Figure 5.

The effect of high and low concentrations of exogenous pyruvate on the initial hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion rates in cellulo. Using Mia Paca-2 live cell–encapsulated alginate beads, NMR spectra of hyperpolarized [1-¹³C]pyruvate and [1-¹³C]lactate were measured over repetitive 6-s time intervals. A, signal intensities of hyperpolarized [1-¹³C]pyruvate and [1-¹³C]lactate over time. The light green band demarcates the time intervals for the initial rate calculations (6–18 s; inset, expanded time scale) of intracellular lactate production and pyruvate conversion. B, initial or total hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion rates in cellulo. Initial hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion in cellulo was calculated by the sum of converted hyperpolarized [1-¹³C]lactate during the first 6 to 18 s normalized to the sum of hyperpolarized [1-¹³C]pyruvate during the first 6 to 18 s in the presence of 0.57 mM or 5.7 mM [1-¹³C]pyruvate (left). Total hyperpolarized [1-¹³C]pyruvate-to-[1-¹³C]lactate conversion in cellulo was calculated by the sum of converted hyperpolarized [1-¹³C]lactate over the 3-min experiment normalized to the sum of hyperpolarized [1-¹³C]pyruvate in the presence of 0.57 mM or 5.7 mM [1-¹³C]pyruvate (right). Error bars represent SEM. All data represent n = 4 independent experiments (biological replicate); ∗p < 0.05; one-tailed t test.