Time-dependent variation in the biodistribution of C60 in rats determined by liquid chromatography-tandem mass spectrometry

We examined the biodistribution of C-60 in rats after tail vein administration using LC-MS/MS. C-60 was detected in various tissues, such as brain, kidneys, liver, lungs, and spleen of rats. On the other hand, no C-60 was found in blood. The highest C-60 concentration was observed in the lungs, followed by spleen, liver, kidneys, and brain. These results suggested that C-60 injected in the tail vein could be filtered by lung capillary vessels and accumulate in the lungs prior to being distributed to other tissues. Moreover, C-60 not being detected in the blood indicates that clearance of C-60 from the blood by filtration might effectively occur in the lungs. The time-dependent variation in the biodistribution of C-60 was evaluated. A time-dependent decrease in C-60 concentrations was observed in all tissues, except spleen. Moreover, a decreasing trend of C-60 levels differed among tissues, which could be due to differences in accumulation. These results suggest that unmodified C-60 and/or C-60 metabolites by metabolic enzymes could be excreted into feces and/or urine. In further studies, the metabolic and excretion pathways of C-60 should be evaluated to understand the toxicokinetics of C-60. (C) 2011 Elsevier Ireland Ltd. All rights reserved.