Linked Life Data

6773574

Source:http://linkedlifedata.com/resource/pubmed/id/6773574

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1980-11-24
pubmed:abstractText
The particulate fraction from osmotically shocked synaptosomes ('synaptosomal membrances') sequesters Ca when incubated with ATP]containing solutions. This net accumulation of Ca can reduce the free [Ca2+] of the bathing medium to sub-micromolar levels (measured with arsenazo III). Two distinct types of Ca sequestration site are responsible for the Ca2+ buffering. One site, presumed to be smooth endoplasmic reticulum, operates at low [Ca2+] (less than 1 microM), and has a relatively small capacity. Ca sequestration at this site is prevented by the Ca2+ ionophore, A-23187, but not by mitochondrial poisons. The secone (mitochondrial) site, in contrast, is blocked by the mitochondrial uncoupler carbonyl cyanide p-trifluoromethoxyphenylhydrazone, and oligomycin. Since the intraterminal organelles can buffer [Ca2+] to about 0.3-0.5 microM, this may be an upper limit to the normal resting level of [Ca2+]i in nerve terminals. In the steady state, total cell Ca and [Ca2+]i will be governed principally be Ca transport mechanisms in the plasmalemma; the intracellular organelle transport systems then operate in equilibrium with this [Ca2+]. During activity, however, Ca rapidly enters the terminals and [Ca2+]i rises. The intracellular buffering mechanisms then come into play and help to return [Ca2+]i toward the resting level; the non-mitochondrial Ca sequestration mechanism probably plays the major role in this Ca buffering.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
600
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
912-21
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1980
pubmed:articleTitle
Calcium buffering in presynaptic nerve terminals. Free calcium levels measured with arsenazo III.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.