Document Detail

Ca2+ uptake to purified secretory vesicles from bovine neurohypophyses.
MedLine Citation:
PMID:  6838868     Owner:  NLM     Status:  MEDLINE    
Purified secretory vesicles isolated from bovine neurohypophyses were found to take up Ca2+ when incubated at 30 degrees C in media containing 10(-7) to 10(-4) M free Ca2+. At 10(-4) free Ca2+ 19 nmol/mg protein were taken up within 30 min. The initial uptake at this Ca2+ concentration was about 2 nmol/mg protein per min. The uptake of Ca2+ to secretory vesicles was not affected by ATP, oligomycin, ruthenium red, trifluoperazine, Mg2+ or K+, but was inhibited by Na+ and Sr2+. From these characteristics it can be concluded that the uptake system does not utilize directly ATP (as the Ca2+-ATPases known to be present in the cell membrane and the endoplasmic reticulum) and is different from the mitochondrial Ca2+ uptake system driven by respiration and/or ATP hydrolysis. However, Ca2+-Na+ exchange may well operate: In experiments using different concentrations of Na+ we found half-maximal inhibition of Ca2+ uptake with 33.3 mM Na+. An analysis of the data in a Hill plot indicated that at least 2 Na+ would be exchanged for 1 Ca2+. Also, it was found that Ca2+ previously taken up could be released again by external Na+ but not by K+.
T Saermark; H I Krieger-Brauer; N A Thorn; M Gratzl
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  727     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1983 Jan 
Date Detail:
Created Date:  1983-06-10     Completed Date:  1983-06-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  239-45     Citation Subset:  IM    
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MeSH Terms
Biological Transport, Active / drug effects
Calcium / metabolism*
Cytoplasmic Granules / metabolism*
Lithium / pharmacology
Neurosecretory Systems / metabolism
Oxytocin / analysis
Pituitary Gland, Posterior / metabolism*
Potassium / pharmacology
Sodium / pharmacology
Vasopressins / analysis
Reg. No./Substance:
11000-17-2/Vasopressins; 50-56-6/Oxytocin; 7439-93-2/Lithium; 7440-09-7/Potassium; 7440-23-5/Sodium; 7440-70-2/Calcium

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