Calcium-induced heterogeneous changes in membrane potential detected by flow cytofluorimetry

• Published in: Biochimica et biophysica acta, Protein structure and molecular enzymology Vol. 778; no. 3; pp. 457 - 462
• Main Authors: Hickman, JA, Blair, O C, Stepanowski, AL, Sartorelli, A C
• Format: Journal Article
• Language: English
• Published: 01.01.1984
• Subjects: calcium; flow cytometry; leukemia L1210; membrane potential; potassium; sodium
• ISSN: 0167-4838

Ionophore-induced changes in the cell-associated fluorescence of samples of approx. 50,000 individual murine L1210 leukemia cells which had been incubated with the voltage-sensitive dye 3,3'-dihexyloctacarbocyanine iodide (DiOC6(3)) were monitored by flow cytometry. The K super(+) ionophore valinomycin (1 mu M) produced homogeneous changes in the fluorescence of the entire population, the magnitude of which was dependent upon the concentration of extracellular K super(+). These changes allowed the estimation of the potassium equilibrium potential of the cells, by the null-point method, to be - 11.9 mV. The Ca super(2+)ionophore A23187 (500 nM) produced heterogeneous changes in fluorescence, with populations of both hyperpolarised and depolarised cells. The findings provide evidence for the presence of Ca super(2+)-induced Na super(+) exchange and Ca super(2+)-induced K super(+) efflux mechanisms in these cells which may be expressed simultaneously in the cell population.