Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1989-8-11
pubmed:abstractText
High-affinity binding sites for platelet-activating-factor (PAF) have been identified in human polymorphonuclear leukocytes (PMNs). The aim of this investigation was to assess their functional relevance by characterizing PAF-induced elastase release, an enzyme present in azurophilic granules. At 37 degrees C, maximal release (measured with a spectrofluorimetric method) was achieved with 0.3 microM PAF. PAF analogs (e.g. lyso-PAF, 2-O-methyl-lyso-PAF) and enantio-PAF, which exhibit poor PAF-like activity in binding studies, were very weak releasers of elastase. The degranulation induced by PAF was fully and competitively inhibited by RP 59227, a potent, d-enantiomeric PAF antagonist. This effect was stereoselective and specific inasmuch as this compound was 500-fold more potent than its l-enantiomer and was devoid of effects on the degranulation promoted by N-formyl-l-methionyl-l-leucine-l-phenylalanine or [5S,12R]hydroxyeicosa-6,14-cis-8,10-trans-tetraenoic acid. The PAF-induced elastase extrusion was enhanced by physiological concentrations of CaCl2 and MgCl2. For instance, 1 mM Ca++ increased by 200% the release produced by 100 nM PAF. The mechanism of this effect is probably related to the capability of Ca++ and Mg++ to enhance the maximum number of [3H]PAF binding sites in whole or lysed PMNs without affecting the affinity (Kd) of the ligand. An additional possibility is that these ions intervene at the level of the signal transduction system leading to degranulation. For a series of 22 known PAF receptor antagonists, belonging to different chemical families, there was a strong correlation (r = 0.95) between their ability to displace [3H]PAF and to inhibit the PAF-evoked elastase release.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
250
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
293-300
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Evidence for the existence and ionic modulation of platelet-activating factor receptors mediating degranulatory responses in human polymorphonuclear leukocytes.
pubmed:affiliation
Rhone-Poulenc Sante, C.R.V., Vitry-Sur-Seine, France.
pubmed:publicationType
Journal Article, In Vitro