Tissue distribution of indium after repeated intratracheal instillations of indium-tin oxide into the lungs of hamsters.
OBJECTIVE
The aim of this study was to analyze the tissue distribution of indium after intratracheally instilling indium-tin oxide (ITO) into the lungs of hamsters.


METHODS
Male Syrian hamsters received an intratracheal dose of 3 mg/kg or 6 mg/kg of ITO particles containing 2.2 mg/kg or 4.5 mg/kg of indium, twice weekly for 8 weeks. In parallel, control hamsters received only an intratracheal dose of distilled water. A subset of hamsters was euthanized periodically throughout the study from 8 up to 78 weeks after the final instillation. The distribution of indium in the lungs, liver, kidneys and spleen, as well as pathological changes in the liver, kidneys, and spleen, was determined.


RESULTS
The contents of indium in the lungs in the two ITO groups gradually decreased over the 78-week observation period, with elimination half-lives of approximately 142 weeks for the 3 mg/kg ITO group and 124 weeks for the 6 mg/kg ITO. The indium concentrations in the liver, kidneys, and spleen gradually increased throughout the observation period. Although foci of the lesions were observed histopathologically in the extrapulmonary organs among the two ITO groups, the control group showed similar lesions.


CONCLUSIONS
The results clearly demonstrate that the clearance of indium from the body is extremely slow after intratracheal instillation in hamsters.
Department of Environmental Medicine, Graduate School of Medical Sciences, Kyushu University.
Akiyo
A
Tanaka
Miyuki
M
Hirata
Nagisa
N
Matsumura
Yutaka
Y
Kiyohara
D000818:Animals; D007204:Indium / Q000032:analysis / Q000493:pharmacokinetics*; D007322:Instillation, Drug; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008647:Mesocricetus; D013154:Spleen / Q000378:metabolism / Q000473:pathology; D017971:Tin Compounds / Q000008:administration & dosage*; D014018:Tissue Distribution; D014132:Trachea
D017971:Tin Compounds; D007204:Indium; C109984:indium tin oxide