Aboral changes in D-glucose transport by human intestinal brush-border membrane vesicles

Area of Science:

• Gastroenterology
• Molecular Biology
• Physiology

Background:

• D-glucose absorption is crucial for nutrient uptake in the human small intestine.
• Understanding the regional differences in D-glucose transport mechanisms is essential for comprehending overall intestinal function.

Purpose of the Study:

• To investigate and compare the characteristics of D-glucose transport in isolated brush-border membrane vesicles from different regions of the human small intestine (jejunum, mid-ileum, and terminal ileum).
• To determine the role of sodium (Na+) and electrical potential in D-glucose transport across these regions.

Main Methods:

• Isolation of brush-border membrane vesicles from human jejunum, mid-ileum, and terminal ileum.
• Measurement of D-glucose transport kinetics using tracer-exchange experiments.
• Assessment of sodium-dependence and electrogenic nature of transport.

Main Results:

• D-glucose transport was found to be sodium-dependent and electrogenic in both the jejunum and mid-ileum.
• Jejunal D-glucose transport exhibited a significantly greater transient overshoot compared to the mid-ileum.
• The terminal ileum did not show sodium-dependent D-glucose transport, but did exhibit sodium-dependent taurocholate transport.
• Na+-glucose co-transport activity was highest in the jejunum and decreased distally.

Conclusions:

• D-glucose transport in the proximal human intestine (jejunum and mid-ileum) is mediated by sodium-dependent, electrogenic mechanisms involving brush-border membrane transporters.
• D-glucose transport in the terminal ileum appears to differ from the proximal regions and resembles colonic D-glucose transport patterns.