Document Detail

Weak bases mimic the fertilization-associated chloride conductance increase and induce morphological changes in the cortex of Xenopus laevis eggs.
MedLine Citation:
PMID:  2469526     Owner:  NLM     Status:  MEDLINE    
Ammonia and other weak bases (methylamine, trimethylamine) including certain local anesthetics (benzocaine, procaine, lidocaine) depolarized the plasma membrane of unactivated Xenopus eggs. Exposure to different [Cl-]o or to the other halides (F-, Br-, I-) revealed a similar anion dependency of the weak base-induced conductance change to that found for the normal fertilization potential. Although transient, the induced depolarization was slower and of longer duration than the fertilization potential. Furthermore, [NH4+] greater than 40 mM elicited depolarizations of greater amplitude than the latter. In fertilized eggs, the amplitude of the induced depolarization decreased as the interval between fertilization potential and time of application of the NH4+ solution was increased. Treatment of unactivated eggs with NH4+ or procaine produced dramatic changes in the configuration of surface microvilli and thickening of the peripheral layer of cytoplasm. These effects were obtained only if the pH of the bathing solution was close to the pKa of the amine. This implicates intracellular pH, which would be expected to rise due to entry of the uncharged amine.
M Charbonneau
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Cell differentiation and development : the official journal of the International Society of Developmental Biologists     Volume:  26     ISSN:  0922-3371     ISO Abbreviation:  Cell Differ. Dev.     Publication Date:  1989 Jan 
Date Detail:
Created Date:  1989-06-16     Completed Date:  1989-06-16     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  8811335     Medline TA:  Cell Differ Dev     Country:  IRELAND    
Other Details:
Languages:  eng     Pagination:  39-51     Citation Subset:  IM    
Laboratoire de Biologie et Génétique du Développement, UA CNRS, 256, Université de Rennes I, France.
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MeSH Terms
Ammonia / pharmacology*
Benzocaine / pharmacology
Calcium / physiology
Cell Membrane Permeability / drug effects
Chlorides / metabolism,  pharmacokinetics*
Fertilization / drug effects*
Hydrogen-Ion Concentration
Ion Channels / metabolism
Lidocaine / pharmacology
Membrane Potentials / drug effects*
Methylamines / pharmacology
Microscopy, Electron
Microscopy, Electron, Scanning
Microvilli / drug effects,  ultrastructure
Oocytes / drug effects*,  ultrastructure
Procaine / pharmacology
Xenopus laevis / physiology*
Reg. No./Substance:
0/Chlorides; 0/Ion Channels; 0/Methylamines; 137-58-6/Lidocaine; 59-46-1/Procaine; 7440-70-2/Calcium; 75-50-3/trimethylamine; 7664-41-7/Ammonia; 94-09-7/Benzocaine

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

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