FIG. 6.

Inhibition of neutrophil ciprofloxacin transport by papaverine. Quiescent neutrophil suspensions were incubated with ciprofloxacin at 300 μg/ml for the indicated intervals (○). Transport was terminated by the addition of ice-cold papaverine to a final concentration of 16.6 mM, and the cells were pelleted through an oil cushion. In the papaverine plus delay experiments, cold papaverine was added just prior to addition of ciprofloxacin (●) or after 10 s of incubation of cells with ciprofloxacin (⧫). After the indicated delay periods, the cells were pelleted through oil. V, velocity.