s-pentachlorobuta-1-3-dien-yl-cysteine and Kidney-Diseases

Glutathione (GSH) conjugation reactions in the metabolism of hexachlorobutadiene (HCBD), in rats and mice, initiate a series of metabolic events resulting in the formation of reactive intermediates in the proximal tubular cells of the kidney. The GSH S-conjugate 1-(glutathion-S-yl)-1,2,3,4,4-pentachlorobutadiene (GPCB), which is formed by conjugation of HCBD with GSH in the liver, is not reactive and is eliminated from the liver in the bile or plasma, or both. GPCB may be translocated intact to the kidney and processed there by gamma-glutamyl transpeptidase and dipeptidases to the corresponding cysteine S-conjugate. Alternatively, gamma-glutamyl transpeptidase and dipeptidases present in epithelial cells of the bile duct and small intestine may catalyse the conversion of GPCB to cysteine S-conjugates. The kidney concentrates both GSH and cysteine S-conjugates and processes GSH conjugates to cysteine S-conjugates. A substantial fraction of HCBD cysteine S-conjugate thus concentrated in the kidney is metabolized by renal cysteine conjugate beta-lyase to reactive intermediates. The selective formation of reactive intermediates in the kidney most likely accounts for the organ-specific effects of HCBD. Alternatively, cysteine S-conjugates may be acetylated to yield excretable mercapturic acids.

Topics: Animals; Biotransformation; Butadienes; Cysteine; Glutathione; Kidney Diseases; Liver

Glutathione conjugation and subsequent formation of cysteine conjugates are key steps in the nephrotoxicity of halogenated alkenes. In this metabolic activation several organs are involved. However little is known about the transporters responsible for the uptake of cysteine conjugates. Recent evidence suggest that amino acid transporters play a role in this uptake. Monolayers of LLC-PK1 cells, a kidney cell line, were exposed to S-(1,2,3,4,4-pentachlorobutadienyl)-L-cysteine (PCBD-CYS). Cytotoxicity was used as a parameter for PCBD-CYS uptake. Basolateral exposure (1 h: 400 microM and 16 h: 25 microM) to PCBD-CYS resulted in a much higher aminooxyacetic acid inhibitable cytotoxicity than apical exposure, suggesting a preferential basolateral uptake of PCBD-CYS. Exposure to PCBD-CYS in the absence of sodium did not result in a decrease of the cytotoxicity, suggesting a sodium independency of the PCBD-CYS uptake. Amino acids and amino acid analogues were used as diagnostic compounds in the further identification of the PCBD-CYS transporter. In cis-inhibition experiments monolayers were co-incubated with PCBD-CYS and these diagnostic compounds during one hour. System L substrates such as 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid (BCH) and cycloleucine did not inhibit cytotoxicity. D-Tryptophan, a model inhibitor of System T, caused a strong inhibition. System L has, in contrast to System T, a high sensitivity to trans-stimulation. Pre-loading the monolayers with the diagnostic compounds should cause an increase in cytotoxicity when System L is involved. Neither System L substrates such as BCH and cycloleucine nor D-tryptophan increased cytotoxicity. These results suggest a preferential basolateral uptake of PCBD-CYS in LLC-PK1 monolayers and involvement of an amino acid transporter with characteristics of System T.

Topics: Amino Acids; Animals; Biological Transport; Butadienes; Carrier Proteins; Cell Survival; Cells, Cultured; Cysteine; Kidney Diseases; Sodium; Swine

The nephrotoxicity of hexachloro-1,3-butadiene (HCBD), its glutathione conjugate (HCBD-GSH), cysteine conjugate (HCBD-CYS), and its N-acetyl cysteine conjugate (HCBD-NAC) were compared in male and female Alderley Park rats. Rats, six to eight weeks of age, were given a single intra-peritoneal injection of HCBD or its conjugates and killed 24 hours later. Nephrotoxicity was assessed by histological examination and plasma urea. All three glutathione-derived conjugates produced an elevation of plasma urea and proximal renal tubular necrosis with a similar localization in the pars recta as seen with HCBD. All the conjugates were more nephrotoxic than HCBD itself. HCBD was about four times more toxic to female rats than males. This sex difference was also shown by all the HCBD metabolites.

Topics: Acetylcysteine; Animals; Butadienes; Cysteine; Female; Glutathione; Kidney Diseases; Kidney Medulla; Kidney Tubules, Proximal; Male; Necrosis; Rats; Sex Factors; Urea