Fig. 5.

Relative pyruvate entry into the citric acid cycle (CAC) through either pyruvate decarboxylation (PDC) or pyruvate carboxylation (PC). A: PDC-to-citrate synthase (CS) flux ratio as determined by gas chromatography-mass spectrometry (GC-MS). Included are the relative contributions of [2-¹³C]pyruvate vs. other pyruvate sources (presumable glucose and lactate) to the PDC-to-CS flux ratio. Note that error bars represent SE of the overall PDC-to-CS flux ratio. B: ratio of PC to total pyruvate entry into the CAC as determined by positional glutamate ¹³C-labeling via magnetic resonance spectroscopy (MRS). T3 increased PDC flux relative to CS flux (a surrogate for overall CAC flux) after cardiopulmonary bypass while maintaining the ratio of PC to total pyruvate CAC entry. *P < 0.05 I/R vs. control (Cont); #P < 0.05 I/R-Tr vs. I/R. No other significant differences were identified. Values are means ± SE; n = 6 per group.