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Novel choline transport characteristics in Caco-2 cells
A P Crowe1, P R Lockman, T J Abbruscato
1Division of Health Sciences, School of Pharmacy, Curtin University of Technology, Perth, Western Australia 6845.
Drug Development and Industrial Pharmacy
|September 19, 2002
Summary
Choline transport across Caco-2 cells is active, pH- and calcium-dependent, and differs from established models. This study characterizes its unique properties for better understanding nutrient absorption.
Area of Science:
- Cell biology
- Biochemistry
- Physiology
Background:
- Choline transport involves sodium-dependent and independent mechanisms with varying affinities.
- Understanding these mechanisms is crucial for nutrient absorption and cellular function.
- The blood-brain barrier exhibits unique sodium-independent choline transport.
Purpose of the Study:
- To characterize choline transport across Caco-2 cell monolayers.
- To determine the affinity, capacity, and inhibition patterns of this transport.
- To compare Caco-2 choline transport to known models.
Main Methods:
- Choline transport was measured in both apical-to-basal and basal-to-apical directions across Caco-2 monolayers.
- Calcium dependence and inhibition by specific agents were assessed.
- Apparent permeability coefficients were calculated using established methods.
Main Results:
- Apical-to-basal permeability (11.11 x 10(-6) cm/sec) was significantly higher than basal-to-apical (5.55 x 10(-6) cm/sec), indicating active transport.
- Choline transport was inhibited by nifedipine (82%), verapamil (80%), EGTA (36%), and cyclosporin (15%).
- Cellular association of choline was 21.3%.
Conclusions:
- Choline transport across Caco-2 cells is an active, pH- and calcium-dependent process.
- This transport system exhibits unique characteristics distinct from traditional choline transport models.
- Findings provide insights into intestinal choline absorption mechanisms.