MEASUREMENT OF INTRACELLULAR PH USING FLOW-CYTOMETRY WITH CARBOXY-SNARF-1

The new intracellular pH (pH(i)) dye carboxy-seminaphthorhodafluor (SN ARF-1) was compared to the established dye 2,3-dicyanohydroquinone (DC H) using flow cytometry. Both dyes give high-resolution pH(i) measurem ents. SNARF-1 remains trapped within cells much longer than DCH, so th at pH(i) can be monitored during and after treatments with chemicals o r hyperthermia. The toxicity of the dyes is similar, and both dyes can be used at concentrations that result in low toxicity to cells. Adequ ate staining of cells with SNARF-1 is dependent on the cell concentrat ion. The absolute pH(i) values indicated by SNARF-1 are higher than va lues measured with DCH. However, the trends measured by both dyes are consistent, and both are useful for making pH(i) measurements. (C) 199 3 Wiley-Liss, Inc.