INTRACELLULAR SIGNALING EVENTS IN SUPEROXIDE GENERATION AND ADHESION OF CHANNEL CATFISH, ICTALURUS-PUNCTATUS RAFINESQUE, NEUTROPHILS TO THEEXTRACELLULAR-MATRIX PROTEIN FIBRINOGEN

Activation of channel catfish neutrophils is essential if these cells are to participate in adhesion to extracellular matrix proteins or gen erate intracellular superoxide for killing of microbes. Various signal ing pathways are required for these activities to occur. The objective of this study was to identify components of the signal transduction p athways in channel catfish neutrophils. A23187, bryostatin, and phorbo l dibutyrate (PDBU) all induced catfish neutrophil adhesion to fibrino gen coated plates and the adhesion could be significantly reduced when neutrophils were pretreated with staurosporine (1 x 10(-7) M). Stauro sporine was the only inhibitor used in the study that inhibited or red uced PDBU-induced adhesion of catfish neutrophils to fibrinogen. Phorb ol dibutyrate at the concentrations used in the adhesion assay was the only stimulant that caused generation of intracellular superoxide and therefore was the only stimulant used in the remainder of the study, Aristolochic acid (1 x 10(-4) and 3 x 10(-5) M) + PDBU and staurospori ne (1 x 10(-7) and 1 x 10(-8) M) + PDBU caused a significant decrease (p less than or equal to 0.05) in PDBU-induced intracellular oxygen ge neration. The role of protein kinase C and phospholipases in channel c atfish neutrophil adhesion and superoxide generation are discussed. (C ) 1998 Elsevier Science Ltd. All rights reserved.