Uptake, Transport and Distribution of dl-α-Tocopheryl Acetate Compared to D-α-Tocopherol in Rainbow Trout (Salmo gairdneri)

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Abstract
The appearance of radioactivity after the oral administration of 3 µCi d-α-[5-methyl-3H]tocopherol and 10 µCi dl-α-[3′,4′-14C]tocopheryl acetate in plasma, liver, kidney, spleen and heart of rainbow trout showed an exponential increase up to 32 hours, followed by a plateau or slight decline from 32 to 64 hours. Radioactivity in the skeletal muscle increased exponentially up to 8 hours followed by a slower linear increase up to 64 hours. Comparisons of plasma 3H and 14C radioactivity suggested that the uptake of d-α-tocopherol (EOH) was 6 to 18 times greater than dl-α-tocopheryl acetate (EAc) in the first 4 hours and 2 to 3 times greater between 8 and 64 hours. At the plateau, the amount of 3H and 14C radioactivity incorporated per unit wet weight of tissue decreased in the order liver > kidney > plasma > spleen > heart » skeletal muscle. More than 87% of the 3H and 14C radioactivity after 16 hours was found to be free α-tocopherol in both plasma and liver. The radioactively labeled vitamins were bound primarily to plasma low-density lipoprotein (density 1.015 to 1.085). These studies support the hypothesis that the uptake, transport and distribution of EAc after hydrolysis in the gastrointestinal tract of trout follows a pattern similar to that of EOH.