1 14c pyruvate

The pyruvate and glucose oxidation rates were determined by measuring ¹⁴CO₂ production from the oxidation of [1-¹⁴C]pyruvate and [U-¹⁴C]glucose (American Radiolabeled Chemicals, MO), respectively, as described^{29 (link)}. Complete and incomplete FAO rates were determined by measuring the ¹⁴CO₂ production and ¹⁴C-labeled acid-soluble metabolites production, respectively, from the oxidation of [1-¹⁴C]palmitate (American Radiolabeled Chemicals, MO), as described^{30 (link)}. Cells were lysed in 0.05% sodium dodecyl sulfate for protein estimation, and the data was normalized to total protein content.

[1‐¹⁴C]Pyruvate, with a specific activity of 50–60 mCi/mmol, was supplied by American Radiolabeled Chemicals (Royston, Hertfordshire, UK). An 82mM pyruvic acid solution containing 200 kBq ¹⁴C was injected per animal. The ¹⁴C pyruvic acid was mixed with cold pyruvic acid in order to achieve the same pyruvate concentration as that used in the imaging experiments (10 mL/kg, 82mM).
Fifteen tumor‐bearing mice were maintained under anesthesia for 30 min (the duration of the hyperpolarized ¹³C studies) prior to injection with [1‐¹⁴C]pyruvate. Animals were killed at 15, 30 and 60 s after injection and the blood and organs were removed. The organs were homogenized in RIPA buffer (1: 5) (50mM HEPES, 1mM EDTA, 0.7% sodium deoxycholate, 1% Nonidet P‐40, 0.5 M lithium chloride, pH 7.6) using a Precellys 24 homogenizer (Stretton Scientific Ltd., Stretton, Derbyshire, UK) and the blood was centrifuged as described above. The counts from the tissues and serum were determined using a liquid scintillation counter (Perkin Elmer, Beaconsfield, Buckinghamshire, UK). The measured radioactivity was normalized to tissue weight or serum volume, accordingly.