Abstract | BACKGROUND: Experimental cholelithiasis is associated with elevated biliary calcium concentration and altered gallbladder absorption. Recent studies showed that extracellular calcium ([Ca2+]ec) plays a role in regulating gallbladder ion transport. The extent to which intracellular calcium ([Ca2+]ic) mediates the changes in gallbladder ion transport is not clear. We hypothesize that [Ca2+]ic is an important regulator of gallbladder ion transport. METHODS: Prairie dog gallbladders were mounted in Ussing chambers, standard electrophysiologic parameters were recorded, and unidirectional Na+, Cl- and H2O fluxes were measured before and after mucosal exposure of 10-5 mol/L calcium ionophore A23187 was performed. RESULTS:
A23187 caused an increase in transepithelial short-circuit current and potential difference and a decrease in transepithelial resistance. A23187 inhibited mucosa to serosa Cl- flux and stimulated serosa to mucosa Na+ flux, resulting in increased net Cl- secretion and decreased net Na+ absorption. A23187 converted H2O from absorption to secretion. Transepithelial short-circuit current effect of A23187 was delayed by indomethacin pretreatment and was completely blunted by low bathing Ca2+. CONCLUSIONS: This is the first demonstration that increased [Ca2+]ic converts the gallbladder from its normal absorptive state to a secretory one. Furthermore [Ca2+]ic appears to regulate ion transport through mechanisms that are partially prostaglandin-dependent. Studies are necessitated to define possible links between gallbladder secretion of Cl- and H2O and mucus hypersecretion, a well-described phenomenon associated with cholesterol gallstone formation.
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Authors | A J Moser, M Z Abedin, J A Cates, D I Giurgiu, J A Karam, J J Roslyn |
Journal | Surgery
(Surgery)
Vol. 119
Issue 4
Pg. 410-6
(Apr 1996)
ISSN: 0039-6060 [Print] United States |
PMID | 8644006
(Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
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Chemical References |
- Chlorides
- Calcimycin
- Sodium
- Cyclic AMP
- Calcium
- Indomethacin
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Topics |
- Animals
- Calcimycin
(pharmacology)
- Calcium
(physiology)
- Chlorides
(metabolism)
- Cholelithiasis
(metabolism)
- Cyclic AMP
(physiology)
- Dogs
- Gallbladder
(metabolism)
- Indomethacin
(pharmacology)
- Male
- Sodium
(metabolism)
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