N-(3,5-dichlorophenyl)succinimide Nephrotoxicity Research Articles

Role of leukotrienes in N-(3,5-dichlorophenyl)succinimide (NDPS) and NDPS metabolite nephrotoxicity in male Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) can induce marked nephrotoxicity in rats following a single intraperitoneal (ip) administration of 0.4mmol/kg or greater. Although NDPS induces direct renal proximal tubular toxicity, a role for renal vascular effects may also be present. The purpose of this study was to examine the possible role of vasoconstrictor leukotrienes in NDPS and NDPS metabolite nephrotoxicity. Male Fischer 344 rats (4 rats/group) were administered diethylcarbamazine (DEC; 250 or 500mg/kg, ip), an inhibitor of LTA4 synthesis, 1h before NDPS (0.4mmol/kg, ip), N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS, 0.1, 0.2, or 0.4mmol/kg, ip), or N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA, 0.1mmol/kg, ip) or vehicle. In a separate set of experiments, the LTD4 receptor antagonist LY171883 (100mg/kg, po) was administered 0.5h before and again 6h after NDHS (0.1mmol/kg, ip) or 2-NDHSA (0.1mmol/kg, ip) or vehicle. Renal function was monitored for 48h post-NDPS or NDPS metabolite. DEC markedly reduced the nephrotoxicity induced by NDPS and its metabolites, while LY171883 treatments provided only partial attenuation of NDHS and 2-NDHSA nephrotoxicity. These results suggest that leukotrienes contribute to the mechanisms of NDPS nephrotoxicity.

Effect of gender on phase I and phase II metabolism of N‐(3,5‐dichlorophenyl)succinimide (NDPS)

NDPS is a model compound for examining chemically-induced kidney damage. The parent compound and its direct oxidative metabolite, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS), induce nephrotoxicity in rats. Toxicity of NDPS is thought to require hepatic formation of NDHS followed by conjugation to reactive phase II metabolites. Further studies have shown that female rats are more susceptible to toxicity than males. In this study, the relationship between turnover and gender was examined. Metabolism was studied by incubating rat liver microsomes with the appropriate substrate and cofactor (oxidation: NDPS, NADPH; glucuronidation: NDHS, UDPGA) for time periods between 15 and 120 min. Samples were analyzed by HPLC with UV detection or HPLC-ESI-MS, and relative metabolite formation was determined. Results indicate that females are capable of producing the same oxidative metabolites and glucuronide conjugates that were previously found in males. A quantitative difference in the formation of oxidative metabolites was not observed. However, NDHS glucuronidation was significantly higher in male microsomes at incubation periods of 60 min or less. Whether this is relevant to the differential susceptibility of the genders to NDPS nephrotoxicity remains to be determined. Other phase II pathways, such as sulfation, may also vary between female and male rats. Supported by PHS grant ES012499.

EFFECT OF THREE N -ACETYLAMINO ACIDS ON N -(3,5-DICHLOROPHENYL)SUCCINIMIDE (NDPS) AND NDPS METABOLITE NEPHROTOXICITY IN FISCHER 344 RATS

The agricultural fungicide N -(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity in mammals characterized as polyuric renal failure and proximal tubular necrosis. Recent studies have suggested that NDPS-induced nephrotoxicity may be mediated by metabolites arising from the nephrotoxic NDPS metabolites N -(3,5-dichlorophenyl)2-hydroxysuccinimide (NDHS) and/or N -(3,5-dichlorophenyl)-2-succinamic acid (2-NDHSA). The purpose of this study was to examine the effects of N -acetylcysteine (NAC), a nucleophilic agent, and two nonnucleophilic N -acetylamino acids, N -acetylserine (NAS) and N -acetylalanine (NAA), on NDPS and NDPS metabolite-induced nephrotoxicity. Male Fischer 344 rats (4-8/group) were administered intraperitoneally (ip) an N -acetylamino acid (1 mmol/kg) 2 h before an ip injection of NDPS (0.4 mmol/kg), NDHS (0.1 mmol/kg), 2-NDHSA (0.1 mmol/kg), or vehicle. Renal function was then monitored at 24 and 48 h. NAC pretreatment markedly attenuated NDPS-, NDHS-, and 2-NDHSA-mediated nephrotoxicity. The nonnucleophilic N -acetylamino acids (NAS, NAA) only partly reduced NDPS and NDHS nephrotoxicity, and they had little effect on 2-NDHSA nephrotoxicity. These results suggest that reactive NDPS metabolites may be formed from NDHS and 2-NDHSA and that nucleophilic substrates (e.g., NAC) may offer protection from NDPS-induced nephrotoxicity. However, mechanisms other than chemical neutralization of reactive NDPS metabolites may also be contributing to the attenuation of NDPS nephrotoxicity, since nonnucleophilic N -acetylamino acids (e.g., NAA) also provided some protection against NDPS and NDHS nephrotoxicity.

In vitro nephrotoxicity induced by N-(3,5-dichlorophenyl)succinimide (NDPS) metabolites in isolated renal cortical cells from male and female Fischer 344 rats: evidence for a nephrotoxic sulfate conjugate metabolite

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity in vivo that is characterized as acute polyuric renal failure and proximal tubular necrosis. However, earlier in vitro studies have failed to reproduce the in vivo nephrotoxicity seen with NDPS or its nephrotoxic metabolites N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA). The purpose of this study was to examine the nephrotoxic potential of NDPS, its known non-conjugated metabolites, the O-sulfate conjugate of NDHS (NSC), and the putative metabolite N-(3,5-dichlorophenyl)maleimide (NDPM) and its hydrolysis product N-(3,5-dichlorophenyl)maleamic acid (NDPMA) using freshly isolated renal cortical cells (IRCC). IRCC were obtained from untreated male or female Fischer 344 rats following collagenase perfusion of the kidneys. Cells (∼4 million per ml) ( N=4) were incubated with up to 1.0 mM NDPS or an NDPS metabolite or vehicle for up to 120 min. Cytotoxicity was determined by measuring lactate dehydrogenase (LDH) release into the medium. Only NSC (>0.5 mM) and NDPM (≥0.5 mM) exposure increased LDH release from IRCC. NSC 1.0 mM or NDPM 0.5 mM increased LDH release from IRCC within 15–30 min of exposure. NDPS or the remaining NDPS metabolites did not increase LDH release at bath concentrations of 1.0 mM for exposures of 120 min. IRCC from male and female rats responded similarly to the toxic effects of NDPS and its metabolites. These results demonstrate that sulfate conjugates of NDPS metabolites can be fast acting nephrotoxicants and could contribute to NDPS nephrotoxicity in vivo. These results also suggest that the kidney probably accumulates toxic sulfate conjugates of NDPS metabolites rather than forming the conjugates. In addition, mechanisms responsible for gender differences in nephrotoxicity seen with NDPS and NDPS metabolites in vivo either occur prior to renal accumulation of sulfate conjugates and/or represent biochemical/physiological differences between the genders.

Sodium sulfate potentiates N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) nephrotoxicity in the Fischer 344 rat

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces nephrotoxicity as its major toxicity in rats. Previous studies have shown that NDPS induces nephrotoxicity following oxidation of the succinimide ring to form N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and the hydrolysis product of NDHS, N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA). Our recent work found that sodium sulfate potentiated NDPS nephrotoxicity, suggesting that sulfate conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. The purpose of this study was to determine if sodium sulfate also potentiated the nephrotoxicity of the two nephrotoxic metabolites of NDPS and further to see if sodium sulfate potentiated NDHS and 2-NDHSA nephrotoxicity to the same degree. Male Fischer 344 rats (4–16 rats/group) received an intraperitoneal (ip) injection of sodium sulfate (10 mg/kg) 20 min before a non-nephrotoxic dose (0.05 mmol/kg, ip) of NDHS or 2-NDHSA, or vehicle (12.5% dimethyl sulfoxide in sesame oil). Renal function was then monitored over 48 h. Sodium sulfate pretreatment potentiated the renal effects of a non-nephrotoxic dose of NDHS and 2-NDHSA to induce nephrotoxicity. Nephrotoxicity was characterized by diuresis, increased proteinuria, elevated blood urea nitrogen (BUN) concentration, increased kidney weight and proximal tubular necrosis. Differences in the potentiation of NDHS and 2-NDHSA nephrotoxicity by sodium sulfate were also observed as NDHS nephrotoxicity was potentiated to a lesser degree than 2-NDHSA-induced nephrotoxicity. These results support the likelihood that one or more sulfate conjugate(s) of NDPS metabolites contribute to NDPS nephrotoxicity.

EFFECT OF SULFATION SUBSTRATES/INHIBITORS ON N-(3,5-DICHLOROPHENYL)SUCCINIMIDE NEPHROTOXOCITY IN FISCHER 344 RATS

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an acute nephrotoxicant in rats. Our previous studies suggested that sulfate conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. In this study, effects of substrates and/or inhibitors of sulfation on NDPS nephrotoxicity were examined to explore further the role of sulfation in NDPS nephrotoxicity. Male Fischer rats (4-8/group) were administered one of the following intraperitoneal (ip) pretreatment (dose, pretreatment time) prior to NDPS (0.6 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg): (1) no pretreatment, (2) dehydroepiandrosterone (DHEA) (0.5 mmol/kg, 1 h), or (3) 2,6-dichloro4-nitrophenol (DCNP) (0.04 mmol/kg, 1 h). Following NDPS or NDPS vehicle administration, renal function was monitored at 24 and 48 h. Pretreatment with DHEA, a typical substrate for and an inhibitor of hydroxysteroid (alcohol) sulfotransferase, resulted in marked protection against NDPS nephrotoxicity. A selective inhibitor of phenol sulfotransferase, DCNP, afforded little attenuation in NDPS nephrotoxicity. These results suggest that alcohol sulfate conjugates of NDPS metabolites, rather than phenolic sulfate conjugates, may be a penultimate or ultimate nephrotoxicant species mediating NDPS nephrotoxicity. The marked, but not complete, protection by DHEA also suggests that there are other metabolites or mechanisms responsible for NDPS nephrotoxicity.

Effect of glucuronidation substrates/inhibitors on N-(3,5-dichlorophenyl)succinimidenephrotoxicity in Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an acute nephrotoxicant in rats. Our previous studies have strongly suggested that glucuronide conjugation of NDPS metabolites might be a bioactivation step mediating NDPS nephrotoxicity. In this study, effects of substrates and/or inhibitors of primarily glucuronidation on NDPS nephrotoxicity were examined to explore further the role of glucuronidation in NDPS nephrotoxicity. Male Fischer 344 rats (4–6/group) were administered one of the following intraperitoneal (i.p.) pretreatments (dose, pretreatment time) prior to NDPS (0.4 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg): (1) no pretreatment; (2) borneol (900 mg/kg, 30 min); (3) eugenol (500 mg/kg per day, 3 days); (4) clofibric acid (400 mg/kg, 15 min before (1/2 dose) and 3 h after (1/2 dose)), or (5) valproic acid, sodium salt (1.0 mmol/kg, 15 min). Following NDPS or NDPS vehicle administration, renal function was monitored at 24 and 48 h. Pretreatment with borneol or eugenol, substrates for ether glucuronidation and sulfation (mainly glucuronidation), afforded complete protection against NDPS nephrotoxicity. Substrates for acyl glucuronidation, clofibric acid or valproic acid, mildly reduced or had little effect on NDPS nephrotoxicity, respectively. These results suggest that ether glucuronide conjugates of NDPS metabolites, rather than acyl glucuronide conjugates, may be the primary ultimate nephrotoxicant species mediating NDPS nephrotoxicity.

GENDER DIFFERENCES IN ACUTE N -(3,5- DICHLOROPHENYL)-2-HYDROXYSUCCINIMIDE (NDHS) AND N -(3,5-DICHLOROPHENYL)-2-HYDROXYSUCCINAMIC ACID (2-NDHSA) NEPHROTOXICITY IN FISCHER 344 RATS

N -(3,5-Dichlorophenyl)succinimide (NDPS) is an agricultural fungicide that induces nephrotoxicity as its major toxicity. NDPS is also a more potent nephrotoxicant in female than in male rats. The purpose of this study was to examine the nephrotoxic potential of the two NDPS metabolites N -(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N -(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (2-NDHSA) in agematched male and female Fischer 344 rats to determine if gender differences exist for the nephrotoxicity induced by the two NDPS metabolites. Rats (4 per group) were administered a single intraperitoneal (ip) injection of NDHS or 2-NDHSA (0.025 or 0.05 mmol/kg) or vehicle, and renal function was monitored for 48 h. Neither compound induced significant nephrotoxicity in male rats at the doses tested. However, in female rats both metabolites induced marked nephrotoxicity at the 0.05 mmol/kg dose level, and treatment with 0.025 mmol/kg 2-NDHSA induced some changes in renal function (transient diuresis, transient proteinuria, decreased organic ion accumulation). Little effect on renal function was induced in females by treatment with 0.025 mmol/kg NDHS. At toxic levels in female rats, the renal lesions were located primarily in the S2 and S3 segments of the proximal tubule. These results indicate that, like the parent compound, gender differences exist in the nephrotoxic potential of NDHS and 2-NDHSA. The results also suggest that in females, as in males, NDPS nephrotoxicity is mediated via NDHS and/or 2-NDHSA. However, it is not clear if the ultimate nephrotoxicant species following NDPS exposure is different in males and females or if the same ultimate nephrotoxicant species is produced in both species but handled differently by male and female kidneys. Thus, further studies are needed to determine the exact nature of the ultimate nephrotoxicant species and the mechanisms of the observed gender differences.

Effects of sodium sulfate on acute N-(3,5-dichlorophenyl)succinimide (NDPS) nephrotoxicity in the Fischer 344 rat

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) induces acute polyuric renal failure in rats. Results of previous studies have suggested that NDPS may induce nephrotoxicity via conjugates of NDPS metabolites. Thus, the purpose of this study was to examine if administered sodium sulfate could alter NDPS nephrotoxicity. Male Fischer 344 rats (four rats per group) were administered a single intraperitoneal (i.p.) injection of sodium sulfate (0.035, 0.07, 0.35 or 3.5 mmol/kg) or sodium chloride (7.0 mmol/kg) 20 min before NDPS (0.2, 0.4 or 0.8 mmol/kg) or NDPS vehicle (sesame oil, 2.5 ml/kg) and renal function monitored at 24 and 48 h. High dose sodium sulfate (3.5 mmol/kg) markedly attenuated NDPS nephrotoxicity, while sodium chloride had no effect on NDPS-induced renal effects. NDPS nephrotoxicity was also attenuated by a pretreatment dose of 0.35 mmol/kg sodium sulfate, while 0.07 mmol/kg sodium sulfate pretreatment potentiated NDPS 0.2 mmol/kg to produce nephrotoxicity without markedly attenuating NDPS 0.4 mmol/kg to induce renal effects. A dose of 0.035 mmol/kg sodium sulfate did not potentiate NDPS 0.2 mmol/kg to induce nephrotoxicity. These results suggest that sulfate conjugates of NDPS metabolites might contribute to NDPS nephrotoxicity.

Cytochrome P450-mediated metabolism and nephrotoxicity of N-(3,5-dichlorophenyl)succinimide in Fischer 344 rats.

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is nephrotoxic in rats. Previous studies have suggested that oxidative hepatic biotransformation is required for the induction of kidney damage. The experiments described in this paper were designed to further investigate the relationship between NDPS metabolism and nephrotoxicity using various modulators of cytochrome P450 activity. Male Fischer 344 rats were pretreated with the P450 inducers Aroclor 1254 (ARO), isoniazid (INH), 3-methylcholanthrene (3-MC), and phenobarbital (PB), or the P450 inhibitor 1-aminobenzotriazole (ABT). Control animals received vehicle only. NDPS metabolism was investigated using hepatocytes isolated from the various treatment groups. Separate experiments were also conducted to evaluate the effects of these pretreatments on NDPS-induced nephrotoxicity in rats. PB and ARO enhanced formation of the known nephrotoxic NDPS metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide, N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid, and N-(3,5-dichlorophenyl)-3-hydroxysuccinamic acid, by the hepatocytes. In contrast, ABT inhibited formation of the nephrotoxic metabolites, whereas INH and 3-MC did not alter NDPS biotransformation. NDPS-induced renal damage was potentiated by pretreating the rats with PB or ARO and was attenuated by ABT. Compared with control animals, toxicity was unaffected by INH or 3-MC pretreatments. Thus, there was a correlation between pretreatments that induce P450-mediated NDPS metabolism and the effects that these compounds have on NDPS-induced nephrotoxicity. The data indicate that specific P450 isozymes metabolize NDPS to its hydroxylated products and suggest that these metabolites mediate the nephrotoxicity induced by NDPS.

Buthionine sulfoximine (BSO) and N-(3,5-dichlorophenyl)succinimide nephrotoxicity: temporal aspects of BSO administration and BSO effects on renal transport systems

The agricultural fungicide, N-(3,5-dichlorophenyl)succinimide (NDPS) induces acute polyuric renal failure which is attenuated by pretreatment with the glutathione depletors, diethyl maleate or buthionine sulfoximine (BSO). In the present study, the temporal aspects of BSO attenuation of NDPS nephrotoxicity were investigated. In addition, the ability of BSO to alter the renal accumulation of selected organic ions was examined as a possible mechanism for BSO's ability to attenuate NDPS nephrotoxicity. In the first set of experiments, NDPS (0.2 or 0.4 mmol/kg) or vehicle (sesame oil, 2.5 ml/kg) was administered intraperitoneally (i.p.) to groups of male Fischer 344 rats (4–8 rats/group) 0.25 or 2 h prior to BSO (890 mg/kg, i.p.) and renal function was monitored at 24 and 48 h. NDPS (0.4 mmol/kg) nephrotoxicity was markedly attenuated by administration of BSO at 0.25 h post-NDPS, but was not substantially altered by injection of BSO at 2 h post-NDPS. NDPS (0.2 mmol/kg)-induced renal effects were not potentiated by BSO injected at 0.25 h post-NDPS, and only 1 of 8 rats exhibited marked nephrotoxicity when BSO was administered at 2 h post-NDPS. In the second set of experiments, rats (4/group) were administered BSO (890 mg/kg, i.p.) or vehicle (0.9% saline, 10 ml/kg) and kidneys harvested at 2 or 5 h post-treatment. The ability of renal cortical slices to accumulate organic ions ( p-aminohippurate [PAH], α-aminoisobutryic acid [AIB] or tetraethylammonium [TEA]) during a 90 min incubation was studied. Only TEA accumulation by renal cortical slices prepared from the 2 h post-treatment group was reduced. Studies were also conducted to examine the in vitro effects of BSO (10 −7 − 10 −4 M) on the accumulation of PAH, AIB and TEA by renal cortical slices following 5, 15 or 90 min co-incubations of BSO and an organic ion. BSO had no significant effects on the accumulation of any organic ion studied at any time

Cytochrome P450-Mediated Metabolism and Nephrotoxicity of N-(3,5-Dichlorophenyl)succinimide in Fischer 344 Rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is nephrotoxic in rats. Previous studies have suggested that oxidative hepatic biotransformation is required for the induction of kidney damage. The experiments described in this paper were designed to further investigate the relationship between NDPS metabolism and nephrotoxicity using various modulators of cytochrome P450 activity. Male Fischer 344 rats were pretreated with the P450 inducers Aroclor 1254 (ARO), isoniazid (INH), 3-methylcholanthrene (3-MC), and phenobarbital (PB), or the P450 inhibitor 1-aminobenzotriazole (ABT). Control animals received vehicle only. NDPS metabolism was investigated using hepatocytes isolated from the various treatment groups. Separate experiments were also conducted to evaluate the effects of these pretreatments on NDPS-induced nephrotoxicity in rats. PB and ARO enhanced formation of the known nephrotoxic NDPS metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide, N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid, and N-(3,5-dichlorophenyl)-3-hydroxysuccinamic acid, by the hepatocytes. In contrast, ABT inhibited formation of the nephrotoxic metabolites, whereas INH and 3-MC did not alter NDPS biotransformation. NDPS-induced renal damage was potentiated by pretreating the rats with PB or ARO and was attenuated by ABT. Compared with control animals, toxicity was unaffected by INH or 3-MC pretreatments. Thus, there was a correlation between pretreatments that induce P450-mediated NDPS metabolism and the effects that these compounds have on NDPS-induced nephrotoxicity. The data indicate that specific P450 isozymes metabolize NDPS to its hydroxylated products and suggest that these metabolites mediate the nephrotoxicity induced by NDPS.

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.

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

Dimethyl sulfoxide (DMSO) is frequently used as a solvent to assist in dissolving compounds which are not readily soluble in other injection vehicles. The purpose of this study was to determine the suitability of DMSO as a vehicle for administering the nephrotoxicant, N-(3,5-dichlorophenyl)succinimide, (NDPS) and two nephrotoxicant NDPS metabolites, N-(3,5-dichlorophenyl)-2-hydroxysuccinimide (NDHS) and N-(3,5-dichlorophenyl)-2-hydroxysuccinamic acid (NDHSA). Male Fischer 344 rats (4/group) were administered a single intraperitoneal injection of NDPS (0.4 or 0.8 mmol/kg), NDHS (0.1 or 0.2 mmol/kg), or NDHSA (0.1 or 0.2 mmol/kg) dissolved in 25% DMSO in sesame oil or 100% sesame oil (2.5 ml/kg), while control rats received vehicle only. Renal function was then monitored at 24 and 48 h. Including DMSO in the vehicle markedly attenuated NDPS 0.4 mmol/kg-induced nephrotoxicity and reduced NDPS 0.8 mmol/kg-induced renal effects. Thus, the magnitude of the attenuating effect of DMSO depended in part on the nephrotoxicant dose of NDPS. In addition, NDHS nephrotoxicity was not altered by DMSO and only slight effects on NDHSA nephrotoxicity were observed. These results suggest that DMSO is capable of attenuating NDPS nephrotoxicity, and that the primary mechanism of this interaction might be due to an inhibition of the biotransformation of NDPS to NDHS.

Acute N-(3,5-dichlorophenyl)succinimide nephrotoxicity in female Fischer 344 rats

The agricultural fungicide N-(3,5-dichlorophenyl)succinimide (NDPS) is an established nephrotoxicant in male Fischer 344 rats at i.p. doses of ≥ 0.4 mmol/kg. Since gender differences often exist in the susceptibility to toxicants, the nephrotoxic potential of NDPS was examined in female Fischer 344 rats. Rats (4–5/group) were administered NDPS (0.1, 0.2, 0.4, or 1.0 mmol/kg, i.p.) or vehicle (sesame oil, 2.5 ml/kg) and renal function monitored for 48 h. At a dose of 0.1 mmol/kg, NDPS had no effect on renal function. However, administration of NDPS at a dose of 0.2 or 0.4 mmol/kg resulted in marked nephrotoxicity characterized by diuresis, increased proteinuria, glucosuria, hematuria, elevated blood urea nitrogen (BUN) concentration and kidney weight, decreased organic ion accumulation and proximal tubular necrosis. NDPS treatment of 1.0 mmol/kg resulted in oliguric renal failure rather than polyuric renal failure in 3 of 4 rats. Proximal tubular damage was observed primarily in the S 3 segment of the proximal tubule in NDPS-treated female rats, while in male rats the S 1 and S 2 segments are the initial renal targets. These results demonstrate that female Fischer 344 rats are more susceptible to NDPS nephrotoxicity than male Fischer 344 rats and that the site of the renal lesion is gender dependent.

Effect of calcium antagonism by nifedipine and chlorpromazine on acute N-(3,5-dichlotophenyl)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 (Ca 2+) 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.