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Cytosolic Calcium Measurements in Renal Epithelial Cells by Flow Cytometry
Published on: October 28, 2014
Ursodeoxycholate increases cytosolic calcium concentration and activates Cl- currents in a biliary cell line
G H Shimokura1, J M McGill, T Schlenker
1Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
Gastroenterology
|September 1, 1995
Summary
Ursodeoxycholate (UDC) increases intracellular calcium and stimulates chloride efflux in biliary cells. This suggests UDC may enhance bile flow and benefit cystic fibrosis patients.
Area of Science:
- Hepatobiliary physiology
- Cellular signaling
- Ion transport
Background:
- Ursodeoxycholate (UDC) is known to stimulate bicarbonate-rich choleresis.
- The precise cellular mechanisms underlying UDC's choleretic effect are not fully understood.
- Ductular secretion contributes to increased biliary bicarbonate concentration.
Purpose of the Study:
- To investigate the direct effects of Ursodeoxycholate (UDC) on biliary duct cells.
- To measure intracellular calcium concentration ([Ca2+]i) and membrane chloride (Cl-) permeability in response to UDC.
- To utilize Mz-ChA-1 human cholangiocarcinoma cells as a model system.
Main Methods:
- Intracellular calcium levels ([Ca2+]i) were quantified using fura-2 fluorescence.
- Membrane chloride (Cl-) permeability was assessed via 125I efflux assays in cell monolayers.
- Whole-cell patch clamp techniques were employed to evaluate ion currents in individual cells.
Main Results:
- Exposure to Ursodeoxycholate (UDC) significantly increased intracellular calcium ([Ca2+]i) via release from intracellular stores.
- UDC stimulated 125I efflux, indicating enhanced membrane chloride (Cl-) permeability.
- Both extracellular and intracellular UDC activated chloride (Cl-) currents, with intracellular UDC showing a marked increase in current density.
Conclusions:
- Pharmacological concentrations of Ursodeoxycholate (UDC) increase intracellular calcium ([Ca2+]i) and stimulate chloride (Cl-) efflux by opening Cl- channels in biliary cells.
- UDC may enhance bile flow through direct stimulation of ductular secretion.
- UDC holds potential therapeutic value for cystic fibrosis patients with impaired cAMP-dependent biliary secretion.
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