Carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) is an uncoupler of mitochondrial oxidative phosphorylation in mitochondria. This study evaluated the effects of FCCP on the growth of juxtaglomerular As4.1 cells in relation to the cell cycle and apoptosis. FCCP inhibited the growth of As4.1 cells with an IC(50) of approximately 10 muM at 48 hours. DNA flow cytometry indicated that FCCP did not induce the specific phase arrests of the cell cycle. This agent efficiently reduced mitochondrial membrane potential (MMP; DeltaPsi(m)) levels within 1 hour and dose-dependently induced loss of MMP (DeltaPsi(m)) at 48 h. FCCP also induced apoptosis in As4.1 cells, as evidenced by sub-G(1) cells and annexin V binding assay. This apoptotic process was accompanied by caspase-3 activation and PARP cleavage. Although caspase-3 inhibitor significantly reduced the activity of caspase-3, all of the caspase inhibitors tested in this study failed to rescue As4.1 cells from FCCP-induced cell death. In conclusion, this study demonstrated that FCCP, as a mitochondria-damaging agent, potently induces apoptosis in As4.1 juxtaglomerular cells via a caspase-independent manner.