N-(3,5-Dichlorophenyl)succinimide nephrotoxicity in the Fischer-344 rat

The nephrotoxic potential of N-(3,5-dichlorophenyl)succinimide (NDPS) was examined, in male Fischer-344 rats. Rats were administered NDPS (0.1, 0.2, 0.4 or 1.0 mmol/kg intraperitoneally (i.p.) or sesame oil (2.5 ml/kg, i.p.), and renal function was monitored at 24 and 48 h. NDPS (0.1 mmol/kg) stimulated organic ion uptake at 48 h. NDPS (0.2 mmol/kg) produced diuresis but did not alter blood urea nitrogen (BUN), kidney weight or organic ion uptake by renal cortical slices at 48 h. High-dose NDPS (0.4 and 1.0 mmol/kg) administration produced diuresis, decreased accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA), increased BUN and kidney weight and caused acute tubular necrosis. At 24 h, NDPS (0.2 mmol/kg) decreased uptake of PAH and TEA and tended to increase BUN. These results are similar to previous reports of NDPS-induced nephrotoxicity in Sprague-Dawley rats and suggest that either rat model would be suitable for future studies on the mechanism(s) of NDPS-induced nephropathy.     

Onset of and recovery from acute N-(3,5-dichlorophenyl)succinimide-induced nephrotoxicity in Sprague-Dawley rats

The time course for the onset of N-(3,5-dichlorophenyl)succinimide (NDPS)-induced nephrotoxicity was studied in male Sprague-Dawley rats. The ability of rats to recover from a single nephrotoxic dose (100 or 200 mg/kg) of NDPS also was examined. One hour following NDPS administration (200 mg/kg, i.p.), p-aminohippurate (PAH) accumulation by renal cortical slices was decreased 51%. Changes in renal morphology, proteinuria, hematuria, and diuresis were observed at 3 h. Renal damage at 6 h was similar to that seen at 24 h with tubular necrosis greater than that observed at 3 h and some lumina plugged with PAS+ material. Accumulation of both PAH and tetraethylammonium (TEA) by renal cortical slices was decreased; and proteinuria, hematuria, and polyuria were increased at 6 h and 24 h. Blood urea nitrogen (BUN) was not increased until 24 h. Renal function began to return to normal in rats receiving NDPS (100 mg/kg, i.p.) by 48 h, and functional recovery was complete by 168 h, although slight morphological changes were still evident. However, not all rats receiving NDPS (200 mg/kg, i.p.) recovered by 168 h, and some rats (3 of 7) died of renal failure between 96 h and 168 h. Widespread tubular necrosis and increased kidney weight were also present in this group at 168 h. Thus, NDPS-induced nephrotoxicity was evident by 1 h, established by 6 h and maximum between 24 h and 48 h. Recovery from NDPS-induced nephropathy was found to be dose-dependent, and incomplete in some animals at a dose of 200 mg/kg.     

The effect of probenecid on acute N-(3,5-dichlorophenyl)succinimide-induced nephrotoxicity in the Fischer 344 rat

N-(3,5-Dichlorophenyl)succinimide (NDPS), an experimental agricultural fungicide, has been shown to produce selective nephrotoxicity in rats. Previous studies have shown that a metabolite(s) of extrarenal origin contributes to acute NDPS-induced nephrotoxicity. The purpose of this study was to determine if the organic acid transport inhibitor probenecid could modify the renal toxicity produced by NDPS administration. Male Fischer 344 rats were administered a single intraperitoneal (i.p.) injection of probenecid (60, 90 and 120 mg/kg) or 0.9% saline (1.0 ml/kg) followed 30 min later by NDPS (0.4 or 1.0 mmol/kg, i.p.) or sesame oil (2.5 ml/kg, i.p.) Renal function was monitored at 24 h and 48 h. Probenecid (60 mg/kg) did not markedly alter NDPS-induced renal effects on either post-treatment day. However, pretreatment with probenecid (90 or 120 mg/kg) blocked or attenuated the diuresis, increased proteinuria, decreased tetraethylammonium (TEA), uptake, elevation in blood urea nitrogen (BUN) concentration and increased kidney weight produced by NDPS (0.4 mmol/kg) administration. Only increased kidney weight and BUN concentration, and decreased lactate-stimulated p-aminohippurate (PAH) uptake were altered by probenecid (120 mg/kg) pretreatment when NDPS (1.0 mmol/kg) was given. NDPS-induced changes in renal morphology were not prevented by pretreatment with any probenecid dose. These results suggest that at least one nephrotoxic metabolite of NDPS is an organic acid. However, this acidic metabolite might not be the major nephrotoxic metabolite or a precursor to the major nephrotoxic metabolite(s). The identity of these metabolites remains to be determined.     

N-(3,5-dichlorophenyl)succinimide nephrotoxicity in streptozotocin-induced diabetic rats

N-(3,5-Dichlorophenyl)succinimide (NDPS) is an experimental fungicide which induces renal toxicity. The following study examined the nephrotoxicity induced by NDPS in streptozotocin (STZ) diabetic rats. Male Fischer 344 (F344) rats were injected with 35 mg/kg STZ (i.p.) or citrate buffer. Fourteen days after STZ or citrate buffer injection, the rats (4-6 rats/group) were injected with (0.4 or 1.0 mmol/kg) NDPS or vehicle (sesame oil, 2.5 ml/kg). Kidney weight, blood urea nitrogen (BUN) levels, morphology and renal cortical slice uptake of organic ions was quantitated 48 h after NDPS administration. A 0.4 mmol/kg dose of NDPS induced diuresis, increased kidney weight and a moderate elevation in BUN levels in the normoglycemic group. The 1.0 mmol/kg dose of NDPS produced diuresis, proteinuria, increased kidney weight and a marked increase in BUN levels in the normoglycemic group. The renal cortical slice uptake of p-aminohippurate (PAH) and tetraethylammonium (TEA) was also decreased 48 h after NDPS injection in the normoglycemic group. No alterations in kidney weight, BUN levels, morphology or renal cortical slice uptake of organic ions was observed in the diabetic animals treated with (0.4 or 1.0 mmol/kg) NDPS. The results of this study indicate that the renal toxicity of NDPS was reduced in the diabetic rat.     

Nephrotoxicity of N-(3-bromophenyl)-2-hydroxysuccinimide: role of halogen groups in the nephrotoxic potential of N-(halophenyl)succinimides

Among N-(halophenyl)succinimides, N-(3,5-dichlorophenyl)succinimide (NDPS) is a potent nephrotoxicant as well as an agricultural fungicide. Although two chloride groups on the phenyl ring are essential to induce optimal nephrotoxicity, the role of halogen groups in NDPS nephrotoxicity is not clear. In this study, N-(3-bromophenyl)-2-hydroxysuccinimide (NBPHS) was prepared as a monohalophenyl derivative of N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS), an oxidative and nephrotoxicant metabolite of NDPS. The nephrotoxic potential of NBPHS was evaluated in vivo and in vitro to determine the role of halogen groups in N-(halophenyl)succinimide nephrotoxicity. Male Fischer 344 rats (four/group) were administered a single intraperitoneal (i.p.) injection of NBPHS (0.1, 0.4 or 0.8 mmol/kg) or vehicle (25% dimethyl sulfoxide in sesame oil) and renal function monitored for 48 h. Administration of NBPHS (0.8 mmol/kg) induced nephrotoxicity, while very mild changes or no changes in renal function were observed following administration of 0.4 mmol/kg or 0.1 mmol/kg of NBPHS, respectively. Nephrotoxicity induced by NBPHS (0.8 mmol/kg) was characterized by diuresis, transiently increased proteinuria, glucosuria and hematuria, elevated kidney weight, and reduced tetraethylammonium (TEA) uptake by renal cortical slices, and was not as marked as nephrotoxicity induced by NDHS (0.1 mmol/kg) or NDPS (0.4 mmol/kg). In the in vitro studies, the effects of NBPHS on organic ion accumulation, pyruvate-stimulated gluconeogenesis, and lactatc dehydrogenase (LDH) release were measured using renal cortical slices. NBPHS decreased p-aminohippurate (PAH) and TEA accumulation at NBPHS bath concentrations of 0.05 mM and 0.5 mM or greater, respectively. Renal gluconeogenesis was inhibited by NBPHS at 1 mM bath concentration, while LDH leakage was not increased at NBPHS bath concentrations up to 1 mM. The results demonstrate that NBPHS is a mild nephrotoxicant in vivo and in vitro, but does not have cytotoxic effects to renal tissues at the concentrations tested. From these results, it appears that halogen groups are essential to the nephrotoxic potential of N-(halophenyl)-2-hydroxysuccinimides or N-(halophenyl)succinimides and play an important role in the mechanism of NDPS nephrotoxicity following NDHS formation.     

Nephrotoxicity of N-(3,5-dichlorophenyl)succinimide metabolites in vivo and in vitro

The experimental fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) has been shown to produce selective nephrotoxicity at least in part through the actions of one or more metabolites. The purpose of this study was to (1) determine the nephrotoxic potential of three known NDPS metabolites; N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS), N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA), and N-(3,5-dichlorophenyl)malonamic acid (DMA) and (2) examine the role of renal biotransformation in NDPS-induced nephrotoxicity. In one set of experiments, male Fischer 344 rats were administered a single intraperitoneal (ip) injection of NDPS or a NDPS metabolite (0.2, 0.4, or 1.0 mmol/kg) or vehicle (sesame oil, 2.5 ml/kg) and renal function was monitored at 24 and 48 hr. Both NDHS and NDHSA administration (0.2 or 0.4 mmol/kg) resulted in nephrotoxicity similar to that produced by NDPS (0.4 or 1.0 mmol/kg). DMA administration resulted in only minor renal effects. Addition of NDPS to renal cortical slices prepared from naive Fischer 344 rats resulted in decreases in p-aminohippurate (PAH) and tetraethylammonium (TEA) accumulation at NDPS media concentrations of 10(-4) and 10(-5) M or greater, respectively. Pretreatment of rats with microsomal enzyme activity modifiers (phenobarbital, 3-methylcholanthrene, cobalt chloride, or piperonyl butoxide) had little effect on in vitro effects of NDPS on PAH or TEA accumulation. A pattern of PAH or TEA uptake similar to that observed for NDPS was observed in vitro with NDPS-d4, a nonnephrotoxic analog of NDPS labeled on the succinimide ring with deuterium. Of the NDPS metabolites tested in vitro for nephrotoxicity, only NDHS produced decreases in PAH and TEA accumulation similar to those produced by NDPS. These results suggest that the NDPS metabolites NDHS and NDHSA are nephrotoxic compounds. However, the role of these metabolites in NDPS-induced nephrotoxicity remains to be determined. In addition, it appears that NDPS has direct effects on renal function, but these effects do not appear to be of major toxicological significance in vivo. Direct renal bioactivation of NDPS or its known metabolites to nephrotoxic species does not appear to occur in vitro.     

Acute nephrotoxicity of N-phenyl and N-(monochlorophenyl) succinimides in Fischer 344 and Sprague-Dawley rats

The experimental fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) has been shown to be nephrotoxic in Sprague-Dawley and Fischer 344 rats. The purpose of this study was to evaluate the role of the chlorine atoms in NDPS-induced nephropathy. Male Sprague-Dawley or Fischer 344 rats received a single intraperitoneal injection of a phenylsuccinimide (0.4 or 1.0 mmol/kg) or sesame oil (2.5 ml/kg), and renal function was monitored at 24 h and 48 h. In Sprague-Dawley rats urine volume was increased by NDPS and N-(3-chlorophenyl)succinimide (3-NCPS) (0.4 and 1.0 mmol/kg) at 24 h but only by NDPS at 48 h. Accumulation of both p-aminohippurate (PAH) and tetraethylammonium (TEA) was decreased only by NDPS (1.0 mmol/kg) administration. N-(2-chlorophenyl)succinimide (2-NCPS) or N-(4-chlorophenyl) succinimide (4-NCPS) (1.0 mmol/kg) administration reduced only basal and lactate-stimulated PAH accumulation. Only NDPS increased blood urea nitrogen (BUN) concentration and kidney weight. In Fischer 344 rats results were similar to those obtained in Sprague-Dawley rats, except that 3-NCPS was the only monochlorophenylsuccinimide which produced a decrease in PAH accumulation by renal cortical slices. N-Phenylsuccinimide had little effect on any renal parameter studied in either rat strain. The order of increasing nephrotoxicity generally paralleled the increasing partition. coefficients of the compounds. These results indicate that reducing the chlorine substitution of NDPS produces compounds with reduced nephrotoxic potential. In addition, lipophilic character might be a predictor for the nephrotoxic potential of N-(halophenyl)succinimides in Sprague-Dawley and Fischer 344 rats.     

Acute N-(3,4,5-trichlorophenyl)succinimide-induced nephrotoxicity in Sprague-Dawley and Fischer-344 rats

Previous studies have shown that the experimental agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) produces acute nephrotoxicity via a reactive intermediate in Sprague-Dawley and Fischer-344 rats. The purpose of this study was to examine if an arene oxide intermediate is a toxic metabolite contributing to NDPS-induced nephropathy in rats. N-(3,4,5-Trichlorophenyl)succinimide (NTPS) was prepared to prevent arene oxide formation of NDPS, and its nephrotoxic potential was determined in Sprague-Dawley and Fischer-344 rats. Rats were administered a single intraperitoneal injection of NTPS (0.4 or 1.0 mmol/kg) or sesame oil (2.5 ml/kg), and renal function was monitored at 24 and 48 h. NTPS (0.4 or 1.0 mmol/kg) administration produced diuresis, proteinuria, glucosuria, hematuria, decreased accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA), and increased blood urea nitrogen (BUN) and kidney weight in both strains. Extensive proximal tubular necrosis was observed in both strains of rat. The magnitude of these effects was similar to those previously reported for NDPS-induced nephrotoxicity in Sprague-Dawley and Fischer-344 rats. It was concluded that an arene oxide metabolite does not contribute to the nephrotoxic potential of NDPS. The results of the present study indicate that lipophilic character alone is not a good predictor of the nephrotoxic potential for NDPS and NTPS.     

Acute nephrotoxicities and hepatotoxicities of 1,2-dibromo-3-chloropropane and 1,2-dibromoethane in male and female F344 rats

Four consecutive intraperitoneal (i.p.) injections with 40 mg/kg of 1,2-dibromo-3-chloropropane (DBCP) reduced the in vitro accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA) by slices of renal cortex and increased blood urea nitrogen (BUN) concentration in both male and female rats, but elevated serum glutamic pyruvic transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) activities in females only. Four consecutive treatments with 1,2-dibromoethane (EDB) reduced the accumulation of PAH in male rats, but failed to alter TEA accumulation, BUN concentration or GPT and GOT activities in rats of either sex. Single i.p. injections of EDB or DBCP (40 mg/kg, approximately one-half of the acute, i.p. LD50 values) were without effect on serum GPT and GOT activities, BUN concentration or the accumulations of PAH and TEA in male rats when measured 24, 48 or 96 h after treatment, except that PAH accumulation was reduced at 96 h.These results indicate that BUN and the accumulations in vitro of PAH and TEA by renal cortical slices are appropriate endpoints for studying DBCP nephrotoxicity. Measurements of serum GOT and GPT activities detected DBCP hepatotoxicity in female rats only. The nephrotoxicity of EDB was indicated by measurement of TEA accumulation only.     

Cephaloridine nephrotoxicity in streptozotocin induced diabetic Fischer 344 (F344) rats

The purpose of this study was to determine if cephaloridine nephrotoxicity is attenuated in streptozotocin (STZ)-induced diabetic rats. Fischer 344 (F344) rats (205-250 g) were given a single injection (i.p.) of STZ (27-35 mg/kg) or citrate buffer. The nephrotoxicity of (750 mg/kg) cephaloridine (i.p.) was then compared with normoglycemic and 14-day diabetic rats. Increased blood urea nitrogen (BUN) levels as well as diminished renal cortical slice accumulation of tetraethylammonium (TEA) and lactate-stimulated p-aminohippurate (PAH) were measured (P less than 0.05) in normoglycemic rats 48 h after cephaloridine administration. Cephaloridine failed to alter BUN levels and organic ion accumulation in diabetic rats. Diabetes did not totally protect against cephaloridine toxicity since kidney weights were elevated in normoglycemic and diabetic rats 48 h after administration of 750 mg/kg cephaloridine. A series of experiments also measured BUN levels, kidney weight and renal cortical slice uptake of PAH and TEA 24, 48 and 72 h after (1500 mg/kg) cephaloridine administration. Cephaloridine increased (P less than 0.05) kidney wt and decreased PAH and TEA uptake (P less than 0.05) in the normoglycemic group at 24-72 h. No change in kidney wt, PAH or TEA uptake was observed in the diabetic rats. These data indicate diabetes reduces cephaloridine nephrotoxicity.     

Contribution of acetone and osmotic-diuresis by streptozotocin-induced diabetes in attenuation of cephaloridine nephrotoxicity.

Previous studies have indicated that cephaloridine nephrotoxicity was reduced in streptozotocin (STZ)-induced diabetic rats. Experiments were performed to investigate if a shorter duration of diabetes would reduce cephaloridine nephrotoxicity. Studies were also conducted to examine the contribution of osmotic diuresis and ketone accumulation to the mechanism for reduced toxicity. Male Fischer 344 (F344) rats were injected with 30 mg/kg STZ or vehicle. Seven days after STZ or vehicle administration, the animals were treated (i.p.) with 1500 mg/kg cephaloridine. Increased kidney weight, blood urea nitrogen (BUN) level and decreased renal cortical slice accumulation of p-aminohippurate (PAH) and tetraethyl-ammonium (TEA) were measured in the normoglycemic group. No differences in renal function were detected between diabetic groups treated with cephaloridine or vehicle (PFC). Pretreatment of euglycemic rats with 0 or 10% dextrose in the drinking water and by oral gavage failed to prevent the renal damage produced by 1500 mg/kg cephaloridine despite glucosuria and urine output comparable to diabetic animals. However, dextrose-diuresis afforded a slight reduction in toxicity as indicated by changes in kidney weight and renal cortical slice accumulation of PAH and TEA. Pretreatment (oral) with 0 or 1.5 ml/kg acetone had no effect on cephaloridine toxicity (1000 mg/kg, i.p.). These findings suggested that attenuation of cephaloridine toxicity may be independent of the duration of diabetes. These results also indicated that glucose-mediated osmotic diuresis and acetone accumulation cannot account for reduced cephaloridine toxicity in diabetic rats.     

Gender differences in the potentiation of N-(3,5-dichlorophenyl)succinimide metabolite nephrotoxicity by phenobarbital

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces acute nephrotoxicity characterized as polyuric renal failure with proximal tubular necrosis. Phenobarbital pretreatment potentiates NDPS and N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS, a nephrotoxic metabolite of NDPS) nephrotoxicity in male rats. The purpose of this study was to determine the ability of phenobarbital pretreatment to potentiate (1) NDHS nephrotoxicity in female rats and (2) N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA, a nephrotoxic metabolite of NDHS) nephrotoxicity in male and female rats. Age-matched male and female Fischer 344 rats (4/group) were pretreated intraperitoneally (ip) with phenobarbital (75 mg/d, 3 d). At 24 h after the last injection of phenobarbital, an ip injection of NDHS (0.025 mmol/kg), 2-NDHSA (0.025 mmol/kg, females; 0.05 mmol/kg, males), or vehicle was given and renal function was monitored at 24 and 48 h post NDPS metabolite or vehicle. Additional groups received the NDPS metabolite or vehicle only and were also monitored for 48 h. In a separate experiment, male Fischer 344 rats were pretreated with piperonyl butoxide (PIBX, 1360 mg/kg) or the PIBX vehicle. 2-NDHSA (0.1 mmol/kg) or vehicle was administered (ip) 30 min after PIBX, and renal function was monitored for 24 h. Phenobarbital markedly potentiated 2-NDHSA nephrotoxicity in male rats as evidenced by increased kidney weight, increased blood urea nitrogen (BUN) concentration, and decreased tetraethylammonium (TEA) accumulation by renal cortical slices. PIBX had no effect on 2-NDHSA nephrotoxicity. Phenobarbital pretreatment did not markedly enhance the nephrotoxic potential of NDHS or 2-NDHSA in female rats. These results indicate that phenobarbital exhibits differential potentiation of NDPS metabolite nephrotoxicity in male and female rats and that the potentiation of 2-NDHSA nephrotoxicity observed in males is not due to cytochrome P-450-mediated oxidative biotransformation.     

Role of chloride groups in the nephrotoxic potential of N-(3,5-dichlorophenyl)-2-hydroxysuccinimide,an oxidative metabolite of N-(3,5-dichlorophenyl)succinimide

Although the addition of chloride groups to the phenyl ring of N-phenylsuccinimide (NPS) is known to enhance the nephrotoxic potential of NPS, the mechanism of this enhancement is unknown. One chlorinated NPS derivative, N-(3,5-dichlorophenyl)succinimide (NDPS), is a potent nephrotoxicant which induces marked proximal tubular necrosis at i.p. doses of 0.4 mmol/kg or greater. The purpose of this study was to compare the nephrotoxic potential of 2-hydroxy-N-phenylsuccinimide (HNPS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS), an oxidative and nephrotoxicant metabolite of NDPS, to determine the importance of the chloride groups for the nephrotoxic potential of NDHS. Male Fischer 344 rats (4/group) were administered a single i.p. injection of HNPS (1.0 or 1.5 mmol/kg), NDHS (0.1 mmol/kg) or vehicle (25% dimethyl sulfoxide in sesame oil), and renal function measured at 24 and 48 h. HNPS was a nonnephrotoxicant at both doses tested, while NDHS induced marked nephrotoxicity characterized by diuresis, increased proteinuria, glucosuria, elevated blood urea nitrogen (BUN) concentration a kidney weight, decreased organic ion accumulation by renal cortical slices and proximal tubular necrosis. In vitro, HNPS reduced p-aminohippurate (PAH) and tetraethylammonium (TEA) accumulation beginning at HNPS bath concentrations of 0.05 and 0.5 ?M, respectively. The results of this study indicate that although HNPS has direct effects on renal function in vitro, HNPS is not a nephrotoxicant in vivo at doses up to 15 times the minimal nephrotoxicant dose of NDHS. Therefore, the chloro groups present on NDHS play an essential role in the nephrotoxic potential NDHS and contribute to aspects of the nephrotoxic mechanism of NDPS beyond NDPS oxidation to form NDHS.     

Effect of autacoid modulation on N-(3,5-dichlorophenyl)succinimide (NDPS) and NDPS metabolite nephrotoxicity

N-(3,5-Dichlorophenyl)succinimide (NDPS) is an agricultural fungicide which has been shown to induce acute tubular necrosis. The purpose of the present study was to determine if creatinine clearance was altered early in the development of NDPS nephrotoxicity. This study also examined the effect of autacoid modulation on the renal effects induced by NDPS and two metabolites of NDPS, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA). In one set of experiments, male Fischer 344 rats (4 rats/group) were administered a single intraperitoneal (i.p.) injection of NDPS (1.0 mmol/kg) or vehicle and creatinine clearance was determined at 3 and 6 h post-treatment. NDPS administration resulted in a marked decrease in creatinine clearance at both time points. In a second set of experiments, rats (4–8 rats/group) were pretreated with the cyclooxygenase inhibitor indomethacin (3.0 or 5.0 mg/kg, i.p.) or the thromboxane synthase inhibitor dazmegrel (20 mg/kg, i.p.) 1 h before the i.p. administration of NDPS (0.2 or 0.4 mmol/kg), NDHS (0.05 or 0.1 mmol/kg), NDHSA (0.05 or 0.1 mmol/kg) or vehicle. Indomethacin pretreatment potentiated the nephrotoxic potential of NDPS and its two metabolites, while dazmegrel pretreatment attenuated NDPS nephrotoxicity without marked effects on NDHS or NDHSA nephropathy. These results indicate that renal hemodynamic changes occur early in the development of NDPS nephrotoxicity and that autacoids are important modulators of NDPS- and NDPS metabolite-induced renal effects.     

Effect of calcium antagonism by nifedipine and chlorpromazine on acute N-(3,5-dichlorophenyl)succinimide-induced nephrotoxicity in Fischer 344 rats

The nephrotoxicity induced by a wide variety of chemical compounds can be attenuated by agents which modify calcium ion (Ca2+) movement across membranes or calcium-dependent processes. The purpose of this study was to examine the ability of nifedipine, a calcium channel blocking drug, and chlorpromazine (CPZ), an antagonist of many calcium-dependent processes, to attenuate the nephrotoxicity induced by the agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) or its metabolite N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS). Male Fischer 344 rats (4 rats per group) were pretreated intraperitoneally (i.p.) with nifedipine (0.25 or 0.50 mg/kg), CPZ (1.0 or 5.0 mg/kg) or vehicle 1 h before NDPS (0.4 mmol/kg), NDHS (0.1 mmol/kg) or vehicle (sesame oil, 2.5 ml/kg). In separate experiments, rats were pretreated with nifedipine (0.25 or 0.50 mg/kg/day, i.p.) starting 2 days before NDPS or NDPS vehicle and continuing throughout the experiment. Renal function was monitored at 24 and 48 h. Nifedipine (single or multiple treatments) and CPZ (1.0 mg/kg) were ineffective in substantially altering NDPS (0.4 mmol/kg)-induced nephrotoxicity. However, CPZ (5.0 mg/kg) markedly attenuated all aspects of NDPS-induced nephropathy. Also, CPZ (5.0 mg/kg) partially protected against NDHS (0.1 mmol/kg)-induced renal effects. These results demonstrate the inability of the calcium channel blocker nifedipine to attenuate NDPS nephrotoxicity. Attenuation of NDPS nephrotoxicity by CPZ could suggest that CPZ is antagonizing calcium influx into renal tissue and/or renal intracellular calcium-dependent processes to modify the renal response to NDPS. However, the inability of CPZ to markedly attenuate NDHS nephrotoxicity could indicate that CPZ protected against NDPS nephrotoxicity by inhibiting biotransformation of the parent compound to its toxic chemical species.     

Effect of autacoid modulation on N-(3,5-dichlorophenyl)succinimide (NDPS) and NDPS metabolite nephrotoxicity.

N-(3,5-Dichlorophenyl)succinimide (NDPS) is an agricultural fungicide which has been shown to induce acute tubular necrosis. The purpose of the present study was to determine if creatinine clearance was altered early in the development of NDPS nephrotoxicity. This study also examined the effect of autacoid modulation on the renal effects induced by NDPS and two metabolites of NDPS, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA). In one set of experiments, male Fischer 344 rats (4 rats/group) were administered a single intraperitoneal (i.p.) injection of NDPS (1.0 mmol/kg) or vehicle and creatinine clearance was determined at 3 and 6 h post-treatment. NDPS administration resulted in a marked decrease in creatinine clearance at both time points. In a second set of experiments, rats (4–8 rats/group) were pretreated with the cyclooxygenase inhibitor indomethacin (3.0 or 5.0 mg/kg, i.p.) or the thromboxane synthase inhibitor dazmegrel (20 mg/kg, i.p.) 1 h before the i.p. administration of NDPS (0.2 or 0.4 mmol/kg), NDHS (0.05 or 0.1 mmol/kg), NDHSA (0.05 or 0.1 mmol/kg) or vehicle. Indomethacin pretreatment potentiated the nephrotoxic potential of NDPS and its two metabolites, while dazmegrel pretreatment attenuated NDPS nephrotoxicity without marked effects on NDHS or NDHSA nephropathy. These results indicate that renal hemodynamic changes occur early in the development of NDPS nephrotoxicity and that autacoids are important modulators of NDPS- and NDPS metabolite-induced renal effects.     

Interactions among nephrotoxicants: N-(3,5-dichlorophenyl)succinimide and cephaloridine

Numerous studies have demonstrated the interactive potential between nephrotoxicants. The purpose of this study was to examine the interactive potential between two model nephrotoxicants, N-(3,5-dichlorophenyl)succinimide (NDPS) and cephaloridine (CPH). Male Fischer 344 rats (4 rats per group) were administered an intraperitoneal (i.p.) injection of CPH (500 mg/kg), NDPS (0.2 mmol/kg) or the appropriate vehicle 1 h prior to administration of an i.p. injection of NDPS (0.2, 0.4, or 1.0 mmol/kg), CPH (500, 750 or 1000 mg/kg) or the appropriate vehicle. Renal function was monitored at 24 and 48 h. Combination of non-nephrotoxic doses of CPH (500 mg/kg) and NDPS (0.2 mmol/kg) did not result in nephrotoxicity, regardless of which compound was administered first. NDPS (0.2 mmol/kg) weakly enhanced the nephrotoxicity observed following CPH (1000 mg/kg) injection but had little effect on CPH (750 mg/kg)-induced renal effects. However, CPH (500 mg/kg) markedly attenuated NDPS (0.4 or 1.0 mmol/kg)-induced nephrotoxicity. These results demonstrate that prior NDPS exposure has little effect on the outcome of CPH-induced renal effects, but prior CPH exposure can markedly alter the renal response to NDPS administration.     

N-(3,5-dichlorophenyl)succinimide nephrotoxicity: evidence against the formation of nephrotoxic glutathione or cysteine conjugates.

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity via one or more metabolites. Previous studies suggested that glutathione is important for mediating NDPS-induced nephropathy. The purpose of this study was to examine the possibility that a glutathione or cysteine conjugate of NDPS or an NDPS metabolite might be the penultimate or ultimate nephrotoxic species. In one set of experiments, male Fischer 344 rats were administered intraperitoneally (i.p.) NDPS (0.4 or 1.0 mmol/kg) 1 h after pretreatment with the gamma glutamyltranspeptidase inhibitor AT-125 (acivicin) (10 mg/kg, i.p.) and renal function was monitored at 24 and 48 h. In general, AT-125 pretreatment had few effects on NDPS-induced nephropathy. In a second set of experiments, rats were treated i.p. or orally (p.o.) with a putative glutathione (S-(2-(N-(3,5-dichlorophenyl)succinimidyl)glutathione (NDPSG), a cysteine (S-(2-(N-(3,5-dichlorophenyl)succinimidyl)cysteine (NDPSC) (as the methyl ester) or N-acetylcysteine (S-(2-(N-(3,5-dichlorophenyl)succinimidyl)-N-acetylcysteine (NDPSN) conjugate of NDPS (0.2, 0.4 or 1.0 mmol/kg) or vehicle and renal function was monitored at 24 and 48 h. An intramolecular cyclization product of NDPSC, 5-carbomethoxy-2-(N-(3,5-dichlorophenyl)carbamoylmethyl)-1,4-th iazane-3-one (NDCTO) was also examined for nephrotoxic potential. None of the compounds produced toxicologically important changes in renal function or morphology. The in vitro ability of the conjugates to alter organic ion accumulation by cortical slices was also examined. All of the conjugates tested caused a reduction in p-aminohippurate (PAH) accumulation at a conjugate bath concentration of 10(-4) M, but none of the conjugates reduced tetraethylammonium (TEA) uptake. In a third experiment, the ability of the cysteine conjugate beta-lyase inhibitor aminooxyacetic acid (AOAA) (0.5 mmol/kg, i.p.) to alter the nephrotoxicity induced by two NDPS metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) or N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA) (0.2 mmol/kg, i.p.), was examined. AOAA pretreatment had no effect on NDHS- or NDHSA-induced nephrotoxicity. These results do not support a role for a glutathione or cysteine conjugate of NDPS or and NDPS metabolite as being the penultimate or ultimate nephrotoxic species.     

Effect of buthionine sulfoximine on acute N-(3,5-dichlorophenyl)succinimide-induced nephrotoxicity in Fischer 344 rats

The experimental agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) has been shown to be a nephrotoxicant in Fischer 344 rats. Results of a previous study conducted in our laboratory suggested that glutathione might be an important modulator of NDPS-induced nephrotoxicity. The purpose of this study was to examine the effect of DL-buthionine-(S,R)-sulfoximine (BSO), an inhibitor of glutathione synthesis, on NDPS-induced renal effects. Male Fischer 344 rats received an intraperitoneal (i.p.) injection of BSO (890 mg/kg) in 0.9% saline (10 ml/kg) followed 2 h later by an i.p. injection of NDPS (0.4 or 1.0 mmol/kg) or sesame oil (2.5 ml/kg), and renal function monitored at 24 and 48 h. BSO pretreatment attenuated the diuresis, proteinuria, elevation in blood urea nitrogen (BUN) concentration and kidney weight, and decreases in organic ion accumulation by renal cortical slices induced by NDPS (0.4 or 1.0 mmol/kg) administration. Proximal tubular necrosis induced by NDPS administration also was attenuated by BSO pretreatment. These results indicate that BSO pretreatment attenuates NDPS-induced renal effects and that glutathione is important for modulating acute NDPS-induced nephropathy.     

Role of glutathione in acute N-(3,5-dichlorophenyl) succinimide-induced nephrotoxicity in Sprague-Dawley and Fischer 344 rats

N-(3,5-Dichlorophenyl)succinimide (NDPS), an experimental agricultural fungicide, has been shown to be a selective nephrotoxin in Sprague-Dawley and Fischer 344 rats. Previous studies have demonstrated that a toxic metabolite contributes to or is responsible for acute NDPS-induced nephrotoxicity. The purpose of this study was to investigate the role of glutathione in NDPS-induced renal effects. In 1 set of experiments, male Sprague-Dawley or Fischer 344 rats received a single intraperitoneal (i.p.) injection of NDPS (0.4 or 1.0 mmol/kg) or sesame oil (2.5 ml/kg). Rats were killed at 1, 3, 6 or 24 h, and reduced (GSH) and oxidized (GSSG) glutathione concentrations determined in liver and renal cortex. In both rat strains NDPS (0.4 or 1.0 mmol/kg) administration produced small decreases in GSH concentrations (1 and 3 h) but moderate increases in GSSG concentrations (1 and 3 h) in liver and kidney. At 24 h both GSH and GSSG concentrations were increased, particularly in kidney. In a second set of experiments, rats were pretreated with the glutathione depletor diethyl maleate (DEM) (0.4 ml/kg, i.p.) 1 h prior to NDPS (0.2, 0.4 or 1.0 mmol/kg, i.p.) or sesame oil (2.5 ml/kg, i.p.) administration, and renal function monitored at 24 and 48 h. DEM pretreatment attenuated the increase in urine volume (24 and 48 h), proteinuria, glucosuria, hematuria and elevated blood urea nitrogen (BUN) concentration produced by NDPS (0.4 or 1.0 mmol/kg) in both Sprague-Dawley and Fischer 344 rats. NDPS-induced increases in kidney weight also were generally prevented by DEM pretreatment. Proximal tubular necrosis produced by NDPS administration was reduced by DEM but not prevented. Pretreatment with the cysteine conjugate beta-lyase inhibitor amino-oxyacetic acid (0.5 mmol/kg, i.p.) 1 h prior to NDPS (0.4 or 1.0 mmol/kg) markedly attenuated all NDPS-induced effects on renal function and morphology. These results suggest that glutathione does not play a protective role against NDPS-induced renal effects and that a glutathione or cysteine conjugate of NDPS might contribute to NDPS-induced nephrotoxicity.