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Abstract (228) Adenosine 5’-triphosphate (ATP), released at the leading edge of migrating neutrophils, amplifies chemotactic signals. The aim of our study was to investigate whether neutrophils express ATP-gated P2X1 ion channels and whether these channels could play a role in chemotaxis. Whole-cell patch clamp experiments showed rapidly desensitizing currents in both human and mouse neutrophils stimulated with P2X1 agonists, alpha,beta-methylene ATP (αβMeATP) and beta,gamma-methylene ATP (βγMeATP). These currents were strongly impaired or absent in neutrophils from P2X1-/- mice. In Boyden chamber assays, αβMeATP provoked chemokinesis and enhanced formylated peptide- and interleukin-8-induced chemotaxis of human neutrophils. This agonist similarly increased W-peptide-induced chemotaxis of wild-type mouse neutrophils while it had no effect on P2X1-/- neutrophils. In human as in mouse neutrophils, αβMeATP selectively activated the small RhoGTPase RhoA that caused reversible myosin light chain phosphorylation. Moreover, the αβMeATP-elicited neutrophil movements were prevented by the two Rho kinase inhibitors, Y27632 and H1152. In a gradient of W-peptide, P2X1-/- neutrophils migrated with reduced speed and displaye