ESTIMATION OF INTRACELLULAR CHLORIDE IN LYMPHOCYTES USING A FLUORESCENT INDICATOR - EFFECT OF FUROSEMIDE

Intracellular chloride concentration ([Cl-]i) was measured in intact l ymphocytes using the chloride-sensitive fluorescence dye 6-methoxy-1-( 3-sulfonato-propyl)-quinolinium (SPQ). Fluorescence was measured at 43 3 nm with the excitation wave length of 344 nm. The calibration of the fluorescence was performed after suspending the lymphocytes in buffer s with varying extracellular chloride concentrations in the presence o f the ionophores, nigericin and tributyltin. Cell fluorescence was rel ated to the intracellular chloride by a Stem-Volmer relation. The appa rent [CI-]i in resting lymphocytes was 28 +/- 4 mmol/l (n = 15). Admin istration of the inhibitor of the Na+/K+/2 Cl- cotransport produced a slow decrease of lymphocytic[cr-]i.