Membrane Potential & Nerve Terminal Dyes

TMRM (Tetramethylrhodamine methyl ester, perchlorate) and TMRE are preferred dyes for quantitative measurements of membrane potentials using the Nernst equation.

Dipicrylamine (DPA) is a nonfluorescent anionic membrane dye. With its absorbance in the blue region of the visible spectrum, DPA can be used as a FRET quencher for a variety of fluorescent donor dyes.

DiOC₆(3) (3,3′-Dihexyloxacarbocyanine,iodide) is a green fluorescent membrane dye that has been used to stain the ER in both live and fixed cells. The dye has also been used to study structural interactions and dynamics of the ER in neurons and yeast.

A fixable red fluorescent nerve terminal probe that is spectrally identical to SynaptoRed™ C2 (also called FM®4-64).

HM1-43 is a fixable, activity-dependent fluorescent nerve terminal probe.

DiOC₂(3) (3,3′-Diethyloxacarbocyanine, iodide) has been used for measuring membrane potentials in bacteria. The green fluorescent dye forms red fluorescent aggregates with increasing membrane potential.

The styryl dye RH795 is a fast-responding potentiometric probe that is primarily used for functional imaging of neurons. The dye is spectrally similar to RH414 (61016), but exhibits different physiological effects during staining. For example, RH414 causes arterial constriction during cortex staining, while RH795 does not (see references 1,2).

DiOC5(3) and DiOC6(3) are two of the most widely used carbocyanine dyes used for membrane potential measurements.

The styryl dye RH237 is a fast-responding potentiometric probe that is primarily used for functional imaging of neurons.

RH421 is a fast responding membrane potential dye, exhibiting >20% fluorescence change per 100 mV on neuroblastoma cells.

SGC5 is a coumarin styryl dye that binds to membranes in a manner similar to the FM® dyes. It becomes highly fluorescent upon insertion into lipid bilayers.

SGC3 is a coumarin styryl dye that binds to membranes in a manner similar to the FM® dyes. It becomes highly fluorescent upon insertion into lipid bilayers.

AM3-25 is a lipophilic styryl dye that has an amine group at the hydrophilic head. The amine group reacts with formaldehyde or glutaldehyde to make the dye fixable.

SynaptoGreen™ C5 is similar to SynaptoGreen™ C4 (70020), except that the lipophilic tail is one carbon longer.

SynaptoGreen™ C18 (equivalent to FM®3-25) is a membrane stain with a chemical structure similar to other nerve terminal dyes, except that it has the longest lipophilic tail (C18). Because of its large size, it is used as a control for ion channel permeability of nerve terminal dyes.

SynaptoGreen™ C1 has the shortest (one-carbon) lipophilic tail and is the most water soluble of the nerve terminal dye series. Thus it is expected to have the slowest on-rate and the fastest off-rate among the SynaptoGreen™ dyes.