4-Bromophenacyl bromide induces Ca2+ influx in human gingival fibroblasts

Abstract 4-Bromophenacyl bromide (BPB) is generally used as a phospholipase A 2 (PLA 2 ) inhibitor. In the present study, we demonstrate that BPB induces Ca 2+ influx in human gingival fibroblasts. In fura-2-loaded human gingival fibroblasts, BPB evoked a transient increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) in a dose-dependent manner. The BPB-induced Ca 2+ mobilization was also shown in a single fluo-3-loaded-fibroblast. The BPB-induced increase in [Ca 2+ ] i was completely abolished by the elimination of the external Ca 2+ . Ca 2+ influx induced by the Ca 2+ -mobilizing agonist histamine was markedly enhanced in the presence of BPB. These suggest that the BPB-induced Ca 2+ mobilization is due to the influx of extracellular Ca 2+ . However, it is unlikely that the effect of BPB is dependent on the inhibition of PLA 2 activity, because other PLA 2 inhibitors, such as AACOCF3, quinacrine dihydrochloride and manoalide, failed to induce Ca 2+ mobilization. Chemical compounds similar to BPB, but which have no CH 2 Br at position 1 in the benzene ring failed to evoke Ca 2+ mobilization, indicating that the position of CH 2 -Br in BPB is important for causing the Ca 2+ influx.