title: Response to platelet-activating factor in human platelets stored and aged in plasma. Decrease in aggregation, phosphoinositide turnover, and receptor affinity.
abstract: Human platelet concentrates were stored in polyolefin bags at 22 to 24 degrees C on a horizontal shaker for up to 8 days. At different intervals, aliquots of platelet-rich plasma (PRP) were removed aseptically and five variables, i.e., platelet counts, morphology, platelet-activating factor (PAF)-stimulated aggregation, phosphoinositide turnover, and [3H]PAF binding to platelet receptors, were studied. The number of platelets did not change during the 8 days of storage. Scanning electron microscopy of the platelets revealed a gradual morphologic change from biconcave flat discs to irregular, crenated forms. The PAF-induced aggregation of platelets declined with time of storage. A decrease to 50 percent of the Day 1 aggregatory response to PAF was evident on Day 2, and there was a further decline to about 20 percent by Day 6. Similarly, PAF receptor-coupled phosphoinositide turnover, as monitored by 32P incorporation into individual phosphoinositides, decreased dramatically with storage. After 2 to 3 days of storage, the phosphoinositide turnover was reduced to 50 percent of the original response, and it continued to decline to about 25 percent of original response by Day 5 or 6. The binding of [3H]PAF to washed human platelets indicated subtle changes between Days 2 and 4, which became more noticeable by Day 6. These results have raised the possibility of changes in the number of the receptors and/or their affinity for the ligand during storage. We conclude that although the number of platelets was maintained during storage for 8 days, a general deterioration of their responses to PAF occurred at the levels of cell surface receptor, transmembrane signaling (phosphoinositide turnover), and response (aggregation).
authors.affiliation: Department of Pharmacology, School of Medicine, University of Missouri-Columbia.
authors.forename: S D
authors.initials: SD
authors.lastname: Shukla
authors.forename: W J
authors.initials: WJ
authors.lastname: Morrison
authors.forename: D M
authors.initials: DM
authors.lastname: Klachko
mesh_terms: D001667:Binding, Competitive; D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D001793:Blood Preservation / Q000379:methods; D002470:Cell Survival; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010716:Phosphatidylinositols / Q000097:blood*; D010949:Plasma; D010972:Platelet Activating Factor / Q000378:metabolism / Q000494:pharmacology*; D010974:Platelet Aggregation; D010976:Platelet Count; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface / Q000032:analysis*; D043562:Receptors, G-Protein-Coupled; D014316:Tritium
chemical_list: D010716:Phosphatidylinositols; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D014316:Tritium