Figure 2

Mitochondrial respiration of permeabilized platelets. A. Representative trace of oxygen consumption rate using a substrate, uncoupler, inhibitor titration protocol. Respiratory complexes activated and the induced respiratory states are defined below the x-axis. Platelets were permeabilized with digitonin with simultaneous addition of malate and pyruvate (DMP). Oxidative phosphorylation (OXPHOS) was stimulated by subsequent addition of ADP followed by an additional Complex I (CI) substrate glutamate (Glu). Addition of the Complex II (CII)-linked substrate succinate (Succ) enabled convergent electron input via both complex I and complex II. OXPHOS was inhibited by oligomycin (Oligo) revealing state 4 respiration. Maximal respiratory capacity of the electron transfer system (ETS) was induced by titration of FCCP. Inhibition of Complex I by rotenone (Rot) revealed Complex II-supported respiration. The Complex III inhibitor antimycin-A (Anti) left residual, primarily non-mitochondrial oxygen consumption. B. Temporal changes of different respiratory states during the first week of sepsis in patients compared to controls. Complex I-dependent respiration during oxidative phosphorylation (CI_OXPHOS), FCCP-titrated maximal respiration with complex II (CII_ETS), and convergent substrate input (CI + II_ETS) all increased significantly in patients during the first week of sepsis both compared to Day 1 to 2 and to controls. State 4 was only increased at Day 6 to 7 compared to controls. Of note, there was no significant difference in respiratory capacity of any respiratory state in patients at the earliest time point analyzed, Day 1 to 2 of admission, compared to controls. C. The control ratio (CI + II_ETS/state 4) increased significantly during the first week of sepsis both compared to Day 1 to 2 as well as to controls. Mean values ± SEM (B) and median ± range (C), n = 16 to 18, *P < 0.05 compared to Day 1 to 2, § P < 0.05 compared to controls.