The Effects of Vitamin E Depletion and Repletion on Prostaglandin Synthesis in Semitendinosus Muscle of Young Rabbits

Abstract

The effects of dietary vitamin E-depletion and repletion on the cyclooxygenase activity was studied in the semitendinosus muscle of rabbits. The prostaglandin (PG) cyclooxygenase system in rabbit semitendinosus muscle was characterized and found to depend on reduced glutathione and 1-epinephrine as cofactors. Skeletal muscle cyclooxygenase generates PGE₂ and PGF₂α at a ratio approximately equal to one. Weanling New Zealand white rabbits were fed a vitamin E-deficient diet for 4 to 5 weeks. Controls received 50 mg dl-α-tocopherol acetate twice weekly. Vitamin E deficiency caused a significant reduction in cyclooxygenase activity but did not change the PGE₂/PGF₂α ratio. Oral supplementation of tocopherol acetate promptly returned the cyclooxygenase activity back to the control values within 48 hours. The decreased cyclooxygenase activity explains in part the increased level of arachidonic acid in skeletal muscle phospholipid previously reported in this laboratory. The possible involvement of decreased prostaglandin endoperoxides with platelet aggregation in vitamin E deficiency is discussed.