A. L. Slaughter2, H. B. Moore2, A. Bacon2, N. Butler1, A. Banerjee2, C. Silliman2,3, A. D’Alessandro2, E. Peltz2, E. Moore1,2 1Denver Health Medical Center,Aurora, CO, USA 2University Of Colorado Denver,Aurora, CO, USA 3Children’s Hospital Colorado,Aurora, CO, USA
Introduction:
Previous data demonstrate that the plasma concentration of succinate can increase 20-fold within minutes of hemorrhagic shock. Succinate receptors are highly expressed on platelets and dysfunctional platelets play a pivotal role in trauma-induced coagulopathy (TIC). However, the contribution of post-shock succinate accumulation to platelet-mediated TIC is unknown. Fibrinolysis is an important cause of early post-traumatic death due to hemorrhage, yet the mechanism driving acute platelet/fibrin clot failure remains elusive. We hypothesize that succinate alters platelet function, accelerating fibrinolysis, at plasma concentrations observed during hemorrhagic shock.
Methods:
Venous whole blood (WB) from healthy individuals (n=8) was mixed with 5μl of succinate solution to achieve 250-1000μM concentrations per 500μl of WB. Tissue plasminogen activator (75ng/mL, +tPA) was added at each concentration to simulate post-shock endogenous tPA release. Samples were analyzed using native thromboelastography (TEG) and functional fibrinogen (measurement of clot formation independent of platelets, FF-TEG) assays. Repeated measures ANOVA with Bonferroni adjustment was used to determine statistically significant change from baseline TEG and FF-TEG parameters at increasing succinate concentration ± tPA.
Results:
Elevated succinate concentrations (±tPA) decreased time to clot initiation (R), while increasing clot potentiation (angle) and the maximum amplitude of clot formation (MA) (R 250μM+tPA vs. R WB+tPA, p=0.026; angle 500μM+tPA vs. angle WB+tPA, p=0.004; MA 500μM+tPA vs. MA WB+tPA, p=0.026, Figure 1). tPA independently decreased R and increased angle (R WB+tPA vs. R WB, p=0.016; angle WB+tPA vs. angle WB, p=0.016); however these effects were more profound in the setting of succinate (R +tPA vs. R succinate+tPA, -33% vs. -51%, p=0.042; angle +tPA vs. angle succinate+tPA, +37% vs. +67%, p=0.001). Functional fibrinogen levels (FLEV) were unchanged by elevated tPA and succinate concentration ± tPA.
Conclusion:
Pathophysiologic concentrations of succinate in whole blood accelerate clot initiation and potentiation, precipitating earlier tPA-mediated fibrinolysis. Functional fibrinogen levels, measuring clot formation independent of platelets, are unchanged by increasing succinate (± tPA), implicating platelets as culprit mediators. These data support succinate’s role in a platelet-dependent mechanism that drives early post-shock hyperfibrinolysis.
