E.A. Lock ( ) · R.B. Moore Zeneca Central Toxicology Laboratory, Alderley Park, Cheshire SK10 4TJ, UK Y. Sani · A.A. Seawright National Research Center for Environmental Toxicology, University of Queensland, Brisbane, Australia M.B. Finkelstein · M.W. Anders Department of Pharmacology, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA Arch Toxicol (1996) 70: 607— 619  Springer-Verlag 1996 ORIGINAL INVESTIGATION Edward A. Lock · Yulvian Sani · Richard B. Moore Martin B. Finkelstein · M.W. Anders · Alan A. Seawright Bone marrow and renal injury associated with haloalkene cysteine conjugates in calves Received: 16 October 1995/Accepted: 9 January 1996 Abstract Almost 40 years ago, it was reported that cattle-feed which had been extracted with hot trichlo- roethylene and then fed to calves produced renal injury and a fatal aplastic anaemia. The toxic factor was subsequently identified as S-(1,2-dichlorovinyl)-L-cys- teine (DCVC). These original findings have been con- firmed, a single intravenous dose of DCVC at 4 mg/kg, or 0.4 mg/kg intravenously per day administered for 10 days to calves produced aplastic anaemia, and renal injury after a single dose of 4 mg/kg. The toxicity to calves of a number of other haloalkene cysteine conju- gates has been examined to ascertain whether, like DCVC, they produce bone marrow and renal injury. Intravenous administration of the N-acetyl cysteine conjugate of DCVC produced renal but not bone mar- row injury at a molar equivalent dose to DCVC, indic- ating that the calf can deacetylate the mercapturic acid and further that sufficient chemical had reached the kidney to be a substrate for the enzyme cysteine conju- gate -lyase. However, intravenous administration of the -methyl analogue of DCVC, which cannot under- go metabolism via the enzyme cysteine conjugate - lyase, was without toxicity at doses about five-fold higher than DCVC. These latter findings provide strong evidence that metabolism of DCVC via the enzyme -lyase is necessary for bone marrow and renal injury to occur. The cysteine conjugates of perchloro- ethylene and hexachloro-1,3-butadiene(HCBD) when given intravenously to calves at molar equivalent doses to DCVC, or above, did not produce either bone mar- row or renal injury. In contrast, intravenous adminis- tration of the cysteine conjugate of tetrafluoroethylene (TFEC) produced severe renal tubular injury in calves without affecting the bone marrow. In vitro studies with these haloalkene cysteine conjugates showed, like DCVC, that they were good substrates for calf renal cysteine conjugate -lyase and toxic to renal cells as judged by their ability to reduce organic anion and cation transport by slices of calf renal cortex and in- hibit the renal enzyme glutathione reductase. Calves were also dosed either orally or intravenously with HCBD to assess its toxicity. HCBD at higher molar equivalent doses than DCVC produced mid-zonal nec- rosis in the liver, renal tubular necrosis but no bone marrow injury in calves. The key findings emerging from these studies are (1) that none of the other cysteine conjugates, at molar equivalent doses to DCVC and above, produce bone marrow injury in calves, (2) TFEC produced only renal injury, suggesting that sufficient of the other conjugates had not reached the kidney for metabolism by -lyase to produce cytotoxicity and (3) that HCBD itself is more toxic than its cysteine or mercapturic acid conjugate, suggesting that pharmaco- kinetics and disposition are important factors in deter- mining the toxicity of these conjugates to calves. Further studies are needed to understand the basis for the selective toxicity of DCVC to the bone marrow of calves. Key words S-(1,2-Dichlorovinyl)-L-cysteine · S-(1,1,2-Trichlorovinyl)-L-cysteine · (1,1,2,2- Tetrafluoroethyl)-L-cysteine · S-(1,2,3,4,4-Pentachloro- 1,3-butadienyl)-L-cysteine · N-Acetyl-S-(1,2,3,4,4- pentachloro-1,3-butadienyl)-L-cysteine · N-Acetyl-S- (1,2-dichlorovinyl)-L-cysteine · S-(1,2-Dichlorovinyl) -DL--methylcysteine · Hexachloro-1,3-butadiene · Renal injury · Aplastic anaemia · Calves