Linked Life Data

6778992

Source:http://linkedlifedata.com/resource/pubmed/id/6778992

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1981-3-24
pubmed:abstractText
1. The ability of intraterminal organelles to sequester calcium and buffer the cytoplasmic free Ca2+ concentration ([Ca2+]i) has been investigated in isolated mammalian presynaptic nerve terminals (synaptosomes). A combination of biochemical and morphological methods has been used. 2. When the plasmalemma of synaptosomes is disrupted by osmotic shock or saponin, Ca from the medium can be sequestered by two types of intraterminal organelles in the presence of ATP. 2. Typical mitochondrial poisons (e.g., oligomycin, azide and 2,4-dinitrophenol) block the Ca uptake into one type of organelle (mitochondria); the second type of organelle, which has a higher affinity for Ca (half-saturation congruent to 0.35 microM Ca2+) is spared by the mitochondrial poisons. 4. When the "leaky" synaptosomes are incubated in media containing oxalate, and then fixed and prepared for electron microscopy, electron-dense deposits are observed in the intraterminal mitochondria and smooth endoplasmic reticulum (SER). Mitochondrial poisons block the formation of the deposits in the mitochondria, but spare the SER. 5. X-ray microprobe analysis demonstrates that these deposits contain Ca. 6. Experiments with the Ca-sensitive metallochromic indicator, arsenazo III, demonstrate that the intraterminal organelles in the "leaky" synaptosomes can buffer Ca2+ in the medium to below 5 X 10(-7) M. With small (physiological) Ca loads, the Ca2+ is effectively buffered (to < 5 X 10(-7) M) even in the presence of mitochondrial poisons. 7. The data indicate that the SER in presynaptic terminals may play an important role in helping to buffer the Ca that normally enters during neuronal activity.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-7948
pubmed:author
pubmed:issnType
Print
pubmed:volume
76
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
459-70
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1980
pubmed:articleTitle
How is the cytoplasmic calcium concentration controlled in nerve terminals?
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't