Serum half-life, distribution, hepatic uptake and biliary excretion of alpha-tocopherol in rats |
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Authors: | A Bj?rneboe G E Bj?rneboe C A Drevon |
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Institution: | National Institute of Forensic Toxicology, Oslo, Norway. |
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Abstract: | The serum clearance of alpha-3H]tocopherol has been studied after intravenous injection of intestinal lymph labeled in vivo with radioactive alpha-tocopherol. The half-life of the injected alpha-3H]tocopherol was approx. 12 min. Fractionation of plasma by ultracentrifugation 10 min after injection of lymph showed that 91% of the radioactive alpha-tocopherol remaining in plasma was located in chylomicrons (d less than 1.006 g/ml) and 7.8% in high-density lipoproteins (HDL, 1.05 less than d less than 1.21 g/ml). 2 h after administration of alpha-tocopherol, about 35% of the radioactivity recovered in plasma was associated with chylomicrons and approx. 51% with HDLs. alpha-3H]Tocopherol was initially taken up by the liver, which contained more than 50% of the injected radioactivity after 45-60 min. Separation of parenchymal and nonparenchymal cells demonstrated a preferential uptake of alpha-3H]tocopherol by the parenchymal liver cells. After 24 h about 11% of the injected dose was recovered in the liver. Considering whole organs the liver, adipose tissue and skeletal muscle had the highest content of radioactivity after 24 h. Furthermore, about 14% of the administered dose was recovered in bile during 24 h draining. |
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