The effect of CdCl2 and AgNO3 pretreatment on the distribution of 110mAg+ in rat liver

The distribution of 110mAg in the elution fractions obtained from gel filtration (Sephadex G-75) of the supernatants of rat liver homogenates was studied. 110mAgNO3 was administered i.v. at the doses 0.183 and 0.912 mg Ag+ . kg-1 . b . wt.and rats were killed 30 min after the administration. Differential centrifugation of the homogenates was performed to determine 110mAg+ distribution in subcellular structures of hepatocytes. The effect of CdCl2 and AgNO3 pretreatment (2 s.c. injections of 2.5 mg . kg-1 during 48 h) was investigated and results were compared with those obtained without pretreatment. It was found that AgNO3 pretreatment does not affect 110mAg+ distribution in the elution fractions and the major part of the metal is concentrated in the high-molecular-weight protein fraction. On contrary, after CdCl2 pretreatment almost all 110mAg+ is bound in the metallothionein (MT) fraction. Differential centrifugation revealed the main portion of the metal in nuclei and cell membranes and only small amount in lysosomal supernatant. After CdCl2 pretreatment the content of 110mAg+ in supernatant considerably increases. Results confirm the affinity of silver to MT and moreover show that this metal probably does not significantly induce the MT synthesis in the liver tissue.