Prostaglandins and Platelet Aggregation in Vivo

Summary

Prostaglandins E₁ and ω-homo-E₁ which were shown previously to inhibit adenosine diphosphate (ADP)-induced platelet aggregation in vitro have now been found to inhibit this process also in vivo. Both prostaglandins inhibit transient thrombocytopenia induced by intravenous injection of ADP; PGE₁ increases also the LD 50 of ADP when injected in high amounts into young rats. In both cases platelet aggregation in vivo is the primary cause of the phenomena observed.

The symptoms observed on overdosing ADP by intravenous injection are unconsciousness within 10-20 sec after completion of the injection immediately followed by respiratory arrest and eventual death of the animal, generally within 10 min. It seems that blocking of the supply of blood to the brain by platelet thrombi, which on histological examination were found to occlude blood vessels in different organs, is the most important causative factor of the symptoms observed.

^* Author’s address : Olivier van Noortlaan 120, Vlaardingen, The Netherlands.

• References

• 1 Kloeze J. Influence of prostaglandins on platelet adhesiveness and platelet aggregation, Nobel Symposium 2, Stockholm, June 1966. Prostaglandins. Eds. Bergström S, and Samuelsson B. 241 Almqvist and Wiksell; Stockholm: 1967
• 2 Kloeze J. Relationship between chemical structure and platelet-aggregation activity of prostaglandins, 12th International Conference on the Biochemistry of Lipids, Loughborough, 1968. Biochim. Biophys. Acta (Amst.) 187: 285 1969;
• 3 Hellem A. J. The adhesiveness of human blood platelets in vitro. Scand. J. Clin. Lab. Invest 12 (Suppl. 61) 77 1960;
• 4 Regoli R, Clark V. Prevention by adenosine of the effect of adenosine diphosphate on the concentration of circulating platelets. Nature (Lond.) 200: 546 1963;
• 5 Silver M. B, Stehbens W. E. Platelet reaction to adenosine diphosphate in vivo. Nature (Lond.) 205: 91 1965;
• 6 Born G. V. R, Cross M. J. Effect of adenosine diphosphate on the concentration of platelets in circulating blood. Nature (Lond.) 197: 974 1963;
• 7 Davey M. G, Lander H. Effect of adenosine diphosphate on circulating platelets in man. Nature (Lond.) 201: 1037 1964;
• 8 Nordöy A, Chandler A. B. Platelet thrombosis induced by adenosine diphosphate in the rat. Scand. J. Haemat 1: 16 1964;
• 9 Nordöy A, Chandler A. B. The influence of dietary fats on the adenosine diphosphate induced platelet thrombosis in the rat. Scand. J. Haemat 1: 202 1964;
• 10 Ahlhorn J. Studien zur direkten, phasenoptischen Thrombocytenzählung. Z. klin. Med 153: 154 1955;
• 11 Bum J. H, Finney D. F, Goodwin L. G. Biological Standardization. 114 Oxford med. Pubi.; 1950
• 12 Robinson F, Hughes R. A. Effects of adenosine compounds on electrocortical activity. J. Neurophysiol 14: 387 1951;