro-l-arginine methylester spontaneously hypertensive rat (l-NAME/SHR) model of nephrosclerosis.

METHODS

Five groups of 20-week-old male SHR were studied using renal micropuncture techniques and histopathological analyses: group 1, control; group 2, cilnidipine (10 mg/kg per day) by gavage, for 3 weeks; group 3, l-NAME (50 mg/l) in drinking water, for 3 weeks; group 4, combination of l-NAME and cilnidipine, for 3 weeks; group 5, l-NAME for 3 weeks, followed by cilnidipine for a subsequent 3 weeks.

RESULTS

Cilnidipine significantly reduced mean arterial pressure, total peripheral resistance and renal vascular resistance, while increasing effective renal blood flow and glomerular filtration rate (P < 0.01) in l-NAME/SHR. These hemodynamic changes were associated with significantly increased single nephron glomerular filtration rate (SNGFR) and plasma flow (SNPF) and decreased afferent glomerular arteriolar resistances when cilnidipine was used alone, and with increased SNGFR and SNPF, but decreased glomerular capillary pressure, afferent and efferent arteriolar resistances, urinary protein excretion, serum creatinine and uric acid concentrations (at least P < 0.05) in l-NAME-exacerbated SHR nephrosclerosis. In addition, glomerular and arteriolar injuries were markedly reversed (both P < 0.01), and glomerular apoptosis and cellular proliferation were inhibited and associated with glomerular tuft enlargement and an increase in cell number.

CONCLUSION

Cilnidipine not only prevented, but reversed, the severe renal hemodynamic and glomerular dynamic changes, including apoptosis and glomerular cellular proliferation, in l-NAME/SHR-exacerbated nephrosclerosis. This dual-channel calcium antagonist thus exerted renoprotective pathophysiological effects in the l-NAME/SHR.

Mibefradil prevents L-NAME-exacerbated nephrosclerosis in spontaneously hypertensive rats

OBJECTIVE

To determine the potential renal protective effects of a novel calcium channel blocker mibefradil in chronic renal failure.

METHOD

We compared the long-term effects of mibefradil with an angiotensin-converting enzyme inhibitor cilazapril on blood pressure, proteinuria, renal function and histological alterations in N-nitro-L-arginine methylester (L-NAME)-treated spontaneously hypertensive rats (SHR). Three groups of SHR were studied for 45 days: group 1 (n = 14), treated with L-NAME only (50 mg/l in the drinking water); group 2 (n = 15) L-NAME plus co-treatment with mibefradil (30 mg/kg per day); group 3 (n = 15), L-NAME plus co-treatment with cilazapril (10 mg/kg per day).

RESULTS

Both mibefradil and cilazapril attenuated the increased systolic blood pressure, and prevented the development of proteinuria and the decreased creatinine clearance (Ccr) seen at day 42 in the group treated with L-NAME alone. Notably, mibefradil had similar effects to cilazapril on proteinuria and Ccr, despite a reduced antihypertensive effect All animals receiving mibefradil co-treatment remained alive throughout the experiment, whereas the mortality rate was 43% in SHR treated with L-NAME alone. Both mibefradil and cilazapril completely prevented renal structural damage as assessed by scoring glomerular, tubulo-interstitial and vascular lesions.

CONCLUSIONS

Our data show that mibefradil prevented the development of hypertension and proteinuria, renal functional impairment and nephrosclerosis, and also improved animal survival. The renal protective effects of mibefradil were at least equivalent to those of an ACE inhibitor in this animal model of chronic renal failure.

Strain differences of hypertension induced by dietary NG-nitro-L-arginine in normotensive rats

When the potent inhibitor of nitric oxide (NO) synthesis NG-nitro-L-arginine (L-NNA) was incorporated into the diet, hypertension was induced and sustained due to the effects of the long-term inhibition of endothelium-dependent relaxing factor (EDRF)/NO. The effects of L-NNA on normotensive rats of four strains (Donryu, Sprague-Dawley (SD), Wistar, and Wistar-Kyoto (WKY)) were compared relative to control rats. L-NNA administration caused a sharp initial increase in systolic blood pressure (SBP) at 2 weeks in all animals, and this was followed by a gradual and steady increase until 4 weeks. At the end of the experiments (5 weeks), the mean SBP of Donryu and SD rats was decreased. The maximum blood pressure of Donryu and Wistar rats during the experiments exceeded 200 mmHg, but that of SD and WKY rats was below 200 mmHg. Body weight loss and death were observed only in L-NNA-fed Donryu rats. Pathological changes in the kidneys and the morbidity rates for the lesions were determined, and indicated that the Donryu L-NNA group was 100% positive. These results suggest that the Donryu strain is more sensitive to L-NNA than the other strains. That dietary L-NNA-induced hypertension in normotensive rats of the four strains provides a new artificially-induced hypertensive model in which vasoconstriction occurs mainly due to EDRF deficiency.

ET(A) receptor antagonist ameliorates nephrosclerosis and left ventricular hypertrophy induced in rat by prolonged inhibition of nitric oxide synthesis

We investigated the ability of the ETA receptor antagonist T-0115 and the angiotensin-converting enzyme (ACE) inhibitor imidapril hydrochloride to prevent hypertensive complications induced in rats by chronic inhibition of nitric oxide (NO). Male Wistar rats were given distilled water (control), NG-nitro-L-arginine methyl ester (L-NAME) 500 mg/l, or L-NAME plus imidapril 10 mg/l in the drinking water. In rats treated with L-NAME 500 mg/l plus T-0115, T-0115 was given in the food at a dose of 0.2 mg/g food or 0.6 mg/g food. We then collected 24-h urine samples at 2, 4, and 6 wk, obtained blood samples at 6 wk, and histologically examined the kidney and heart. L-NAME markedly reduced the levels of NO metabolites in serum and urine while increasing the tail-cuff blood pressure, the urinary albumin level (1.90+/-0.65 vs. 0.05+/-0.02 mg/d/100 g in control), and the area of the left ventricular wall (83.3+/-3.0 vs. 69.8+/-1.8 mm2 in control). The plasma renin activity was significantly higher in rats treated with L-NAME than in the control rats. The concomitant administration of T-0115 0.6 mg/g food with L-NAME ameliorated the tail-cuff pressure and the albuminuria (0.56+/-0.23 mg/d/100 g), although to a lesser extent than the changes seen with imidapril 10 mg/l. T-0115 0.6 mg/g food prevented left ventricular hypertrophy as effectively as imidapril 10 mg/l (70.8+/-1.8 with T-0115 vs. 68.3+/-2.7 mm2 with imidapril). Chronic inhibition of NO synthesis produced left ventricular hypertrophy and nephrosclerosis. Our results demonstrate that inhibition of the renin-angiotensin system morely effectively prevents nephrosclerosis than does the blockade of ETA receptors in a model of hypertension induced by chronic NO blockade. However, inhibition of the ET-1 pathway appeared to be as effective as ACE inhibitors in preventing left ventricular hypertrophy in this model.

Hydrochlorothiazide exacerbates nitric oxide-blockade nephrosclerosis with glomerular hypertension in spontaneously hypertensive rats

OBJECTIVE

To determine whether a diuretic can also reverse the clinical, systemic, renal and glomerular haemodynamic and pathological changes caused by nephrosclerosis.

METHODS

Three groups of 20-week-old spontaneously hypertensive rats (SHR) were investigated: control male SHR; a similar group, administered 50 mg/l NG-nitro-L-arginine methyl ester (L-NAME) for 3 weeks; and SHR treated similarly with L-NAME but also with 80 mg/kg per day hydrochlorothiazide (HCTZ) by gavage for 3 weeks.

RESULTS

The mean arterial pressure, cardiac output, effective renal plasma flow and glomerular filtration rate decreased as urinary volume increased in the SHR treated with HCTZ and L-NAME. A micropuncture study demonstrated increased glomerular capillary pressure (PG, 56 +/- 1 versus 68 +/- 3 mmHg) associated with increased efferent (2.1 +/- 0.2 versus 2.9 +/- 0.3 u) but no change in afferent arteriolar resistances compared with the SHR group treated with L-NAME only. In addition, HCTZ administration increased the juxtamedullary glomerular injury score (47 +/- 13 versus 114 +/- 29) associated with elevated urinary protein excretion (35 +/- 1 versus 53 +/- 13 mg/100 g body weight per 24 h) The afferent arteriolar injury score was not changed. The PG elevation was related not only to severe glomerulosclerosis but also to increased fibronectin and alpha-smooth muscle actin deposition.

CONCLUSION

HCTZ administration exacerbated the changes in renal and micropuncture dynamics, proteinuria and histopathological nephrosclerosis produced by L-NAME in SHR.

ACE inhibition prevents and reverses L-NAME-exacerbated nephrosclerosis in spontaneously hypertensive rats

Chronic nitric oxide inhibition exacerbates hypertension and nephrosclerosis in spontaneously hypertensive rats (SHRs). In this study, we determined whether angiotensin-converting enzyme (ACE) inhibition could prevent or reverse the systemic, renal, and glomerular hemodynamic alterations and the pathological changes of nephrosclerosis. Four groups of 20-week-old SHRs were studied: group 1, untreated controls; group 2, treated with N omega-nitro-L-arginine methyl ester (L-NAME, 50 mg/L for 3 weeks); group 3, L-NAME cotreated with quinapril (3 mg.kg-1.d-1 for 3 weeks); and group 4, L-NAME for 3 weeks followed by quinapril for 3 weeks (same doses). The results of this study demonstrated that both cotreatment (group 3) and posttreatment (group 4) with quinapril reduced mean arterial pressure (186 +/- 9 and 192 +/- 9 mm Hg, respectively, compared with group 2 SHRs, 221 +/- 5 mm Hg) and total peripheral resistance index associated with significant reductions in afferent and efferent arteriolar resistances; nephrosclerosis pathological scores; and urinary protein excretion (all at least P < .01). ACE inhibition also significantly increased stroke index, single-nephron glomerular filtration rate, and ultrafiltration coefficient compared with the L-NAME SHRs. Most notable were the findings that cotreatment with quinapril completely prevented the renal glomerular hemodynamic alterations with reduced glomerular capillary hydrostatic pressure and efferent arteriolar resistance compared with both the untreated and the L-NAME-treated SHRs (all at least P < .01). Posttreatment with quinapril also reversed the glomerular injury (subcapsular, -83%; juxtamedullary, -56%) and arteriolar (-87%) injury scores obtained from renal biopsy specimens (P < .005 and P < .0001, respectively). These changes were associated with decreased periarteriolar fibronectin and increased afferent arteriolar alpha-smooth muscle actin deposition (immunohistochemistry). These data, therefore, demonstrate that ACE inhibition not only prevents but also reverses L-NAME-exacerbated severe nephrosclerosis in SHRs, as indicated by improved systemic, renal, and glomerular hemodynamic changes, proteinuria, and histological alterations.

Exercise-induced acute renal failure associated with ibuprofen, hydrochlorothiazide, and triamterene

Nonsteroidal anti-inflammatory drugs predispose to acute renal failure in conditions associated with decreased RBF. Such conditions include advanced age, hypertension, chronic renal insufficiency, diuretic use, and any condition decreasing effective circulating volume. Strenuous exercise also causes marked reductions in RBF. The patient discussed developed severe acute renal failure after strenuous exercise and therapeutic doses of ibuprofen and hydrochlorothiazide-triamterene. Urinalysis showed a nephritic sediment with red blood cell casts. Renal biopsy showed acute tubular necrosis and arteriolar nephrosclerosis. Although exercise-associated acute renal failure is uncommon, susceptible patients with exercise-induced renal ischemia and prostaglandin inhibition may develop this complication.

Kidney tumors induced in rats by the antischistosomal drug niridazole

An increased incidence of kidney tumors was found in MRC rats fed the antischistosomal drug niridazole at four dose levels in the diet. Histologically, the adenomas and adenocarcinomas were solid papillary, clear cell, and tubular types, with the latter type predominating. Seven mesenchymal tumors were found among the 107 renal epithelial neoplasms. Severe nephrosclerosis occurred in both treated and control rats and has been suggested as important in renal carcinogenesis. Niridazole is considered a potent inducer of epithelial kidney tumors.

Heavy metal nephropathy of rodents

Heavy metal nephropathy is a pathologic entity of the renal tubular epithelium of rats, evoked by lead, gold, and other heavy metals. It is characterized acutely by coagulative necrosis, subacutely by cortical fibrosis, and chronically by cytomegaly and karyomegaly. Finally, adenomas develop, some of which become malignant.

[Renal thrombotic microangiopathy with benign hypertension and uremia secondary to oral contraceptives (author's transl)]

A 34-year-old woman developed uremia secondary to severe renal thrombotic microangiopathy after 3 years intake of oral contraceptives. In this particular case manifestation of end stage renal failure was preceded by an unusually long lasting period of nine months with benign hypertension. Even during the final stage (3-4 weeks) prior to complete development of uremia only once hemolysis but no malignant hypertension was observed. Only close long term follow up including renal biopsy and subtile functional tests may provide information whether and/or when hypertension due to oral contraceptives turns to become--at least in part--renal hypertension and also becomes persistent. This observation does not give evidence that benign hypertension causes renovascular damage and thus renal failure. Plasma renin activity was found to be basically elevated and furthermore stimulated e.g. by dialyses. However, this single observation does not permit any conclusion about a pathogenetic role of renin in creating hypertension by e.g. renal vasoconstriction or--despite hypertension--collapse of the capillary network.

[Oral contraceptives, hypertension and nephrosclerosis (author's transl)]

Five personal cases and many reports in the literature demonstrate the not rare development of hypertension after oral contraceptives or an increase of an existing hypertension. In addition, the drug may also cause vascular changes in the kidneys with development of benign or malignant nephrosclerosis, similar to the increased risk of thrombo-embolic complications of the venous-arterial system. It is, therefore, necessary to check the blood pressure of women on oral contraceptive and, if hypertension exists or develops, discontinue these drugs.

Nephrosclerosis postpartum and in women taking oral contraceptives

The condition of a patient with postpartum nephrosclerosis improved during heparin therapy. Review of the literature disclosed 29 other patients with the same histopathologic characteristics, eight of whom also recovered substantial renal function after anticoagulation therapy. Also reported is a patient in whom renal failure occurred while she was taking oral anovulatory agents. Renal biopsy specimen showed the same histopathologic features, which raises the question of similar factors mediating the expression of this disease. We suggest a uniform terminology for this syndrome, either postpartum nephrosclerosis or nephrosclerosis in women taking oral contraceptives.

Toxic glomerulosclerosis-morphology and pathogenesis. Light and electron microscopic studies fo the glomerular changes in the kidney of rats poisoned by N-nitrosomorpholine

75 male rats were given toxic dosage of the hepatotoxin N-nitrosomorpholine (NNM) using varied concentrations over varied time intervals. During and after the toxic dosings the kidneys were examined by light and electron microscopy in order to decide, whether the kidneys are also damaged by NNM. Our studies reveal that under the influence of a low concentration of NNM a distinct thickening of the GBM and an increase of the mesangial matrix occurs (changes referred by us as glomerulosclerosis). When a high concentration of NNM was given, toxic lesions of the mesangial and epithelial cells of the glomeruli were found, but a glomerulosclerosis was not observed during the intoxication. After this toxic dose was stopped, however, a progressive glomerulosclerosis did develop, which at first was accompanied by a transient proliferation of the mesangial cells. The glomerular changes found in the course of poisoning with NNM were interpreted as a direct effect of the NNM. From studies of the formal pathogenesis of the glomerulosclerosis presented here one can conclude that the poisoning leads to a decrease in breakdown of the components of the basement membrane and the mesangial matrix, thus causing the widening of the GBM and the augmentation of the mesangial matrix.

Nephropathy in sucrose-fed rats. Electron and light microscopic studies

Diffuse intercapillary glomerulosclerosis and exudative glomerulosclerosis were produced in rats fed high-sucrose diet for periods of nine to eighteen months. These lesions were observed by light and electron miscroscopy. Impairment of glucose tolerance was observed in the sucrose-fed animals and marked proteinuria developed in the course of long-term sucrose feeding. Such lesions did not develop in a control group of age-matched fed high-starch diets.