Fate of cadmium bound to phytochelatin in rats.

The fate cadmium(Cd) bound to phytochelatin [PC, (gamma-Glu-Cys)n-Gly)] was studied in rats using synthesized 109Cd-PC. Less Cd was absorbed through the digestive tracts than CdCl2, but the ratio of renal Cd to hepatic Cd was higher. After parenteral administration of Cd-PC, Cd was distributed mainly in the liver, kidney, small intestine and pancreas. More Cd was found in the kidney than the liver after Cd-PC (n = 5) administration. Most of the Cd was bound to the high molecular weight fraction in the hepatic cytosol 0.5 hr after administration and moved to the metallothionein fraction at 6 hr. The tissue distribution of Cd was not affected even when free PC (n = 5) was administered 3 hr after or before Cd injection. The distribution in the kidney increased only in the case of the simultaneous administration of Cd with PC. These findings show that the absorbance of Cd bound to PC from the alimentary tract is lower than that of CdCl2 although absorbed Cd is distributed to the kidney more than CdCl2, and Cd is liberated from PC soon after uptake by the cells.