Linked Life Data

15923062

Source:http://linkedlifedata.com/resource/pubmed/id/15923062

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
2005-6-29
pubmed:abstractText
Bolus injection of [13N]ammonia into the femoral vein of pentobarbital-anesthetized rats was followed by rapid clearance from the blood and first-pass extraction of nearly 30% by the lungs. Of the label present in the lungs at 6 s after injection (about 27% of the dose), more than 20% was in metabolized form. Of the label present in the lungs at 2 min after injection (about 10% of the dose), 18-25% was in ammonia, about 75% was in glutamine (amide) and less than 1% was in glutamate and aspartate. Thus, despite the presence of significant amounts of glutamate dehydrogenase, the overwhelming route for metabolism of ammonia entering the rat lung in vivo was the glutamine synthetase reaction. Lung tissue that was removed 6 s after intravenous injection of [13N]ammonia and incubated in Krebs-Ringer glucose medium at 37 degrees C for 20 min, showed a significant increase (more than one-third), compared to unincubated lung tissue in the quantity of label in glutamine. Between 6s and 2 min after injection, during which time the total 13N content of the lungs decreased by more than 60%, the maintenance of a quasi-steady state in the concentration of labeled glutamine suggested a short-term balance between formation from extracted ammonia and loss of glutamine into the circulation. Our data support the concept that the lungs are a source of circulating glutamine in the rat. Despite the large fractional extraction of blood-borne [13N]ammonia by the lungs, only minute amounts of tracer (0.2-0.6 ppm of the injected dose) were detected in the expired air within the first 5 min after administration of [13N]ammonia to anesthetized rats, so that pulmonary excretion was not a significant pathway of ammonia elimination. The present findings emphasize the importance of the lungs in the maintenance of whole-body nitrogen homeostasis and suggest the use of [13N]ammonia and 13N-labeled amino acids as non-invasive probes in the study of normal and diseased lung metabolism.
pubmed:grant
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0197-0186
pubmed:author
pubmed:issnType
Print
pubmed:volume
47
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
103-18
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2005
pubmed:articleTitle
Metabolism of [13N]ammonia in rat lung.
pubmed:affiliation
Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021, USA. acooper@Burke.org
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, N.I.H., Extramural