Effects of G-CSF and bafilomycin on pH homeostasis. Neutrophils were incubated in sodium-free media and pH-sensitive BCECF fluorescence was monitored over time. Data are presented as the average pH difference between G-CSF and controls (GCSF minus Control) and between G-CSF + bafilomycin and controls + bafilomycin (Gbaf minus Cbaf ) for six independent experiments each containing three replicates. Bars on the 100-minute time point denote standard error for six experiments. The 100-minute standard error was similar to that observed for the remainder of the time points. Areas under each of the 12 curves (6 GCSF minus control and 6 Gbaf minus Cbaf ) were calculated in arbitrary units. The difference between these two sets of areas was significant at the level of P < .02 (one-tailed Wilcoxson two-sample test).