Propofol inhibits in vitro platelet aggregation in human whole blood.

To help clarify the mechanism of propofol-induced vasodilation, we investigated whether propofol, at concentrations ranging from 10(-6) to 10(-3) M, inhibited platelet aggregation in human whole blood. Propofol inhibited platelet aggregation induced by adenosine diphosphate, collagen, or arachidonic acid in a concentration-dependent manner, with a 50% inhibited concentration (micromol/L) of 136 +/- 9.8 for adenosine diphosphate, 77.8 +/- 6.6 for collagen, and 71.8 +/- 5.4 for arachidonic acid. In platelet-rich plasma, propofol had no significant antiaggregant effect except when arachidonic acid was used as the aggregant (50% inhibited concentration 105 +/- 9.9 micromol/L). The antiaggregant effect of propofol in platelet-rich plasma was increased in the presence of red blood cells or leukocytes in a cell number-dependent manner. We conclude that propofol reduces the platelet activity in human whole blood in vitro.