SUPEROXIDE GENERATION BY GUINEA-PIG PERITONEAL-MACROPHAGES IS INHIBITED BY ROLIPRAM, STAUROSPORINE AND MEPACRINE IN AN AGONIST-DEPENDENT MANNER

Platelet-activated factor (PAF) (Ec(50) -7.9+/-0.6 M), formyl-methiony l-leucyl-phenylalanine (fMPL) (Ec(50) -7.7+/-0.1 M), phorbol 12-myrist ate 13 acetate (PMA) (Ec(50) -8.4+/-0.3 M), opsonized zymosan (OPZ) (0 .01-1 mg/ml) were potent stimuli to superoxide generated by guinea-pig peritoneal macrophages. Superoxide generation by low (less than or eq ual to -8M) concentrations but not high (greater than or equal to -7M) concentrations of PAF or fMLP were attenuated by rolipram (100 mu M) in the presence of 1 mu M prostaglandin E(2) (PGE(2)). That stimulated by PMA or OPZ, however, was unaffected. At 1 mu M, staurosporine was a potent inhibitor of superoxide generation stimulated by both fMLP an d PAF but was without effect on that stimulated by OPZ. Superoxide gen eration stimulated by fMLP, PAF and OPZ was inhibited by 100 mu M mepa crine. We conclude that superoxide generation stimulated by the chemoa ttractants fMLP and PAF involves a cyclic AMP regulated and cyclic AMP independent process. The cyclic AMP independent process is mediated b y protein kinase C. Although protein kinase C seems a central element in the respiratory burst stimulated by fMLP, PAF and PMA that stimulat ed by OPZ bypasses this mechanism. Phospholipase A(2) however, represe nts a common stage in the signal transduction pathway.