Quantifying Central Metabolic Fluxes in Human Platelets Using Metabolic Flux Analysis

Platelet metabolism is linked to platelet hyper- and hypoactivity in numerous human diseases. Most studies of platelet metabolism use extracellular uptake and excretion measurements or metabolomics to infer metabolism changes but have not quantified the carbon flux through central metabolism. The reaction-level resolution is necessary to identify the major contributors to different platelet phenotypes. The goal of this study was to develop the metabolic flux map of resting and agonist activated platelets based on intracellular flux measurements of central metabolism. Isotopically nonstationary 13C metabolic flux analysis (INST-MFA) was used to measure metabolic fluxes in platelets from labeling profiles obtained with parallel glucose and acetate labeling experiments. Flux results show that resting platelets primarily metabolize glucose to lactate via glycolysis, while acetate is oxidized to fuel the tricarboxylic acid cycle. Upon activation with thrombin, a potent platelet agonist, global flux increases occur, and platelets display a metabolic shift toward glucose oxidation.