ABSTRACT
<p><b>OBJECTIVE</b>To observe the platelet activating factor (PAF) antagonistic effect of kaempferol.</p><p><b>METHOD</b>The specific binding of [3H] PAF to rabbit platelet receptor was investigatedwith radio ligand binding assay (RLBA). Platelet adhesion induced by PAF was measured with spectrophotometry. The elevation of inner free calcium concentration in rabbit polymorphonuclear leukocytes (PMNs) induced by PAF was determined with Fura-2 fluorescent technique.</p><p><b>RESULT</b>The 1, 2 or 4 nmol x L(-1) [3H]PAF specific binding to rabbit platelet receptor was inhibited by Kae dosage dependently and the IC50 were 30.8, 74.6 and 92.0 micro mol x L(-1), respectively. The PAF induced reactions of rabbit platelet adhesion and PMNs inner free calcium concentration elevation were inhibited by Kae in a dose-dependent manner. The IC50 of Kae to inhibit platelet adhesion was 65 micromol x L(-1).</p><p><b>CONCLUSION</b>Kae is effective in inhibiting the action of PAF and it is a new PAF receptor antagonist.</p>
Subject(s)
Animals , Male , Rabbits , Blood Platelets , Physiology , Calcium , Metabolism , Kaempferols , Pharmacology , Neutrophils , Metabolism , Platelet Activating Factor , Metabolism , Platelet Adhesiveness , Platelet Membrane Glycoproteins , Metabolism , Radioligand Assay , Receptors, G-Protein-Coupled , MetabolismABSTRACT
<p><b>AIM</b>To study the antagonistic effect of myricetin on platelet activing factor (PAF).</p><p><b>METHODS</b>The specific binding of [3H] PAF to rabbit platelet receptor was investigated using radio ligand binding assay (RLBA). Platelet adhesion induced by PAF was measured with spectrophotometry. The elevation of inner free calcium concentration in rabbit polymorphonuclear leukocytes (PMNs) induced by PAF was assayed by Fura-2 fluorescent technique.</p><p><b>RESULTS</b>The specific binding inhibition potency of Myr was found to be concentration-dependent. The IC50 of Myr in [3H] PAF 1, 2 and 4 nmol.L-1 were 34.8, 85.7 and 118.6 mumol.L-1, respectively. The PAF induced reactions of rabbit platelet adhesion and PMNs inner free calcium concentration increase were inhibited by Myr in a dose-dependent manner. The IC50 of Myr to inhibit platelet adhesion was 13.1 mumol.L-1.</p><p><b>CONCLUSION</b>The specific receptor binding of PAF can be antagonized by myricetin.</p>
Subject(s)
Animals , Male , Rabbits , Calcium , Metabolism , Flavonoids , Pharmacology , Neutrophils , Metabolism , Platelet Activating Factor , Metabolism , Platelet Activation , Platelet Adhesiveness , Platelet Aggregation Inhibitors , Pharmacology , Platelet Membrane Glycoproteins , Metabolism , Receptors, G-Protein-Coupled , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To explore the inhibitory effect and mechanism of rutin against platelet activating factor (PAF) induced platelet aggregation, 5-HT release and intra-platelet free calcium concentration.</p><p><b>METHODS</b>The rate of washed rabbit platelet (WRP) aggregation was measured by turbidimetry and O-phthaldialdehyde (OPT) fluoro-spectrophotometry (FSPM) was used to determine 5-HT content. The intraplatelet free calcium concentration was measured with Fura-2/AM FSPM assay.</p><p><b>RESULTS</b>Rutin in vitro was concentration-dependently inhibiting PAF (9.55 x 10(-9) mol/L) induced WRP aggregation, the IC50 of 5-HT release was 0.73, 1.13 mmol/L respectively and the intraplatelet free calcium concentration elevation evoked by PAF (4.78 x 10(-10) mol/L) were inhibited by 68.3, 136, 274, 545 mumol/L of rutin dose-dependently.</p><p><b>CONCLUSION</b>Rutin could inhibit PAF induced platelet aggregation, 5-HT release and the increase of intraplatelet free calcium.</p>