Use of respiration pattern analysis for study of serine metabolism in vivo

The simple and nondestructive in vivo technique of respiration pattern analysis (RPA) was used to estimate the relative importance of the formate pathway for oxidation of C 3 of L-serine in fasted mice. About 11.4 per cent of injected L-3- 14C-serine was oxidized via formate and 4.6 per cent via alternate pathways in the first hour after injection. Thus, the formate pathway accounted for about 71 per cent of the C 3 of L-serine that was oxidized.