Induced synthesis of chromochelatin, the low molecular weight bismuth-binding protein in rat kidneys

Bismuth administered subcutaneously to rats as BiCl3 is deposited in the kidneys, where it is bound to two classes of proteins: one of high molecular weight and a fraction of molecular weight approx. 7500 (chromochelatin). The latter fraction prevails on repeated exposure to bismuth. The bismuth-binding protein is heterogenous and using polyacrylamide gel may be divided into three fractions of which all contain bismuth and copper. In parallel with increasing concentration of chromochelatin due to bismuth administration, the incorporation of L-[35S]cysteine is elevated in all three fractions. The incorporation is augmented especially if repeated administration of bismuth is applied. Cycloheximide (CH) completely abolishes the inducing effect of bismuth on the incorporation of L-[35S]cysteine into chromochelatin both following single and repeated administration of bismuth. Actinomycin D (AcD) eliminates the incorporation only in the case of single dose of bismuth. The obtained results suggest that the elevation of chromochelatin levels in the kidney following administration of bismuth is due to the induction of the de novo protein synthesis.