Effect of endrin and endrin derivatives on hepatobiliary function and carbon tetrachloride-induced hepatotoxicity in male and female rats

The effects of the cyclodiene pesticide, endrin, and its aldehyde and ketone metabolites on hepatobiliary function and CCl4-induced hepatotoxicity were investigated in Sprague-Dawley rats. The rats were given control diet or diets containing 5 or 10 ppm endrin, 10 ppm endrin aldehyde or 5 ppm endrin ketone for 15 days. Three to six rats from each treatment group were given a single ip dose (100 microliter/kg body weight) of CCl4 in corn oil (1 ml/kg) on day 15. Levels of serum glutamic-oxalacetic transaminase (SGOT), glutamic-pyruvic transaminase (SGPT), isocitrate dehydrogenase and ornithine-carbamyl transferase, bile flow and biliary excretion of an anionic model compound, phenolphthalein glucuronide (PG), were measured on day 16. Dietary treatment with endrin at either dose level did not significantly elevate serum enzyme levels, while endrin aldehyde produced a slight increase in SGOT and SGPT and endrin ketone produced a small elevation in SGPT levels. Treatment with endrin aldehyde or endrin ketone did not result in significant alterations of bile flow or biliary PG excretion. Treatment with 5 ppm endrin produced a significant reduction in bile flow and a corresponding reduction in PG excretion by male rats, whereas treatment with 10 ppm endrin reduced only the PG excretion by male rats. Female rats treated with 5 or 10 ppm endrin showed a dose-dependent choleretic effect with a commensurate increase in PG excretion. With the exception of a further slight reduction in PG excretion by male rats, treatment with the endrin or endrin derivative did not potentiate CCl4-induced alterations in hepatobiliary functions. Although the levels of some serum enzymes of rats given endrin or endrin derivatives plus CCl4 were elevated over those of rats given CCl4 alone, the increases were not of the magnitude of those that have been reported previously for chlordecone. Generally, female rats challenged with CCl4 or endrin/CCl4 exhibited greater increases in serum enzyme levels than did male rats given corresponding treatments.     

The effects of kepone pretreatment on biliary excretion of xenobiotics in the male rat.

Hepatic excretory function of Kepone (chlordecone)-preexposed (10, 50, 150 ppm in daily ration for 15 days) male rats was examined in conjunction with hepatic mitochondrial Mg²⁺ ATPase (MATPase) activity. Biliary excretion of intravenously administered polar metabolites of imipramine (PMIMP) and phenolphthalein glucuronide (PG) was studied in bile duct-cannulated intact animal preparations, and MATPase was assayed via the continuous method using isolated mitochondria. Biliary excretion of PG and PMIMP was suppressed (73 and 69%, respectively) at 150 ppm, and that of PG at 10 ppm (23%). No significant effect on biliary excretion of these chemicals was evident in the other groups. Volume of bile flow was increased at the highest dose of Kepone exposure while the excretory function was compromised. Inhibition of MATPase was 34% at 50 ppm and 40% at 150 ppm, while 10 ppm Kepone-pretreated animals showed no significant inhibition of this enzyme system. These data suggest that although observed inhibition of hepatobiliary function resulting from Kepone pretreatment can be linked to the inhibition of the MATPase system, a direct correlation may not exist.     

Alterations in biliary excretory function by streptozotocin-induced diabetes

Hepatic clearance and biliary excretion of model substrates for each of four carrier-mediated transport systems were studied in male Sprague-Dawley rats treated 28 days earlier with 45 mg/kg streptozotocin iv to induce uncontrolled insulin-deficient diabetes. Diabetic rats exhibited hyperglycemia (560 mg/dl), polyuria (160 ml/24 hr), polyphagia, polydipsia, and generalized myopathy. The plasma disappearance, biliary excretion, and elimination half-life of the anionic dye phenol red was unchanged in diabetic rats, but total clearance of phenol red was increased. Conjugation of phenol red with glucuronic acid appeared to be increased in diabetic rats, whereas acetylation of procainamide ethobromide was decreased. Plasma elimination and total clearance of cationic procainamide ethobromide, uncharged ouabain, and the bile acid taurocholate were significantly increased in diabetic animals. Biliary excretion of these three compounds was only slightly elevated in the first 15 min after administration and was decreased after 1 hr. Biliary and total systemic clearance were also increased from 2-3-fold for procainamide ethobromide, ouabain, and taurocholate. These changes in clearance are predominantly due to the 2-5-fold increase in steady state volume of distribution. Basal bile flow rates were increased by 62% after the induction of diabetes to 88 microliter/min/kg. Diabetic rats secreted higher levels of bile acids, cholesterol, and phospholipids into bile. These data indicate that long term insulin-dependent diabetes does alter hepatic excretory function.     

Methylene dianiline: acute toxicity and effects on biliary function.

4,4'-Methylene dianiline (4,4'-diaminodiphenylmethane, DAPM), which is used in the polymer industry, causes hepatobiliary damage in exposed humans. Our objectives were to characterize the acute toxicity of DAPM in liver, particularly on secretion of biliary constituents and on biliary epithelial cell gamma-glutamyl transpeptidase (GGT) activity. Biliary cannulas were positioned in Sprague-Dawley male rats under pentobarbital anesthesia. After 1 hr of control bile collection, each rat was given 250 mg DAPM/kg (50 mg/ml) po in 35% ethanol or 35% ethanol only; bile was collected for a further 4 hr. Groups of rats were also examined for liver injury and biliary function at 8 and 24 hr after DAPM. Four hours after DAPM administration, main bile duct cells were severely damaged with minimal damage to peripheral bile ductule cells. Focal periportal hepatocellular necrosis and extensive cytolysis of cortical thymocytes occurred by 24 hr. Serum indicators of liver injury were elevated by 4 hr and continued to rise through 24 hr. By 4 hr, biliary protein concentration was increased 4-fold while concentrations of biliary bile salt, bilirubin, and glutathione were decreased by approximately 80, 50, and 200%, respectively. DAPM also induced a striking effect on biliary glucose with an approximately 20-fold increase. Histochemical staining of main bile duct GGT was absent by 8 hr after DAPM. Bile flow was diminished by 40% at 4 hr; three of five rats had no bile flow by 8 hr and none had any bile flow by 24 hr. These results indicate that DAPM rapidly diminishes bile flow and alters the secretion of biliary constituents and is highly injurious to biliary epithelial cells.     

Effect of carbon tetrachloride on biliary excretion of 3,4-benzpyrene in rats]

14C-labelled 3,4-benzpyrene (14C-BP) in dose of 100 mug/animal was injected into female Sprague-Dawley rats under urethane anesthesia. The rats were cannulated at the duct and the output of metabolites in the bile was determined. Non-treated rats excreted 35.5% of the given dose within one hr. The main metabolites excreted in bile were fractionated chromatographically into three. One of these was a metabolite which was hydrolyzed by beta-glucuronidase, the other two were unknown substances. Unchanged BP was not detected. In rats pretreated with CCl4 (0.5 ml/kg, p.o.) 24 hr before experiment, the biliary excretion of BP-metabolites was found to be reduced, that is only 10% of the given dose was excreted within one hr. It was noted that the output within the first 90 min after injection of BP was significantly reduced. In the CCl4-treated rats, bile flow was found to be lowered. However, the reduced output of BP-metabolites was considered not as the result of lowered bile flow, but as the result of disturbance of BP-metabolism in the liver. Thus it is suggested that impaired hepatic junction as the result of CCl4 intoxication may last for more than two weeks, when the hepatic junction is evaluated in terms of biliary excretion of BP.     

Excretion of nitrofurantoin in dog hepatic bile

1. After the intravenous administration of nitrofurantoin sodium to dogs at nitrofurantoin doses of 1.5-24.0 mg/kg, a substantial amount of nitrofurantoin is excreted in bile. The bile to blood drug ratios were about 200. A marked hydrocholeretic effect which correlated directly with the amount of nitrofurantoin administered was also observed.2. The excretion of nitrofurantoin in bile and the hydrocholeretic effect were linear with the dose of drug over the range 1.5-12.0 mg/kg. Maximum increases in hepatic bile flows were usually from 5-10 ml/0.5 h, while average control bile flow was 1.6 ml +/- S.D. 0.6/0.5 hours. The lowest dose at which the hydrocholeretic effect was still detectable was 0.09 mg/kg.3. Apparent saturation of the biliary excretion system for nitrofurantoin and the hydrocholeretic mechanism occurred after a dose of 24.0 mg/kg. Saturation of the urinary system for nitrofurantoin excretion was noted after a dose of 6.0 mg/kg.4. Biliary nitrofurantoin recoveries ranged from 16.5% +/- S.D. 4.2 to 22.6% +/- S.D. 4.7 for the 6 h period after doses of 1.5, 3.0, and 6.0 mg/kg. Urinary nitrofurantoin recoveries for the same interval ranged from 24.1% +/- S.D. 6.6 to 36.2% +/- S.D. 8.3.5. In comparison to values obtained in normal dogs, only about one-tenth of the drug excretion in bile and about one-fifth of the hydrocholeretic effect were obtained after intravenous drug administration to dogs with hepatic impairment induced by CCl(4).     

Probenecid-impaired biliary excretion of acetaminophen glucuronide and sulfate in the rat.

Acetaminophen (APAP; 100 mg/kg iv) and probenecid (50 mg/kg bolus + 11.4 mg/hr/kg infusion) were administered to male Sprague-Dawley rats to examine the disposition of APAP, and its glucuronide (AG) and sulfate (AS) conjugates in plasma, bile, and urine. Probenecid significantly decreased the formation clearance of AG from 3.65 +/- 0.434 to 1.94 +/- 0.441 ml/min/kg and the renal clearance of AS from 9.32 +/- 2.26 to 3.15 +/- 1.21 ml/min/kg. The biliary excretion of AG was reduced approximately 3- to 4-fold by probenecid, from 6.54 to 1.87% of the APAP dose, and the AG biliary excretion rate was decreased 4- to 5-fold during probenecid treatment. The more extensive impairment of AG biliary excretion relative to AG formation suggests that probenecid may inhibit the hepatobiliary transport of AG. The significant reduction in the biliary excretion rate at early time points for AS suggests that probenecid may inhibit hepatic AS transport. The study results indicate that probenecid impairs AG and AS formation, AS renal secretion, and AG and AS biliary excretion.     

Potentiation of CCl4 hepatotoxicity and lethality by chlordecone in female rats

Female Sprague-Dawley rats (175-200 g) were maintained on a commercial powdered rat chow containing 0 or 10 ppm chlordecone (Kepone; CD). On day 15 of the dietary protocol, a single dose of CCl4 (5-100 microliters/kg) was administered i.p. in corn oil vehicle. Controls received corn oil vehicle only. Twenty-four hours after CCl4 administration, hepatotoxicity was assessed using biochemical, functional, and histopathological parameters. Serum enzymes (GPT, GOT, ICD and OCT) were elevated in a dose related manner in the animals receiving CD-CCl4 combination. CCl4 alone at the doses used had no marked effect. Centrilobular necrosis was observed in the animals receiving CD-CCl4 combination. Biliary excretion of phenolphthalein glucuronide (PG) and the rate of bile flow were decreased in a dose-dependent manner. Forty-eight hour LD50 of CCl4 was decreased 26-fold by CD pretreatment. These results indicate that CD potentiates CCl4 toxicity in female rats as well. Since the hepatic functional status is greatly compromised, the CD potentiated lethality is preceded by hepatic failure. Furthermore, female rats are sensitized to smaller doses of CCl4 in comparison to male rats.     

Extensive biliary excretion of the sulfasalazine analogue, susalimod, but different concentrations in the bile duct in various animal species correlating to species-specific hepatobiliary toxicity.

Studies on biliary concentrations of susalimod were conducted in rat, dog and monkey to clarify the interspecies differences observed in toxicology studies with respect to hepatobiliary toxicity after long-term administration of the compound. Dose-related bile duct hyperplasia appeared only in dogs at doses > or =75 mg/kg/day, while in rats and monkeys it did not appear at doses up to 1500 and 2000 mg/kg/day respectively. Biliary excretion was investigated after intraduodenal administration of susalimod in anaesthetised animals. In addition excretion routes were determined by collecting urine and faeces following a radiolabelled intravenous dose. Susalimod was extensively excreted via the bile in all animal species, > or =90%, mainly as non-conjugated parent compound. However, the local concentrations in bile varied between the species. Highest concentrations were obtained in the dog. The bile/plasma concentration ratio was 3400 in the dog, 300 in the monkey and 50 in the rat. In the dog, bile duct concentrations of susalimod about 30,000 micromol/l was obtained at plasma concentrations approximately similar to those at which hepatobiliary toxicity occurred, while in rat and monkey the levels were < or =7000 micromol/l at plasma concentrations similar to those obtained at the highest doses in the toxicology studies. From these results supported by a previous biliary excretion study in conscious dogs with chronic bile fistula receiving repeated administration of susalimod (P?hlman et al. 1999), it is likely that the hepatotoxic findings in dog are induced by the high concentrations of susalimod in the bile duct.     

Extensive Biliary Excretion of the Sulfasalazine Analogue,Susalimod, but Different Concentrations in the Bile Duct in Various Animal Species Correlating to Species-Specific Hepatobiliary Toxicity

Abstract: Studies on biliary concentrations of susalimod were conducted in rat, dog and monkey to clarify the interspecies differences observed in toxicology studies with respect to hepatobiliary toxicity after long-term administration of the compound. Dose-related bile duct hyperplasia appeared only in dogs at doses ≥75 mg/kg/day, while in rats and monkeys it did not appear at doses up to 1500 and 2000 mg/kg/day respectively. Biliary excretion was investigated after intraduodenal administration of susalimod in anaesthetised animals. In addition excretion routes were determined by collecting urine and faeces following a radiolabelled intravenous dose. Susalimod was extensively excreted via the bile in all animal species, ≥90%, mainly as non-conjugated parent compound. However, the local concentrations in bile varied between the species. Highest concentrations were obtained in the dog. The bile/plasma concentration ratio was 3400 in the dog, 300 in the monkey and 50 in the rat. In the dog, bile duct concentrations of susalimod about 30,000 μmol/l was obtained at plasma concentrations approximately similar to those at which hepatobiliary toxicity occurred, while in rat and monkey the levels were ≤7000 μmol/l at plasma concentrations similar to those obtained at the highest doses in the toxicology studies. From these results supported by a previous biliary excretion study in conscious dogs with chronic bile fistula receiving repeated administration of susalimod (Påhlman et al. 1999), it is likely that the hepatotoxic findings in dog are induced by the high concentrations of susalimod in the bile duct.     

Protective effect of Aucuba japonica against carbon tetrachloride-induced liver damage in rats

Pretreatment of rats with ethanol extract from leaves of Aucuba japonica (600 mg/kg/day, po) for two days protected against CCl4-induced depression in plasma disappearance and biliary excretion of injected sulfobromophthalein (BSP) determined 24 hr after the CCl4 challenge (0.5 ml/kg, ip). Percent recovery of BSP in bile in 60 min for control, CCl4, extract + CCl4 treated rats was 66.8 +/- 1.9, 56.2 +/- 1.4, and 68.9 +/- 2.2, respectively. Pretreatment of the extract also protected CCl4-induced increased serum glutamic-pyruvic transaminase activity and liver necrosis as demonstrated by histological evaluations. However, pretreatment of the extract did not modify the intensity of CCl4-induced lipid peroxidation process or cytochrome P-450 destruction. The results suggest that ethanol extract of Aucuba japonica protects CCl4 hepatotoxicity at a site in the chain events leading to necrosis but not the activation step of CCl4 to X CCl3 and X C1 free radicals.     

Biliary excretion and tissue distribution of penta- and hexavalent molybdenum in rats

Biliary excretion, whole-body excretion, and distribution of pentavalent and hexavalent forms of molybdenum in blood, liver, and jejunoileocecum were studied in rats at 1, 2, 3, and 4 hr after iv administration of 0.08 and 4.6 mg of molybdenum/kg. The excretion of both valence forms of molybdenum was found to be dose dependent. No difference was observed between the two valence forms in the biliary and whole-body excretion after the dose of 0.08 mg Mo/kg, whereas after the administration of 4.6 mg Mo/kg the excretion of pentavalent molybdenum was considerably decreased. This was accompanied by a slower decline in the content of pentavalent molybdenum in all the analyzed tissues.     

Effects of gomisin A on liver functions in hepatotoxic chemicals-treated rats

The effects of gomisin A, which is a lignan component of schizandra fruits, on liver functions in various experimental liver injuries and on bile secretion in CCl4-induced liver injury were studied. Gomisin A weakly accelerated the disappearance of plasma ICG by itself at a high dose (100 mg/kg, i.p.). All of the hepatotoxic chemicals used in this study inhibited the excretion of ICG from plasma. Gomisin A showed a tendency to prevent the delays of the disappearance of plasma ICG induced by CCl4, d-galactosamine and orotic acid, but not that by ANIT. Bile flow and biliary outputs of total bile acids and electrolytes (Na+, K+, Cl- and HCO3-) were decreased in CCl4-treated rats. Gomisin A maintained bile flow and biliary output of each electrolyte nearly to the level of the vehicle-treated group, but did not affect biliary output of total bile acids. These findings suggest that gomisin A possesses a liver function-facilitating property in normal and liver injured rats and that its preventive action on CCl4-induced cholestasis is due to maintaining the function of the bile acids-independent fraction.     

Studies on the metabolic fate of gomisin A (TJN-101). II. Absorption and excretion in CCl4 treated rats]

The absorption and excretion of gomisin A (TJN-101) in rats whose livers were injured by carbon tetrachloride (CCl4) were investigated. After intravenous administration of TJN-101 at a dose of 5 mg/kg, the terminal elimination half-life was 1.5 h in the CCl4-treated rats, which was two times that in normal rats. The mean area under the blood concentration-time curve (AUC) value of TJN-101 in the CCl4-treated rats was twice that in normal rats, and this difference was significant (p less than 0.05). Therefore, the total body clearance of TJN-101 in the CCl4-treated rats decreased less than half of that in normal rats. Similar results were observed when it was administered orally. In the CCl4-treated rats, the serum concentration of Met. B, which was identified as a demethylenated substance and one of major metabolites, tended to decrease more than that in normal rats. On the other hand, the cumulative biliary excretion ratio of TJN-101 in 24 h after dosing in the CCl4-treated rats was 2.5 times that in normal rats. The excretion rate of Met. B in the bile in the CCl4-treated rats tended to be delayed. However, the quantitative variance of biliary excretion of Met. B was not found in both groups. The urinary excretion of TJN-101 or Met. B in 72 h after dosing in the CCl4-treated rats was lower than that in normal rats. Similar results were also observed in excretion in the feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of altered hepatic function on the toxicity, plasma disappearance and biliary excretion of diethylstilbestrol

The present investigation was prompted by the observation that the toxicity of diethylstilbestrol (DES) was about 140 times greater in bile duct-ligated (BDL) rats than in control rats when dimethylsulfoxide was the vehicle (24-hr LD50: 0.75 vs 100 mg/kg, respectively). The DES was also more toxic (about 70 times) in the BDL rats when ethyl alcohol was the solvent (0.47 vs 34 mg/kg), and was 5 times more toxic in the BDL rats when administered in propylene glycol (100 vs 530 mg/kg). Since it appeared that altered hepatic function markedly alters the acute toxicity of DES, the plasma disappearance and biliary excretion of DES (0.118 mg/kg, iv) were measured in control rats and in rats with altered hepatic function (produced by surgical removal of two-thirds of the liver, ip injection of 1 ml CCl₄/kg, or bile duct ligation). All three procedures of altering hepatic function decreased the plasma disappearance of DES. In the BDL rats, the total plasma concentration of DES did not decrease over the 2-hr period, suggesting that even when the biliary route of excretion is blocked, other routes are not efficent for the excretion of DES. During the furst 15 min after DES administration, the biliary excretory rate of DES was 2.1 μg/min/kg in control rats and 1.2 μg/min/kg in the rats that had a $\text{2}\text{3}$ hepatectomy or CCl₄. Therefore, impaired hepatic function increased the plasma concentration and toxicity of DES as it decreased its conjugation and biliary excretion.     

Modulation of hepatic canalicular or basolateral transport proteins alters hepatobiliary disposition of a model organic anion in the isolated perfused rat liver.

This study examined the impact of hepatic transport protein modulation on the hepatobiliary disposition of a nonmetabolized probe substrate, 5- (and 6)-carboxy-2',7'dichlorofluorescein (CDF) in rat isolated perfused livers (IPLs). In vivo treatment with modulators (100 and 200 mg/kg/day clofibric acid, 80 mg/kg/day phenobarbital, and 25 mg/kg/day dexamethasone) was used to alter the expression of hepatic transport proteins [organic anion transporting polypeptide 1a1, multidrug resistance-associated protein (Mrp) 3, and Mrp2] governing the disposition of CDF. The basolateral and biliary excretion of CDF was measured in single-pass IPLs from control and treated rats. Modulators increased the percentage of CDF eliminated into perfusate of IPLs from treated rats ( approximately 20-35%) compared with controls ( approximately 10%); CDF biliary excretion was decreased in the treated groups. These observations are consistent with modulator-associated increases in the first-order rate constant governing CDF excretion from the hepatocytes into perfusate (k(perfusate)) or decreases in the first-order rate constant governing CDF excretion into bile (k(bile)). Pharmacokinetic modeling of the data and subsequent simulations revealed that the routes of CDF excretion were most sensitive to changes in k(perfusate). In contrast, hepatic accumulation of CDF was most sensitive to k(bile). The differential sensitivity of CDF excretory routes and hepatic accumulation to these rate constants is a function of intrahepatic distribution kinetics, which must be taken into consideration in assessing the potential impact of altered hepatobiliary transport processes.     

The effect of salicylate on the biliary excretion of 14C-bishydroxycoumarin in rat

1. The effect of intravenous sodium salicylate on the biliary excretion of 14C-bishydroxycoumarin ((14)C-BHC) was studied in rats.2. Salicylate (88.9 mg/kg) increased the biliary excretion of (14)C-radioactivity from a control value of 12.3 +/- 2.7% to 29.3 +/- 2.5% of the administered dose in 6 h after injection.3. During the 6 h period, 11% of the dose of radioactivity underwent biliary recycling in the salicylate-treated rats compared to only 6% in the absence of salicylate.4. About 15.3% of the radioactivity excreted in the bile of rats given BHC alone was detected as unchanged BHC, 8.6% was present as BHC-conjugate, conjugates of BHC metabolites accounted for 30.9%, and the remainder consisted of unidentified metabolites.5. Salicylate treatment did not significantly alter the excretory pattern of unchanged BHC and its metabolites.     

Increased biliary excretion of glutathione is generated by the glutathione-dependent hepatobiliary transport of antimony and bismuth.

We have recently demonstrated that the hepatobiliary transport of arsenic is glutathione-dependent and is associated with a profound increase in biliary excretion of glutathione (GSH), hepatic GSH depletion and diminished GSH conjugation (Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 41: 937-944 and Gyurasics A, Varga F and Gregus Z, Biochem Pharmacol 42: 465-468, 1991). The present studies in rats aimed to determine whether antimony and bismuth, other metalloids in group Va of the periodic table, also possess similar properties. Antimony potassium tartrate (25-100 mumol/kg, i.v.) and bismuth ammonium citrate (50-200 mumol/kg, i.v.) increased up to 50- and 4-fold, respectively, the biliary excretion of non-protein thiols (NPSH). This resulted mainly from increased hepatobiliary transport of GSH as suggested by a close parallelism in the biliary excretion of NPSH and GSH after antimony or bismuth administration. Within 2 hr, rats excreted into bile 55 and 3% of the dose of antimony (50 mumol/kg, i.v.) and bismuth (150 mumol/kg, i.v.), respectively. The time courses of the biliary excretion of these metalloids and NPSH or GSH were strikingly similar suggesting co-ordinate hepatobiliary transport of the metalloids and GSH. However, at the peak of their excretion, each molecule of antimony or bismuth resulted in a co-transport of approximately three molecules of GSH. Diethyl maleate, indocyanine green and sulfobromophthalein (BSP), which decreased biliary excretion of GSH, significantly diminished excretion of antimony and bismuth into bile indicating that hepatobiliary transport of these metalloids is GSH-dependent. Administration of antimony, but not bismuth, decreased hepatic GSH level by 30% and reduced the GSH conjugation and biliary excretion of BSP. These studies demonstrate that the hepatobiliary transport of trivalent antimony and bismuth is GSH-dependent similarly to the hepatobiliary transport of trivalent arsenic. Proportionally to their biliary excretion rates, these metalloids generate increased biliary excretion of GSH probably because they are transported from liver to bile as unstable GSH complexes. The significant loss of hepatic GSH into bile as induced by arsenic or antimony may compromise conjugation of xenobiotics with GSH.     

Evaluation of the gender differences in 4,4'-methylenedianiline toxicity, distribution, and effects on biliary parameters

Exposure to 4,4'-diaminodiphenylmethane (DAPM) has been linked to jaundice, toxic hepatitis, cholangitis, and cholestasis. In rodents, DAPM initially injures biliary epithelial cells, and toxicity is greater in female than male rats. Our goal was to determine if gender differences in DAPM toxicity were due to differences in biliary excretion or covalent binding of DAPM metabolites in the liver. Bile duct-cannulated female and male Sprague-Dawley rats were gavaged with vehicle or with 25 or 50 mg [14C]DAPM/kg, and bile was collected for 6 h. Serum and bile indicators of hepatobiliary toxicity were assessed, and radioactivity was measured in bile, serum, urine, and liver. At the 25 mg/kg dose, serum parameters were elevated only in female rats, while increases in serum parameters were observed in both genders at the 50 mg/kg dose. In males rats, biliary constituents altered by DAPM [inorganic phosphate (Pi), glucose, gamma-glutamyl transpeptidase (GGT)] showed time- and dose-dependent responses. In female rats, however, biliary constituents showed either minimal dose-response effects (glucose), were increased equivalently at both doses (Pi), or were not altered by DAPM treatment (GGT). At the 50 mg/kg dose, liver alkaline phosphatase decreased in female but not male rats. Gender also affected the disposition of DAPM metabolites. At 25 mg DAPM/ kg, male rats had greater amounts of DAPM/metabolite in bile and liver, while females had greater amounts in serum and urine. These studies thus confirm that (1) DAPM is more toxic in female than male rats, and (2) gender has a significant effect on the disposition and biliary excretion of DAPM metabolites.     

Evalutaion of the Gender Differences in 4,4'-Methylenedianiline Toxicity,Distribution, and Effects on Biliary Parameters

Exposure to 4,4'-diaminodiphenylmethane (DAPM) has been linked to jaundice, toxic hepatitis, cholangitis, and cholestasis. In rodents, DAPM initially injures biliary epithelial cells, and toxicity is greater in female than male rats. Our goal was to determine if gender differences in DAPM toxicity were due to differences in biliary excretion or covalent binding of DAPM metabolites in the liver. Bile duct-cannulated female and male Sprague-Dawley rats were gavaged with vehicle or with 25 or 50 mg [¹⁴C]DAPM/kg, and bile was collected for 6 h. Serum and bile indicators of hepatobiliary toxicity were assessed, and radioactivity was measured in bile, serum, urine, and liver. At the 25 mg/kg dose, serum parameters were elevated only in female rats, while increases in serum parameters were observed in both genders at the 50 mg/kg dose. In males rats, biliary constituents altered by DAPM [inorganic phosphate (P_i