A method for quantitating platelet aggregation and analyzing drug-receptor interactions on platelets in whole blood in vitro.

A method for quantitating platelet aggregation in whole blood is described. The method is rapid and reproducible. By utilizing the Ultra-Flo 100 whole blood platelet count, platelet numbers before and after addition of an aggregating agent are counted electronically, without the need to separate platelets from other blood cell types. Although designed primarily for use with human blood, the Ultra-Flo can also be used successfully with blood from other species. The method has been used to study the antagonism of adrenaline-induced aggregation of platelets in human whole blood by the alpha-adrenoceptor blocking drug phentolamine. The potential of the method for studying drug-receptor interactions on platelets in vitro as well as rapid assessment of platelet function ex vivo is discussed.