Plasma activity of pyruvate kinase and glutamic oxalacetic transaminase as indices of myopathy in the vitamin E deficient rat.

Weanling rats were fed vitamin E deficient diets for 6 to 15 weeks and then given vitamin E orally for 4 days. Plasma obtained 1 day after the last dose was assayed for glutamic oxalacetic transaminase (GOT) and pyruvate kinase activity (PK). Administration of vitamin E resulted in reduction in activity of both enzymes. Plasma levels of alkaline phosphatase, lactic dehydrogenase, and bilirubin were unaffected by vitamin E and there was no histological evidence of liver degeneration. The number of phagocytized muscle fibers was greatly reduced by vitamin E treatment, but a substantial number of necrotic fibers were still present. With more prolonged (8 days) treatment, plasma PK and GOT levels were reduced to levels found in plasma of vitamin E replete animals and few degenerated muscle fibers could be observed. It was concluded that resolution of the necrotizing myopathy in vitamin E deficient rats is a rapid process and that the decreased activity of PK and GOT in plasma is a sensitive indicator of the resolution process. The decrease in plasma enzyme levels is an easily quantitated and reproducible biological response to vitamin E administration. Thus, this approach provides a basis for a sensitive and accurate bioassay for vitamin E activity.