Comparative biochemical effects of low doses of mercury II chloride in the F344 rat and the multimammate mouse ( Mastomys natalensis)

Abstract

The biochemical effects and comparative nephroxicity of mercury II chloride (HgCl 2) dosed at 0.75 mg/kg i.p. was investigated in the Fisher 344 rat (F344) and Mastomys natalensis using high resolution 1H nuclear magnetic resonance (NMR) spectroscopy of urine, histopathology and clinical chemical techniques. The effects of HgCl 2 treatment were followed for up to 4 days post-dosing (p.d.). In F344 rats there was extensive proximal tubular damage and renal cortical necrosis together with elevated levels of urinary γ-glutamyl transpeptidase (γGT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). The 1H NMR spectra of urine obtained from Hg-treated F344 rats also showed increased levels of glucose, alanine, lactate, valine and hippurate (0–48h p.d.) with decreased levels of citrate, succinate and 2-Oxoglutarate (24–48h p.d.). Mastomys were found to be highly resistant to HgCl 2 toxicity at 0.75 mg/kg and the histological appearance of the renal cortex of treated animals was virtually identical to controls. There were no elevations in urinary ALP, γGT and LDH activities in HgCl 2-treated Mastomys and there were no biochemical abnormalities in low MW components of Mastomys urine following HgCl 2-treatment, as shown by 1H NMR spectroscopy. Urinary γGT activity was found to be much higher in F344 rats than Mastomys. Since γGT activity is involved in the tubular reabsorption of Hg 2+, the lower levels of γGT in Mastomys might partially account for the lower toxicity of Hg 2+ in this species.