Linked Life Data

1982459

Source:http://linkedlifedata.com/resource/pubmed/id/1982459

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1991-5-30
pubmed:abstractText
Glutamine synthetase (GS) activity in cultured rat astrocytes was measured in extracts and compared to the intracellular rate of glutamine synthesis by intact control astrocytes or astrocytes exposed to 1 mM 8-bromo-cAMP (8Br-cAMP) + 1 microM dexamethasone (DEX) for 4 days. GS activity in extracts of astrocytes treated with 8Br-cAMP + DEX was 7.5 times greater than the activity in extracts of control astrocytes. In contrast, the intracellular rate of glutamine synthesis by intact cells increased only 2-fold, suggesting that additional intracellular effectors regulate the expression of GS activity inside the intact cell. The rate of glutamine synthesis by astrocytes was 4.3 times greater in MEM than in HEPES buffered Hank's salts. Synthesis of glutamine by intact astrocytes cultured in MEM was independent of the external glutamine or ammonia concentrations but was increased by higher extracellular glutamate concentrations. In studies with intact astrocytes 80% of the original [U-14C]glutamate was recovered in the medium as radioactive glutamine, 2-3% as aspartate, and 7% as glutamate after 2 hours for both control and treated astrocytes. The results suggest: (1) astrocytes are highly efficient in the conversion of glutamate to glutamine; (2) induction of GS activity increases the rate of glutamate conversion to glutamine by astrocytes and the rate of glutamine release into the medium; (3) endogenous intracellular regulators of GS activity control the flux of glutamate through this enzymatic reaction; and (4) the composition of the medium alters the rate of glutamine synthesis from external glutamate.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0364-3190
pubmed:author
pubmed:issnType
Print
pubmed:volume
15
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1115-22
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Effect of 8-bromo-cAMP and dexamethasone on glutamate metabolism in rat astrocytes.
pubmed:affiliation
Department of Pediatrics, University of Maryland School of Medicine, Baltimore 21201.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.