Borate and glycerol inhibition of the aggregation of guinea pig platelets by bovine factor VIII and ristocetin.

Abstract

To demonstrate the importance of the carbohydrate portions of bovine factor VIII and ristocetin for the induction of platelet aggregation, guinea pig platelets were treated with either borate or glycerol before and after addition of ristocetin or bovine factor VIII. Both borate and glycerol were capable of inhibiting the aggregation of blood platelets induced by adding bovine factor VIII or ristocetin to platelet-rich plasma. Furthermore, aggregates formed after treatment with either agent could be dispersed by high concentrations of either borate or glycerol. These effects did not appear to be solely the result of high ionic strength or of irreversible damage to the platelets. The results obtained support the hypothesis that the binding of the carbohydrate groups of factor VIII plays an important role in the induction of platelet aggregation and in the maintenance of aggregates formed in response to the treatment of platelet-rich plasma with bovine factor VIII or ristocetin.