TY - JOUR TI - Optical estimation of absolute membrane potential using fluorescence lifetime imaging AU - Lazzari-Dean, Julia R AU - Gest, Anneliese MM AU - Miller, Evan W A2 - Cohen, Lawrence A2 - Aldrich, Richard A2 - Ross, Bill A2 - Loew, Leslie M A2 - Baker, Bradley VL - 8 PY - 2019 DA - 2019/09/23 SP - e44522 C1 - eLife 2019;8:e44522 DO - 10.7554/eLife.44522 UR - https://doi.org/10.7554/eLife.44522 AB - All cells maintain ionic gradients across their plasma membranes, producing transmembrane potentials (Vmem). Mounting evidence suggests a relationship between resting Vmem and the physiology of non-excitable cells with implications in diverse areas, including cancer, cellular differentiation, and body patterning. A lack of non-invasive methods to record absolute Vmem limits our understanding of this fundamental signal. To address this need, we developed a fluorescence lifetime-based approach (VF-FLIM) to visualize and optically quantify Vmem with single-cell resolution in mammalian cell culture. Using VF-FLIM, we report Vmem distributions over thousands of cells, a 100-fold improvement relative to electrophysiological approaches. In human carcinoma cells, we visualize the voltage response to growth factor stimulation, stably recording a 10–15 mV hyperpolarization over minutes. Using pharmacological inhibitors, we identify the source of the hyperpolarization as the Ca2+-activated K+ channel KCa3.1. The ability to optically quantify absolute Vmem with cellular resolution will allow a re-examination of its signaling roles. KW - membrane potential KW - cellular physiology KW - fluorescent indicators JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -