Effects of colchicine and vinblastine on platelet contractility and release

Abstract

Pre-incubation of normal platelet-rich plasma for 30 minutes at 37°C with concentrations of colchicine (2.5×10 −4M) or vinblastine (1.1×10 −4M) which disrupt platelet microtubles did not inhibit aggregation induced by ADP or collagen. Even following pre-incubation of platelets with a 10-fold higher concentration of colchicine (2.5×10 −3M), platelets released 14C-serotonin and aggregated in response to collagen. In the presence of a 10-fold higher vinblastine concentration (1.1×10 −3M), platelets lysed and released 51Cr. Dynamic viscoelastic measurements on recalcified platelet-rich plasma in a Weissenberg rheogoniometer demonstrated that neither colchicine (2.5×10 −4M to 5×10 −3M) nor vinblastine (1.1×10 −4M) interferes with the initiation, rate of generation, or extent of contractile force produced in platelet-fibrin clots. These results indicate that polymerized tubulin is not essential for collagen-induced release of platelet dense granule contents. In addition, intact tubulin polymers are not required to support the platelet surface configuration necessary for platelet-fibrin adherence and the platelet contractile events which result in platelet-fibrin clot retraction.