Uptake, transport and distribution of DL-alpha-tocopheryl acetate compared to D-alpha-tocopherol in rainbow trout (Salmo gairdneri).

The appearance of radioactivity after the oral administration of 3 microCi D-alpha-[5-methyl-3H]tocopherol and 10 microCi DL-alpha-[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 liner increase up to 64 hours. Comparisons of plasma 3H and 14C radioactivity suggested that the uptake of D-alpha-tocopherol (EOH) was 6 to 18 times greater than DL-alpha-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 weights of tissue decreased in the order liver greater than kidney greater than plasma greater than spleen greater than heart much greater than skeletal muscle. More than 87% of the 3H and 14C radioactivity after 16 hours was found to be free alpha-tocopherol in both plasma and liver. The radioactivity 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 fo EAc after hydrolysis in the gastrointestinal tract of trout follows a pattern similar to that of EOH.