Linked Life Data

11948248

Source:http://linkedlifedata.com/resource/pubmed/id/11948248

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2002-4-11
pubmed:abstractText
Choline (Ch) is an essential nutrient as the biosynthetic precursor of acetylcholine (ACh) and phospholipids. Under resting conditions, the intracellular accumulation of Ch (above 10-fold), which is positively charged, is governed by the membrane potential and follows the Nernst equation. Accordingly, in synaptosomes from adult rats during depolarization, we observed a linear relationship between release of free cytoplasmic Ch and KCl concentration (2.7-120 mm). The K(+) -evoked Ch release was Ca(2+) -independent and did not originate from ACh or phospholipid hydrolysis. In superfused brain slices of adult rats, however, a K(+) -induced Ch efflux was absent. Also, under in vivo conditions, 30-60 mm KCl failed to increase the extracellular Ch level as shown by microdialysis in adult rat hippocampus. On the contrary, in brain slices from 1-week-old rats, high K(+) as well as 4-aminopyridine evoked a marked Ch efflux in a concentration-dependent fashion. This phenomenon faded within 1 week. Hemicholinium-3 (HC-3, 1 and 10 microm), a blocker of cellular choline uptake, caused a marked efflux of choline from adult rat slices but no or significantly less release from immature slices. We conclude that depolarization of synaptic endings causes a Ca(2+) -independent release of free cytoplasmic Ch into the extracellular space. In adult rat brain, this elevation of Ch is counteracted by a homeostatic mechanism such as uptake into brain cells.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-3042
pubmed:author
pubmed:issnType
Print
pubmed:volume
80
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
843-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
A homeostatic mechanism counteracting K(+) -evoked choline release in adult brain.
pubmed:affiliation
Department of Pharmacology, University of Mainz, Mainz, Germany. jklein@mail.uni-mainz.de
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't