Pathways for the synthesis of sorbitol from 13C‐labeled hexoses, pentose, and glycerol in renal papillary tissue

Suspensions of rabbit renal papillary tissue were incubated with D-[6-13C]glucose, D-[1-13C]fructose, D-[1-13C]ribose, and [2-13C]glycerol. The perchloric acid extracts of the above incubations were investigated with 13C NMR spectroscopy. All 13C-labeled substrates give rise to 13C-labeled D-sorbitol. D-[6-13C]Glucose and D-[1-13C]fructose are converted directly into D-sorbitol via the aldose reductase and sorbitol dehydrogenase pathway, respectively, whereas D-[1-13C]ribose and [2-13C]glycerol give rise to labeling of the D-glyceraldehyde pool which on its turn causes a labeling of D-sorbitol. Label exchanges observed from incubations with glycerol and D-ribose indicate that the pentose shunt plays a role in this synthesis of D-sorbitol.