pH and membrane potential indicators
Find the best fluorescent indicator for detecting pH and membrane potential
Changes in cytosolic intracellular pH (pHi) and membrane potential play a central role in many physiological processes, including nerve-impulse propagation, muscle contraction, and cell signaling.
We offer a range of highly cited and novel indicators enabling you to track pH and membrane potential in different cell types.
pH indicators
The most popular indicator for studying pHi is BCECF. Its pKa of 6.98 is ideal because all cells have pHi near 7.0, with physiological changes of no more than a few tenths of a pH unit. BCECF has an excitation spectrum with a maximum at 507 nm and an isoexcitation point at 438 nm (at which the fluorescence emission is independent of pH). Intracellular pH can therefore be estimated by measuring the ratio of the fluorescence intensities at 500 and 450 nm.
FFNs (Fluorescent False Neurotransmitters)
FFN102 (Mini 102) is a novel, pH-responsive fluorescent false neurotransmitter (FFN). Rodent DAT and VMAT2 substrate. Enables two-photon microscopic imaging of localization and activity of dopaminergic presynaptic terminals in the striatum of mouse acute brain slice. Exhibits greater fluorescence emission in neutral than acidic environments allowing optical measurement of synaptic vesicle content release. Sufficiently bright, photostable and suitable for two-photon fluorescence microscopy and standard fluorescent microscopy. Compatible with GFP tags.
FFN202 (Mini 202) is a novel, pH-responsive fluorescent false neurotransmitter (FFN). Rodent VMAT1 and VMAT2 substrate. Enables in situ pH measurement of secretory catecholamine vesicles in PC-12 cells. Sufficiently bright, photostable and suitable for two-photon fluorescence microscopy and standard fluorescent microscopy. Compatible with GFP tags.
Membrane potential indicator
The membrane-permeant JC-1 dye is widely used for determining mitochondrial membrane potential in flow cytometry and fluorescent microscopy. 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). This property is due to the reversible formation of JC-1 aggregates upon membrane polarization that causes shifts in emitted light from 530 nm (i.e., emission of JC-1 monomeric form) to 590 nm (i.e., emission of J-aggregate) when excited at 515 nm. Both colors can be detected using filters for FITC and PE/phycoerythrin/rhodamine, respectively. 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.