TABLE 1.

Kinetics parameters for influx and efflux of ciprofloxacin and moxifloxacin in control cells, calculated from the regression analyses of the data presented in Fig. 2 (influx) and Fig. 5 (efflux)

QuinoloneExtracellular concn (mg/liter)InfluxEfflux
t1/2 of initial phase (min)aInitial influx rate (pmol/mg prot/s)bt1/2 (min)cInitial efflux rate (pmol/mg prot/s)b
Ciprofloxacin50.21 ± 0.084.8 ± 0.7
170.09 ± 0.0420.2 ± 5.51.62 ± 0.2510.2 ± 1.6
Moxifloxacin50.18 ± 0.0419.9 ± 1.4
170.26 ± 0.0866.7 ± 3.40.27 ± 0.0378.9 ± 5.7
  • a Curve fitting by two-phase exponential association; values are given for the first, rapid phase of uptake.

  • b Calculated from the difference in cell associated amount between t = 0 s and t = 15 s in experiments shown in Fig. 2 and Fig. 5.

  • c Curve fitting by one-phase exponential decay.