Related Experiment Videos
Electrogenic Ca2+ entry in the rat colonic epithelium.
M Frings1, G Schultheiss, M Diener
1Institut für Veterinär-Physiologie, Justus-Liebig-Universität Giessen, Germany.
Pflugers Archiv : European Journal of Physiology
|January 29, 2000
Summary
Researchers found that a non-selective cation channel in rat colonic crypts is activated by calcium signaling. Blocking this channel affects electrolyte transport, suggesting its role in regulating colonic function.
Area of Science:
- Physiology
- Cell Biology
- Gastroenterology
Background:
- Capacitative calcium entry plays a role in cellular signaling.
- Colonic crypts are crucial for electrolyte and fluid absorption.
- Muscarinic receptor stimulation influences colonic function.
Purpose of the Study:
- To investigate the role of non-selective cation channels in rat colonic crypts.
- To determine the involvement of these channels in calcium signaling and electrolyte transport.
Main Methods:
- Whole-cell patch-clamp electrophysiology on isolated rat colonic crypts.
- Manipulation of intracellular calcium buffering and muscarinic receptor stimulation.
- Fura-2 imaging and Ussing chamber experiments to assess ion transport.
Main Results:
- Dialysis with high calcium buffers induced capacitative calcium entry.
- Blockers of non-selective cation channels (Flufe-namate, La3+, Gd3+) hyperpolarized cells and reduced membrane current.
- This current showed selectivity for Na+ over Ca2+, with Ca2+ inhibiting it at higher concentrations.
- Carbachol (cholinergic agonist) induced a transient hyperpolarization and increased outward current, which was sensitive to La3+.
- La3+ inhibited carbachol-induced intracellular calcium increase and chloride secretion.
Conclusions:
- A non-selective cation conductance, activated by store depletion, is present in rat colonic crypts.
- This conductance is involved in regulating electrolyte transport stimulated by calcium signaling pathways.
- These findings contribute to understanding colonic ion transport mechanisms.