In Vivo Detection of 13C Isotopomer Turnover in the Human Brain

Shizhe S. Li¹, Yan Zhang¹, Maria Ferraris Araneta¹, Christopher Johnson¹, Yun Xiang¹, Robert B. Innis¹, Jun Shen¹

Previously ¹³C isotopomers were observed in the human brain in the aliphatic spectral region using [1-¹³C]glucoseinfusion and long signal averaging time. Carboxylic/amide carbons can only form singlets and doublets even when uniformly labeled substrates are used, resulting in spectral simplification. To investigate the feasibility of simultaneously detecting two different isotopomers on the same carbon in the carboxylic/amide region in the human brain, we infused [U-¹³C]glucose and [2-¹³C]glucose because [U-¹³C]glucose produces doublets in the carboxylic/amide region while [2-¹³C]glucose only produces singlets. Dynamic turnover of these isotopomers were detected for the first time in the human brain.