A Sex Difference in the Effect of Aspirin on “Spontaneous” Platelet Aggregation in Whole Blood

Summary

Platelet aggregation can be measured in whole blood by monitoring the fall in single platelet count in an electronic platelet counter. The aggregation that occurs when whole blood is stirred in a small cuvette (“spontaneous aggregation”) or upon the addition of collagen has been studied in citrated whole blood from male and female volunteers. Aspirin 40 μg ml/1 inhibited aggregation induced by collagen in both sexes but spontaneous aggregation was only affected by aspirin in males. These results may help explain the sex difference apparent in the results of some clinical trials of aspirin as an antithrombotic agent.

Keywords

Platelet aggregation - Aspirin - Whole blood aggregation Sex difference

• References

• 1 Harris WH, Saltzman EW, Athansoulis CA, Waltman AC, De Sanctis RW. Aspirin prophylaxis of venous thromboembolism after total hip replacement. N Eng J Med 1977; 297: 1246-1249
• 2 Gent M, Carter CJ. Some unresolved methodological problems in long-term clinical trials. In: Acetylsalicyclic and new uses for an old drug. Barnett HJ M, Hirsh J, Mustard JF. (eds) Raven Press; New York: 1982. pp 251-262
• 3 Dyken M. Natural history of ischaemic stroke. In: Cerebral vascular disease. Harrison MJ G, Dyken M. (eds) Butterworths; London: 1983. pp 139-170
• 4 Preston FE, Whipps S, Jackson CA, French AJ, Wyle PJ, Stoddard CJ. Inhibition of prostacyclin and thromboxane A2 after low dose aspirin. N Eng J Med 1981; 304: 76-79
• 5 Fox SC, Burgess-Wilson M, Heptinstall S, Mitchell JR A. Platelet aggregation in whole blood using the ultra-flo 100 platelet counter. Thromb Haemostas 1983; 48: 327-329
• 6 Nunn B. Comparison of the effects of aspirin in humans ex vivo in platelet-rich plasma and whole blood. Thromb Haemostas 1981; 46: 50 (Abstr)
• 7 Harrison MJ G, Mitchell JR A. The influence of red blood cells on platelet adhesiveness. Lancet 1966; 2: 1163-1164