Thrombin stimulates both glycolysis and oxidative phosphorylation in platelets, and combined inhibition of both pathways synergistically inhibits platelet aggregation.
Does inhibition of specific metabolic pathways (glycolysis, fatty acid oxidation, glutaminolysis) prevent thrombin-dependent platelet aggregation and alter bioenergetics in human platelets?
Platelets exhibit metabolic plasticity during thrombin activation, relying on both glycolysis and oxidative phosphorylation, with glycolysis able to compensate for the loss of fatty acid oxidation or glutaminolysis to sustain aggregation.
Platelet thrombus formation includes several integrated processes involving aggregation, secretion of granules, release of arachidonic acid and clot retraction, but it is not clear which metabolic fuels are required to support these events. We hypothesized that there is flexibility in the fuels that can be utilized to serve the energetic and metabolic needs for resting and thrombin-dependent platelet aggregation. Using platelets from healthy human donors, we found that there was a rapid thrombin-dependent increase in oxidative phosphorylation which required both glutamine and fatty acids but not glucose. Inhibition of fatty acid oxidation or glutamine utilization could be compensated for by increased glycolytic flux. No evidence for significant mitochondrial dysfunction was found, and ATP/ADP ratios were maintained following the addition of thrombin, indicating the presence of functional and active mitochondrial oxidative phosphorylation during the early stages of aggregation. Interestingly, inhibition of fatty acid oxidation and glutaminolysis alone or in combination is not sufficient to prevent platelet aggregation, due to compensation from glycolysis, whereas inhibitors of glycolysis inhibited aggregation approximately 50%. The combined effects of inhibitors of glycolysis and oxidative phosphorylation were synergistic in the inhibition of platelet aggregation. In summary, both glycolysis and oxidative phosphorylation contribute to platelet metabolism in the resting and activated state, with fatty acid oxidation and to a smaller extent glutaminolysis contributing to the increased energy demand.
Ravi et al. (Mon,) conducted a other in Healthy (platelet metabolism) (n=9). Thrombin and metabolic inhibitors vs. Resting platelets (vehicle/media) was evaluated on Platelet aggregation and bioenergetics (OCR and ECAR). Thrombin stimulates both glycolysis and oxidative phosphorylation in platelets, and combined inhibition of both pathways synergistically inhibits platelet aggregation.