In vivo tracing of 13C5 15N2-glutamine in RBCs from rats undergoing HS. (A) Samples were collected at baseline (B) or end (E) (60 minutes through shock) time points in sham (MAP, >80 mm Hg; no trauma) and shock (MAP, <30 mm Hg; no trauma) Sprague-Dawley rats (n = 8). (B) An overview of the expected labeling scheme in downstream metabolites to glutamine catabolism in mitochondria-devoid RBCs. (C) Box-and-whisker plots of key heavy isotopologues of glutamine and its catabolites.