Figure 4.

Chronic BHB exposure stimulates mitochondrial pyruvate consumption and surface MCT activity. (a) Expression of the pyruvate sensor Pyronic in astrocytes of mixed cortical cultures. Bar = 50 µm. (b) Rationale of the method to measure the rate of mitochondrial pyruvate consumption by monitoring cytosolic pyruvate in the presence of the pyruvate transport blockers AR-C155858 (1 µM) and probenecid (1 mM). (c) Measurement of pyruvate consumption rates of astrocytes exposed for 3 days to control conditions (gray symbols) or to 2 mM BHB (open symbols). Bars represent the average rates obtained in three separate experiments (20–30 cells per experiment). Monocarboxylate transporter activity was measured by monitoring the rate of intracellular acidification in the presence of 10 mM lactate (d) or 10 mM BHB (e) in control cells or in cell treated for 3 days with 2 mM BHB. Bars represent the average rates obtained in six separate experiments (10–20 cells per experiment).