Influence of acute alcohol exposure on hemorheological parameters and platelet function in vivo and in vitro

We have analysed the influence of acute alcohol exposure in vivo and in vitro on blood flow properties and platelet function. 12 healthy male volunteers drank either 4.36 ml red wine/kg body weight (=0.5 g ethanol/kg) or water at 06.00 p.m. under fasting conditions. Blood was drawn immediately before, and 1, 2, 4 and 13 h after alcohol ingestion. Alcohol had a detectable osmotic effect on erythrocytes; the mean cellular volume (MCV) was significantly smaller 1-4 h after ingestion. Whole blood viscosity remained unaffected, but blood viscosity at a standardized Hct of 45% measured at a high shear rate (94.5 s(-1)) was increased 2 h after wine ingestion. In the morning, 13 h after wine drinking, platelet aggregation measured with a platelet function analyser PFA-100 was increased to a greater extent than after water drinking. In vitro, no effect was seen when blood was incubated with 0, 12.5, 25, 50 and 100 mmol/l ethanol for 1 h at 37 degrees C. We conclude that an acute exposure to alcohol has only modest effects on hemorheological parameters and platelet aggregation in vivo and no effect in vitro, which suggests that other factors must be involved in both beneficial and harmful effects of wine drinking.