Figure 3: Serum Is Essential to Maintain Glycolysis and Glycolytic ATP

The effect of serum on energetics was assessed by serum withdrawal for 24 h prior to assays. (A) Respirometry. The OCR/ECAR ratio was increased following serum withdrawal, due to greater reduction of ECAR than OCR. Respirometry following serum withdrawal (24 h) led to significant reduction in ECAR and OCR. The Student t test was used to determine significance for OCR/ECAR data, and 1-way ANOVA with Tukey’s post-hoc test was used to determine significance for OCR and ECAR data. (B) ATP. Serum withdrawal depressed cellular ATP levels, reduced glycolytic ATP, and increased the contribution of ATP generation by OxPhos. Statistical significance for total ATP levels was determined using the Student t test. Data is presented as mean ± SD; n = 6. (C) Signaling. Serum withdrawal leads to Akt dephosphorylation and AMPK activation. Glycolytic inhibition using iodo leads to AMPK activation in both serum and serum-free conditions; n = 3. *p < 0.05. Abbreviations as in Figure 1.