title: Action of aspirin on whole blood-aggregation evaluated by the screen filtration pressure method.
abstract: BACKGROUND
  There are few monitoring systems widely used in clinical practice for evaluating the effectiveness of aspirin therapy, so in the present study aspirin's antiplatelet effects we investigated with a whole blood aggregometer using a screen filtration pressure (SFP) method.
  
  
  RESULTS
  Thirty-five healthy male volunteers took 100 mg/day aspirin for 14 days. Whole-blood aggregation was analyzed at baseline and on days 7 and 14, using collagen and adenosine diphosphate as the stimuli, and compared with the platelet-rich plasma (PRP) aggregation measured by optical aggregometer. The platelet-aggregation threshold index (PATI) for both methods, which was defined as the putative agonist-concentration giving half-maximal aggregation, and the PRP-maximal aggregation rate were analyzed. The maximal aggregation rate induced by 1.6 mg/L collagen decreased from 85.5% (80.8-92.8) [median (interquartile range)] at baseline to 51.5% (39-63.8) on day 14 (p<0.0001). The PRP-PATI and whole-blood PATI for collagen increased from 0.32 (0.28-0.70) to 1.82 mg/L (1.25-2.89) (p<0.0001) and from 0.28 (0.22-0.3) to 1.06 mg/L (1.01-1.29) (p<0.0001) respectively.
  
  
  CONCLUSIONS
  The whole-blood PATI and PRP-PATI for collagen, as well as the maximal PRP aggregation rate, clearly distinguish platelet aggregability before and after aspirin intake. However, whole-blood analysis by the SFP-method is easier to perform, and is a promising method of monitoring aspirin's effects.
authors.affiliation: Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Arata
authors.initials: A
authors.lastname: Tabuchi
authors.forename: Ryoji
authors.initials: R
authors.lastname: Taniguchi
authors.forename: Kanako
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kondo
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kawato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Morimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kimura
authors.forename: Toru
authors.initials: T
authors.lastname: Kita
authors.forename: Hisanori
authors.initials: H
authors.lastname: Horiuchi
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D001241:Aspirin / Q000494:pharmacology*; D001792:Blood Platelets; D003094:Collagen / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005374:Filtration / Q000379:methods; D006403:Hematologic Tests / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D011312:Pressure
chemical_list: D010975:Platelet Aggregation Inhibitors; D000244:Adenosine Diphosphate; D003094:Collagen; D001241:Aspirin