Enhancing effect of collagen on platelet aggregation in whole blood.

In order to know whether or not red cell or/and white cell influence on collagen, epinephrine or ADP-induced platelet aggregation, the following experiments were done by using human citrated blood and Coulter Counter®. The aggregation reaction was performed in an aggregometer at 37°C, and the reaction was monitored by checking residual free-platelet number in whole blood or platelet rich plasma (PRP) of which platelets were fixed by 2% formaldehyde-Isoton II® before platelet number determination. Concentration of agents in whole blood was adjusted by heamatocrit value of 45%. Obtained results are the followings: 1. Collagen induced aggregation-reaction in whole blood was more distinct than that in PRP. 2. The enhancement was not observed when ADP or epinephrine was used as an inducer of the aggregation-reaction. 3. At very low concentration, Dilazep®, red cell membrane stabilizer, inhibited the reaction more effectively than that of Aspirin (ASA). 4. Combination use of the drugs was shown to be very effective method for suppressing the collagen induced aggregation reaction in whole blood. From the above results and others, collagen-red cell interaction was suggested to enhance platelet aggregation reaction.