Membrane Potential Indicators

Membrane potential plays a central role in many physiological processes, including nerve-impulse propagation, muscle contraction, and cell signaling. Potentiometric probes are important tools for studying these processes and are generally characterized as slow- or fast-response probes. The fast-response probes change their electronic structure, and consequently their fluorescence properties, in response to changes in the surrounding electric field. The response is fast enough to detect transient (millisecond) potential changes in excitable cells, including single neurons, cardiac cells, and intact brains. However, the magnitude of their potential-dependent fluorescence change is often small (2–10% fluorescence change per 100 mV). The slow-response probes function by entering depolarized cells and binding to proteins or membranes, and exhibit enhanced fluorescence and a red spectral shift.
Fast-response probes are commonly used to image electrical activity from intact heart tissues or measure membrane potential changes in response to pharmacological stimuli. Slow-responding probes are often used to explore mitochondrial function and cell viability.

Membrane Potential Indicators Selection Guide