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

Suspensions of rabbit renal papillary tissue were incubated with D‐[ 6‐ 13 C]glucose, D‐[1‐ 13 C]fructose, D‐[1‐ 13 C] ribose, and [2‐ 13 C]glycerol. The perchloric acid extracts of the above incubations were investigated with 13 C NMR spectroscopy. All 13 C‐labeled substrates give rise to 13 C‐labeled D‐sorbitol. D‐[6‐ 13 C]Glucose and D[1‐ 13 C]fructose are converted directly into D‐sorbitol via the aldose reductase and sorbitol dehydrogenase pathway, respectively, whereas D‐[1‐ 13 C] ribose and [2‐ 13 C]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. © 1989 Academic Press, Inc.