Fig. 4.

Inhibition of MPO attenuates cytosolic acidification during phagocytosis. (A) Time course of pH_i in phagocytosing neutrophils synchronized as in Fig. 3A, in 36 control cells (■), 35 cells in the presence of 500 μM ABAH, and 18 cells treated with 500 μM ABAH and 200 μM ZnCl₂, each in 3 separate experiments. (B) The maximum rate of acidification in the cells depicted in (A) was not changed by ABAH (P = 0.48), but increased significantly in the presence of ABAH and 200 μM Zn²⁺ (P < 0.0001).