The effects of mitochondrial energetics inhibitors on the fluorescence of potential-sensitive dyes rhodamine 123 and diS-C3-(5) in lymphocyte suspensions.

The effects of uncouplers (FCCP, DNF), oligomycin, and rotenone on the fluorescence of potential-sensitive dyes, rhodamine 123 and diS-C3-(5), in lymphocyte suspensions were compared. The fluorescence of these optical probes gradually increased at higher FCCP concentrations. The dependences of fluorescence intensities and FCCP concentrations were similar for both dyes, and only diS-C3-(5) fluorescence started increasing at lower FCCP concentrations. Rotenone (1 microM) significantly increased rhodamine 123 fluorescence. TMPD-induced and uncoupler-induced diS-C3-(5) fluorescence changes increased 1.5- to 2-fold if the incubation mixture was supplemented with oligomycin (0.1-0.2 microgram/ml). The fluorescence responses of the dyes in the lymphocyte suspension correlate with the effects of mitochondrial energetics inhibitors on delta psi m in isolated mitochondria. The results suggest the possibility of using these dyes for estimating the direction of the delta psi m changes in the lymphocyte suspension.