Distribution of glutathione and its related enzymes in small intestinal mucosa of rats.

Glutathione (GSH) concentration of whole mucosa was 2.96 +/- 0.26 (mean +/- SEM) mumol/g wet weight in all segments: however the tip cell layer contained significantly less GSH than the lower mucosal cells. GSH S-transferase (GSH-T) activities displayed a striking gradient with highest values in the duodenum and lowest in the terminal ileum. gamma-glutamyl transpeptidase (GGT) activities were also highest in the proximal segment but lowest in the fifth segment among eight divided segments. Along the villus/crypt axis GGT and to a lesser degree GSH-T were also polarized with highest activities in the villus tip cell region. GSH peroxidase (GSH-Px) and glutathione reductase (GSSG-R) had an even distribution along the intestinal tube and among the mucosal cell populations. This distinct pattern of distribution suggests a functional adaptation of GSH and its related enzymes; GSH-T might be important for detoxification of exogenous luminal compounds which enter the body in the upper intestinal segments while GSH-Px might be responsible for peroxidation of endogenously produced compounds.