Degradation of cadmium-thionein in rat liver and kidney
(/sup 3/H)Cystine and /sup 115m/Cd were incorporated into hepatic and renal Cd-thionein in response to sc administration of 4.4 ..mu..mol of Cd/sup 2 +/ containing /sup 115m/Cd. Cd-thionein-bound /sup 115m/Cd reached a plateau by 24 and 72 h after the Cd/sup 2 +/ injection in liver and kidney, respectively. The half-life (t/sub 1/2/) of /sup 3/H-labeled hepatic Cd-thionein was 3.5 d, whereas the average t/sub 1/2/ of the soluble proteins was 3.7d. The t/sub 1/2/ of /sup 3/H-labeled renal Cd-thionein was 3.7d, whereas the average t/sub 1/2/ of the renal proteins was 3.8 d. In marked contrast, the /sup 115m/Cd content of both hepatic and renal Cd-thionein was virtually unchanged, even 9 d after administration of this radionuclide. These data indicate that the protein moiety of metallothionein is degraded, although there appears to be a concomitant rebinding of Cd/sup 2 +/ to nascent thionein polypeptide chains. Thus the lack of metallothionein degradation per se does not account for the long-term retention of Cd/sup 2 +/ in liver and kdney during chronic exposure.
- Research Organization:
- Rutgers Univ., New Brunswick, NJ
- OSTI ID:
- 6537884
- Journal Information:
- J. Toxicol. Environ. Health; (United States), Vol. 4:5-6
- Country of Publication:
- United States
- Language:
- English
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PROTEINS
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TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
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CARBOXYLIC ACIDS
COMPLEXES
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
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INTAKE
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ORGANIC SULFUR COMPOUNDS
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560305* - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)