Relationships between vitamin E status and erythrocyte stability in sheep

Stability of erythrocytes from sheep with vitamin E deficiency (E-deficient) was compared by two haemolytic tests, one based on osmotic fragility in hypotonic saline and the other on detergent sensitivity in Tween 20. Relationships between haemolysis, plasma α-tocopherol concentration and creatine kinase (CK) activity were evaluated. E-deficient animals were clinically healthy but had elevated (> 1000 iu per 1) CK activities and low (< 1 μmol per 1) α-tocopherol concentrations compared with control sheep (< 500 iu per 1 and > 1·5 μmol per 1, respectively). Erythrocytes from E-deficient sheep were markedly more susceptible to detergent treatment than those from controls, but osmotic fragility was similar in both groups. Detergent sensitivity was directly related to plasma α-tocopherol concentration and CK activity but not to erythrocyte glutathione peroxidase activity. Within 24h of supplementation (300 mg α-tocopherol subcutaneously) of E-deficient sheep, plasma α-tocopherol concentrations were increased, CK activities decreased and erythrocyte susceptibility to detergent-induced haemolysis was significantly reduced. Concentrations of α-tocopherol returned rapidly (< 3 days) to pre-supplement values, although decreased haemolytic responses persisted longer (> 7 days). Cells from E-deficient animals were protected against detergent-induced haemolysis by pre-incubation with α-tocopherol in vitro. The results indicate that detergent sensitivity of erythrocytes may provide the basis of a simple functional test for vitamin E deficiency in sheep.