Related Experiment Videos
Fate of erythrocyte Cd-metallothionein in mice
Abstract:
Degradation of metallothionein (MT), which appears in erythrocytes following cadmium (Cd) administration, was investigated in mice. Cd-MT underwent only slight decomposition by hemolysate in an in vitro experiment unlike an 800g supernatant fraction of the liver homogenate. In an in vivo study, [3H]diisopropylfluorophosphate was given to mice which had received 109CdCl2 to investigate the relationship between the decay of 109Cd-MT in the erythrocyte and the life span of the erythrocyte. A similar reduction pattern of radioactivity of 109Cd and 3H was observed. Erythrocytes containing 109Cd-MT obtained from mice preadministered with 109CdCl2 was transfused to normal mice. The 109Cd radioactivity of erythrocytes decreased in a manner similar to Cd in erythrocytes of 109CdCl2-administered mice. Contrary to this decrease of erythrocyte Cd in the transfused mice, Cd concentration of the spleen increased markedly. Cd increased also in the liver. These results indicate that erythrocyte MT degrades along with the erythrocyte. The Cd from this MT is deposited in the spleen and liver where blood cells are catabolized.
Insights
Metallothionein (MT) in red blood cells degrades with the cell's lifespan after cadmium exposure. Cadmium from degraded MT is then stored in the spleen and liver.
Area of Science:
- Toxicology
- Biochemistry
- Cell Biology
Background:
- Metallothionein (MT) is induced in erythrocytes following cadmium (Cd) exposure.
- The degradation pathway and fate of erythrocyte-bound Cd-MT are not fully understood.
Purpose of the Study:
- To investigate the degradation of cadmium-metallothionein (Cd-MT) in mouse erythrocytes.
- To determine the relationship between Cd-MT decay in erythrocytes and erythrocyte lifespan.
- To track the in vivo distribution of cadmium released from erythrocyte MT.
Main Methods:
- In vitro degradation assays using hemolysate and liver homogenate.
- In vivo studies involving administration of 109CdCl2 and [3H]diisopropylfluorophosphate to mice.
- Erythrocyte transfusion experiments to track Cd-MT fate in recipient mice.
Main Results:
- Cd-MT showed limited degradation by hemolysate in vitro compared to liver homogenate.
- Radioactivity of both 109Cd and 3H decreased similarly in erythrocytes, correlating with erythrocyte lifespan.
- Transfused erythrocytes containing 109Cd-MT showed decreasing 109Cd levels, with a marked increase in spleen and liver cadmium concentrations.
Conclusions:
- Erythrocyte metallothionein degrades concurrently with the erythrocyte.
- Cadmium released from degraded erythrocyte MT is sequestered in the spleen and liver.
- The spleen and liver act as deposition sites for cadmium during red blood cell catabolism.