FIGURE 4.

Depiction of the kinetic model describing hyperpolarized [1-¹³C]lactate and [1-¹³C]pyruvate in MCF7 and PC3 cells. Three parameters are fitted: r_gluc, which describes the decay of hyperpolarized glucose through transport and 10 enzymatic steps in the glycolysis, K_lac/pyr, which describes the fast equilibrium between pyruvate and lactate, and k_exp, which describes the first order rate constant for export of lactate out of the cells. See “Experimental Procedures” for a detailed description of the applied kinetic model. The T₁ⁱⁿ describing the relaxation of the hyperpolarized 1-¹³C-labeled nuclei on intracellular pyruvate (Pyr) and lactate (Lac) is also fitted in the model.