Linked Life Data

1846904

Source:http://linkedlifedata.com/resource/pubmed/id/1846904

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-3-8
pubmed:abstractText
It has long been known that intracellular cAMP inhibits and cGMP enhances intact neutrophil function. However, these effects are modest and require relatively high concentrations of the cyclic nucleotides. We decided to re-examine the effects of cyclic nucleotides on Ca2(+)-induced secretion by electroporated cells. This system allowed us to bypass normal cell surface receptor-ligand interactions as well as to directly expose the intracellular space to native cyclic nucleotides. We found that concentrations of cAMP as low as 3 microM inhibited Ca2(+)-induced secretion; 30-300 microM cAMP was maximally inhibitory. cAMP was actually slightly more potent than dibutyryl cAMP, a membrane-permeant derivative. In contrast, cGMP was only slightly stimulatory at 3 microM and modestly inhibitory at 300 microM; dibutyryl cGMP was ineffective. A more detailed investigation of the effects of cAMP showed that inhibition was only obtained in the presence of Mg2+. Half-maximal inhibition by cAMP occurred at 10-30 microM. Inhibition by cAMP was achieved by shifting the Ca2+ dose-response curve for secretion to the right; this was observed for the release of both specific granules (vitamin B12 binding protein) and azurophil granules (B-glucuronidase). We previously showed that ATP could enhance Ca2(+)-induced secretion in the presence of Mg2+, apparently by interacting with a cell surface purine receptor. However, increasing concentrations of ATP could not overcome inhibition by cAMP; this suggested that cAMP acted at some site other than the purine receptor. Inhibition by cAMP was also less apparent in the presence of the protein kinase C agonist phorbol myristate acetate (PMA), suggesting that the cyclic nucleotide did not produce systemic desensitization of the neutrophils. In summary, these results demonstrate that low, physiologically relevant concentrations of cAMP can modulate neutrophil responsiveness.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0741-5400
pubmed:author
pubmed:issnType
Print
pubmed:volume
49
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
172-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Cyclic AMP inhibits secretion from electroporated human neutrophils.
pubmed:affiliation
Department of Pediatric Hematology/Oncology, University of Michigan Medical Center, Ann Arbor.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.