Sex-related differences in the effects of aspirin on the interaction of platelets with subendothelium.

Using the Baumgartner perfusion technique, marked sex-related differences in the extent of platelet-subendothelium interaction and in the effect of aspirin (ASA) have been observed. The administration of ASA (150 mg daily for 15 days) to two groups of healthy volunteers, one composed of males and the other of females, proved to block the generation of TXB2 in both cases. The basic pattern of platelet subendothelium interaction, however, was found to be markedly different in both groups studied. In men, aspirin treatment induced a significant reduction in the percentage of platelet thrombi, whereas in women, post ASA values remained at the same level as in control experiments. These results show that in the Baumgartner perfusion system women display a less thrombogenic tendency than men and that 150 mg of ASA administered daily are effective in reducing the extent of platelet-subendothelium interaction in the male group but not in the female group. These findings could explain the absence of benefit observed for women in clinical trials with aspirin.