A Pharmacologic Approach To The Modification Of The Electrokinetic And Aggregability Characteristics Of Rabbit Platelets In Vitro

An attempt was made to correlate changes in the electrokinetic characteristics of rabbit platelets with alterations in platelet function. In an effort to modify the surface charge characteristics of the rabbit platelet, several pharmacologic agents were used, i.e., heparin, chlorpromazine, and neuraminidase. A Seaman microelectrophoresis apparatus and a chronolog platelet aggregometer were used to measure platelet membrane changes and aggregation. The control electrophoretic mobility (EM) was 0.875±0.005µ for 18 independent blood samples. Heparin increased the EM to 0.99±0.005 in 10 samples. Chlorpromazine decreased the EM to 0.860±0.005 and neuraminidase decreased the EM to 0.73±0.001. The results were significant when compared to baseline (p=0.005). Heparin inhibited thrombin induced platelet aggregation while neuraminidase enhanced primary aggregation and chlorpromazine blocked the secondary wave of platelet aggregation. The results indicate that increased surface negativity reduces platelet aggreg-ability, while a decrease in surface negativity results in altered platelet function affecting primary platelet interaction. The results suggest altered platelet surface charge characteristics as a possible mechanism for platelet aggregation and thrombosis. This study also suggests in part the role of heparin in reducing thrombosis formation by inhibiting platelet-platelet interaction via increased surface negativity.