Inhibition and Reversal of Platelet Aggregation by Methyl Xanthines

Summary

The 3 methyl xanthines, caffeine, theobromine, and aminophylline inhibited and reversed platelet aggregation induced by ADP in vitro. Inhibition appeared to be noncompetitive and the effects of the methyl xanthines were not mediated through inhibition of platelet sulphydryl groups, chelation of calcium ions, or plasma pH change. A possible explanation for these properties has been suggested.

• References

• 1 Born G. V. R. Aggregation of blood platelets by adenosine diphosphate and its reversal. Nature (Lond). 194: 927 1962;
• 2 Ardlie N. G, Glew G, Schwartz G. J. Influence of catecholamines on nucleotide-induced platelet aggregation. Nature (Lond). 212: 415 1966;
• 3 Lineweaver H, Burk D. The determination of enzyme dissociation constants. J. Amer. chem. Soc. 56: 658 1934;
• 4 Harrison M. J. G, Emmons P. R, Mitchell J. R. A. The effect of sulphydryl and enzyme inhibitors on platelet aggregation in vitro. Thrombos. Diathes. haemorrh. (Stuttg). 16: 122 1966;
• 5 Butcher R. W, Sutherland E. W. Adenosine 3’, 5’-phosphate in biological materials. I. Purification and properties of cyclic 3’, 5’-nucleotide phosphodiesterase and use of this enzyme to characterise adenosine 3’, 5’-phosphate in human urine. J. biol. Chem. 237: 1244 1962;
• 6 Davoren P. R, Sutherland E. W. The effect of L-epinephrine and other agents on the synthesis and release of adenosine 3’, 5’-phosphate by whole pigeon erythrocytes. J. biol. Chem. 238: 3009 1963;