ObjectiveTo explore the relationship between mitochondrial function and the severity of sepsis by detecting the platelet mitochondrial permeability transition pore, transmembrane potential and adenosine triphosphate (ATP) levels in peripheral blood. MethodsAccording to random number table, 40 male SD rats were randomly divided into three sepsis model groups (group A, B and C) and a sham group (group D). The rats in the model groups received cecal ligation and puncture (CLP) treatment with different percent of ligated length in total length of the cecum (10% in group A, 30% in group B and 50% in group C, respectively). Twenty-four hours later, peripheral blood was collected for TNF-α, IL-1βand IL-6 levels determination, also the mitochondrial permeability transition pore, transmembrane potential and ATP content were tested in the isolated platelet. One-way ANOVA test was used to determine the relevance between above indices and the severity of sepsis. Meanwhile, 29 patients with sepsis were enrolled for clinical study. After APACHEⅡscoring, platelet samples of peripheral blood in the patients were collected for mitochondrial function determination. The relationship between mitonchondrial function and APACHEⅡscore was analyzed by Spearman method. ResultsCalcein fluorescence, membrane potential and ATP synthesis in platelet mitochondria of the rat sepsis model were gradually decreased with the increased severity of CLP, and the difference among these groups were all statistically significant (all P < 0.05). In clinical specimens, APACHEⅡscore was negatively correlated with ATP level of platelet mitochondria(r=-0.895, P < 0.05). ConclusionMitochondrial function of platelet in peripheral blood can be used as an effective indicator for the severity of sepsis.