alpha-Lipoic acid: the potential for use in cancer therapy.

This review deals with alpha-lipoic acid (LA) from the point of its chemical and biological characteristics affecting enzymatic activities that are part of cellular biochemical processes in normal and cancer cells. This includes attributes of LA that are related to its ability to act as a free-radicals scavenger and also as a radical generator. LA is discussed in the light of its physico-chemical features, toxicity, biochemical bases of LA biological activities, and mechanisms of action. Additionally, it is discussed how these properties of LA are reflected by results of in vivo experiments with cancer cells and in experimental cancer chemotherapy. Finally, the results of LA use in human cancer chemotherapy and as chemopreventive agent are discussed in the light of LA future inclusion into chemotherapeutic protocols.

Protection against cephalosporin-induced lipid peroxidation and nephrotoxicity by (+)-cyanidanol-3 and vitamin E.

The ability of the clinically used cephalosporins: cephalothin, cefotaxime and cefotiam to induce lipid peroxidation (LPO) and renal damage was compared to that of nephrotoxic cephaloridine under in vivo conditions. Glutathione was measured in rat liver or in renal cortex as non-protein sulfhydryls. LPO was measured in plasma, renal cortex and liver by the generation of malondialdehyde or as the increase in renal cortical concentration of conjugated dienes. Impairment of renal function was measured as the decrease in renal cortical accumulation of the organic anion p-aminohippurate (PAH). Administration of cephalosporins to rats as a single dose (2000 mg/kg, ip) induced a significant glutathione-depletion in the renal cortex with cephaloridine, and in the liver with cephaloridine, cephalothin and cefotiam. Treatment of rats with cephaloridine, cephalothin and cefotiam (200, 500, or 1000 mg kg-1 day-1, ip) for 5 days resulted in a dose-dependent increase of LPO in the renal cortex. While cephaloridine induced the highest concentration of conjugated diene, cefotaxime had no effect. Measurements of PAH accumulation in renal cortical slices from cephalosporin-treated rats showed a dose-dependent decrease in the renal cortical accumulation of PAH. Pretreatment with the antioxidants vitamin E or cyanidanol (400 mg kg-1 day-1, ip) 1 h before treatment with cephaloridine, cephalothin or cefotiam (1000 mg kg-1 day-1, ip) for 3 days inhibited cephalosporin-induced LPO and significantly reduced the impairment of renal cortical accumulation of PAH. The potential of different cephalosporins for inducing LPO and reducing PAH accumulation was ranked as follows: cephaloridine > cephalothin > cefotiam > cefotaxime.

Protection against cephalosporin-induced lipid peroxidation and nephrotoxicity by (+)-cyanidanol-3 and vitamin E

The ability of the clinically used cephalosporins: cephalothin, cefotaxime and cefotiam to induce lipid peroxidation (LPO) and renal damage was compared to that of nephrotoxic cephaloridine under in vivo conditions. Glutathione was measured in rat liver or in renal cortex as non-protein sulfhydryls. LPO was measured in plasma, renal cortex and liver by the generation of malondialdehyde or as the increase in renal cortical concentration of conjugated dienes. Impairment of renal function was measured as the decrease in renal cortical accumulation of the organic anion p-aminohippurate (PAH). Administration of cephalosporins to rats as a single dose (2000 mg/kg, ip) induced a significant glutathione-depletion in the renal cortex with cephaloridine, and in the liver with cephaloridine, cephalothin and cefotiam. Treatment of rats with cephaloridine, cephalothin and cefotiam (200, 500, or 1000 mg kg-1 day-1, ip) for 5 days resulted in a dose-dependent increase of LPO in the renal cortex. While cephaloridine induced the highest concentration of conjugated diene, cefotaxime had no effect. Measurements of PAH accumulation in renal cortical slices from cephalosporin-treated rats showed a dose-dependent decrease in the renal cortical accumulation of PAH. Pretreatment with the antioxidants vitamin E or cyanidanol (400 mg kg-1 day-1, ip) 1 h before treatment with cephaloridine, cephalothin or cefotiam (1000 mg kg-1 day-1, ip) for 3 days inhibited cephalosporin-induced LPO and significantly reduced the impairment of renal cortical accumulation of PAH. The potential of different cephalosporins for inducing LPO and reducing PAH accumulation was ranked as follows: cephaloridine > cephalothin > cefotiam > cefotaxime.

Mutagenic and carcinogenic potential of menadione.

Menadione (2-methyl-l,4-naphthoquinone) or vitamin K3 is a lipid-soluble substance and promotes the hepatic biosynthesis of blood clotting factors. Carcinogenic potential of menadione was determined by a DC polarography method in strictly anhydrous N,N-dimethylformamide (DMF) in the presence of alpha-lipoic acid. Superoxide anion formation was measured after incubation of rat lung, liver and kidney microsomes with menadione. The genotoxic potential of menadione was investigated using the unscheduled DNA synthesis (UDS) and alkaline elution assays. The parameter of potential menadione carcinogenicity tg alpha was 0.0025 indicating no carcinogenic activity of menadione. Superoxide anion was generated in a concentration- and time-dependent manner when menadione was incubated with microsomes. In the mammalian cells (A 549) used for alkaline elution and UDS assays, menadione was cytotoxic at concentrations above 20 nmol/ml. The use of S9 mix (metabolic activation) fractions decreased the cytotoxicity of menadione. In the concentration range of above 20 nmol/ml menadione was genotoxic in the UDS test in absence of metabolic activation. In the presence of metabolic activation the menadione-induced DNA damage and repair was greatly reduced. Treatment of A 549 lung cells with 4-nitroquinoline-N-oxide (NQO) caused significant formation of DNA single-strand breaks both in the absence and presence of metabolic activation. Treatment of A 549 lung cells with menadione caused formation of DNA single-strand breaks in the absence of S9 mix. In the presence of metabolic activation menadione caused no significant formation of DNA strand breaks. Menadione-induced DNA repair in A 549 cells was concentration-, time-, and temperature- dependent. Measurement of unscheduled DNA (UDS) synthesis (repair) following treatment with NQO and menadione yielded strong UDS responses in the absence of S9 mix. Taken together the results of these studies suggest the mutagenic potential of NQO and menadione. These results indicate that menadione undergoes redox cycling with formation of reactive oxygen species which cause DNA damage and repair without having a carcinogenic potential.

Angiotensin-(1-7) prevents development of severe hypertension and end-organ damage in spontaneously hypertensive rats treated with L-NAME.

We examined the influence of chronic treatment with ANG-(1-7) on development of hypertension and end-organ damage in spontaneously hypertensive rats (SHR) chronically treated with the nitric oxide synthesis inhibitor L-NAME (SHR-L-NAME). L-NAME administered orally (80 mg/l) for 4 wk significantly elevated mean arterial pressure (MAP) compared with SHR controls drinking regular water (269 +/- 10 vs. 196 +/- 6 mmHg). ANG-(1-7) (24 microg x kg(-1) x h(-1)) or captopril (300 mg/l) significantly attenuated the elevation in MAP due to L-NAME (213 +/- 7 and 228 +/- 8 mmHg, respectively), and ANG-(1-7) + captopril completely reversed the L-NAME-dependent increase in MAP (193 +/- 5 mmHg). L-NAME-induced increases in urinary protein were significantly lower in ANG-(1-7)-treated animals (226 +/- 6 vs. 145 +/- 12 mg/day). Captopril was more effective (96 +/- 12 mg/day), and there was no additional effect of captopril + ANG-(1-7) (87 +/- 5 mg/day). The abnormal vascular responsiveness to endothelin-1, carbachol, and sodium nitroprusside in perfused mesenteric vascular bed of SHR-L-NAME was improved by ANG-(1-7) or captopril, with no additive effect of ANG-(1-7) + captopril. In isolated perfused hearts, recovery of left ventricular function from 40 min of global ischemia was significantly better in ANG-(1-7)- or captopril-treated SHR-L-NAME, with additive effects of combined treatment. The beneficial effects of ANG-(1-7) on MAP and cardiac function were inhibited when indomethacin was administered with ANG-(1-7), but indomethacin did not reverse the protective effects on proteinuria or vascular reactivity. The protective effects of the ANG-(1-7) analog AVE-0991 were qualitatively comparable to those of ANG-(1-7) but were not improved over those of captopril alone. Thus, during reduced nitric oxide availability, ANG-(1-7) attenuates development of severe hypertension and end-organ damage; prostaglandins participate in the MAP-lowering and cardioprotective effects of ANG-(1-7); and additive effects of captopril + ANG-(1-7) on MAP, but not proteinuria or endothelial function, suggest common, as well as different, mechanisms of action for the two treatments. Together, the results provide further evidence of a role for ANG-(1-7) in protective effects of angiotensin-converting enzyme inhibition and suggest dissociation of factors influencing MAP and those influencing end-organ damage.

Modulation of the transforming growth factor beta1 by vitamin E in early nephropathy.

OBJECTIVE: The aim of this study was to investigate the pharmacological activity of an antioxidant, alpha-tocopherol (vitamin E, VE) in streptozotocin-induced diabetic rats and study its role in modulating the transforming growth factor beta1 (TGF-beta1). METHODS: Male Sprague-Dawley rats were treated with streptozotocin to induce diabetes. VE and/or insulin (INS) were administered daily during treatment periods of 3, 5, 7 and 10 days. Plasma glucose and fructosamine were measured in diabetic rats at the end of each treatment period. Samples of plasma, urine and renal cortex were analyzed for changes in protein and lysozyme excretion, reduced glutathione and malondialdehyde formation. TGF-beta1 was determined by ELISA and expression of TGF-beta1 mRNA was investigated by RT-PCR and Northern blot analysis. RESULTS: Diabetes-induced glycemic stress was suppressed by INS, VE or a combination of INS and VE. Diabetes-induced increases of glucose, protein and lysozyme excretion were markedly depressed after 10-day treatment with INS, VE and the combination of INS and VE. Decreased glutathione content in the renal cortex of diabetic rats recovered towards control values, especially after 10-day treatment. Malondialdehyde content increased in diabetic rats and was reduced towards control value following 7- and 10-day treatments. Treatment of diabetic rats with INS, VE or the combination of INS and VE decreased elevated TGF-beta1 in plasma, decreased excretion of TGF-beta1 in urine, and decreased renal cortex TGF-beta1 mRNA levels. CONCLUSIONS: Diabetes-induced overexpression of TGF-beta1 mRNA was suppressed by VE and INS after 5-, 7- and 10-day treatments. The results obtained with the antioxidant VE suggest that oxidative stress is involved in the development of diabetic nephropathy. Therefore, VE treatment may be effective in early stages of diabetic nephropathy to decrease or prevent pathological complications.

Contribution of cytochrome P450 metabolites of arachidonic acid to hypertension and end-organ damage in spontaneously hypertensive rats treated with L-NAME.

1 The purpose of this study was to examine the effect of inhibition of the formation of cytochrome P450 metabolites of arachidonic acid with 1-aminobenzotriazole (ABT) on the development of hypertension and end-organ damage in spontaneously hypertensive rats (SHR) chronically treated with nitric oxide synthesis inhibitor L-NAME (SHR-L-NAME). 2 Administration of L-NAME in drinking water (80 mg l(-1)) to SHR for 3 weeks significantly elevated mean arterial blood pressure (MABP) (223 +/- 4 mmHg) as compared to SHR controls drinking regular water (165 +/- 3 mmHg). The administration of ABT (50 mg kg(-1) i.p. alt diem) for 6 days significantly attenuated elevation of blood pressure in SHR-L-NAME (204 +/- 4 mmHg). 3 L-NAME-induced increase in urine volume and protein was significantly lower in ABT-treated animals. 4 The impaired vascular responsiveness to noradrenaline and isoprenaline in the perfused mesenteric vascular bed of SHR-L-NAME-treated animals was significantly improved by ABT treatment. 5 Morphological studies of the kidneys and hearts showed that treatment with ABT minimized the extensive arterial fibrinoid necrosis, arterial thrombosis, significant narrowing of arterial lumen with marked arterial hyperplastic arterial changes that were observed in vehicle treated SHR-L-NAME. 6 In isolated perfused hearts, recovery of left ventricular function from 40 min of global ischaemia was significantly better in ABT-treated SHR-L-NAME. 7 These results suggest that in hypertensive individuals with endothelial dysfunction and chronic NO deficiency, inhibitors of 20-HETE synthesis may be able to attenuate development of high blood pressure and end-organ damage.

Protective effect of resveratrol against 6-hydroxydopamine-induced impairment of renal p-aminohippurate transport.

In the present study, the effects of resveratrol on 6-hydroxydopamine (6-OHDA)-induced p-aminohippurate (PAH) transport impairment were investigated in vitro using rat renal cortical slices. Cisplatin and cephaloridine (CPH), known nephrotoxins, were used as positive controls. In one series of experiments, renal cortical slices were incubated in a cisplatin-containing medium or a cisplatin-free medium. In another series of experiments, renal cortical slices were incubated in a CPH-containing medium, in a CPH- and probenecid-containing medium, or in a CPH-free medium. Subsequently, for each series of experiments kidney slices were incubated in a media containing PAH or tetraethylammonium. In a further series of experiments, renal cortical slices were incubated in a 6-OHDA-containing medium and in a 6-OHDA-free medium. In another series of experiments, renal cortical slices were incubated in a medium containing 50 micro M 6-OHDA, in a 6-OHDA- and resveratrol-containing medium or in a 6-OHDA- and resveratrol-free medium. Subsequently, for each series of experiments kidney slices were incubated in media containing PAH. The results of this study in which slices were incubated in 6-OHDA-containing media indicate that 6-OHDA induced a time- and concentration-dependent decrease in PAH accumulation by renal cortical slices. Resveratrol inhibited the 6-OHDA-induced time-dependent decrease of PAH accumulation in a concentration-dependent manner. Therefore, 6-OHDA causes functional injuries of renal proximal tubule cell membrane, thus leading to impairment of transport processes across the cell membrane and to nephrotoxicity. Resveratrol has a nephroprotective effect.

Impairment of the renal p-aminohippurate transport induced by 6-hydroxydopamine.

In this study, the effects of 6-hydroxydopamine (6-OHDA) on renal p-aminohippurate transport were investigated in-vitro using rat renal cortical slices. Cisplatin, a known nephrotoxin, was used as positive control. Renal cortical slices were incubated for 60 min in a cisplatin-containing medium (0.83-5.0 microM) at 37 degrees C under a 100% O(2) atmosphere. In another series of experiments, renal cortical slices were incubated in a 3.33 microM cisplatin-containing medium for 15-120 min or in a cisplatin-free medium. Subsequently, for each series of experiments, kidney slices were incubated at 25 degrees C for 90 min in a media containing p-aminohippurate. In a further series of experiments, renal cortical slices were incubated for 60 min in a 6-OHDA containing medium (3.125-100 microM) at 37 degrees C under a 100% O(2) atmosphere. In another series of experiments, renal cortical slices were incubated in a 50 microM 6-OHDA-containing medium for 15-120 min or in 6-OHDA-free medium. Subsequently, for each series of experiments, kidney slices were incubated at 25 degrees C for 90 min in a media containing p-aminohippurate. The results of this study where slices were incubated in 6-OHDA- or cisplatin-containing media indicate that both 6-OHDA and cisplatin induced a time- and concentration-dependent decrease in p-aminohippurate accumulation by renal cortical slices. Therefore, similarly to cisplatin, 6-OHDA causes functional injury of renal proximal tubule cells, leading to impairment of transport processes across the cell membrane.

Comparison of the carcinogenic potential of streptozotocin by polarography and alkaline elution.

The carcinogenic potential of streptozotocin (STZ) was evaluated by the polarographic determination of its reduction potential in the presence of alpha-lipoic acid and detection of DNA single-strand brakes by alkaline elution. After STZ electrochemical reduction in an anhydrous solvent, the half-wave potential (E1/2 ) was determined to be -1.340 V. The parameter of the carcinogenic potential (tg alpha) for STZ was 0.400. This is in good agreement with WHO data regarding STZ carcinogenicity. Additionally, it is in the good agreement with the tg alpha value determined for the positive control used, N-nitroso-N-methylurea (NMU), which was found to be 0.459. The 3 hours exposure of A549 human lung tumor cells to 250, 500, and 1000 nmol/ml STZ was followed by DNA single-strand brakes detection using the alkaline elution method. NMU, the positive control, was tested under identical experimental conditions at the same concentrations. Without metabolic activation, NMU induced a significant formation of DNA single-strand brakes only at 1000 nmol/ml. In the presence of the metabolic activation, NMU caused a significant, concentration-dependent formation of DNA single-strand brakes. In the absence of metabolic activation, STZ induced no significant formation of DNA single-strand brakes at any concentration used. In the presence of metabolic activation, STZ caused a significant, concentration-dependent formation of DNA single-strand brakes. The results of this study underline the crucial role of using a metabolic activation system when carcinogenic potential of drugs and chemicals is investigated in vitro studies. Results of polarographic experiments and alkaline elution correlate well with each other and they indicate that these methods are useful to early predict the carcinogenic potential of STZ and other xenobiotics.

Effect of 6-hydroxydopamine on gluconeogenesis in the rat renal cortex.

1. In the present study, the effects of 6-hydroxydopamine (6-OHDA) on renal gluconeogenesis were investigated in vitro using rat renal cortical slices. Cisplatin, a known nephrotoxin, was used as a positive control. The working hypothesis for the present study was that 6-OHDA, as a reactive oxygen species-producing agent, could inhibit renal gluconeogenesis. 2. 6-Hydroxydopamine is used for chemical sympathectomy because it selectively destroys adrenergic nerve endings. Long-term use of levodopa causes a variety of side-effects in parkinsonian patients. 6-Hydroxydopamine has been reported to be present in the urine of parkinsonian patients on levodopa medication. The renal toxicity of endogenously formed 6-OHDA is a matter of concern in these patients. 3. In one series of experiments, renal cortical slices were incubated for 60 min in medium containing 0.5, 1.0, 2.08, 5.15, 10.30 or 20.60 mg/mL 6-OHDA at 37 degrees C under a 100% O2 atmosphere. In another series of experiments, renal cortical slices were incubated in medium containing 10.30 mg/mL 6-OHDA for 15, 30, 45, 60, 90 or 120 min or in 6-OHDA-free medium. 4. In a second series of experiments, renal cortical slices were incubated for 60 min in medium containing 0.25, 0.50, 0.75, 1.0, 1.25 or 1.50 mg/mL cisplatin at 37 degrees C under a 100% O2 atmosphere. In another set of experiments, renal cortical slices were incubated in medium containing 1 mg/mL cisplatin for 15, 30, 45, 60, 90 or 120 min or in a cisplatin-free medium. 5. The results of the studies in which slices were incubated in 6-OHDA-containing media indicate that 6-OHDA induced a time- and concentration-dependent decrease in renal gluconeogenesis. Therefore, 6-OHDA causes functional injury of renal proximal tubule cells responsible for renal gluconeogenesis, thus leading to nephrotoxicity.

Evaluation of the genotoxic potential of sorbic acid and potassium sorbate.

The genotoxic potential of sorbic acid and potassium sorbate was investigated in vivo and in vitro. Oral administration of sorbic acid (up to 5000 mg/kg body weight) did not induce sister chromatid exchanges or the formation of micronuclei in bone marrow cells of mice. Intraperitoneal treatment of rats with 400-1200 mg potassium sorbate/kg body weight did not alter the elution profile of DNA from isolated liver cells in the in vivo alkaline elution assay. Sorbic acid did not induce DNA repair in cultured human A549 cells in the unscheduled DNA synthesis (UDS) assay. In vitro incubation of the cells with 1-1000 micrograms potassium sorbate/ml, in the absence or presence of rat liver homogenate, did not result in the formation of DNA single-strand breaks in the alkaline elution assay. These results demonstrate that sorbic acid and its potassium salt are not genotoxic in vivo or in vitro. In contrast to sorbic acid and potassium sorbate, sodium sorbate is very sensitive to oxidative degradation; the main oxidation product was identified to be 4,5-oxohexenoate, which was mutagenic in the Ames test.

[Comprehension of the side effect profile of a new substance under development. Experimental toxicological aspects]. / Erfassung des Nebenwirkungsprofils einer neuen Substanz aus der Sicht der Entwicklung. Experimentell toxikologische Aspekte.

The detection of undesirable side effects takes place at several stages in the development of a drug. For this purpose all important endpoints such as acute toxicity, local tolerance, allergenicity, genotoxicity, subchronic/chronic toxicity and reproduction toxicity (male and female fertility, teratogenicity, peri- and postnatal studies) serve to establish the major toxicological characteristics. Comparative metabolism studies are carried out in order to optimize the extrapolation of the results obtained in animal experiments to humans. Special, non-routine studies must be adopted for testing cephalosporins and quinolones. Examples of these are provided.

Absence of genotoxic activity of penbutolol in bacterial and mammalian cell screening systems.

The genotoxic potential of the beta-adrenergic blocker penbutolol was assessed using the Ames and HGPRT tests, unscheduled DNA synthesis (UDS) and alkaline elution assays. In the Ames test, penbutolol was tested for cytotoxicity and genotoxic activity in concentration ranges of 0.8-500 micrograms/plate and 0.1-125 micrograms/ml in the HGPRT, UDS and alkaline elution assays. In the Ames test penbutolol showed significant toxicity above 500 micrograms/plate. In the mammalian cells (V79) used for the HGPRT test and A459 cells used for alkaline elution and UDS assays, penbutolol was cytotoxic at concentrations above 30 micrograms/ml. In another series of experiments, male Wistar rats were treated i.p. with penbutolol (1, 10 and 100 mg/kg) and after 2 h liver nuclei were isolated and formation of single DNA-strand breaks was measured. The results of the present study demonstrate the absence of genotoxic activity of penbutolol in the 5 strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537 and TA1538) and in the strain of Escherichia coli WP2 uvrA in the presence or absence of metabolic activation. In V79 cells, penbutolol showed no mutagenic effects at the HGPRT locus in the presence or absence of metabolic activation. Additionally, no significant incorporation of [3H]thymidine into the DNA in the UDS test or formation of DNA-strand breaks in the alkaline elution assay was detected in the non-toxic concentration range of penbutolol with or without metabolic activation. Furthermore, penbutolol did not cause DNA damage in liver nuclei isolated from penbutolol-treated rats.

Biochemical aspects of the renal tolerance for cefpirome and other cephalosporins.

Effects of cefpirome (CFP, HR 810; CAS 84957-29-9) and other cephalosporins such as cefotaxime (CFX), cephaloridine (CPH) and ceftazidime (CFZ) on the renal biochemical processes such as peroxidation of lipids, organic cation transport or gluconeogenesis were investigated in vitro or after i.v.-administration of cephalosporins to 200 g male Wistar rats. In a series of in vitro experiments renal cortical slices were incubated for 60 min in a cephalosporin free medium or in a cephalosporin containing medium (1.25, 2.5, 5.0 and 10 mg/ml) at 37 degrees C under a 100% O2 atmosphere. Subsequently, peroxidation of lipids (LPO), measured as malondialdehyde (MDA) production, tissue accumulation of the organic cation tetraethylammonium (TEA) and gluconeogenesis were determined. In one series of in vivo experiments, 2 h after i.p.-administration of saline, CFP, CFX, CPH and CFZ (0, 500, 1000 and 2000 mg/kg), rats were killed and the amount of the reduced glutathione (GSH) in the renal cortex was measured. In another series of experiments, CFP, CFX, CPH and CFZ were administered (1200 mg/kg/d, i.v.) for 5 days. Subsequently, the effects of these cephalosporins on MDA production, cytosolic lactate dehydrogenase (LDH) activity, TEA accumulation and gluconeogenesis in the renal cortex were investigated. Results of the in vitro experiments show a significant concentration-dependent increase in MDA production only after incubation of renal cortical slices with CPH. CFZ and CPH caused a dose-dependent decrease in gluconeogenesis and except CFX, all other investigated cephalosporins induced a dose-dependent decrease in TEA accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Peroxidative damage and nephrotoxicity of dichlorovinylcysteine in mice.

Male NMRI mice were treated i.p. with dichlorovinylcysteine (DCVC) in a dosage of 2.5-500 mg/kg-1 and renal cortical slices from naive mice were incubated with 0-125 micrograms/ml-1 DCVC. The effects of DCVC on blood urea nitrogen (BUN), reduced glutathione (GSH) content, malondialdehyde (MDA) production, p-aminohippuric acid (PAH)- and tetraethylammonium (TEA)-accumulation and glucose synthesis (gluconeogenesis) were measured. DCVC depleted GSH in a time- and dose-dependent manner. Depletion of renal cortical GSH by DCVC was more pronounced in the kidney cortex than in the liver. DCVC caused a dose-dependent increase of ethane exhalation and of MDA production in the renal cortex. When animals were kept in a closed system, decrease in oxygen concentration increased the peroxidative damage. No increase of MDA concentration was observed in the liver. Treatment of mice with DCVC induced a dose-dependent increase in BUN and decreased the accumulation of PAH and TEA in renal cortical slices. Pretreatment of mice with aminooxyacetic acid (AOAA) and (+) cyanidanol-3 (CY) caused a significant reduction in DCVC-induced lipid peroxidation and nephrotoxicity. In vitro incubation of renal cortical slices of naive mice with DCVC resulted in a concentration-dependent increase in MDA and a concentration-dependent decrease in the accumulations of PAH, TEA and of gluconeogenesis. In conclusion, the interaction of DCVC and/or its metabolites with membrane lipids may be responsible for lipid peroxidation and nephrotoxicity. The formation of lipid peroxidation products was greater under hypoxic conditions and appeared to be related to the DCVC-induced nephrotoxicity. This data suggests lipid peroxidation as a possible mechanism of DCVC-induced nephrotoxicity.

Lipid peroxidation: a possible mechanism of trichloroethylene-induced nephrotoxicity.

The purpose of this study was to investigate whether lipid peroxidation plays a role in (TCE) trichloroethylene-induced nephrotoxicity in mice at different oxygen concentrations. Male NMRI mice (25-30 g) were treated i.p. with TCE in a dosage of 125-1000 mg/kg in sesame oil. To determine the TCE-induced depletion of reduced glutathione (GSH) in the kidney cortex and liver tissue, mice were given 1000 mg/kg TCE i.p., then killed between 0 and 6 h after TCE administration and GSH was measured was non-protein sulfhydryls. In another series of experiments, mice were administered 125 to 1000 mg/kg TCE i.p. with or without a 2 h i.p. pretreatment with 1500 mg/kg L-buthionine-S-R-sulfoximine (BSO). Mice were then exposed to a 10, 15, 20 or 100% oxygen atmosphere for 3 h and lipid peroxidation in vivo was measured as exhalation of ethane. Subsequently, mice were killed and malondialdehyde (MDA) generation was measured in the liver and kidney cortex. Ethane evolution was estimated by gas chromatography and MDA was determined as thiobarbituric acid reactive substances. In a further series of experiments mice were treated in the same manner as for ethane and MDA determination and the changes in blood urea nitrogen (BUN) and accumulation of the organic ion p-aminohippurate (PAH) were determined. PAH accumulation by renal cortical slices were measured as the slice to medium (S/M) ratio. Six hours after administration of 1000 mg/kg TCE to mice, GSH was significantly depleted to about 60% of control in the kidney cortex but not in the liver. Three hours after TCE administration, MDA content in the kidney cortex and ethane exhalation increased in a dose-dependent manner only under a 10% oxygen atmosphere. Under the same experimental conditions, MDA content remained unchanged in the liver. BSO depletion of GSH prior TCE administration induced an increase of the MDA content in the kidney cortex and an increase of the ethane exhalation in vivo. At 10% oxygen concentration, TCE induced a dose-dependent increase in BUN and a dose-dependent decrease of PAH accumulation by the renal cortical slices. Thus, the results of the present study suggest that, under hypoxic conditions, lipid peroxidation plays a role in TCE nephrotoxicity.

Sex differences in nephrotoxic and gastrointestinal effects of phenylbutazone.

Male and female Wistar rats were used to study the sex differences in nephrotoxic, ulcerogenic and lethal effects of phenylbutazone (PBZ). In one series of experiments, male and female rats were given daily oral doses of 25, 125, 250, 400 and 500 mg PBZ/kg for 7 days to assess mortality, gross and microscopic lesions of the stomach, intestine and kidneys and to determine the PBZ effects on renal protein and glucose excretion. In another series of experiments, PBZ effects on renal gluconeogenesis and p-aminohippurate (PAH) accumulation in renal cortical slices were measured 12 h after administration of the same PBZ doses to male and female rats. Reduced glutathione (GSH) depletion and malondialdehyde (MDA) content in kidney cortex and liver were determined 2 h after a single administration of 250 mg PBZ/kg to male and female rats. To measure the effects of PBZ on blood urea nitrogen (BUN), male and female rats were given a single dose of PBZ (125 mg/kg) and were sacrificed at different time intervals, from 0 to 48 h. Gross and microscopic examination of the kidneys and gastrointestinal tract showed more pronounced renal and gastrointestinal lesions in surviving female than in male rats at the same doses. In PBZ treated male rats, BUN did not differ from control rats 48 h after PBZ administration. In female rats, BUN increased from 18 to 96 mg/100 ml 48 h after PBZ administration. After 7 days of PBZ treatment there was a greater increase of protein excretion in female than in male rats, but there were almost no sex differences in glucose excretion. Twelve hours after PBZ administration, renal PAH accumulation and gluconeogenesis were not different from controls in male rats but decreased in a dose-dependent fashion in females. A significant depletion of GSH and a significant increase in MDA content in liver and renal cortex occurred in female but not in male rats. In conclusion, the PBZ treatment was associated with nephrotoxic and gastrointestinal effects which could be detected earlier and were greater in female than in male rats.