title: Evidence for prothrombotic effects of exercise and limited protection by aspirin.
abstract: BACKGROUND
  Exercise may activate platelets and leukocytes and promote thrombosis. The effects of aspirin treatment on the prothrombotic effects of exercise have not been established.
  
  
  RESULTS
  A total of 15 healthy men performed exhaustive exercise without and with 1 week of pretreatment with aspirin (500 mg/day). Before and immediately after exercise, platelet aggregability ex vivo was measured by filtragometry, and venous blood samples were obtained. Whole-blood flow cytometry was used to determine platelet and leukocyte activation and platelet-leukocyte aggregates. Exercise increased platelet P-selectin expression, CD11b expression in neutrophils and lymphocytes, and platelet and leukocyte responses to thrombin, ADP, platelet activating factor, and N-formyl-methionyl-leucyl-phenylalanine (fMLP) in vitro. Consistent with enhanced platelet and leukocyte activation, more circulating platelet-platelet and platelet-leukocyte aggregates were detected after exercise (P<0.001 for both). Filtragometry readings were shortened, and plasma soluble P-selectin and prothrombin fragment 1+2 were elevated. Aspirin markedly reduced the urinary excretion of 11-dehydrothromboxane B(2), decreased P-selectin expression in single platelets at rest (P<0.05), and inhibited fMLP-induced neutrophil CD11b expression, but it did not attenuate exercise-induced increases in platelet aggregability, platelet P-selectin expression, leukocyte CD11b expression, platelet-leukocyte aggregate formation, soluble P-selectin, or prothrombin fragment 1+2.
  
  
  CONCLUSIONS
  Exercise induced platelet and leukocyte activation and platelet-leukocyte aggregation in vivo, and it increased platelet and leukocyte responsiveness to in vitro stimulation. Aspirin treatment attenuated certain signs of platelet activity in vivo at rest and fMLP-induced neutrophil activation in vitro, but it did not attenuate the prothrombotic effects of exercise.
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Pharmacology, Karolinska Hospital, Stockholm, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Li
authors.forename: N H
authors.initials: NH
authors.lastname: Wallén
authors.forename: P
authors.initials: P
authors.lastname: Hjemdahl
mesh_terms: D000328:Adult; D001241:Aspirin / Q000494:pharmacology*; D001769:Blood / Q000187:drug effects; D001790:Blood Physiological Phenomena; D001792:Blood Platelets / Q000502:physiology; D002449:Cell Aggregation / Q000187:drug effects / Q000502:physiology; D018592:Cross-Over Studies; D015444:Exercise; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000502:physiology; D008297:Male; D015539:Platelet Activation / Q000187:drug effects / Q000502:physiology; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D013927:Thrombosis / Q000209:etiology*
chemical_list: D010975:Platelet Aggregation Inhibitors; D001241:Aspirin