title: "Shear induced platelet activation"--a critical reappraisal.
abstract: Platelets were found to be stimulated by high shear exposure for 5 minutes. Using a new technique, shear stresses up to 255 N/m2, acting for pathophysiological relevant intervals of milliseconds did not elicit active release of beta-TG, beyond the amount explained by LDH-monitored passive lysis. Neither the plasma level of ionized calcium (citrate vs heparin anticoagulation), nor a potent platelet inhibiting agent like PgI2 (20 nM) did significantly alter platelet responses to short acting high shear stress. Ultrastructural signs of activation could largely be suppressed by adding ADP-scavengers. Direct "shear induced platelet activation" appears rather unlikely and mostly reducible to secondary biochemical activation by mediators, probably adenine nucleotides, from a small percentage of passively shear-destroyed platelets. The extent of this secondary activation is largely a matter of experimental conditions.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D001792:Blood Platelets / Q000145:classification / Q000502:physiology*; D001809:Blood Viscosity; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008854:Microscopy, Electron; D013314:Stress, Mechanical; D001620:beta-Thromboglobulin / Q000378:metabolism
chemical_list: D001620:beta-Thromboglobulin; D000244:Adenosine Diphosphate; D007770:L-Lactate Dehydrogenase