Figure 3. Mitochondrial respiration was not altered, but glycolysis was enhanced in replicative senescence. (A) Cellular oxygen consumption rate (OCR) in non-senescence (quiescent) and senescent cells. The basal respiration, spare respiratory capacity, and ATP production are calculated based on the sequential compound injection according to the manufacture’s instruction. (B) The extracellular acidification rate (ECAR) in non-senescent (quiescent) and senescent cells. (C) Glucose uptake rate were measured by 2-NBDG, a fluorescently labeled deoxyglucose analog. Data are reported as mean ± SEM of three to eight independent experiments. Significant differences were determined with Student’s t-tests. *p<0.05, **p<0.01, ***p<0.001. Abbreviations: NS, Non-senescent cells (quiescent); SEN, Senescent cells.