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pH-dependent fluoride transport in intestinal brush border membrane vesicles
H He1, V Ganapathy, C M Isales
1Department of Oral Biology-Physiology, Medical College of Georgia, Augusta, GA 30912-1129, USA.
Biochimica Et Biophysica Acta
|July 24, 1998
Summary
Fluoride absorption in rabbit intestines is pH-dependent, suggesting a carrier-mediated process. This study indicates fluoride (F) transport involves proton (H+) cotransport or hydroxyl (OH-) exchange across intestinal membranes.
Area of Science:
- Physiology
- Biochemistry
- Gastroenterology
Background:
- Fluoride (F) absorption across various epithelia is pH-dependent, leading to the hypothesis of undissociated hydrofluoric acid (HF) transport.
- Recent studies suggest F absorption in the rat small intestine may be pH-insensitive, challenging the HF hypothesis.
Purpose of the Study:
- To investigate the mechanism of fluoride uptake by rabbit intestinal brush border membrane vesicles (BBMV).
- To determine the role of proton gradients and specific transport pathways in F absorption.
Main Methods:
- Utilized rabbit intestinal BBMV to study F uptake under varying pH gradients.
- Employed inhibitors like DIDS, DEP, diBAC, and PCMBS to probe transport mechanisms.
- Investigated the effect of chloride and nitrate ions on F uptake.
Main Results:
- F uptake by BBMV was rapid and showed an overshoot only with an inward-directed proton gradient.
- PCMBS significantly inhibited F uptake, while DIDS and DEP showed partial inhibition.
- Chloride and nitrate ions partially inhibited F uptake compared to control conditions.
Conclusions:
- Fluoride transport across the rabbit intestinal BBMV is a carrier-mediated process.
- The transport mechanism likely involves cotransport of F with H+ or exchange with OH-.
- Inhibitor effects suggest specific interactions with the F transport carrier.