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Published on: December 17, 2011
Acute adaptive cellular base uptake in rat duodenal epithelium
Y Akiba1, O Furukawa, P H Guth
1School of Medicine, University of California Los Angeles, Los Angeles, CA 90024, USA.
Summary
The duodenum protects itself from acid by rapidly transporting bicarbonate ions, a process enhanced by Na(+)-HCO cotransport. This cellular ion transport mechanism adapts to repeated acid exposure, safeguarding duodenal epithelial cells.
Area of Science:
- Gastroenterology
- Physiology
- Cell Biology
Background:
- The duodenum faces rapid luminal pH shifts.
- Epithelial defense mechanisms are crucial for duodenal protection.
- Cellular ion transport plays a role in maintaining pH homeostasis.
Purpose of the Study:
- To investigate duodenal cellular ion transport during rapid luminal pH changes.
- To elucidate the role of specific ion transporters in duodenal epithelial defense.
- To understand the adaptive mechanisms protecting the duodenum from acid.
Main Methods:
- In vivo microscopy in anesthetized rats.
- Measurement of intracellular pH (pH(i)), mucus gel thickness, blood flow, and HCO secretion.
- Pharmacological inhibition of Na(+)/H(+) exchange (using DMA) and anion transport (using DIDS).
Main Results:
- Acid perfusion decreased pH(i) but increased mucus and blood flow; subsequent neutral perfusion caused pH(i) overshoot.
- A second acid challenge showed lessened pH(i) decrease (adaptation), linked to augmented cellular HCO uptake.
- DIDS, but not DMA, abolished pH(i) overshoot and adaptation, and reduced acid-enhanced HCO secretion.
Conclusions:
- Duodenal epithelial cells exhibit adaptive buffering power against rapid pH shifts, likely via Na(+)-HCO cotransport.
- This adaptation represents a novel and early protective mechanism for the duodenum.
- Anion transport inhibition (DIDS) significantly impairs these protective responses.
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