Platelet-activating factor stimulates receptor-mediated formation of reactive oxygen intermediates in human monocytes.
Stimulation of production of reactive oxygen intermediates (ROI) was examined in human peripheral blood monocytes by luminol-dependent chemiluminescence. The dose-response curve characterizing the dependence of ROI production on the concentration of platelet-activating factor (PAF) showed that stimulation occurred within a concentration range of 2 x 10(-9)M to 5 x 10(-6)M. Transformation of the dose-response curve to an Eadie-Hofstee plot indicated that the process is characterized by two Km values. The Km value corresponding to the high-affinity branch of the curve is 1.3 +/- 0.14 nM. In the same cells, the dissociation constant for the [3H]PAF/receptor complex was determined. The Kd value was 0.8 +/- 0.1 nM, which agreed quite well with the high-affinity Km value obtained in the Eadie-Hofstee plot. The data indicate that stimulation of ROI generation is mediated through PAF binding at specific receptor sites at nanomolar PAF concentrations. Along with the specific receptor-mediated ROI generation, a nonspecific effect of PAF at a high concentration was demonstrated.
Pustynnikov
M G
MG
Research Center of Molecular Diagnostics, USSR Ministry of Health, Moscow.
Porodenko
N V
NV
Makarova
O V
OV
Kozyukov
A V
AV
Moskaleva EYu
Sokolovsky
A A
AA
Severin
E S
ES
D002478:Cells, Cultured; D006801:Humans; D008163:Luminescent Measurements; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D010100:Oxygen / Q000097:blood*; D010972:Platelet Activating Factor / Q000378:metabolism / Q000494:pharmacology*; D010980:Platelet Membrane Glycoproteins; D011869:Radioligand Assay; D011956:Receptors, Cell Surface / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D013482:Superoxide Dismutase / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; D013482:Superoxide Dismutase; D013755:Tetradecanoylphorbol Acetate; D010100:Oxygen