Regulation by vitamin E of phosphatidylcholine metabolism in rat heart.

Lysophosphatidylcholine is the major lysophospholipid in mammalian tissues and has been shown to be cytolytic at high concentrations. In the present study we demonstrated that the level of lysophosphatidylcholine was significantly increased in the heart of rats fed with a vitamin E-deficient diet. Moreover, the cardiac lysophosphatidylcholine level was decreased in rats fed with a high vitamin E diet. The alterations in cardiac lysophosphatidylcholine level by dietary vitamin E were attributed to the changes in the activity of cardiac phospholipase A. Dietary vitamin E affected both phospholipase A1 and A2 in the same manner, but had no effect on the other major enzymes which are responsible for the metabolism of lysophosphatidylcholine. Kinetic studies revealed that the inhibition of enzyme activity by vitamin E was essentially non-competitive. The accumulation of lysophosphatidylcholine in the rat heart may be one of the underlying biochemical causes of the observed cardiac dysfunctions produced during vitamin E deficiency.