Plasma and tissue concentrations of alpha-tocopherol during vitamin E depletion in sheep.

To determine the relationship between plasma and tissue alpha-tocopherol concentrations during vitamin E depletion, weaned lambs were placed on a vitamin E-deficient diet for 0, 1, 2, 4, 8 and 12 weeks. alpha-Tocopherol was measured in plasma, erythrocytes, liver, adrenal, adipose tissue, three different skeletal muscles and heart muscle. The alpha-tocopherol concentration in plasma fell at the same rate as the alpha-tocopherol concentration in skeletal muscles, heart muscle, adrenal and adipose tissue. The alpha-tocopherol concentration in liver and erythrocytes fell at a faster rate than that of plasma and all muscle tissues. There were significant correlations between alpha-tocopherol concentration in plasma and alpha-tocopherol concentrations in all the tissues measured. Different skeletal muscles had significantly different concentrations of alpha-tocopherol which may relate to their differing susceptibility to nutritional myopathy. The increase in malondialdehyde in oxidatively-stressed muscle tissue and the correlation with alpha-tocopherol concentration in most muscle tissues indicated that the muscles had reduced antioxidant capacity in vitro as a result of vitamin E depletion. It was concluded that during vitamin E depletion in sheep alpha-tocopherol concentration in plasma was a good index of vitamin E status under the experimental conditions employed.