Asante Potassium Green-1
Asante Potassium Green 1 (APG-1) is a fluorescent indicator with a useful Kd for measuring cytosolic K+ concentration. It loads readily and is excited by visible light. Although non-ratiometric, its large fluorescence dynamic range allows sensing of even small changes in K+ concentration. Optimal excitation occurs at 517 nm, but the indicator can also be excited at the conventional wavelength of 488 nm. APG-1 works well with 2-photon excitation at near-infrared wavelengths and is quite resistant to photobleaching. Like its sodium counterpart, it is useful for confocal microscopy, flow cytometry, and screening.