Inhibition by Ethanol of Shear Stress-Induced Formation of Platelet Thrombi in Whole Blood.

Aims: The risk of thromboatherosclerotic disease is lower in moderate drinkers than in non-drinkers. We investigated the effects of ethanol on platelet aggregation under a condition with shear stress.

Short Summary: Shear stress-induced formation of platelet thrombi is inhibited by ethanol at its attainable concentrations after drinking. This effect is prominent at the early stage of thrombus formation, being in agreement with inhibitory actions of ethanol on the initial steps of platelet activation such as Ca2+ entry and phospholipase A2 activation.

Methods: Platelet aggregation was evaluated by using a total thrombus-formation analysis system, and shear rates of 1000 s-1 (low), 1500 s-1 (middle) and 2000 s-1 (high) were loaded to whole blood. The times required to generate increases in flow pressure of 10 kPa (T10), 30 kPa (T30) and 50 kPa (T50) in microchips containing the blood, which depend on the degree of thrombus generation, were recorded.

Results: Under the conditions of the low-grade and middle-grade shear rates, T10 and T30 were significantly longer in the presence of ethanol at 0.25-1% than in the absence of ethanol. T10 under the condition of the low-grade shear rate and T30 under the conditions of the low-grade and middle-grade shear rates were also significantly longer in the presence of ethanol at 0.125% than in the absence of ethanol. On the other hand, T50 under the conditions of the low-grade and middle-grade shear rates was not significantly different in the absence and presence of ethanol at 0.125, 0.25 and 0.5%. Under the condition of the high-grade shear rate, T10, T30 and T50 were not significantly different in the absence and presence of ethanol at its lower concentrations.

Conclusions: Ethanol at attainable concentrations inhibits platelet thrombus formation induced by shear stress, and the inhibitory effect of ethanol is prominent at the early stage of thrombus formation.