Actin filament content in platelets—A sensitive index of cellular reactivity

Blood platelets have the capacity to participate in a number of physiological as well as pathological processes within the circulation. In order to evaluate their cellular reactivity a number of platelet function tests have been developed. The main in vitro function tests are assessment of aggregation and adhesion, secretion, arachidonate metabolism, coagulant activities and the characterization of surface membrane glycoproteins (Day and Rao, 1986). Here we measure alterations of the G-/F-actin equilibrium of platelets. High F-actin values of unstimulated platelets indicate a hyperreactivity of the cell as examined in platelets from diabetics. Determination of the actin filament content in platelets can be considered as a new sensitive function test.