title: Spiking in cytosolic calcium concentration in single fibrinogen-bound fura-2-loaded human platelets.
abstract: Fura-2-loaded human platelets were immobilized on a fibrinogen-coated surface and the cytosolic free calcium concentration ([Ca2+]i) was measured in single platelets by low-light-level video-ratio image-processing of the optical probe signal. Some fibrinogen-bound platelets showed repetitive spiking in [Ca2+]i with a mean frequency of about 2/min, which increased to 5/min in the presence of ADP. Other cells showed no activity until the addition of agonist. When immobilized in the presence of prostaglandin I2 and the fibrinogen antagonist Arg-Gly-Asp-Ser, the platelets adhered less firmly to fibrinogen, and in many [Ca2+]i remained low and constant. Subsequent activation of such platelets with ADP evoked oscillations in [Ca2+]i with a peak frequency of about 5/min and which persisted for at least 5 min. These results indicate that human platelets, like many other non-excitable cells, have an elaborate system of calcium signalling involving spiking.
authors.affiliation: Physiological Laboratory, University of Cambridge, U.K.
authors.forename: J W
authors.initials: JW
authors.lastname: Heemskerk
authors.forename: J
authors.initials: J
authors.lastname: Hoyland
authors.forename: W T
authors.initials: WT
authors.lastname: Mason
authors.forename: S O
authors.initials: SO
authors.lastname: Sage
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000097:blood*; D003600:Cytosol / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D005340:Fibrinogen / Q000378:metabolism / Q000494:pharmacology*; D016257:Fura-2; D006801:Humans; D007700:Kinetics; D009842:Oligopeptides / Q000494:pharmacology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D010980:Platelet Membrane Glycoproteins / Q000502:physiology; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D009842:Oligopeptides; D010975:Platelet Aggregation Inhibitors; D010980:Platelet Membrane Glycoproteins; D004533:Egtazic Acid; D000244:Adenosine Diphosphate; D005340:Fibrinogen; C046617:arginyl-glycyl-aspartyl-serine; D002118:Calcium; D016257:Fura-2