Figure 5. There is a delayed synthesis of amino acids from ¹⁵N proline in the retina compared to the RPE/Cho.

(A) A schematic of in vivo tracing of ¹⁵N proline with double injection. Mice were fasted for 18 hours and received two injections of ¹⁵N proline (150 mg/kg) or PBS at 0 min and 10 min, respectively. Retina and RPE/Cho were harvested at 0min, 5min, 15min and 30min after the second injection for metabolite analysis with GC MS. (B-K) ¹⁵N fraction of proline and metabolites derived from ¹⁵N proline in RPE/Cho and retina at different time points. N=8 (L) A schematic of proline catabolism into amino acids in RPE to be exported into the neural retina.