Ivermectin induces plasma membrane hyperpolarization dependent on chloride influx. OCI-AML2 cells were treated with increasing concentrations of ivermectin for 24 hours (A) or 6μM ivermectin for increasing times of incubation (B). After treatment, plasma membrane potential was measured by staining cells with DiBAC4(3) and flow cytometric analysis. Data represent the mean ± SD fold change in plasma membrane potential compared with control treated cells. Representative experiments performed in triplicate are shown. Differences in change of membrane potential compared with control were analyzed by an unpaired t test. ***P < .001; *P < .05. U937 and TEX leukemia cells, a primary AML sample (AML), (C) DU145 and PPC-1 prostate cancer, and 2 samples of normal hematopoietic cells (D) were treated with 6μM ivermectin for increasing times. After treatment, plasma membrane potential was measured as described above. Data represent the mean ± SD fold change in plasma membrane potential compared with control treated cells. Representative experiments performed in triplicate are shown. Differences in change of membrane potential, compared with control, were analyzed by an unpaired t test. ***P < .001; *P < .05. (E) OCI-AML2 cells were treated with 6μM ivermectin in chloride-replete and chloride-free media for 5 hours. After incubation, plasma membrane potential was measured as described above. Data represent the mean ± SD change in plasma membrane potential, compared with untreated cells in chloride-replete media. Representative experiments performed in triplicates are shown. Differences in change of membrane potential, compared with control, were analyzed by an unpaired t test. ***P < .001; *P < .05.