Calmodulin inhibitors block neutrophil degranulation at a step distal from the mobilization of calcium

Two calmodulin inhibitors, trifluoroperazine and N-(6-aminohexyl-5-chloro-1-naphtalene sulfonamide, were found to be potent inhibitors of the chemotactic factor plus cytochalasin B induced lysosomal enzyme release from rabbit peritoneal neutrophils. On the other hand, these inhibitors did not affect the chemotactic factor induced intracellular calcium redistribution and membrane permeability increase. These results strongly suggest that calmodulin is involved in the expression of the various neutrophil functions. In addition, these compounds provide a unique experimental tool for the dissection of the excitation-secretion coupling sequence in neutrophils and other secretory cells.