Details of a rotor system for investigating platelet aggregation in whole blood

Working details of the prototype apparatus, for producing and monitoring platelet aggregation in whole blood, are described. The blood is subjected first to varying degrees of turbulence or agitation by the discontinuous rotation of a transparent cylindrical rotor chamber. During the period of turbulence platelets may aggregate under the influence of aggregating agents or of appropriate shear forces alone.The blood in the same chamber is subsequently subjected to continuous rotational centrifugation which leads to zonal separation of the plasma and platelets from the red cells by appropriate gravity forces. Any platelet clumps which have formed move outwards with the red cells leaving an inner zone of plasma through which a light beam is passed; optical measurements of the plasma zone indicate the number of unclumped platelets, since the formed aggregates have been centrifuged out of the light path. By comparison with the optical densities of platelet-free and platelet-rich plasma zones the degree of platelet aggregation which has taken place may be deduced.The technique of sampling different plasma zones for analysis by introducing a suitably shaped scoop into the zones of blood in the spinning chamber is described.The movement of blood and the rotor during discontinuous rotation has been analysed by high speed cinematography.