Effect of polyaspartic acid on CdCl2-induced nephrotoxicity in the rat

Effects of a hepato-protective agent and a hepato-secreting chelator on cadmium-induced nephrotoxicity in Syrian hamsters

Cadmium (Cd)-induced nephropathy in male Syrian hamsters was treated with D/L-penicillamine (D/L-p) or neomynophagen C (NMC). The subcutaneous injection of CdCl(2), 3 mg/kg, three times a week led to marked renal damage, ie., increased proteinuria and the excretion of urinary N-acetyl-beta-D-glucosaminidase (NAG) as compared with the saline-injected controls. Cd-treated hamsters that were injected intraperitoneally with D/L-p, 0.1 mg/kg, five times a week, showed less renal damage, including a reduction in urinary protein from 3.60 + or - 0.42 to 1.77 + or - 0.7 mg/d. NMC-treated hamsters showed a reduced excretion of NAG (from 1.47 +/ - 0.34 to 0.91 + or - 0.68 u/d). The concentration of Cd in renal cortical tissue was reduced slightly (from 2.78 + or - 0.08 to 2.34 + or - 0.3 mg/g.prot) by NMC treatment, but not by D/L-p. The elevated malondialdehyde (MDA) in renal cortical tissue was unaffected by administering D/L-p or NMC. The concentration of glutathione (CSH) in the renal cortex was not elevated after administering Cd, but the ratio of the reduced to the oxidized GSH was elevated. The Cd induced liver dysfunction, as compared with untreated controls. The dysfunction was improved slightly by NMC administration, but not by that of D/L-p. Changes in renal morphology induced by Cd involving marked degeneration and necrosis of tubules as shown by light microscopy, were unaffected by treatment with D/L-p or NMC. We thus demonstrated the efficacy of D/L-p of NMC in treating the nephropathy induced by Cd in hamsters. The mechanism of therapeutic effect is not known.

Effect of triethylenepentaminehexaacetic acid on the renal damage in cadmium-treated Syrian hamsters

Cadmium (Cd)-induced nephropathy was treated by triethylenepentaminehexaacetic acid (TTHA) in male Syrian hamsters. Hamsters injected three times a week with 3 mg/kg body wt CdCl2 showed proteinuria, urinary N-acetyl-beta-D-inglucosaminidase (NAG), and fractional excretion of sodium (FENa) when compared to saline-injected control. Cd-treated hamsters injected ip with TTHA 10 mg/kg body wt five times a week showed reduction of renal damage, including reductions in urinary protein (from 6.7 +/- 2.2 to 4.3 +/- 0.5 mg/d) and NAG (0.17 +/- 0.06 to 0.04 +/- 0.02 U/d). Urinary excretion of Cd was significantly increased (from 87 +/- 51.3 to 3052 +/- 1485 mg/L) by TTHA administration. Cd concentration in renal cortical tissue was slightly reduced (26.4 +/- 3.0 to 21.8 +/- 2.7 mg/g. protein). Excretion of malondialdehyde (MDA) was increased only in Cd-injected hamsters (to 2.1 +/- 1.6 nM/L), and elevated MDA in renal cortical tissue was not reduced by the administration of TTHA (1041 +/- 105 vs 1104 +/- 358 nM/g protein). Glutathione (GSH) concentration in the renal cortex was significantly elevated after Cd administration and further increased after TTHA administration (5.5 +/- 2.1 to 9.8 +/- 2.0 micrograms/50 mg protein). There were no marked effects on creatinine clearance (Ccr) and hematocrit. Moreover, renal morphological changes were improved significantly by treatment with TTHA. We demonstrated the efficacy of TTHA in the treatment of Cd-induced nephropathy in hamsters. Although the precise mechanism of the TTHA effects on Cd-induced nephropathy has not been elucidated, it might involve GSH reducing the elevated MDA concentration in renal tissue.

Cadmium induced lipid peroxidation in kidney function

Since the kidney is the main target organ for many metals including cadmium, the generation of the products of lipid peroxidation due to accumulation of these toxic metals in the kidney may have importance in the mechanism of their nephrotoxicity. In order to test this hypothesis, we carried out an experimental study in rats. The functions and the levels of tiobarbituric acid reactive substances (TBARS) of the kidney were investigated in animals receiving 15 micrograms/ml aqueous Cd solution for 30 days. Due to cadmium accumulation in kidney cortex, the ratio of Cd/Zn increased significantly and this increase was associated with elevated TBARS in both renal cortex and medulla. The content of TBARS in renal cortex rose from 211.6 +/- 64.2 to 303.4 +/- 46.4 nmol/g protein (p<0.01) and GFR decreased to 390.5 +/- 109.4 from 1008.7 +/- 4.8 microliters/min (p<0.01) in cadmium exposed animals. Daily coadministration of selenium, vitamins A, C, E did not reverse the adverse effect of cadmium on kidney function, despite the significant decrease in cortex TBARS levels (p<0.01). In conclusion, these data suggest to us that lipid peroxidation assessed by TBA test may not be the only mechanism in cadmium induced nephrotoxicity.

Effect of pentoxifylline on CdCl2-induced nephrotoxicity in the rat

We developed a rat model of cadmium (Cd)-induced nephrotoxicity and tried to prevent renal damage by treating the animals with pentoxifylline (PTX). Sprague-Dawley (SD) rats given CdCl2 3.0 mg/kg sc, daily for 2 wk showed evidences of renal proximal tubular damage, including significant increases in urine volume, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), alanine aminopeptidase (AAP), and fractional excretion of sodium (FENa), and a decrease in the percentage of tubular reabsorption of phosphate (%TRP). PTX significantly improved the urinary excretion of NAG and %TRP. Urine volume was increased threefold in the CdCl2-treated rats and fivefold in the Cd + PTX-treated rats, respectively, as compared with saline-treated control. Total protein, AAP, and creatinine clearance, showed no change after PTX administration. Concentration of Cd in the renal cortex was three times higher than that in the renal medulla, but there were no differences in concentration between the Cd-treated rats and the Cd + PTX-treated rats. Our animal model was useful in studying the renal tubular damage produced by cadmium. PTX appears useful for improving the nephrotoxicity of Cd.