Platelet aggregation rate

Light transmission aggregometry (540VS aggregometer; Chronolog Corp., Havertown, PA, USA) was adopted to measure the platelet aggregation rates prior to and following 4-week treatment with anti-platelet drugs. Fasting vein blood samples (5 ml) collected in the morning were centrifuged for 8 min at a speed of 81 × g in order to isolate the platelet-rich plasma (PRP). Subsequent to the first step, the remaining blood samples were centrifuged for 10 min at a speed of 1308 × g to obtain the platelet-poor plasma (PPP), which was used to contrast with the PRP. The 8-min maximum platelet aggregation rate was tested by loading the PRP sample in the tank of the optical platelet aggregation analyzer and adding adenosine diphosphate (ADP) to a final concentration of 5 µmol/l. The rate was compared with the PPP sample value, which was set as the blank control.