51. Platelet-Activating Factor Inhibits the Secretion of Platelet-Activating Factor Acetylhydrolase by Human Decidual Macrophages
- Author
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Hisashi Narahara, Kaei Nasu, Isao Miyakawa, Yasushi Kawano, Jun Yoshimatsu, and John M. Johnston
- Subjects
medicine.medical_specialty ,medicine.drug_class ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Biology ,Biochemistry ,Calcium in biology ,chemistry.chemical_compound ,Endocrinology ,Internal medicine ,Decidua ,medicine ,Humans ,Decidual cells ,Secretion ,Platelet Activating Factor ,Cells, Cultured ,Protein Kinase C ,Protein kinase C ,Sphingosine ,Platelet-activating factor ,Macrophages ,Calcium channel ,Biochemistry (medical) ,Phospholipid Ethers ,respiratory system ,Flow Cytometry ,Receptor antagonist ,chemistry ,1-Alkyl-2-acetylglycerophosphocholine Esterase ,Calcium ,Female ,lipids (amino acids, peptides, and proteins) - Abstract
To clarify the role of platelet-activating factor (PAF) in parturition, the effects of PAF on the secretion of PAF-acetylhydrolase (PAF-AH), a PAF-inactivating enzyme, by decidual macrophage populations were examined. The cells were isolated from human decidual tissue by enzymatic digestion, Ficoll-Paque centrifugation, or flow cytometric sorting. The nonhydrolyzable agonist of PAF, carbamyl-PAF (C-PAF), inhibited the secretion of PAF-AH by either decidual cells or flow cytometrically purified decidual macrophages. A specific PAF receptor antagonist, WEB 2086, blocked the C-PAF-induced inhibition. Lyso-PAF, a metabolite of PAF, had no effect on the enzyme secretion. An intracellular calcium channel blocker, bis-(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid, tetra(acetoxymethyl)-ester, partially blocked the inhibition by C-PAF, whereas extracellular calcium channel blockers, nifedipine and verapamil, were without effect. The inhibitory effect of C-PAF was also partially blocked by protein kinase C (PKC) inhibitors, sphingosine and H-7. A PKC activator, 12-O-tetradecanoylphobol 13-acetate, decreased the secretion of PAF-AH. The decrease was abolished by the addition of sphingosine and H-7. It is suggested that PAF inhibits the PAF-AH secretion by decidual macrophages and that the inhibitory action is mediated by a signal transduction mechanism involving intracellular calcium and PKC.
- Published
- 2003
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