The effect of calcium antagonists on the activation of guinea pig neutrophils

The role of calcium ions in the activation of guinea pig neutrophil functions was examined by evaluating the effects of calcium antagonists. The data presented here show that calcium antagonists inhibit the activation of guinea pig neutrophil functions elicited by N-formyl-methionyl-leucyl-phenylalanine (FMLP) such as chemotaxis, superoxide anion generation and granule enzyme release in a concentration-dependent manner. The concentrations of calcium antagonists demonstrating the inhibition of neutrophil functions may be somewhat different for each function and higher than that of smooth muscle cells. Calcium ionophore A23187 (A23187) caused superoxide anion generation and granule enzyme release of the neutrophils. A23187 also potentiated the FMLP-induced superoxide anion generation and granule enzyme release of the neutrophils. On the contrary, A23187 neither elicited neutrophil chemotaxis nor affected FMLP-induced neutrophil chemotaxis. These results indicate the possibility that the inhibitory effect of calcium antagonists on the activation of neutrophil functions is probably not simply mediated by inhibition of calcium uptake but also by inhibition of a calcium-dependent intracellular target.