Figure 4.

Concentration-dependence of inhibition of cholic acid fluxes across Caco-2 monolayers by grepafloxacin. (A) Transepithelial fluxes of cholic acid (20 μM) alone and in the presence of increasing concentrations of grepafloxacin for apical to basal flux (J_a-b) and basal to apical flux (J_b-a). Net secretory flux is J_net=J_b-a – J_a-b. Increasing doses of grepafloxacin were present in both apical and basolateral compartments. n=12 epithelia (uptakes) or 12 paired epithelia (fluxes) per data point. (B) Concentration-dependence of grepafloxacin on cellular cholic acid measured across apical or basolateral surfaces. Other details as in (A).