Document Detail

Mechanism of cAMP-induced H(+)-efflux of Dictyostelium cells: a role for fatty acids.
MedLine Citation:
PMID:  11022225     Owner:  NLM     Status:  MEDLINE    
Aggregating Dictyostelium cells release protons when stimulated with cAMP. To find out whether the protons are generated by acidic vesicles or in the cytosol, we permeabilized the cells and found that this did not alter the cAMP-response. Proton efflux in intact cells was inhibited by preincubation with the V-type H(+) ATPase inhibitor concanamycin A and with the plasma membrane H(+) ATPase blocker miconazole. Surprisingly, miconazole also inhibited efflux in permeabilized cells, indicating that this type of H(+) ATPase is present on intracellular vesicles as well. Vesicular acidification was inhibited by miconazole and by concanamycin A, suggesting that the acidic vesicles contain both V-type and P-type H(+) ATPases. Moreover, concanamycin A and miconazole acted in concert, both in intact cells and in vesicles. The mechanism of cAMP-induced Ca2(+)-fluxes involves phospholipase A2 activity. Fatty acids circumvent the plasma membrane and stimulate vesicular Ca2(+)-efflux. Here we show that arachidonic acid elicited H(+)-efflux not only from intact cells but also from acidic vesicles. The target of regulation by arachidonic acid seemed to be the vesicular Ca2(+)-release channel.
H Flaadt; R Schaloske; D Malchow
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of biosciences     Volume:  25     ISSN:  0250-5991     ISO Abbreviation:  J. Biosci.     Publication Date:  2000 Sep 
Date Detail:
Created Date:  2000-11-27     Completed Date:  2000-11-27     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8100809     Medline TA:  J Biosci     Country:  INDIA    
Other Details:
Languages:  eng     Pagination:  243-52     Citation Subset:  IM    
Faculty of Biology, University of Konstanz, D-78457 Konstanz, Germany.
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MeSH Terms
4-Chloro-7-nitrobenzofurazan / pharmacology
Anti-Bacterial Agents / pharmacology
Arachidonic Acid / pharmacology
Calcium Signaling / drug effects,  physiology*
Cyclic AMP / physiology*
Dictyostelium / cytology,  metabolism*
Fatty Acids / physiology*
Filipin / pharmacology
Hydrogen / metabolism*
Hydrogen-Ion Concentration
Ion Transport / drug effects
Membrane Proteins / antagonists & inhibitors,  physiology*
Miconazole / pharmacology
Models, Biological
Organelles / drug effects,  metabolism*
Phospholipases A / physiology
Phospholipases A2
Proton-Translocating ATPases / antagonists & inhibitors,  physiology*
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Fatty Acids; 0/Macrolides; 0/Membrane Proteins; 0/Protons; 10199-89-0/4-Chloro-7-nitrobenzofurazan; 1333-74-0/Hydrogen; 22916-47-8/Miconazole; 480-49-9/Filipin; 506-32-1/Arachidonic Acid; 60-92-4/Cyclic AMP; 80890-47-7/concanamycin A; EC 3.1.1.-/Phospholipases A; EC A2; EC ATPases

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

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