Figure 1.
Concentration-dependence of transepithelial fluxes and cellular uptake of grepafloxacin by Caco-2 epithelial monolayers. (A) Transepithelial grepafloxacin fluxes were determined in the apical to basal (Ja-b) and basal to apical (Jb-a) directions. Net secretory flux (Jnet) shown as Jb-a – Ja-b. Least-square Michaelis-Menten fit for Jnet is shown. Concurrent measurements of [3H] or [14C] mannitol were determined in order to confirm maintenance of monolayer integrity during flux measurements. n=5 – 6 epithelia (uptakes) or paired epithelia (fluxes) per data point. Data are the mean±s.e.mean. (B) Concentration-dependence of steady-state values of cellular grepafloxacin measured across apical or basal cell borders. Solid lines are the Michaelis-Menten least-square fits. Other details as in (A).