Platelet-activating factor cardiovascular effects

Recently, in 1997, Ghisalberti [14] published a review on the cardiovascular activity of naturally occurring lignans, including the effects on cyclic adenosine monophosphate (cAMP) phosphodiesterase (PDE), Ca2+ channel movement, hypertension, and as platelet activating factor (PAF) and endothelin antagonists. Antioxidant and vasorelaxant effects were also covered. The most relevant finding on this subject from 1996 until 1999 are dealt with below. 

In humans, boron supplements are reported to lower the platelet count and potentially reduce the risk of thrombosis (Nielsen et al., 1991), while experimental evidence has been obtained for the likely usefulness of boron-containing thrombin inhibitors in the treatment of cardiovascular disorders (Tapparelli et al., 1993). In an acute feeding study, the concentration of activated factor VII was unaffected following the consumption of a high-fat meal with or without supplemental boron (Wallace et al., 2002), and in a longer-term supplementation trial, boron had no effect on plasma... 

The levels of cardiovascular factors could also be influenced by the ability of vitamin E to affect activation of arachidonic acid from membrane phospholipids by phospholipase A2. Vitamin E, either given in the diet or by incubation with platelets themselves, was found to inhibit phospholipase A2 in a dose-dependent manner. a-Tocopheryl acetate had little or no effect on the activity of this enzyme, but tocol, without methyl groups in the chroman ring, was more potent than either (+)- or ( )-a-tocopherol, suggesting that the methyl groups were not important for the inhibition but the hydroxy group in the ring was critical for activity [131]. 

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