A low level exposure experiment was conducted on growing rats to investigate the accumulation and organ distribution of protein bound cadmium compared with cadmium chloride. Male Sprague-Dawley rats were fed for 21days with one of the
semisynthetic
diets, which contains cadmium as either bovine liver-or kidney meal bound cadmium, cadmium chloride with uncontaminated liver meal or cadmium chloride without organ meal. In the levels of ca. 0.5 1 and 1.5mg/kg diet, respectively. After 21days of
exposure cadmium was accumulated in liver, kidney and gastrointestinal tracts. Depending upon cadmium levels in diet. Inspite of very low cadmium accumulation in whole blood, it tends also to increase with dietary cadmium levels. The blood
cadmium
concentration of animals fed organ meal containing diets was about 4-7 fold higher than that without organ meal, regardless of cadmium was intrinsically bound to protein or not. However, significant effects of organ protein on cadmium
accumulation
in
liver, kidney and digestive tracts were not detectable, when cadmium was supplemented as cadmium chloride. On the other hands. Animals fed diet containing ca 1.5mg Cd/kg as organ bound cadmium retained more retained more cadmium in liver, kidney
and
digestive tracts compared to cadmium chloride with organ meal, whereby the increase of cadmium concentration in kidney was greater than in liver. However, when the concentration of protein bound cadmium was<1mg/kg diet, organ bound cadmium was
not
significantly different from cadmium chloride in bioavailability and organ distribution, From this result it is suggested that the intestinal absorption of protein bound cadmium is influenced of the amount of cadmium bound in protein. When
cadmium
cadmium concentration in protein is relatively low protein bound cadmium seems to be absorbed in the same way as cadmium ions are absorbed. However, when the concentration is high, at least a small amount of intact protein bound cadmium could be
absorbed and accumulated selectively in kidney.
|