kt-5720 and manoalide

This investigation was undertaken to clarify the mechanisms of superoxide anion (O2-) generation in rat peritoneal mast cells. Compound 48/80, a typical histamine liberator mediated by calcium influx, elicited O2- generation from the mast cells in a dose-dependent fashion. It was demonstrated by immunohistochemical study and Western blot analysis that the mast cells contained the 47-kDa phagocyte oxidase (p47phox) protein, which was one cytosolic component of the NADPH oxidase system. Arachidonic acid stimulated O2- generation in the mast cells, but other unsaturated fatty acids had no effect. On the other hand, 48/80-induced O2- generation was inhibited by phospholipase A2 inhibitors, such as arachidonyl trifluoromethyl ketone and manoalide. Forskolin, isoprenaline, and dibutyryl cyclic AMP inhibited the O2- generation, and KT-5720, a cyclic AMP-dependent protein kinase (A-kinase) inhibitor, markedly enhanced the O2- generation. These findings suggest that O2- is generated by a NADPH oxidase-like enzyme system in mast cells and that this enzyme system is activated by arachidonic acid released by cytosolic phospholipase A2. Thus, it is regulated by the cyclic AMP-A kinase system.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Blotting, Western; Bucladesine; Carbazoles; Colforsin; Cyclic AMP-Dependent Protein Kinases; Granulomatous Disease, Chronic; Immunohistochemistry; Indoles; Isoproterenol; Male; Mast Cells; NADPH Oxidases; p-Methoxy-N-methylphenethylamine; Phosphoproteins; Protein Kinase C; Pyrroles; Rats; Rats, Wistar; Recombinant Proteins; Superoxides; Terpenes