Influence of age on the vitamin E requirement for resolution of necrotizing myopathy.

Weanling rats were fed either a vitamin E-deficient diet or the deficient diet supplemented with vitamin E or the antioxidant ethoxyquin. Ethoxyquin was not effective in preventing the elevation in platelet number or percent aggregation. However, ethoxyquin was as effective as vitamin E in maintaining body weight, testes weight, pigmentation of the incisors and in preventing myopathy, observed either histologically or by an elevation in plasma glutamic oxalacetic transaminase (GOT) activity. Removal of ethoxyquin from the diet after 19 weeks of feeding resulted in a rapid onset of myopathy. These observations permitted us to study the requirement for vitamin E at various ages without the complication of any cumulative pathological effects of vitamin E deficiency. Ethoxyquin was deleted from the diet at 8, 20, 44 and 64 weeks of age. The requirement for vitamin E to reduce plasma GOT and pyruvate kinase (PK) activity was measured at 12, 24, 48 and 68 weeks of age. The requirement for vitamin E did not change significantly during this time period.