Permissive role of cAMP in the oscillatory Ca2+ response to inositol 1,4,5-trisphosphate in rat hepatocytes

Détails

ID Serval
serval:BIB_2FF7ED2C5177
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Permissive role of cAMP in the oscillatory Ca2+ response to inositol 1,4,5-trisphosphate in rat hepatocytes
Périodique
Biochemical Journal
Auteur(s)
Chatton  J. Y., Cao  Y., Liu  H., Stucki  J. W.
ISSN
0264-6021 (Print)
Statut éditorial
Publié
Date de publication
03/1998
Volume
330
Numéro
3
Pages
1411-1416
Notes
Journal Article Research Support, Non-U.S. Gov't --- Old month value: Mar 15
Résumé
Rat hepatocytes respond to alpha-adrenergic stimulation by intracellular production of myo-inositol 1,4,5-trisphosphate (IP3) which stimulates the periodic release and reuptake of intracellular store (IS) Ca2+. The generation of these Ca2+ oscillations was investigated by simultaneously monitoring Ca2+ changes in the cytosol and IS by combined fluorescence microscopy and whole-cell patch clamp. Intracellular IP3 perfusion (1-50 microM in the pipette) produced three types of Ca2+ response: understimulation, oscillations and overstimulation, i.e. with Ca2+ levels not returning to baseline. In a total of 57 experiments, only three displayed oscillations during continuous IP3 infusion, in a narrow range of IP3 concentration centred around 5-8 microM in the pipette. In oscillating cells, cytosolic Ca2+ spikes were synchronized with transient Ca2+ depletions of the IS, consistent with a direct exchange of Ca2+ between the two compartments. Application of 8-Br-cAMP to cells infused with IP3 increased the probability of eliciting Ca2+ oscillations by a factor of 4-5 for IP3 concentrations in the range 1-10 microM, whereas IP3 concentrations above 10 microM always resulted in overstimulation. IP3 photorelease experiments and measurements of IS Ca2+ content indicated that 8-Br-cAMP enhanced the affinity of the IP3 receptor and increased the pool of releasable Ca2+. We propose that cAMP has a permissive role in the generation of IP3-induced Ca2+ oscillations by extending the window of IP3 concentrations able to elicit oscillations.
Mots-clé
8-Bromo Cyclic Adenosine Monophosphate/*pharmacology Animals Calcium/*metabolism Cells, Cultured Cyclic AMP/*metabolism Cyclic AMP-Dependent Protein Kinases/metabolism Inositol 1,4,5-Trisphosphate/*pharmacology Kinetics Liver/drug effects/*metabolism Male Oscillometry Rats Rats, Wistar
Pubmed
Web of science
Création de la notice
24/01/2008 13:08
Dernière modification de la notice
20/08/2019 13:14
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