Effects of vitamin E deficiency on the relative incorporation of 14C-arachidonate into platelet lipids of rabbits.

THe potential influence of vitamin E in vivo on the transformation of 14C-arachidonate (14C-ArA) in washed platelets from vitamin E-depleted, pair-fed control and ad libitum-fed control rabbits was investigated. We considered rabbits vitamin E-depleted when their plasma total tocopherol levels were less than 50% of initial values. By week 7 deficient rabbits exhibited significantly lower (p less than 0.01) plasma and platelet tocopherol levels and significantly higher (p less than 0.01) urinary creatine:creatinine ratios than those of controls. Thrombin treatment of platelet suspensions that were previously incubated with 14C-ArA resulted in significantly greater (P less than 0.05) losses of radiolabel from phospholipids (PL) and significantly greater (P less than 0.05) 14C incorporation into prostaglandin E2 (PGE2) fractions from deficient animals than those of either control group. The significantly greater (P less than 0.05) losses in lipid phosphorus content of phosphatidylcholine (PC) fractions corroborated the significantly diminished (P less than 0.05) radiolabel detected in the PC fraction of deficient animals with thrombin activation. Such findings suggest an enhancement of thrombin-induced phospholipase A2 (PLPA) activity in platelets of vitamin E-deficient rabbits compared to that of controls.