The effect of endothelin-2 (ET-2) on migration and changes in cytosolic free calcium of neutrophils.

The effect of endothelin-2 (ET-2) on neutrophil migration and intracellular calcium was studied. Depending on the concentration, ET-2 enhanced or inhibited neutrophil migration. At low concentrations ET-2 caused a chemotactic stimulation of migration, in contrast with endothelin-1 (ET-1) which caused a chemokinetic stimulation of migration. At higher concentrations ET-2 inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)-activated migration. Both activation and inhibition by ET-2 were completely dependent on extracellular Ca2+. Unlike ET-1 which caused an increase in cytosolic free Ca2+ at a concentration which stimulated migration, ET-2 caused a measurable increase of cytosolic free Ca2+ at a concentration which did not stimulate migration. This strongly suggests that there is no correlation between maximal stimulation of cytoplasmic free calcium, and maximal stimulation of migration. Influx of extracellular Ca2+ was required for both activation of migration and change in cytosolic free Ca2+, because no effect was observed in the absence of extracellular Ca2+, and because blockers of Ca(2+)-influx inhibited ET-2-activated migration. The ETA-receptor antagonist cyclo-(-D-Trp-D-Asp-Pro-D-Val-Leu) (BQ123), and the ETB-receptor antagonist [Cys11-Cys15]-endothelin-1(11-21) (IRL1038) antagonized the stimulatory effect of ET-2 on migration, and the inhibitory effect of high concentrations of ET-2 on fMLP-activated chemotaxis. This suggests that both the ETA-receptor and the ETB-receptor are involved in the stimulatory effect of low concentrations of ET-2, and in the inhibitory effect of high concentrations of ET-2.