Mechanisms of pHiregulation in phagocytosing neutrophils.
The individual and collective contributions of several putative mechanisms of proton extrusion were investigated in isolated human peripheral blood neutrophils. Neutrophils (4 replicates each from 10 healthy donors) were exposed to opsonized heat-killed E coli at a pathogen-to-phagocyte ratio of 20:1 in the presence or absence of inhibitors. (A) The significant effect on pHifollowing phagocytosis of inhibition of passive proton conductance channels (ZnCl2, 50 μM, P < .01 versusE coli alone by 2-way ANOVA). (B) The significant effect on pHi following phagocytosis of inhibition of Na+/H+ exchange (amiloride, 0.2 mM,P < .001 by 2-way ANOVA). (C) The small but significant effect on pHi following phagocytosis of inhibition of V-ATPases (bafilomycin, 100 nM, P < .05 by 2-way ANOVA). (D) The significant effect on pHi following phagocytosis of inhibition of passive proton conductance channels, Na+/H+ exchange, and V-ATPases (P < .0001 by 2-way ANOVA). (E) At a lower pathogen-to-phagocyte ratio (3:1), inhibition of V-ATPases with bafilomycin (100 nM) has a more significant effect on pHi following phagocytosis (*P < .001 by 2-way ANOVA). All data mean ± SEM.
