Fig. 7.

Plasma and brain distribution of [¹³C₅]-5-formylTHF and its metabolite [¹³C₅]-5-methylTHF in WT mice. Plasma (A, ng/mL) and brain tissue (B, ng/g) concentrations were measured over 120 min following an i.v. bolus injection of 0.25 mg/kg [¹³C₅]-5-formylTHF in WT mice. Results are presented as mean ± SEM for each time point (total of 4 animals per time point). Plasma [¹³C₅]-5-formylTHF data were fitted to a 2-compartment i.v. bolus pharmacokinetic model. The change in plasma [¹³C₅]-5-formylTHF concentration over 120 min following i.v. injection was statistically significant (P < 0.001), but the change in plasma [¹³C₅]-5-methylTHF was not. The change in brain [¹³C₅]-5-formylTHF or [¹³C₅]-5-methylTHF concentrations over the 120-min study period was not statistically significant. Asterisks represent significant differences between [¹³C₅]-5-formylTHF and [¹³C₅]-5-methylTHF concentrations in plasma or brain tissue for each time point (*P < 0.05; **P < 0.01; ***P < 0.001).