PBFI

PBFI is a cell-impermeant fluorescent indicator for potassium ions, suitable for detection of physiological concentrations of K+ in the presence of other monovalent cations. PBFI is used to measure intracellular potassium (K+) fluxes in animal cells and in plant cells and vacuoles. The observation that intracellular K+ levels are a controlling factor in apoptotic cell death pathways, increased the interest for PBFI. PBFI has been used for detecting adrenoceptor-stimulated decreases of intracellular K+ concentration in astrocytes and neurons, evaluating the mediating effects of K+ depletion on monocytic cell necrosis, measuring intracellular K+ fluxes associated with apoptotic cell shrinkage, monitoring mitochondrial KATP channel activation, or detecting elevated intracellular K+ levels associated with HIV-induced cytopathology. Flow cytometric measurements using UV argon-ion laser excitation (351nm and 364nm) of PBFI indicate that K+ efflux induces shrinkage of apoptotic cells and is a trigger for caspase activation. Spectral data: λex 336nm;, λem 557nm.