Document Detail


The paracellular pathway in the lepidopteran larval midgut: modulation by intracellular mediators.
MedLine Citation:
PMID:  16765075     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The features of the paracellular pathway, an important route for the transfer of ions and molecules in epithelia, are in insects still poorly investigated and it has not yet been elucidated how the septate junction (SJ) acts as a transepithelial barrier. In this study, some properties of the paracellular pathway of Bombyx mori larval midgut, isolated in Ussing chambers, were determined and the modulation of SJ permeability by intracellular events disclosed. Diffusion potentials evoked by transepithelial gradients of different salts indicated that the junction bore weak negative charges and that the paracellular pathway was selective with respect to ion charge and size. In standard conditions, the transepithelial resistance was 28.2+/-2.1 Omega cm(2), a value indicating that the midgut is a low resistance epithelium. The modulation of midgut SJ by typical enhancers of mammalian tight junction permeability known to act on the cytoskeleton was studied by measuring the shunt resistance and the lumen-to-haemolymph flux of sucrose. An increase of the intracellular level of cAMP and Ca(2+) caused a significant decrease of the shunt resistance and an increase of SJ permeability. The attenuation of Ca(2+) effect in the presence of the calcium channel blocker nifedipine indicated that the influx of external Ca(2+) into the cytoplasm was important for the opening of the SJ, as well as the release of Ca(2+) from the intracellular stores.
Authors:
L Fiandra; M Casartelli; B Giordana
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-04-28
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  144     ISSN:  1095-6433     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2006 Aug 
Date Detail:
Created Date:  2006-07-10     Completed Date:  2006-09-25     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  464-73     Citation Subset:  IM    
Affiliation:
Department of Biology, University of Milan, Via Celoria 26, 20133 Milano, Italy. luisa.fiandra1@unimi.it
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MeSH Terms
Descriptor/Qualifier:
Adenosine Diphosphate / analysis
Animals
Biological Transport / drug effects
Bombyx / growth & development,  physiology*
Bucladesine / pharmacology
Calcium / analysis,  metabolism*,  pharmacology
Calcium Channel Blockers / pharmacology
Cytochalasins / pharmacology
Epithelial Cells / drug effects,  physiology*
Evoked Potentials
Intercellular Junctions / drug effects,  physiology*
Intestines / drug effects,  physiology*
Ions / metabolism
Larva / physiology
Nifedipine / pharmacology
Permeability
Potassium Chloride / pharmacology
Sodium Chloride / pharmacology
Sucrose / metabolism
Chemical
Reg. No./Substance:
0/Calcium Channel Blockers; 0/Cytochalasins; 0/Ions; 21829-25-4/Nifedipine; 362-74-3/Bucladesine; 57-50-1/Sucrose; 58-64-0/Adenosine Diphosphate; 7440-70-2/Calcium; 7447-40-7/Potassium Chloride; 7647-14-5/Sodium Chloride

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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