Effects of heparin and aspirin on circulating P-selectin, E-selectin and von Willebrand Factor levels in healthy men.

As thrombin stimulates P-selectin expression on platelets and its release into plasma, we hypothesized that enhancing antithrombin activity by unfractionated heparin (UFH) could decrease plasma levels of circulating (c)P-selectin, (c)E-selectin, and von Willebrand Factor (vWF). Hence the effect of UFH and aspirin were examined on these activation markers in healthy volunteers. UFH decreased cP-selectin levels by -10% (CI: -16 - (-4%); P = 0.005) at 24 h, but did not change levels of vWF-Ag. In contrast, aspirin did not affect cP-selectin levels but decreased vWF-Ag levels by -12% (CI: -18 - (-7%); P = 0.005) at 24 h. Neither drug affected cE-selectin levels. Thus, UFH decreases cP-selectin levels, which may reflect decreased platelet activation in vivo. An increase in cP-selectin under UFH therapy should alert the clinician to look for platelet destruction.