Decreases and increases in membrane potential play a central role in many physiological processes such as nerve-impulse propagation, muscle contraction, and cell signaling. Voltage Indicators are important tools for studying these processes and are generally characterized as slow- or fast-response probes. Creative Biolabs offers a range of highly cited and novel indicators enabling you to track membrane potential in different cell types.
Voltage Indicators at a Glance
The fast-response indicators 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 potential changes in excitable cells. However, the magnitude of their potential-dependent fluorescence change is often small. Fast-response Voltage Indicators are commonly used to image electrical activity from intact heart tissues or measure membrane potential changes in response to pharmacological stimuli.
The slow-response indicators function by entering depolarized cells and binding to proteins or membranes and exhibit enhanced fluorescence and a red spectral shift. Slow-responding Voltage Indicators are often used to explore mitochondrial function and cell viability.
Mitochondrial Voltage Indicators to Detect Apoptosis
A distinctive feature of the early stages of apoptosis is the disruption of the mitochondria, including changes in membrane and redox potential. Creative Biolabs offers a range of indicator products specifically designed to assay mitochondrial membrane potential flow cytometry (FC) or imaging
The membrane-permeant JC-1 dye is widely used for determining mitochondrial membrane potential in fluorescent microscopy and FC. JC-1 dye can be used as an indicator of mitochondrial membrane potential in a variety of cell types, including myocytes and neurons, as well as in intact tissues and isolated mitochondria. This dye is more specific for mitochondrial versus plasma membrane potential and it reversibly changes color as membrane potentials increase (over values of about 80-100 mV). JC-1 is both qualitative, in regards to the shift from green to orange fluorescence emission, and quantitative, as measured by fluorescence intensity, in both filter sets. JC-1 can be used to indicate the initiation of apoptosis.
Versatility of JC-1 dye
1. Applicable to a variety of cell types
2. Highly selective for mitochondria
3. Referenced protocols for FC and imaging
Although JC-1 is widely used, there are alternative reagents to fit different filters in flow cytometry, options for studying detection of dynamic changes using single-emission, non-ratiometric reagents, and also options for using end point assays to assess mitochondrial membrane potential.
How to Find the Optimal Membrane Potential Indicators for your Experiments?
|Readout||Fluorescence emission ratio 585/520 nm increases upon membrane hyperpolarization||Fluorescence response to depolarization depends on the staining concentration and detection method||Fluorescence excitation ratio 440/505 nm decreases upon membrane hyperpolarization||Fluorescence excitation ratio 440/505 nm decreases upon membrane hyperpolarization||Fluorescence decreases upon membrane depolarization|
|Range||1% per 1 mV||1% per 1 mV||2-10% per 100 mV||2-10% per 100 mV||2-10% per 100 mV|
|Response time||20 ms||20 ms||Sub-millisecond||Sub-millisecond||Sub-millisecond|
|Ex/Em (nm)||514/529; 585/590||485/500||482/686||467/631||486/689|
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