Effects of sodium citrate, low molecular weight heparin, and prostaglandin E1 on aggregation, fibrinogen binding, and enumeration of equine platelets.

This research article explores the impact of sodium citrate, low molecular weight heparin (LMWH), and prostaglandin E1 (PGE1) on the aggregation, fibrinogen binding, and count of equine platelets. The findings highlight the influence of sodium citrate in reducing platelet aggregation and fibrinogen binding, the unsuitability of LMWH as an anticoagulant due to platelet clumping, and the ability of PGE1 to reverse platelet aggregation and fibrinogen binding.

Methodology

• The study involved blood samples obtained from 4 Thoroughbreds.
• The collected blood was mixed into syringes in the ratio of 9 parts blood:1 part anticoagulant.
• The anticoagulants applied were sodium citrate, LMWH, a combination of sodium citrate and LMWH, or 300 nM PGE1/ml of anticoagulant.
• Platelet aggregation in response to ADP, collagen, and PGE1 was assessed using optical aggregometry – a laboratory technique used for testing the function of platelets.
• Platelet activation was evaluated with flow cytometry, a tool that helped detect the binding of fluorescein-conjugated anti-human fibrinogen antibody.
• Plasma concentration of ionized calcium was measured using an ion-selective electrode.

Results

• The study found that the number of platelets in samples containing LMWH was significantly less than those containing sodium citrate.
• Increasing concentrations of sodium citrate induced reductions in both platelet aggregation and plasma concentration of ionized calcium.
• Adding PGE1 beforehand led to the inhibition of platelet aggregation in a concentration-dependent manner. Additionally, introducing PGE1 four minutes after adding ADP resulted in a partial reversal of aggregation and fibrinogen binding.

Conclusions

• The high concentration of sodium citrate in blood samples reduces plasma concentration of ionized calcium, which brings about a reduction in platelet aggregation and fibrinogen binding.
• The tendency of platelets to clump in samples collected into LMWH suggests its inappropriateness as an anticoagulant.
• PGE1 can reverse platelet aggregation and fibrinogen binding, indicating that it might result in an underestimation of platelet activation.