EFFECT OF DIETARY DEFICIENCY AND SUPPLEMENTATION WITH ALL-RAC-ALPHA-TOCOPHEROL ON HEPATIC CONTENT IN RATS

We studied the effect of dietary deficiency and supplementation with vitamin E in the form of all-rac-alpha-tocopherol in relation to the content of alpha-tocopherol in parenchymal and nonparenchymal liver cells. The cells were isolated by centrifugal elutriation from rats fed diets containing normal, low or high amounts of vitamin E. The parenchymal cells contained about 90% of total hepatic alpha-tocopherol content in rats fed a nonpurified diet (reference group). However, the Kupffer and the endothelial/stellate cells contained four and two times more alpha-tocopherol, respectively, than the parenchymal cells per milligram of cell protein. When the rats were deprived of vitamin E for 8 wk, the content of alpha-tocopherol in parenchymal cells was reduced to 30% of values obtained from rats fed the nonpurified diet, and nonparenchymal cells contained very low levels of alpha-tocopherol (< 5% of reference values). A diet enriched in vitamin E resulted in a sixfold increase in the content of alpha-tocopherol in parenchymal cells but in small changes in nonparenchymal cells compared to the reference diet. Accordingly, the parenchymal cells may have storage capacity for alpha-tocopherol. The light mitochondrial and microsomal fractions contained high amounts of alpha-tocopherol. These fractions were subdivided by density gradient centrifugation to examine the alpha-tocopherol content in different cell organelles. The lysosomes and the Golgi apparatus were found to contain high levels of alpha-tocopherol, whereas peroxisomes contained small amounts.