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Application of light-scattering theory to the optical effects associated with the morphology of blood platelets

1977; Elsevier BV; Volume: 180; Issue: 1 Linguagem: Inglês

10.1016/0003-9861(77)90019-4

1096-0384

Paul Lattmer, G. V. R. Born, Frank Michal,

Platelet Disorders and Treatments

When fresh citrated platelet-rich plasma was stirred at 900 rpm, stopping the stirrer increased the extinction, E (optical density, absorbance), of the plasma by 25%. After the platelets from humans or rabbits had changed shape on the addition of ADP, stopping the stirrer increased E by only about 2%. Assuming the shape of a platelet to approximate an ellipsoid of revolution which is originally flat and becomes more or less spherical after ADP, the effects of stirring on extinction are accounted for with conventional light-scattering theory. The change in extinction caused by stirring is the basis of a proposed nondestructive and remote assay of platelet shape. Extinction changes induced by chlorpromazine, which causes disk-sphere transformation only, are found to agree with theoretical predictions based on the shape change. The effects of ADP, which also produces pseudopods, are systematically smaller. The optical effects of shape and pseudopods can be separated: those of shape are sensitive to stirring, while those of pseudopods are not. ADP evidently produces a 37% increase in extinction of stirred platelets due to disk-sphere transformation plus a 9% decrease due to pseudopod formation (net increase, 28%). With simplified models of pseudopods, light-scattering theory is found to confirm that pseudopod formation should cause a decrease in extinction and total light scattering.