S. Rota et al., IS PLATELET PHOSPHOLIPID-DEPENDENT THROMBIN GENERATION ALTERED BY ACUTE MYOCARDIAL-INFARCTION OR ASPIRIN, Thrombosis research, 83(4), 1996, pp. 329-338
The ability of unactivated and calcium ionophore activated platelets t
o support thrombin generation in defibrinated plasma was measured by a
chromogenic substrate assay in the absence of clot formation. Platele
t phospholipid-dependent thrombin generation (Platelet-TG) could be me
asured using platelets isolated from blood collected into either sodiu
m citrate or EDTA as anticoagulant. Measurements were stable in sample
s kept at room temperature for 24 hours after venesection. There was n
o significant difference in either the unactivated or activated platel
et-TG with platelets collected into either anticoagulant (mean differe
nce 10.12 nmol/min unactivated and 10.60 nmol/min activated). There wa
s no correlation between unactivated and activated platelet-TG and pat
ient age. Platelet-TG was 179 (153-237) nmol/min (median and inter-qua
rtile range) for unactivated and 489 (462-508) nmol/min for activated
platelets from healthy volunteer subjects (median age 31, range 20-40
years). Platelet-TG was the same in subjects from a population-based c
ohort study (median age 58, range 45-70 years [162 (142-193) nmol/min
and 527 (490-551) nmol/min, unactivated and activated platelets respec
tively] as compared to patients admitted with acute myocardial infarct
ion (median age 68, range 36-85 years [179 (146-200) nmol/min and 473
(440-517) nmol/min unactivated and activated platelets respectively] (
p=0.497 for comparison between unactivated platelet-TGs and p=0.487 fo
r comparison between activated platelet-TGs in the two groups). Aspiri
n inhibited platelet aggregation but did not affect platelet-TG using
either unactivated or activated platelets exposed to aspirin in vitro;
or in vivo, using platelets obtained from individuals after ingestion
of aspirin. In conclusion these results show that for measurement of
platelet -TG, blood samples can be anticoagulated with EDTA as well as
sodium citrate for up to 24 hours after venesection and that this mea
surement is not affected by subject age, aspirin treatment or the acut
e stage of myocardial infarction.