Characterization of platelet-activating factor induced superoxide anion generation by guinea-pig alveolar macrophages.
Guinea-pig alveolar macrophages (AM) exhibited a concentration dependent superoxide anion (.O2-) generation as measured by means of lucigenin-chemiluminescence (CL) in response to platelet-activating factor (PAF) in the range of 1 nM to 100 nM. PAF effects on .O2(-)-generation were specific to the form of PAF that is biologically active in most systems; lyso-PAF had no effect. The CL-response was inhibited following incubation with EDTA (IC50: 859 microM), the intracellular Ca(2+)-antagonist TMB-8 (IC50: 73 microM), or the calmodulin antagonists W-7 (IC50: 13 microM) and trifluoperazine (IC50: 14 microM) indicating the involvement of Ca2+ in the signal transduction pathway. Increasing the intracellular cAMP-levels by PGE2 or forskolin resulted in an inhibition of the CL-response, whereas the beta-adrenoceptor agonist salbutamol showed no effect. On the other hand phosphodiesterase inhibition by IBMX (10 microM: 25%) or zardaverine (10 microM: 29%) also resulted in a transient inhibition of the CL-response. Protein kinase C (PKC) seemed not to be involved in the signal transduction, since the PKC-inhibitors staurosporine, H-7 and D-sphingosine were inactive. In contrast, the PAF receptor antagonists WEB-2086 (IC50: 700 nM) and WEB-2170 (IC50: 176 nM) exerted a strong inhibitory activity. The antiallergic/antiasthmatic drug azelastine also reduced the PAF induced CL-response (IC50: 12 microM), whereas the other antiallergic/antiasthmatic compounds showed almost no inhibition.
Schmidt
J
J
Department of Pharmacology, ASTA Pharma AG, Frankfurt, F.R.G.
Lindstaedt
R
R
Szelenyi
I
I
D000818:Animals; D001249:Asthma / Q000188:drug therapy; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects*; D013481:Superoxides / Q000378:metabolism*
D010972:Platelet Activating Factor; D013481:Superoxides; D000242:Cyclic AMP; D011493:Protein Kinase C; D002118:Calcium