Paracellular back-diffusion of H+ across bullfrog fundic mucosa resulting from Ca2+ depletion and its effects on taurocholate-induced mucosal injury

J G Allison; J J Cullen

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Journal article

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Paracellular back-diffusion of H+ across bullfrog fundic mucosa resulting from Ca2+ depletion and its effects on taurocholate-induced mucosal injury

J G Allison and J J Cullen

The American surgeon, Vol.52(4), pp.226-232

04/1986

PMID: 3082267

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Abstract

The effects of calcium depletion (by washout and by chelation with EDTA) on the net appearance of hydrogen ions (H+) on the secretory surface of in vitro sheets of bullfrog fundic mucosa have been studied. A CO2 distribution method was used to distinguish between true and apparent inhibition of H+ secretion. Our data indicate that Ca2+ depletion produces apparent inhibition of H+ secretion by increasing paracellular back-diffusion of H+ across the mucosa. Ca2+ washout resulted in a decrement of measurable H+ (1.42 +/- 0.07 to 0.93 +/- 0.09 muEq/cm2 hr-1, P less than 0.05) without altering delta CO2 (1.18 +/- 0.15 to 1.26 +/- 0.17 muEq/cm2 hr-1, not significant). Chelation of Ca2+ with EDTA produced a similar decrease in H+ (1.61 +/- 0.09 to 0.78 +/- 0.12 muEq/cm2 hr-1, P less than 0.05) without affecting delta CO2 (1.60 +/- 0.13 to 1.68 +/- 0.22 muEq/cm2 hr-1, not significant). The possibility that H+ back-diffusion (induced by Ca2+ depletion) via a paracellular shunt might ameliorate injury was examined in bullfrog fundic mucosa exposed to a bile salt. H+ secretion, potential difference, resistance, and ultrastructural changes were studied in isolated mucosal sheets treated with 10 mM sodium taurocholate with or without Ca2+ depletion. Measurable H+, potential difference, and resistance were significantly lower in the Ca2+ depleted tissues. Scanning electron microscopy revealed identical changes in the surface epithelial cells of both depleted and nondepleted mucosae, but there was significantly less cell loss from depleted mucosae (P less than 0.05).

Taurocholic Acid - pharmacology

Microscopy, Electron, Scanning

Carbon Dioxide - metabolism

Gastric Fundus - drug effects

Calcium - metabolism

Hydrogen - secretion

Edetic Acid

Gastric Mucosa - metabolism

Gastric Mucosa - ultrastructure

Animals

Gastric Mucosa - secretion

Gastric Mucosa - drug effects

Bicarbonates - metabolism

Gastric Fundus - secretion

Gastric Fundus - ultrastructure

Bile Acids and Salts - physiology

Diffusion

Gastric Fundus - metabolism

Rana catesbeiana

Hydrogen - metabolism

Details

Title: Subtitle: Paracellular back-diffusion of H+ across bullfrog fundic mucosa resulting from Ca2+ depletion and its effects on taurocholate-induced mucosal injury
Creators: J G Allison
J J Cullen
Resource Type: Journal article
Publication Details: The American surgeon, Vol.52(4), pp.226-232
Publisher: United States
PMID: 3082267
ISSN: 0003-1348
eISSN: 1555-9823
Language: English
Date published: 04/1986
Academic Unit: Surgery; Radiation Oncology
Record Identifier: 9984051551302771

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