The renal fractional clearance of platinum antitumour compounds in relation to nephrotoxicity

The fractional renal clearance of platinum relative to inulin was measured in the conscious rat during the period 60-70 min after injection of the nephrotoxic drug, cisplatin, or its non-nephrotoxic analogues (trans-dichlorodiammine platinum II, carboplatin or iproplatin). The fractional clearance of platinum was between 3 and 4 for cisplatin and its analogues. Platinum from cisplatin and its trans isomer is essentially irreversibly bound whilst that from carboplatin and iproplatin is largely reversibly bound to blood proteins. Probenecid and triethanolamine both caused an increase whereas furosemide caused a decrease in the fractional clearance of total platinum from cisplatin. Choline chloride had no nett effect on the fractional clearance of total platinum. Both furosemide and triethanolamine made no significant difference to the severity of cisplatin induced nephrotoxicity. However, probenecid enhanced cisplatin induced nephrotoxicity and choline chloride was capable of blocking cisplatin induced nephrotoxicity. We conclude that the renal tubular transport of platinum is not per se responsible for the nephrotoxicity of platinum compounds. However, in the case of cisplatin, or one of its metabolites, renal tubular transport may be a prerequisite for nephrotoxicity.     

Comparative study of cisplatin and carboplatin on pharmacokinetics, nephrotoxicity and effect on renal nuclear DNA synthesis in rats.

To clarify the difference in nephrotoxicity between cisplatin and carboplatin, the pharmacokinetics of platinum, renal function and nuclear DNA synthesis in renal cortical and outer medullary cells were studied in rats which had received cisplatin or carboplatin. Male Sprague-Dawley rats were given either cisplatin or carboplatin intravenously at an equi-toxic dose (LD10 or LD50) and were killed at various times within 7 days after the injection. Cisplatin bound to plasma proteins more avidly than carboplatin. Much more platinum was detectable in the renal nuclei after cisplatin injection than after carboplatin injection. BUN and serum creatinine levels in the rats treated with 8.5 mg/kg of cisplatin were significantly higher than in those treated with 100 mg/kg of carboplatin. Cisplatin markedly suppressed the renal nuclear DNA synthesis both in vivo and in vitro, when compared with carboplatin. It is concluded that the differences in nephrotoxicity between cisplatin and carboplatin are related to their different inhibitory effects on nuclear DNA synthesis in the renal cells.     

Comparative Study of Cisplatin and Carboplatin on Pharmacokinetics,Nephrotoxicity and Effect on Renal Nuclear DNA Synthesis in Rats

Abstract: To clarify the difference in nephrotoxicity between cisplatin and carboplatin, the pharmacokinetics of platinum, renal function and nuclear DNA synthesis in renal cortical and outer medullary cells were studied in rats which had received cisplatin or carboplatin. Male Sprague-Dawley rats were given either cisplatin or carboplatin intravenously at an equi-toxic dose (LD₁₀ or LD₅₀) and were killed at various times within 7 days after the injection. Cisplatin bound to plasma proteins more avidly than carboplatin. Much more platinum was detectable in the renal nuclei after cisplatin injection than after carboplatin injection. BUN and serum creatinine levels in the rats treated with 8.5 mg/kg of cisplatin were significantly higher than in those treated with 100 mg/kg of carboplatin. Cisplatin markedly suppressed the renal nuclear DNA synthesis both in vivo and in vitro, when compared with carboplatin. It is concluded that the differences in nephrotoxicity between cisplatin and carboplatin are related to their different inhibitory effects on nuclear DNA synthesis in the renal cells.     

Metabolic viability and pharmaco-toxicological reactivity of cryopreserved human precision-cut renal cortical slices.

We have tested the suitability of cryopreserved human precision-cut renal cortical slices for metabolic and pharmaco-toxicological studies. The viability of these slices and their pharmaco-toxicological reactivity were assessed using intracellular ATP and protein contents, lactate dehydrogenase (LDH) leakage, lactate and glutamine metabolism and the ammoniagenic effect of valproate. Despite a decrease in ATP and protein contents when compared with those of fresh slices, cryopreserved slices did not show any LDH leakage and retained the capacity to metabolize glutamine and lactate. Glutamine removal and ammonia, lactate and alanine production were similar in fresh and cryopreserved slices; by contrast, cryopreserved slices accumulated more glutamate as a result of decreased flux through glutamate dehydrogenase which catalyses an oxygen-dependent reaction. Valproate markedly and similarly stimulated glutamine metabolism in fresh and cryopreserved slices. Cryopreservation did not alter lactate removal but inhibited lactate gluconeogenesis. In conclusion, these results demonstrate that, although their mitochondrial oxidative metabolism seems to be diminished, cryopreserved human precision-cut renal cortical slices remain metabolically viable and retain the capacity to respond to the ammoniagenic effect of valproate. Thus, this experimental model may be helpful to optimize the use of human renal tissue for metabolic and pharmaco-toxicological studies.     

Cisplatin-induced Changes in Adenine Nucleotides in Rat Kidney Slices: Amelioration by Tiopronin and Procaine

The adenine nucleotides (ATP, ADP and AMP) in rat renal cortical slices exposed in-vitro to cisplatin, an anticancer drug, were determined by HPLC. Cisplatin had no effect on total adenine nucleotides in the slices but caused a time- and concentration-dependent decrease in ATP levels with a concomitant increase in ADP and AMP levels. The decrease in ATP and increases in ADP and AMP concentrations became statistically significant after incubation with cisplatin (2 mm ) for 90 min or after cisplatin (1 mm ) for 120 min. Both tiopronin, a sulphydryl-containing drug, and procaine, an antioxidant, protected against cisplatin-induced changes in the adenine nucleotides. The results indicate a cisplatin-induced defect in cellular energetics that occurs at a relatively late stage in the process of toxicity to the slices in this in-vitro model. Cisplatin-induced depletion of ATP in the slices might result from an increase in catabolism of ATP to ADP and AMP. Maintenance of the normal concentration of ATP in the slices might be involved in the protection afforded by tiopronin and procaine against cisplatin-induced nephrotoxicity.     

Phase I and II agents in cancer therapy: two cisplatin analogues and high-dose cisplatin in hypertonic saline or with thiosulfate protection

Cisplatin is a chemotherapeutic coordination complex that has been evaluated extensively. It is particularly active against testicular cancer, but carcinomas of the ovary, bladder, cervix, and head and neck are also responsive. To increase efficacy and decrease toxicity, a number of platinum analogues have been developed and tested. One of these, carboplatin, is of particular interest. In clinical trials, it has demonstrated antitumor activity comparable to that of cisplatin, without evidence of significant renal toxicity or neurotoxicity. A second interesting platinum analogue is iproplatin. Preliminary phase I studies suggest reduced adverse renal and neurologic effects similar to those seen with carboplatin, with efficacy comparable to cisplatin. Attempts to overcome the dose-limiting toxicity of cisplatin by administering high-dose cisplatin (40 mg/m2/d for five days) in hypertonic saline or with thiosulfate protection are also reviewed. These techniques have eliminated nephrotoxicity as the dose-limiting toxicity of cisplatin. However, nonrenal toxicity, especially neurotoxicity, remains substantial. The extent to which high-dose cisplatin-based chemotherapy should be used in routine clinical practice has not been determined.     

Nephrotoxicity of a new platinum compound, 254-S, evaluated with rat kidney cortical slices

The addition of a new compound containing platinum, 254-S, an antineoplastic agent, to medium had no effect on p-aminohippurate (PAH) accumulation, gluconeogenesis, or potassium and ATP concentrations in rat kidney cortical slices at the concentrations tested, up to 10 mM. At 1 mM, cisplatin, used for comparison, significantly decreased all of these biochemical indices in the slices. Administration of 254-S at a low dose (10 mg/kg i.v.) to rats decreased the ability of the slices to accumulate PAH and to maintain the potassium concentration, without affecting levels of urea or creatinine in blood plasma. 254-S at a high dose (20 mg/kg i.v.) or cisplatin at 5 mg/kg (i.v.) also decreased these indices in the slices, and affected urea and creatinine in blood plasma. These results suggested that use of the renal slice technique gives data useful for the evaluation of the nephrotoxicity of 254-S, and that PAH accumulation and the potassium concentration in slices from rats treated with 254-S are indicators of nephrotoxic damage.     

大鼠静脉注射3种铂制剂后铂的肾排泄与肾分布比较研究

目的:探讨铂类抗癌药的肾毒性机制。方法:12只大鼠均分为3组,分别按铂元素10mg·kg-1剂量静脉注射顺铂、卡铂和双环铂,采用原子吸收法测定并计算4h尿药累积排泄率及肾组织中浓度。结果:4h累积排泄率顺铂、卡铂、双环铂分别平均为(33.7±5.7)%、(89.1±8.5)%、(70.1±9.8)%,肾组织中铂的浓度分别为(70.6±31.6)、(217.7±97.6)、(278.8±112.0)μg.g-1。结论:与顺铂相比,双环铂与卡铂肾排泄较快,肾组织中的铂浓度相对较高;肾组织中铂浓度高低与肾毒性大小之间可能无直接关系。     

Effect of cisplatin on in vitro production of lipid peroxides in rat kidney cortex

Cisplatin (cis-diamminedichloroplatinum II), an antitumor agent with a dose-limiting adverse effect of nephrotoxicity, increased lipid peroxidation in a time- and concentration-dependent manner in rat renal slices incubated in vitro. The addition of an antioxidant, N-N'-diphenyl-p-phenylenediamine (DPPD), to the incubation medium completely inhibited this increase. We also studied the in vitro effects of agents that modify cisplatin nephrotoxicity on lipid peroxidation in the slices caused by cisplatin. Mannitol, which protects against cisplatin nephrotoxicity, almost completely inhibited the increase in lipid peroxidation caused by cisplatin. Methionine, which potentiates cisplatin nephrotoxicity, made the slices more susceptible to peroxidation. The decrease with cisplatin in p-aminohippurate (PAH) accumulation in incubated kidney cortical slices, the accumulation being a representative biochemical process in the transport ability of renal cells, was partially inhibited when DPPD was in the medium. The results suggested that cisplatin directly affected renal tissues in which free radicals generated by cisplatin may interact with membrane lipids to cause the production of lipid peroxides that damage membrane function. Compounds that modify cisplatin nephrotoxicity such as mannitol and methionine may act by affecting the production of renal lipid peroxides by cisplatin.     

Nephrotoxicity of cisplatin,carboplatin and transplatin

The present study was designed to compare the nephrotoxicity induced by the three platinum compounds cisplatin (CDDP), carboplatin (CBDCA) and transplatin (TDDP) in vitro and to obtain information to elucidate the mechanism of platinum compound-induced nephrotoxicity. Rat or rabbit renal cortical slices were incubated for different periods of time in platinum compound-containing media (0.42 or 1.67 mM) and thereafter monitored for platinum content, tetraethylammonium(TEA) and paraaminohippurate(PAH) accumulation and gluconeogenesis. Malondialdehyde(MDA) content of slices was determined as a parameter of lipid peroxidation. Activity of glucose-6-phosphatase of rat renal microsomes was investigated after platinum-compound exposure. In all series of experiments the effect of the antioxidant N,Ndiphenyl-p-phenylenediamine (DPPD) was tested. CBDCA showed no effects on all parameters of renal cell function at all concentrations and all time points investigated, except for the activity of glucose-6-phosphatase, which was slightly affected by CBDCA. CBDCA-induced MDA production was lower, compared to CDDP, which showed marked toxic effects on TEA and PAH accumulation, gluconeogenesis and glucose-6-phosphatase activity. The onset of CDDP-induced alterations was dependent on drug concentration. MDA production was reduced by DPPD. Protection against the platinum compound-induced decrease in TEA and PAH accumulation was observed after the use of DPPD. DPPD had no protective effect on CDDP-induced inhibition of gluconeogenesis and glucose-6-phosphatase, which might indicate an effect on gluconeogenesis by direct inhibition of glucose-6-phosphatase. DPPD did not alter uptake of platinum compounds in rat renal cortical slices. TDDP showed different in vitro properties compared to in vivo conditions. In conclusion, association of CDDP-induced nephrotoxicity with lipid peroxidation was shown. CBDCA induced less generation of lipid peroxidation products and only very small nephrotoxic effects. Antioxidants may restrict CDDP-induced alterations in renal cell function.     

Adenine nucleotide and calpain inhibitor I protect against atractyloside-induced toxicity in rat renal cortical slices in vitro

Atractyloside is a compound with a documented nephrotoxicity. It induces renal tubular necrosis at high doses and apoptosis at lower doses. This study investigates the potential protective effect of some chemical agents against atractyloside-induced nephrotoxicity in vitro using the precision-cut rat renal cortical slices obtained from kidneys of Wistar rats. For co-incubation experiments, slices were incubated for 3 h at 37 degrees C on a rocker platform with various chemical agents: ADP (5 mM), calpain inhibitor I (CPI, 1 mM), stevioside (STV, 2.5 mM) or probenecid (PRB, 2.5 mM) in the presence or absence of atractyloside (2 mM). For pre-incubation experiments, slices were incubated with the same chemical agents for 1 h before exposure to atractyloside. The nephrotoxic effects of atractyloside (2 mM) alone were manifested in several ways: by a marked increase in lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) leakage, significant inhibition of p-aminohippurate (PAH) accumulation, marked depletion of intracellular ATP and reduced glutathione (GSH), and a significant reduction in pyruvate-stimulated gluconeogenesis. Co-incubation of slices with ADP or CPI and atractyloside completely blocked atractyloside-induced increase in LDH leakage, but not ALP leakage. Atractyloside-induced depletion of ATP and reduced gluconeogenesis was prevented by co-incubation with ADP or CPI. Furthermore, co-incubation of slices with STV and atractyloside, but not PRB, completely abolished atractyloside-induced depletion of ATP and decreased gluconeogenesis in the slices. Pre-incubation of slices with either ADP or CPI protected against atractyloside-induced increase in LDH leakage, reduced ATP and decreased gluconeogenesis. PAH uptake in the slices was inhibited by atractyloside and PRB in a time-dependent manner. While ADP and CPI were found to exert complete protection against atractyloside-induced toxicity irrespective of treatment schedule, STV is effective only under certain conditions, and PRB offer no protection at all. The results of this study demonstrate the usefulness of renal cortical slices as toxicology tool for evaluating and screening compounds for their potential protective effects, and are supportive of a role of adeninine nucleotide (ADP) and protease inhibitor (CPI) in protecting against atractyloside-induced cell injury.     

Further examination of the selective toxicity of CCl4 in rat liver slices.

Lipid peroxidation and loss of enzymes located predominantly in either periportal or centrilobular hepatocytes were investigated in precision-cut liver slices from male Sprague-Dawley rats. Pretreatment of animals with 80 mg/kg phenobarbital for the site-specific enzyme studies enhanced and accelerated CCl4 toxicity in slices resulting from increased radical formation. Liver slices were exposed to 0.57 mM CCl4 by vaporization using a roller incubation system at 37 degrees C for a total of 9 hr. Conjugated diene formation, an index of lipid peroxidation, was detected 15 min following CCl4 administration and increased over time. Loss of cytochrome P450 occurred in a time-dependent manner relative to controls where levels in treated slices were 42% of controls at 9 hr. A 48-hr fast prior to termination increased intracellular K+ leakage relative to that present in slices from fed animals. Significant leakage of glucose-6-phosphate dehydrogenase and beta-glucuronidase from centrilobular hepatocytes occurred 9 hr following CCl4 administration. The content of the periportal enzymes (lactate dehydrogenase and sorbitol dehydrogenase) was unchanged in the same slices over the duration of the experiment. Reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide, a mitochondrial selective dye and indicator of viability, was significantly lower in treated slices from phenobarbital-treated animals at 9 hr relative to controls. These studies demonstrate that precision-cut slices are an ideal in vitro system for mechanistic studies and the investigation of site-specific toxicants since the integral architecture of the liver and cellular identity are maintained.     

Concomitant lansoprazole ameliorates cisplatin-induced nephrotoxicity by inhibiting renal organic cation transporter 2 in rats

Cisplatin is used widely for the treatment of multiple solid tumors. Cisplatin-induced nephrotoxicity is caused by renal accumulation of cisplatin via human organic cation transporter 2 (hOCT2). As lansoprazole, a proton pump inhibitor, is known to inhibit hOCT2 activity, lansoprazole might ameliorate cisplatin-induced nephrotoxicity. A previous study showed that concomitant lansoprazole administration ameliorated nephrotoxicity in patients receiving cisplatin. However, the detailed mechanism remains to be clarified. In the present study, the drug–drug interaction between lansoprazole and cisplatin was examined using hOCT2-expressing cultured cells and rat renal slices. Moreover, the effect of lansoprazole on cisplatin-induced nephrotoxicity and the pharmacokinetics of cisplatin in rats was investigated. In the uptake study, lansoprazole potently inhibited the uptake of cisplatin in hOCT2-expressing cultured cells and rat renal slices. The in vivo rat study showed that concomitant lansoprazole significantly ameliorated cisplatin-induced nephrotoxicity and reduced the renal accumulation of platinum up to approximately 60% of cisplatin alone at 72 h after cisplatin intraperitoneal administration. Furthermore, the renal uptake of platinum at 3 min after intravenous cisplatin administration in rats with cisplatin and lansoprazole decreased to 78% of rats with cisplatin alone. In addition, there was no significant difference in the plasma platinum concentration between rats treated with and without lansoprazole at 3 min after cisplatin intravenous administration. These findings suggested that concomitant lansoprazole ameliorated cisplatin-induced nephrotoxicity by inhibiting rOCT2-mediated cisplatin uptake in rats, thus decreasing cisplatin accumulation in the kidney. The present findings provided important information for the establishment of novel protective approaches to minimize cisplatin-induced nephrotoxicity.     

Platinum antitumour agents: A review of (bio)analysis

This paper summarizes analytical techniques in order to get a clear picture of the ins and outs of the (bio)analysis of platinum-containing compounds. The antitumour agent cisplatin has become an indispensable drug for the cure of a variety of cancer diseases. Since its introduc-tion in the early seventies, about 2,000 related platinum complexes were designed to devoid the dose-limiting nephrotoxicity. Some of them were introduced for clinical trial, such as carboplatin and iproplatin. To investigate the mechanism of action and pharmaco-kinetic behaviour, several interesting assays for total and specific platinum determination in biological matrices have been developed, each with its own possibilities and limitations.     

Stimulatory effect of cisplatin on production of lipid peroxidation in renal tissues

Cisplatin (cis-diamminedichloroplatinum II), an anticancer chemotherapeutic agent with the dose-limiting side effect of nephrotoxicity, caused a statistically significant increase in lipid peroxidation, monitored by measuring the production of malondialdehyde, in rat kidney 72 hr after injection. Treatment of rats beforehand with the antioxidant alpha-tocopherol or N-N'-diphenyl-p-phenylenediamine (DPPD) effectively decreased such peroxidation. DPPD was a more effective inhibitor than alpha-tocopherol, since it is known for its ability to scavenge free radicals more powerfully. The ability of renal cortical slices to accumulate p-aminohippurate (PAH) was examined as a biochemical parameter that would change in nephrotoxicity. The ability to accumulate PAH by the incubated slices decreased 72 hr after administration of cisplatin. The pretreatment with DPPD prevented the decrease in PAH accumulation in the slices from rats treated with cisplatin. Structural changes of the renal proximal tubule caused by cisplatin, analyzed in a transmission electron microscope, were also prevented by the pretreatment with DPPD. The results suggest that cisplatin affects renal tissues in which free radicals generated by cisplatin may interact with membrane lipids to cause the production of lipid peroxidation, which affects both cellular structure and function.     

Lack of Correlation between para-Aminophenol Toxicity in Vivo and in Vitro in Female Sprague--Dawley Rats

The present study was designed to test the hypothesis that para-aminophenol(PAP) nephrotoxicity is due to autooxidation. We compared renalfunctional responses following PAP administration to femaleSprague-Dawley rats and following incubation of renal proximaltubules with PAP. The concentrations of PAP selected for invitro incubations produced cytotoxicity (for example, a decreasein oxygen consumption or adenine nucleotide concentration) inrat renal epithelial cells or rabbit proximal tubule suspensions.In rats, PAP (300 mg/kg ip) caused proximal tubular necrosiswithin 24 hr. Changes in renal function 24 hr following PAPadministration included increased kidney weight and blood ureanitrogen concentration and decreased renal glutathione (GSH)content and adenine nucleotide concentrations. PAP did not causehepatic damage. Within 2–4 hr following PAP administration,renal GSH content and adenine nucleotide concentrations weresignificantly decreased. In renal cortical slices prepared fromPAP-treated rats, oxygen consumption and accumulation of organicions (para-aminohippurate and tetraethylammonium) were significantlydecreased compared with renal cortical slices prepared fromcontrol rats. In liver, GSH content was significantly decreasedfrom 1 to 4 hr following PAP administration. In contrast tothe effects of PAP in vivo, renal proximal tubules showed littleevidence of injury when incubated with 0.1 or 0.5 mM PAP forup to 4 hr in the presence or absence of amino acids in theincubation medium. When tubules were incubated with 1 mM PAPfor 4 hr in the presence of amino acids, GSH content, AMP concentration,and TEA uptake were significantly decreased. When amino acidswere removed from the incubation medium, 1 mM PAP caused decreasesin oxygen consumption and ATP concentration after 4 hr of incubation.Functional changes observed during incubation with PAP in vitrowere not consistent with functional changes observed in vivo.The discrepancy between PAP toxicity in vivo and in vitro suggeststhat autooxidation is unlikely to be responsible for PAP nephrotoxicityand that nephrotoxicity in vivo is primarily mediated by extrarenalbioactivation. Further, depletion of hepatic GSH content priorto changes in renal function suggests that PAP or a PAP metabolitemay conjugate with hepatic GSH. These observations suggest thatPAP nephrotoxicity may be mediated by PAP-GSH conjugates ratherthan autooxidation of PAP in the kidney.     

A new technique for preparing precision-cut slices from small intestine and colon for drug biotransformation studies

INTRODUCTION: A new technique was developed to prepare precision-cut slices from small intestine and colon with the object of studying the biotransformation of drugs in these organs. METHODS: Rat intestinal slices were prepared in two different ways. In the first method, slices were punched out of the small intestine. In the second method, precision-cut slices were made from agarose-filled and -embedded intestines, using the Krumdieck tissue slicer. This method was also applied to colon tissue. Viability of the slices was determined by analysis of intracellular ATP and RNA levels and morphology. Drug metabolizing activity was studied using lidocaine, testosterone, and 7-ethoxycoumarin (7-EC) as phase I substrates, and 7-hydroxycoumarin (7-HC) as a phase II substrate. RESULTS: Precision-cut slices made from agarose-filled and -embedded intestine better preserved ATP levels than tissue that was punched out of the intestinal wall. After 24 h of incubation, morphology in precision cut-slices showed was quite well preserved while punched out tissue was almost completely autolytic after incubation. In addition, total RNA amount and quality was much better maintained in precision-cut slices, when compared to punched out tissue. Both intestinal slices and punched-out tissue showed high, and comparable, phase I and phase II biotransformation activities. DISCUSSION: It is concluded that preparing precision-cut 0.25 mm slices out of agarose-filled and -embedded intestine provides an improvement, compared with punched-out tissue, and that both intestinal and colon slices are useful preparations for in vitro biotransformation studies.     

A study of the protective effect of chloride salts on cisplatin nephrotoxicity

In rats NaCl and NH4Cl (25 mmoles/kg, p.o.) were found to be equally effective at preventing nephrotoxicity when administered to rats 90 min before cisplatin (5 mg/kg i.p.) but (NH4)2SO4 did not protect. The severity of nephrotoxicity, taken as the maximum elevation in blood urea concentration, showed a high degree of correlation with urinary chloride concentration, but not with urinary pH or volume. Sodium chloride did not protect against nephrotoxicity when administered 3 or 24 hr after cisplatin. Sodium chloride showed protection against nephrotoxicity caused by cisplatin metabolites only at low doses of platinum. For animals pretreated with NaCl (25 mmoles/kg) or water p.o. the urinary excretion of total platinum, cisplatin and six of the seven metabolites separated by hplc was not significantly different between the two treatments during the 0-5-hr period post dosing. However, one metabolite, possibly a nephrotoxic hydrolysis product, was excreted in significantly smaller amounts in the urine of animals pretreated with NaCl (P less than 0.05). Furthermore, in all cisplatin treated animals the amount of this species excreted correlated with the severity of nephrotoxicity. Whilst this suggests that chloride ions may protect against the nephrotoxicity of cisplatin by inhibiting its rate of metabolism this metabolite accounts for only 2.5% of the platinum excreted. Furthermore, the data do not exclude the possibility that NaCl prevents cisplatin-induced nephrotoxicity by preventing renal ischaemia, which may normally follow cisplatin treatment, or that the renal uptake or transport of platinum may be inhibited by NaCl.     

Mechanisms of the ifosfamide-induced inhibition of endocytosis in the rat proximal kidney tubule

The Fanconi syndrome is a common side effect of the chemotherapeutic agent ifosfamide. Current evidences suggest that chloroacetaldehyde (CAA), one of the main metabolites of ifosfamide activation, contributes to its nephrotoxicity. However, the pathophysiology of CAA-induced Fanconi syndrome is not fully understood. The present work examined the adverse effects of CAA on precision-cut rat renal cortical slices, which allowed studying the toxic effect of CAA on proximal endocytosis. We demonstrated that clinically relevant concentrations of CAA (/=75 muM has adverse effects, both on viability parameters and on energy metabolism, as shown by the great decrease in total glutathione and ATP levels. In addition, the V-ATPase, which plays a crucial role in intracellular vesicle trafficking, was inhibited by 100 muM of CAA. By contrast, the slight decrease in Na-K-ATPase activity observed for CAA>/= 125 muM (maximum inhibition: 33%) could not totally explain the inhibition of the reabsorption processes. In conclusion, the addition of the two main adverse effects of CAA (decrease in ATP levels and inhibition of the V-ATPase) could explain the inhibition of endocytosis and the Fanconi syndrome observed during ifosfamide treatments.     

Enhancement of renal organic base accumulated by potassium dichromate.

N-Methylnicotinamide (NMN) accumulation by renal cortical slices from potassium dichromate-treated rats was not different from control at 30 min of incubation, but was substantially higher when the incubation was continued for 60 min or longer. Intravenous injection of NMN resulted in significantly higher cortex/serum concentration ratios when rats were treated 24 hr earlier with potassium dichromate. Incubation of renal cortical slices under N₂ or at O°C reduced NMN slice-medium ratios to about 1; reincubation under normal conditions returned the slice/medium ratios to normal values in controls but not in dichromate-treated animals. Replacement of drinking water with saline for 5 wk reduced both the dichromate-induced nephrotoxicity and the enhanced uptake of NMN by kidney slices. Concomitant treatment with dimercaprol and dichromate did not reduce dichromate-induced toxicity or enhancement of NMN slice accumulation. Chromium chloride elicited neither nephrotoxicity nor stimulation of NMN uptake. The enhancement of renal NMN accumulation or retention by potassium dichromate appears to be associated with the nephrotoxicity produced by this compound.