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Taurine transport by rat intestine
J A Barnard1, S Thaxter, K Kikuchi
1Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee 37232.
The American Journal of Physiology
|March 1, 1988
Summary
Rat jejunal transport of taurine involves a high-affinity, sodium-dependent carrier mechanism in the brush-border membrane. This electrogenic process is influenced by chloride ions and exhibits an overshoot phenomenon.
Area of Science:
- Gastroenterology
- Molecular Biology
- Physiology
Background:
- Taurine is a vital amino acid with diverse physiological roles.
- Understanding its intestinal absorption is crucial for nutritional and metabolic research.
Purpose of the Study:
- To investigate the mechanism of taurine transport across the rat jejunal brush-border membrane.
- To characterize the kinetic and energetic properties of this transport system.
Main Methods:
- Utilized rat jejunal brush-border membrane vesicles and everted jejunal sacs.
- Assessed taurine uptake under varying sodium (Na+) and potassium (K+) gradients.
- Employed kinetic analysis (Woolf-Hofstee equation) and electrophysiological techniques.
Main Results:
- Demonstrated Na+-dependent, carrier-mediated taurine uptake with high affinity (Km = 25 ± 9 μM).
- Observed a significant "overshoot" phenomenon, indicating active transport.
- Showed that chloride (Cl-) enhanced Na+-supported uptake, and hypotaurine inhibited transport.
Conclusions:
- Confirmed a high-affinity, electrogenic, Na+-gradient-driven taurine transporter at the rat jejunal brush border.
- Highlighted the modulatory role of chloride and the specificity of the transporter.