Nickel effects on hepatic amino acids.

Female Wistar rats were treated with nickel (single i.p. injection of 6 mg Ni(II)/kg body weight) and twenty amino acids and glutathione (GSH) concentrations were determined in liver 90 minutes later. Hepatic GSH content dramatically diminished after nickel injection. Glycine and glutamate levels, precursor amino acids of GSH, were not affected by nickel treatment, whereas cysteine level, the third precursor, was drastically increased in comparison with control rats. These findings showed that hepatic GSH depletion, caused by acute nickel exposure, was not due to a reduction in the availability of precursor amino acids. Nickel treatment also induced a 2-fold increase in phenylalanine and a decrease in taurine to one fifth. Therefore, the role of taurine in protecting membranes was clearly jeopardized in liver after nickel exposure, which could account for some of the toxicologic actions of this metal. However, further research is needed to explore such suggestion.