diethyl-maleate and acivicin

Influences of biliary ligation and systemic depletion of glutathione (GSH) or modulation of GSH status on the disposition of a low, non-nephrotoxic i.v. dose of inorganic mercury were evaluated in rats in the present study. Renal and hepatic disposition, and the urinary and fecal excretion, of inorganic mercury were assessed 24 h after the injection of a 0.5-micromol/kg dose of mercuric chloride in control rats and rats pretreated with acivicin (two 10-mg/kg i.p. doses in 2 ml/kg normal saline, 90 min apart, 60 min before mercuric chloride), buthionine sulfoximine (BSO; 2 mmol/kg i.v. in 4 ml/kg normal saline, 2 h before mercuric chloride) or diethylmaleate (DEM; 3.37 mmol/kg i.p. in 2 ml/kg corn oil, 2 h before mercuric chloride) that either underwent or did not undergo acute biliary ligation prior to the injection of mercury. Among the groups that did not undergo biliary ligation, the pretreatments used to alter GSH status systemically had varying effects on the disposition of inorganic mercury in the kidneys, liver, and blood. Biliary ligation caused the net renal accumulation of mercury to decrease under all pretreatment conditions. By contrast, biliary ligation caused significant increases in the hepatic burden of mercury in all pretreatment groups except in theacivicin-pretreated group. Blood levels of mercury also increased as a result of biliary ligation, regardless of the type of pretreatment used. The present findings indicate that biliary ligation combined with methods used to modulate GSH status systemically have additive effects with respect to causing reductions in the net renal accumulation of mercury. Additionally, the findings indicate that at least some fraction of the renal accumulation of inorganic mercury is linked mechanistically to the hepato-biliary system.

Topics: Animals; Bile Ducts; Buthionine Sulfoximine; Feces; Glutathione; Isoxazoles; Kidney; Liver; Male; Maleates; Mercury; Rats; Rats, Sprague-Dawley

We investigated the hypothesis that reduced glutathione (GSH) is present in secretions of the female reproductive tract and that this extracellular GSH may protect preimplantation mouse embryos after intracellular GSH depletion. The cleavage-stage mouse embryo cannot synthesize GSH de novo and is unable to recover from glutathione depletion in vitro. Analysis of GSH and total protein of oviduct flushings, quantified by HPLC and the Bradford method, respectively, revealed 51 nmol GSH per mg total protein. Embryos were treated with 60 microM diethyl maleate (DEM) to deplete cellular GSH. When cultured with 1 mM GSH, these embryos exhibited improved development compared to those cultured in control medium (96% vs. 87% morula [p < 0.05], 78% vs. 75% blastocyst, 58% vs. 54% expanded blastocyst, 21% vs. 17% initiating hatching blastocyst). However, intracellular GSH content of embryos was not significantly increased by the culture of DEM-treated embryos in medium containing GSH for 16, 40, or 64 h of incubation, suggesting that the embryo is not capable of taking up intact GSH. Furthermore, addition of buthionine sulfoximine (which inhibits synthesis of GSH) or acivicin (which inhibits breakdown of GSH at the membrane) to culture medium blocked the improvement in development. These data suggest that GSH in reproductive tract fluid may help protect preimplantation embryos from the adverse effects of toxicant-induced and endogenous depletion of embryonic GSH.

Topics: Animals; Buthionine Sulfoximine; Culture Media; Embryonic and Fetal Development; Female; Glutathione; Growth Substances; Isoxazoles; Maleates; Mice; Oxidation-Reduction; Superovulation; Uterus

The importance of renal gamma-glutamyltransferase activity in the hepatic utilization of exogenous glutathione (GSH) was evaluated by injecting GSH (1.67 mmol/kg body wt) i.v. into bilaterally nephrectomized and sham-operated Sprague-Dawley rats in which endogenous hepatic GSH had been decreased (0.20 +/- 0.01 mumol/g liver vs 5.87 +/- 0.26 mumol/g liver in normal controls, mean +/- SD) by diethylmaleate (0.5 ml/kg body wt, i.p.). Hepatic GSH concentration 60 min after GSH administration was lower in the nephrectomized than in the sham-operated rats (0.87 +/- 0.25 mumol/g liver vs 3.08 +/- 0.81 mumol/g liver, P < 0.001), while plasma GSH concentration was higher in the former (4.61 +/- 1.07 mM vs 0.11 +/- 0.06 mM, P < 0.001). In rats with intact kidneys which had been given a gamma-glutamyltransferase inhibitor (acivicin, 25 mumol/kg body wt i.v.) prior to GSH administration, the hepatic GSH concentrations (1.11 +/- 0.49 mumol/g liver) were comparable to those obtained in the nephrectomized rats. When N-acetylcysteine (1.67 mmol/kg body wt, i.v.) was administered instead of GSH, the hepatic GSH concentrations were similar in nephrectomized and sham-operated rats (1.54 +/- 0.23 mumol/g liver vs 2.22 +/- 0.58 mumol/g liver, NS). The gamma-glutamyltransferase activity was much higher in the kidney than in the liver (4460 +/- 830 IU/kg body wt vs 14 +/- 7 IU/kg body wt). These results indicate that the kidney plays an essential role in the hepatic utilization of exogenous GSH through its high gamma-glutamyltransferase activity.

Topics: Acetylcysteine; Animals; gamma-Glutamyltransferase; Glutathione; Injections, Intravenous; Isoxazoles; Kidney; Liver; Male; Maleates; Nephrectomy; Rats; Rats, Sprague-Dawley