Document Detail


Inositol phosphate structural requisites for Ca2+ influx.
MedLine Citation:
PMID:  7611369     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
To understand how inositol phosphates (InsP) cause Ca2+ influx, we injected 37 highly purified compounds containing a total of 49 InsP positional isomers into Xenopus oocytes. The eight InsP that stimulated Ca2+ influx were those that had the highest potency at releasing intracellular Ca2+, indicating that their common target was the inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptor. To cause Ca2+ influx, these InsP had to be injected in a much higher concentration than the minimal concentration required to release intracellular Ca2+. Such high InsP concentrations could inhibit ongoing oscillatory intracellular Ca2+ release. In addition, we found that InsPs could not elicit further intracellular Ca2+ release during the course of Ca2+ influx. Our data are consistent with the "capacitative Ca2+ entry" hypothesis, which states that InsP stimulate Ca2+ influx by depleting the InsP-sensitive intracellular Ca2+ store. In this context, we would suggest that to deplete the InsP-sensitive intracellular Ca2+ store, InsP may have to be present in a sufficiently high concentration to override the oscillatory Ca(2+)-refilling mechanisms of the stores.
Authors:
S DeLisle; G W Mayr; M J Welsh
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  268     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-08-15     Completed Date:  1995-08-15     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  C1485-91     Citation Subset:  IM    
Affiliation:
Veterans Affairs Medical Center, Iowa City, Iowa, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Calcium / metabolism*
Female
Inositol Phosphates / chemistry,  pharmacology*
Manganese / pharmacology
Oocytes / drug effects,  physiology*
Structure-Activity Relationship
Xenopus
Chemical
Reg. No./Substance:
0/Inositol Phosphates; 7439-96-5/Manganese; 7440-70-2/Calcium

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


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