Kidney Of Wistar Rats Research Articles

Mycotoxin fumonisin B 1 alters cellular redox balance and signalling pathways in rat liver and kidney

Mycotoxin fumonisin B 1 (FB 1) is a frequent contaminant of grain, particularly maize, but the mechanism of its toxicity in the kidney and liver is not fully understood. FB 1-stimulated oxidative stress might disturb cellular redox state and signal transduction pathways of the target cells. In this study we measured total intracellular glutathione (GSH), and assessed mitogen-activated protein kinases (MAPKs) activation and the expression of heat shock proteins (Hsps) Hsp25 and Hsp70 in the liver and kidney of male Wistar rats given 0.5 mg FB 1/kg b.w. intraperitoneally for 2 or 7 days. The effect of FB 1 on GSH levels, MAPK activation and Hsp expression was found to be related to the type of tissue affected and the length of treatment. In rat liver, cellular GSH content increased, Hsp expression was up-regulated, and ERK and p38 were activated after the 7-day treatment, while even the 2-day treatment sufficed to produce phospho-JNK signal. In rat kidney, GSH levels decreased after the 2- and 7-day treatment with FB 1, while after the 7-day treatment all three MAPKs were activated, Hsp25 expression increased and Hsp70 expression decreased. In conclusion, FB 1 alters cellular redox balance, which leads to tissue-specific activation and expression of redox-sensitive signalling molecules. It seems that kidney cells are more sensitive to adverse effects of FB 1.

Purification and renal effects of phospholipase A 2 isolated from Bothrops insularis venom

Bothrops insularis venom contains a variety of substances presumably responsible for several pharmacological effects. We investigated the biochemical and biological effects of phospholipase A 2 protein isolated from B. insularis venom and the chromatographic profile showed 7 main fractions and the main phospholipase A 2 (PLA 2) enzymatic activity was detected in fractions IV and V. Fraction IV was submitted to a new chromatographic procedure on ion exchange chromatography, which allowed the elution of 5 main fractions designated as IV-1 to IV-5, from which IV-4 constituted the main fraction. The molecular homogeneity of this fraction was characterized by high-performance liquid chromatography (HPLC) and demonstrated by mass spectrometry (MS), which showed a molecular mass of 13984.20 Da; its N-terminal sequence presented a high amino acid identity (up to 95%) with the PLA 2 of Bothrops jararaca and Bothrops asper. Phospholipase A 2 isolated from B. insularis (Bi PLA 2 ) venom (10 μg/mL) was also studied as to its effect on the renal function of isolated perfused kidneys of Wistar rats ( n=6). Bi PLA 2 increased perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). Sodium (%TNa +) and chloride tubular reabsorption (%TCl −) decreased at 120 min, without alteration in potassium transport. In conclusion, PLA 2 isolated from B. insularis venom promoted renal alterations in the isolated perfused rat kidney.

Enhancement of dissolution amount and in vivo bioavailability of itraconazole by complexation with β-cyclodextrin using supercritical carbon dioxide

The main objective of this study was to improve the inclusion formation between itraconazole and β-cyclodextrin and thus enhance dissolution amount and bioavailability characteristics of itraconazole. Inclusion complexes between itraconazole and β-cyclodextrin were prepared using simple physical mixing, conventional coprecipitation method, and supercritical carbon dioxide (SC CO 2). Effects of process variables (temperature, pressure) and drug:cyclodextrin ratio on inclusion yield and thermal behavior of the solid complexes prepared by SC CO 2 were studied and compared to those obtained by physical mixing and coprecipitation methods. In addition, dissolution amounts of the products obtained by different methods were measured in gastric fluid. Finally, pharmacokinetic studies of the inclusion complexes were conducted in male Wistar rats to assess the bioavailability of the prepared complexes. Results showed that temperature, pressure and itraconazole:β-cyclodextrin ratio had significant effects on the inclusion yield of the complex prepared by SC CO 2 method. Higher inclusion yields were obtained in the SC CO 2 method as compared to physical mixing and coprecipitation methods. In vivo drug pharmacokinetic studies showed that the itraconazole-β-cyclodextrin product prepared using SC CO 2 gave higher bioavailability of itraconazole (in blood, liver and kidney of male Wistar rats) as compared to the products obtained by physical mixing or coprecipitation methods.

Differential expression of cytochrome p450 induced by smokeless tobacco mediates genotoxic damage in rats

Introduction: The use of smokeless tobacco (ST) is popular in USA, Europe and South East Asian countries. Apart from oral cancer, the molecular mechanisms involved in other ST-related health effects are unknown. Hence, the effects of chronic use of aqueous extract of ‘gutkha’ (AEGT) on cytochrome p450 (cyp) mediated genotoxic damage in liver, lung, and kidney of male Wistar rats were studied. Materials and Methods: Animal Experiments were conducted after Institutes Animal Ethical Clearance. The lyophilized AEGT was orally administered to animals at a low-dose (96 mg/kg body weight/day) for 2 and 32 weeks, and at a high-dose (960 mg/kg body weight/day) for 2 weeks. The immunohistochemical expression of cyp1A1, 1A2, 2E1 and GST-μ; myeloperoxidase (MPO) and caspase-3 activity and DNA fragmentation in above organs and plasma TNF-α, protein carbonyls and blood micronuclei formation were measured. Results: Low-dose of AEGT administration for 32 weeks differentially expressed the lung, liver and kidney cyp1A1, 1A2, 2E1 and GST-μ. There was significant increase (p<0.05) in MPO, caspase-3 activity and DNA fragmentation. The extent of this increase was less due to high-dose of AEGT for 2 weeks. High-dose and low-dose AEGT for 2 and 32 weeks significantly enhanced plasma TNF-α by 7% and 23%, protein carbonyls by 4% and 12% respectively. Micronuclei formation in whole blood was increased by 14% in long term group. Conclusion: Chronic use of AEGT induces cytochrome p450's, which mediates genotoxic damage in various organs of rats. The differential damage by AEGT may be due to variable sensitivities and functions carried out by these organs. These changes may be responsible for AEGT-induced pathogenesis. Supported by PGIMER, Chandigarh, India.

Glucose regulation of CDK7, a putative thiol related gene, in experimental diabetic nephropathy

We previously described the identification of the 3′end of an unknown gene CDK7 using differential display which appeared to be up-regulated in diabetic kidneys [R.A. Page, C.A. Morris, J.D. Williams, C.J. von Ruhland, A.N. Malik, Isolation of diabetes-associated kidney genes using differential display, Biochem. Biophys. Res. Commun. 232 (1997) 49–53]. Here we show that CDK7 is a putative thiol related gene which is regulated by glucose in human and rat renal cells. CDK7 mRNA increased by >threefold in cultured human mesangial cells grown in high glucose for 4 days. In the kidneys of the GK rat, a model of type II diabetes, CDK7 showed a steady age-related increase in mRNA, increasing to >sixfold in 40 week GK rats compared to normoglycemic age-matched Wistar rat kidneys, this increase correlates with progressive hyperglycemia. CDK7 mRNA is widely expressed, showing particularly high levels of expression in rat and human liver, and encodes a putative 338 amino acids highly conserved peptide with several conserved domains, including a cys-pro-arg-cys domain conserved in 15 diverse species which is similar to the catalytic centre of thioredoxin, suggesting a role in oxidative stress.

Histological studies of the effects of monosodium glutamate on the kidney of adult Wistar rats

The effect of monosodium glutamate, used as food additive on the Kidneys of adult wistar rat was investigated. Both adult male and female Wistar rats (n=24) average weight of 185g were randomly assigned into two treatments (n=12) and control (n=6) groups. The rats in the treatment groups received 3g and 6g of Monosodium glutamate thoroughly mixed with the grower's mash daily for fourteen days. The control rats received equal amount of the grower's mash without Monosodium glutamate added daily. The grower's mash was obtained from Edo Feeds and Flour Mill Ltd, Ewu, Edo State and the rats were given water liberally. The rats were sacrificed on day fifteen of the experiment. The Kidneys were carefully dissected out and quickly fixed in 10% formal saline for histological procedures. Histological changes observed in the treated kidney sections included the distortion of the renal cortical structures and some degree of cellular necrosis. Our results suggested that the functions of the kidney could have been adversely affected due to the distortion of the cyto-architecture of the renal cortical structures and cellular necrosis associated with the kidney. It is recommended that further studies aimed at corroborating these observations be carried out.

DNA damage by ochratoxin A in rat kidney assessed by the alkaline comet assay

There are few studies of ochratoxin A (OTA) genotoxicity in experimental animals and the results obtained with cell cultures are inconsistent, although the carcinogenic potential of OTA for the kidney of experimental animals has been well established. We studied the genotoxic potential of OTA in the kidney of adult female Wistar rats (5 in each group) treated intraperitoneally with OTA (0.5 mg kg body weight-1 day-1 for 7, 14, and 21 days) measuring DNA mobility on agarose gel stained with ethidium-bromide using standard alkaline single-cell gel electrophoresis (comet assay). Negative control animals were treated with solvent (Tris buffer, 1.0 mg/kg) and positive control animals were treated with methyl methanesulfonate (40 mg/kg) according to the same schedule. OTA concentrations in plasma and kidney homogenates in 7-, 14-, and 21-day treated animals were 4.86 ± 0.53, 7.52 ± 3.32, 7.85 ± 2.24 µg/mL, and 0.87 ± 0.09, 0.99 ± 0.06, 1.09 ± 0.15 µg/g, respectively. In all OTA-treated groups, the tail length, tail intensity, and tail moment in kidney tissue were significantly higher than in controls (P < 0.05). The tail length and tail moment were higher after 14 days than after 7 days of treatment (P < 0.05), and still higher after 21 days (P < 0.05). The highest tail intensity was observed in animals treated for 21 days, and it differed significantly from animals treated for 7 and 14 days (P < 0.05). OTA concentrations in plasma and kidney tissue increased steadily and OTA concentration in kidney tissue strongly correlated with tail intensity and tail moment values. These results confirm the genotoxic potential of OTA, and show that the severity of DNA lesions in kidney correlates with OTA concentration.

DNA damage by ochratoxin A in rat kidney assessed by the alkaline comet assay

There are few studies of ochratoxin A (OTA) genotoxicity in experimental animals and the results obtained with cell cultures are inconsistent, although the carcinogenic potential of OTA for the kidney of experimental animals has been well established. We studied the genotoxic potential of OTA in the kidney of adult female Wistar rats (5 in each group) treated intraperitoneally with OTA (0.5 mg kg body weight-1 day-1 for 7, 14, and 21 days) measuring DNA mobility on agarose gel stained with ethidium-bromide using standard alkaline single-cell gel electrophoresis (comet assay). Negative control animals were treated with solvent (Tris buffer, 1.0 mg/kg) and positive control animals were treated with methyl methanesulfonate (40 mg/kg) according to the same schedule. OTA concentrations in plasma and kidney homogenates in 7-, 14-, and 21-day treated animals were 4.86 +/- 0.53, 7.52 +/- 3.32, 7.85 +/- 2.24 microg/mL, and 0.87 +/- 0.09, 0.99 +/- 0.06, 1.09 +/- 0.15 microg/g, respectively. In all OTA-treated groups, the tail length, tail intensity, and tail moment in kidney tissue were significantly higher than in controls (P < 0.05). The tail length and tail moment were higher after 14 days than after 7 days of treatment (P < 0.05), and still higher after 21 days (P < 0.05). The highest tail intensity was observed in animals treated for 21 days, and it differed significantly from animals treated for 7 and 14 days (P < 0.05). OTA concentrations in plasma and kidney tissue increased steadily and OTA concentration in kidney tissue strongly correlated with tail intensity and tail moment values. These results confirm the genotoxic potential of OTA, and show that the severity of DNA lesions in kidney correlates with OTA concentration.

Effect of gallic acid on renal biochemical alterations in male Wistar rats induced by ferric nitriloacetic acid

The present study is an effort to identify a potent chemopreventive agent against various diseases (including cancer) in which oxidative stress and cell proliferation plays an important causative role. This study was designed to investigate the effect of gallic acid against ferric nitrilotriacetic acid (Fe-NTA)-induced carcinogen/ drug metabolizing phase I and phase II enzymes, antioxidative parameters, kidney markers, tumour promotion markers and lipid peroxidation (LPO) in kidney of male Wistar rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) caused significant depletion in the detoxification and antioxidant enzyme armoury with concomitant elevation in renal LPO, serum creatinine, blood urea nitrogen, hydrogen peroxide generation, ornithine decarboxylase activity and [3H]thymidine incorporation into renal DNA. However, pretreatment of animals with gallic acid (10 and 20 mg/kg body weight) resulted in a significant decrease in the levels of the parameters measured (P <0.001). Renal glutathione content (P <0.001), glutathione metabolizing enzyme (P <0.001) and antioxidant enzyme levels were also recovered to a significant level (P <0.001). The enhanced reduced glutathione level and enzyme activities involved in xenobiotic metabolism and maintaining antioxidant status of cells are suggestive of a chemopreventive efficacy of gallic acid against Fe-NTA-mediated oxidative stress, toxicity and cell proliferative response in Wistar rats.

Inhibition of Creatine Kinase Activity by Cystine in the Kidney of Young Rats

Nephropathic cystinosis is a lethal genetic disease caused by a lysosomal transport disorder leading to intralysosomal cystine accumulation in all tissues. Cystinosis is the most common inherited cause of Fanconi syndrome, but the mechanisms by which cystine causes tissue damage are not fully understood. Thiol-containing enzymes are critical for renal energy metabolism and may be altered by disulfides like cystine. Therefore, in the present study our main objective was to investigate the in vivo and in vitro effects of cystine on creatine kinase, which contains critical thiol groups in its structure, in the kidney of young Wistar rats. We observed that cystine inhibited in vivo and in vitro the enzyme activity and that this inhibition was prevented by cysteamine and glutathione. The results suggest oxidation of essential sulfhydryl groups necessary for creatine kinase function by cystine. Considering that creatine kinase and other thiol-containing enzymes are crucial for renal energy metabolism, and programmed cell death occurs in situations of energy deficiency, the enzyme inhibition caused by cystine released from lysosomes might be a mechanism of tissue damage in patients with cystinosis.

Feeding Period of Selenium-Deficient Diet and Response of Redox Relating Minerals

Dynamics of redox relating biotrace elements, selenium (Se), iron (Fe), and zinc (Zn) in liver, kidney, and spleen of selenium deficient Wistar male rats in a series of feeding period (from 0 to 8 weeks) were studied using instrumental neutron activation analysis (INAA). Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and blood urea nitrogen (BUN) for the plasma fraction of the rat bloods and the concentration of vitamin C and vitamin E in the liver homogenates were measured. The initial purpose of this study was to find Fe and Zn as sensitive indices of the tissue oxidative stress levels. However, the relationships among the biotrace elements and the oxidative stress/injury were much complicated. Control group, which was fed Se-deficient diet with Na2SeO4 (0.1 mg selenium/l) in drinking water, showed strange response of Se and Zn contents in the kidney and showed high BUN. Supplementation of inorganic Se by biased Se source may serve as another source of a stress especially in the kidney. The Fe and Zn contents in the liver and kidney look sensitive to the Se-deficiency and/or relating oxidative stresses. Short term exposure to the Se-deficiency appeared to consume Fe and Zn in the liver and kidney. In contrast, long term or chronic exposure to Se-deficiency appeared to accumulate Fe and Zn in liver and kidney.

Smokeless Tobacco Impairs the Antioxidant Defense in Liver, Lung, and Kidney of Rats

The present study was designed to evaluate the effects of long-term use of aqueous extract of gutkha (a form of smokeless tobacco) on the antioxidant defense status and histopathological changes in liver, lung, and kidney of male Wistar rats. Animals were orally administered aqueous extract of smokeless tobacco (AEST) at a low dose (96 mg/kg body weight per day) for 2 and 32 weeks, and at a high dose (960 mg/kg body weight per day) for 2 weeks. High-dose AEST for 2 weeks decreased the hepatic glutathione (GSH) and glutathione peroxidase (GPx), and increased lipid peroxidation (Lpx) by 17%, 19%, and 20%, respectively. Low-dose AEST for 32 weeks significantly decreased (p < 0.05) the antioxidant status in these organs. In liver, AEST decreased GSH levels and the activities of superoxide dismutase (SOD), catalase (CAT), and GPx by 34.6%, 29%, 17.1%, and 17.4%, respectively, but it increased Lpx by 64%. In kidney, GSH, SOD, CAT, and GPx were decreased by 26.6%, 23%, 33%, and 18%, respectively, with an increase of Lpx by 65%. AEST decreased the lung GSH, SOD, CAT, and GPx, and increased lung Lpx by 43%, 28.5%, 37%, 40%, and 24%, respectively. However, no change in the plasma levels of vitamins A, C, and E were observed with AEST treatment. Histopathological findings suggest that administration of AEST at the high dose for 2 weeks or at the low dose for 32 weeks could cause mild to moderate inflammation in liver and lungs. In conclusion, a decrease in the antioxidant defense system and long-term inflammation caused by smokeless tobacco may be risk factors for gutkha-induced pathogenesis.

Ultrastructural changes during in situ early postmortem autolysis in kidney, pancreas, liver, heart and skeletal muscle of rats

Many morphological studies of the postmortem interval were carried out under conditions in which the tissue was incubated in vitro after extirpation. However, the extirpation affects cell viability. We examined the ultrastructural changes in the kidney, pancreas, liver, heart and skeletal muscle of male Wistar rats occurring postmortem in situ. In each organ, cell edema (cell swelling), appearance of amorphous dense deposits in the mitochondria, loss of glycogen granules, dilation of the endoplasmic reticulum, clumping and margination of nuclear chromatin, and/or condensation of nuclear chromatin were observed, but the duration of the period of ultrastructural change was organ specific. Most of the ultrastructural changes occurred earlier in kidney. In hepatocytes, the morphological degeneration occurred later than in the renal tubule epithelium and earlier than that in the myocardium. Of the five organs we examined, skeletal muscle showed the greatest delay in postmortem change. In the distal tubule epithelium and pancreatic acinar cells, two forms of nuclear change were seen: one resembled necrotic change and the other resembled apoptotic change. The effect of lysosomes and hydrolytic enzymes was not as great as previous findings.

Estrogen modulates ClC-2 chloride channel gene expression in rat kidney.

ClC-2 is a CLC family member of chloride channels sensitive to changes in cell volume, pH and voltage. The ClC-2 is widely distributed along the nephron although in the kidney its role still not well understood. Aldosterone studies suggest that ClC-2 expression in the kidney may be hormonally regulated. To explore the possibility that estrogen control ClC-2 expression, we investigated whether its expression changed in the kidney of female Wistar rats subjected to ovariectomy with or without near-physiological or high doses of 17beta-estradiol benzoate treatment for 10 days. Total RNA isolated from rat kidney and dissected nephron segments was analyzed by ribonuclease protection assay and/or a semi-quantitative RT-PCR. The renal ClC-2 protein expression was analyzed by Western blot. The decreased renal expression of ClC-2 mRNA and protein observed in ovariectomized rats was restored to control levels after treatment with low doses of estradiol. Higher dose estradiol lead to an even greater increase in ClC-2 mRNA and protein expression. This change in overall expression was shown to be caused by the modulation of ClC-2 mRNA expression in the proximal tubule. These results suggest that ClC-2 may be involved in estrogen-induced Cl(-) transport in rat kidney.

Platelet-activating factor and solute transport processes in the kidney.

We examined the hemodynamic and tubular transport mechanisms by which platelet-activating factor (PAF) regulates salt and water excretion. In anesthetized, renally denervated male Wistar rats, with raised systemic blood pressure and renal arterial blood pressure maintained at normal levels, intrarenal PAF infusion at 2.5 ng. min(-1) x kg(-1) resulted in a small fall in systemic blood pressure (no change in renal arterial blood pressure) and an increase in renal blood flow and urinary water, sodium, and potassium excretion rates. The PAF-induced changes in cardiovascular and renal hemodynamic function were abolished and renal excretory function greatly attenuated by treating rats with a nitric oxide synthase inhibitor. To determine whether a tubular site of action was involved in the natriuretic effect of PAF, cortical proximal tubules were enzymatically dissociated from male Wistar rat kidneys, and oxygen consumption rates (Qo(2)) were used as an integrated index of transcellular sodium transport. PAF at 1 nM maximally inhibited Qo(2) in both untreated and nystatin-stimulated (sodium entry into renal cell is not rate limiting) proximal tubules by approximately 20%. Blockade of PAF receptors or Na(+)-K(+)-ATPase pump activity with BN-52021 or ouabain, respectively, abolished the effect of PAF on nystatin-stimulated proximal tubule Qo(2). Inhibition of nitric oxide synthase or guanylate cyclase systems did not alter PAF-mediated inhibition of nystatin-stimulated proximal tubule Qo(2), whereas phospholipase A(2) or cytochrome-P-450 monooxygenase inhibition resulted in a 40-60% reduction. These findings suggest that stimulation of PAF receptors on the proximal tubule decreases transcellular sodium transport by activating phospholipase A(2) and the cytochrome-P-450 monooxygenase pathways that lead to the inhibition of an ouabain-sensitive component of the basolateral Na(+)-K(+)-ATPase pump. Thus PAF can activate both an arachidonate pathway-mediated suppression of proximal tubule sodium transport and a nitric oxide pathway-mediated dilatory action on renal hemodynamics that likely contributes to the natriuresis and diuresis observed in vivo.

Effect of Chromium on Certain Aspects of Metabolic Toxicities

The impact of chromium exposure was studied in the liver, kidney, testis, spleen, cerebrum, and cerebellum of male Wistar rats (80-100 g body weight). It was observed that treatment of rats with chromium (ip, at a dose of 0.8 mg/100 g body weight/day) for a period of 28 days caused significant increase in chromium content while lowering the body weight along with the organ weight, except for the liver. It was also observed that there was a significant decrease in the DNA content of various organs tested. Also, a significant decrease in RNA content was observed in all the organs tested except for the testes. The liver, cerebrum, and cerebellum showed significant decreases in total protein content in chromium-treated animals, whereas the kidney, testes, and spleen showed insignificant alterations. The RNase activity was found to be significantly increased only in the testes and cerebrum. Pronase activity was significantly increased in the tissues, except for the liver. The glutamic-pyruvic acid transaminase activity decreased in all the tissues studied. On the other hand, glutamic-oxaloacetic acid transaminase activity increased in the liver, cerebrum, and cerebellum while decreasing in the kidney and spleen. It is suggested that chromium exposure at the present dose and duration induces metabolic toxicity in the form of depressive effects on nucleic acids and altered activities of RNase, pronase, and transaminases in tissues. The extent of such alterations varies from tissue to tissue and is in some cases diverse in nature.

Histological and Histochemical Alterations in the Kidney Induced by Lead

Although lead intoxication is one of the most common forms of metal intoxication, the histochemical alterations in the renal tissues due to chronic lead exposure is limited and has not yet been well identified. A total of 60 male Wistar albino rats (Rattus norvegicus) were exposed to lead acetate trihydrate (0.0, 0.25, 0.5, 1.0 and 2% for 1 to 12 months) in drinking water to investigate the histological and histochemical alterations in the renal tissues due to lead. Chronic exposure to subtoxic doses of lead produced distinct progressive tubular, glomerular and interstitial damages. Tubular changes occurred earlier than glomerular and interstitial ones, and included anisokaryosis, nuclear pyknosis, karyomeglay, development of intranuclear and cytoplasmic inclusions together with tubular dilation, necrosis, vacuolization, tubular hyperplasia and solid tubular adenoma. The glomerular alterations were mainly mesangial hypercellularity, segmental proliferation, focal and segmental glomeruloscleriosis, glomerural hyalinization and glomerular tuft alterations. The findings indicate that lead produces significant histological and histochemical changes in the kidney that lead to severe complications.

Effects of inhibition of glycation and oxidative stress on the development of diabetic nephropathy in rats

We investigated whether aminoguanidine (AG), an inhibitor of advanced glycated end product formation, or probucol (PB), a free radical scavenger, could influence signs of glomerular and distal tubular function and morphological changes in kidneys of male Wistar rats after 6 months of streptozocin (STZ)-induced diabetes. Diabetic rats had a higher kidney weight/body weight ratio ( P<.001), but neither AG nor PB influenced the increased ratio. Diabetes caused an increased urinary albumin excretion ( P<.05), which was normalized by AG, but further exaggerated by PB ( P<.001). Diabetes also caused an increase in the urinary excretion of Tamm–Horsfall protein ( P<.001). Both AG and PB attenuated this increase ( P<.05 for both). A few glomeruli displayed focal thickening of varying degrees. Silver staining disclosed the glomerulopathy to be intercapillary glomerulosclerosis. Rats on PB-enriched diet displayed less pronounced changes than untreated rats ( P<.01), while AG had no effect. The results suggest that oxidative stress could be involved in the development of diabetic nephropathy.

Effect of Heat-Treated Proteins on Selected Parameters of the Biotransformation System in the Rat

The intake of heat-damaged proteins from food causes various effects, like the loss of essential amino acids and a reduced protein digestibility. There is also an influence on gastrointestinal microorganisms and different digestion enzymes. Until now, very little is known about the influence of heat-treated proteins on the enzymes of the biotransformation system. In the present study, the influence of protein-bound L-lysino-D,L-alanine, N^Ε-fructoselysine, and N^Ε-carboxymethyllysine (CML) on selected enzymes of the biotransformation in liver, kidney, and intestinal mucosa of male Wistar rats was examined. The contents of cytochrome P-450 and cytochrome b₅ and the activity of NADPH-cytochrome c reductase served as indicators of phase I biotransformation. The influence on phase II biotransformation was shown by the content of glutathione and the glutathione S-transferase activity. The results showed that treatment with heat-damaged proteins mainly affected phase II biotransformation enzymes with CML, yielding the strongest effect. The activity of glutathione S-transferase in the kidney was 86% higher in animals treated with diets containing 4,930 mg·kg^–1 protein-bound CML than in animals of the control group which received a diet without any detectable CML. In addition, a higher level of glutathione was found in the kidneys of animals fed on diets containing CML. The glutathione S-transferase activity was 64% higher in the intestinal mucosa of animals fed on protein-bound N^Ε-fructoselysine (2,700 mg·kg^–1). The glutathione S-transferase activity was higher (p >0.05) in the intestinal mucosa of animals fed on protein-bound L-lysino-D,L-alanine (2,582 and 12,474 mg·kg^–1). In conclusion, ingestion of heat-treated proteins led to an activation of the enzymes of phase II biotransformation. Whether or not the released pure compounds or the degradation products of the test proteins are responsible for the altered enzyme activities remains to be evaluated.

Regulation of Na+/H+ exchanger by urogastrone, a potent activator of cell proliferation

We tested the effects of epidermal growth factor (EGF) on Na+/H+ exchanger (NHE) activity using urogastrone for treatment of Wistar rats and rat kidney tissue slices. NHE activity was monitored in isolated kidney brush border membrane vesicles by following fluorescence quenching of acridine orange. A significant increase of NHE activity was detected as early as 5 min after addition of urogastrone to rat kidney slices in vitro. In Wistar rats treated with urogastrone we also found increased NHE activity (by about 12 %). Both changes of NHE activity were the result of a significant rise of Vmax value and an apparent decrease in Km value in in vitro experiments. The rise of NHE activity caused by urogastrone was sensitive to the inhibitors of transcription and translation. The presence of phosphatase inhibitor, NaF, elevated NHE activity of non-stimulated as well as of urogastrone-stimulated exchanger, suggesting that phosphorylation plays an important role in Na+/H+ exchange. Osmolarity of the medium seems to regulate NHE activity in such a manner that both hyper- and hypoosmolar conditions inhibited NHE activity. The absence of Ca2+ions produced a 60 % decrease of NHE activity. The chemical modification of histidine residues with diethyl pyrocarbonate or SH groups with N-ethylmaleimide inhibited NHE activity.