Effect of vitamin B(6) vitamers on platelet aggregation.

The vitamers of vitamin B(6) inhibit platelet aggregation. However, their effect is weak when used separately. After the supplementation of one vitamer, the concentrations of the other ones also increase in plasma due to the interconversion of vitamin B(6) forms. It can be suggested that different vitamers in blood can interact with each other. The aim of this work was to test the effect of different vitamer combinations on platelet aggregation in vitro. Platelet aggregation was induced by ADP, collagen or arachidonic acid and measured photometrically in a Chronolog aggregometer. The inhibition of platelet aggregation by the pairwise combinations of the vitamers was significantly stronger than that of each vitamer separately. The combinations of three and four vitamers were yet more effective, inhibiting platelet aggregation at the concentration of 4 microM. Possible involvement of inhibitory prostaglandins in the effect of vitamin B(6) was studied. The inhibition of platelet aggregation by the vitamers could be prevented by the antagonist of prostacyclin receptors, CAY10441 while the antagonist of prostaglandin D(2) receptors, MK 0524 was ineffective. The results suggest that vitamin B(6) vitamers cause a synergistic inhibitory effect on platelet aggregation at concentrations that can be mediated by the activation of prostacyclin receptors with prostaglandin E(1).