Alcohol and polyphenolic grape extract inhibit platelet adhesion in flowing blood

Background: Moderate and prolonged alcohol consumption has been associated with decreased cardiovascular morbidity and mortality. Inhibition of platelet function in suspension attributes to these effects. Whether alcohol, red wine, or polyphenolic grape extracts (PGE) inhibit platelet adhesion is not known. We investigated platelet adhesion to fibrinogen and collagen in whole blood under standardised flow. Materials and methods: Before perfusion was started, citrated whole blood from 95 volunteers was preincubated for five min with different alcohol concentrations, unfractioned red wine and PGE. Then, blood was perfused in a single-passage flow chamber over coverslips coated with human fibrinogen or collagen type III at shear rates of 300 s-1 and 1600 s-1. Results: Alcohol inhibited platelet adhesion to human fibrinogen at high shear rate (concentrations > 0-15‰) and low shear rate (only at a concentration of 4.8‰), whereas red wine (concentrations > 0.15‰) inhibited platelet adhesion to human fibrinogen at both shear rates. In contrast, PGE (concentrations > 0.0225 g L-1) inhibited platelet adhesion to human fibrinogen only at low shear rate. None of these incubations affected adhesion to collagen. Conclusions: Alcohol, red wine and PGE inhibit adhesion to fibrinogen but not to collagen. This inhibition might contribute to the cardioprotective effects of moderate alcohol consumption.