Key result
Collagen plus endogenous thrombin synergistically cuts platelet aggregation lag time to ~42 seconds versus either alone.
Why the study?
The individual and combined effects of collagen and endogenously generated thrombin on platelet aggregation in whole blood were not fully characterized.
Does the combination of collagen and endogenous thrombin synergistically affect platelet aggregation in whole blood samples?
Does the combination of collagen and endogenous thrombin synergistically affect platelet aggregation in whole blood samples?
Endogenously generated thrombin is a potent platelet agonist in whole blood, and combining it with collagen synergistically shortens the lag time to platelet aggregation onset.
No immediate clinical implications for thrombosis management; leaves open whether collagen-thrombin synergy influences in vivo platelet function.
The aim of the study was to investigate the individual and combined effects of collagen (3.5 microg/ml) and endogenously generated thrombin (due to addition of 0.35 pmol/l tissue factor) on platelet aggregation in the physiological environment of whole blood by means of the impedance method. Lag times were significantly shorter when a combination of collagen and endogenous thrombin was used to provoke platelet aggregation (41.9 +/- 16.3 s) compared with collagen (173.8 +/- 52.1 s, P < 0.0001) or endogenous thrombin (94.3 +/- 43.6 s, P < 0.001). Amplitudes and slopes were the lowest in collagen-induced experiments (2.83 +/- 1.59 Omega and 1.79 +/- 0.45 Omega/min, respectively), whereas they were approximately the same in endogenous thrombin-induced experiments whether collagen was present or not (13.7 +/- 3.1 versus 11.2 +/- 4.0 Omega and 6.3 +/- 2.8 versus 5.6 +/- 2.3 Omega/min, respectively). No synergistic effect of collagen and endogenous thrombin on the clot formation process was observed by means of thrombelastometry. Moreover, thrombin potentials in tissue factor-activated plasma samples were approximately the same whether collagen was present or not (834 +/- 67 versus 809 +/- 63 nmol/l.min). In conclusion, endogenously generated thrombin is a potent platelet agonist in whole blood, and a combination of collagen and endogenous thrombin synergistically shortens the lag time until the onset of platelet aggregation.
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Cvirn et al. (2007) studied this question. Combination of collagen and endogenous thrombin vs. Collagen alone or endogenous thrombin alone was evaluated on Lag time to platelet aggregation (p=<0.0001). A combination of collagen and endogenous thrombin synergistically shortened the lag time until the onset of platelet aggregation (41.9 s) compared with collagen (173.8 s) or thrombin alone (94.3 s).
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