Effect Of Storage On Surface Glycoproteins And Cyto-Skeletons Of Platelets
Platelets stored as concentrates (PC) at 22° C for 72 hours develop a functional defect in vitro tests. Alterations in membrane glycoproteins of platelets have been shown to effect platelet function. We have investigated the effect of storage on membrane glycoproteins (GP) and cytoskeletons (cyto.) of platelets. Gel filtered platelets from fresh PC were labeled with 125Iodine by Iodogen technique and gel filtered again to remove free iodide. Platelets were concentrated by albumin density gradient centrifugation, resuspended in autologous plasma and stored for 72 hours at 22° C. Aliquots of fresh and stored PC were solubilized with 2% sodium dodecyl sulphate (SDS) containing 5% mercaptoethanol and subjected to polyacrylamide gel electrophoresis (PAGE). In one experiment, separate aliquots of fresh and stored platelets were labeled and similarly analyzed. Gels were stained with Coomassie blue and subjected to autoradiography. Coomassie blue staining did not reveal major differences between fresh and stored platelets. Autoradiography revealed a decrease in the 170,000 dalton surface protein (GP-I) of platelets after storage. Triton insoluble cyto. of thrombin activated fresh and stored platelets were solubilized with SDS and analyzed by PAGE and autoradiography. Cytoskeletons from fresh PC revealed the presence of a 110,000 dalton surface protein (GP-III). However, cyto. from similarly treated stored platelets showed a markedly decreased amount of this protein. Thus stored platelets have decreased amounts of the 170,000 dalton surface protein (GP-I) along with decreased amounts of the 110,000 dalton protein (GP-III) associated with the cyto. of thrombin activated platelets. These changes may contribute to the functional defect reported in stored platelets.