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  • Title: Cyclic-AMP level and eicosanoid release from alveolar macrophages are differentially affected by high and low dose of platelet activating factor.
    Author: Beusenberg FD, Bonta IL, van Amsterdam JG.
    Journal: Biochem Pharmacol; 1994 Feb 09; 47(3):588-90. PubMed ID: 8117329.
    Abstract:
    Antigen challenged alveolar macrophages (ac-AM) showed much higher basal prostaglandin E2 (PGE2) release (4,4-fold) and cAMP content (2,4-fold) than naive alveolar macrophages (AM). In naive AM 1 fM platelet activating factor (PAF) enhanced PGE2 release from 115 to 157 ng/5 x 10(6) cells but was inactive at 1 nM or 1 microM. In ac-AC 1 fM PAF enhanced PGE2 release from 510 to 670 ng/5 x 10(6) cells and inhibited leukotriene B4 (LTB4) release (from 6.0 to 4.8 ng/5 x 10(6) cells). At a 10(6)-fold higher concentration PAF inhibited PGE2 release (from 510 to 400 ng/5 x 10(6) cells) and stimulated LTB4 release (from 6.0 to 8.2 ng/5 x 10(6) cells). PAF-induced increase or decrease in PGE2 release was paralleled by changes in cellular cAMP (+35 and -17%, respectively). The specific PAF-antagonist BN 52021 completely reversed all PAF-induced effects while indomethacin inhibited only PAF-induced increase in PGE2 release and cAMP leaving LTB4 release unaffected. Similarly, the lipoxygenase inhibitor AA-861 inhibited PAF-induced rise in LTB4 release leaving the enhancement in PGE2 release and cAMP content unaffected. Present data show that PAF dose-dependently affects eicosanoid production and cAMP level in alveolar macrophages.
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