Fig. 4

Lactate uptake and conversion to TCA intermediates and amino acids in AF cells. A PDH and PDK1 protein expression in AF and NP tissues. Western blot of PDH and PDK1 in rabbit AF and NP tissue protein extract (A.1), and PDH (A.2) and PDK1 (A.3) protein levels were quantified by normalizing to β-actin as loading control (graphs). Data are means ± SD of three independent experiments (three rabbits). * p < 0.05. B ¹³C from ¹³C-Lactate was traced to TCA intermediates and amino acids in AF cells. Rabbit AF cell cultures grown in 2% or 5% O₂ were labeled with the stable isotope 3-¹³C-lactate (4 mM) in the presence of 1 mM or 5 mM glucose; ¹³C was traced to different TCA intermediates by HRMS. Intracellular enrichment of ¹³C on different metabolites in AF cells was measured in APE or atom percent excess. Data are means ± SEM of four independent experiments (four rabbits)