Density increment and decreased survival of rat red blood cells induced by cadmium

Male Wistar rats were injected with CdCl2 subcutaneously to examine in vivo effects of Cd on density and survival of red blood cells. During the 7 days after administration of 1.0 mg Cd/kg, the following sequence of events occurred: (1) a progressive increase in the amount of more dense red blood cells concomitant with a decrease in that of light red blood cells from the first to the third day; (2) an increase in the spleen weight at the third day; (3) a decrease in the hematocrit value and an increase in the amount of light red blood cells at the fifth day; and (4) a recovery of the hematocrit value at the seventh day. Five days after administration, the hematocrit value decreased in a dose-dependent mode and the decrease was significant at the 1% level at 1.0 and 1.5 mg Cd/kg. A highly significant splenomegaly was also observed at 0.5 to 1.5 mg Cd/kg. In order to label red blood cells in vivo, [3H]diisopropylfluorophosphate ([3H]DFP) was injected into rats. At Day 11, Cd at either 0.5 or 1.0 mg/kg was administered to [3H]DFP-prelabeled animals. Cd administration accelerated 3H-labeled red cell clearance from the blood. Six days after Cd administration, the radioactivity of red blood cells was 76 and 68% (P less than 0.05) of the control at 0.5 and 1.0 mg Cd/kg, respectively. In vitro treatment of rat red blood cells with either 0.5 or 1.0 mM CdCl2 also increased red cell density and accelerated in vivo clearance of red blood cells from the recipient circulation. These results show that Cd at low dose can cause anemia by increasing red cell density and by accelerating red cell sequestration, presumably in the spleen.