Document Detail

Water permeability in the human amnion: pH regulation of the paracellular pathway.
MedLine Citation:
PMID:  2930789     Owner:  NLM     Status:  MEDLINE    
Human amnion was mounted, immediately after delivery, as a diaphragm between two lucite chambers and the net transepithelial water movement (Jw) was recorded minute by minute. When Jw was plotted against the applied transepithelial hydrostatic pressure (fetal side positive), in the absence of any other gradient, a linear relationship was observed (Phydr = 0.32 +/- 0.05 cm/s, n = 10). A linear relationship was also found when Jw was measured in the presence of an osmotic gradient, generated by adding (to the maternal side) different concentrations of poly(ethylene glycol) (Mr approximately equal to 3600; reflexion coefficient (sigma) = 1; Posm = 0.015 +/- 0.001 cm/s, n = 10). When sucrose, a paracellular marker, was used as the osmotic probe, the observed sigma was 0.5. Medium acidification in the presence of bicarbonate reduced in the same proportion both the hydrostatic and osmotic permeabilities. The effect was fully reversible, but was not observed when bicarbonate was replaced by Tris. To test the comparative role of transcellular versus paracellular paths, Jw and the [14C]sucrose permeability (Psuc) were simultaneously recorded minute by minute, in the presence of an osmotic or an hydrostatic gradient. In both cases, the percentage reductions in Jw and Psuc induced by medium acidification were similar. Quantification of theoretical and observed values for Jw and Psuc strongly suggests that effects of pH on both the osmotic and hydrostatic flux reflect a modification of the paracellular path.
M Porta; C Capurro; M Parisi
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  980     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1989 Apr 
Date Detail:
Created Date:  1989-05-23     Completed Date:  1989-05-23     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  220-4     Citation Subset:  IM    
Department of Physiology, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
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MeSH Terms
Amnion / metabolism*
Amniotic Fluid / physiology*
Bicarbonates / pharmacology
Biological Transport
Cell Membrane Permeability / drug effects
Homeostasis / drug effects
Hydrogen-Ion Concentration
Hydrostatic Pressure
Osmolar Concentration
Polyethylene Glycols / pharmacology
Water / metabolism*
Reg. No./Substance:
0/Bicarbonates; 0/Polyethylene Glycols; 7732-18-5/Water

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