First, the calibrated transport data at t = 270 s of each tested transporter concentration (mol%) was plotted against the normalised percentage Cl -efflux (%) for ISE-based transport studies. For spectrophotometer fluorescence-or luminescencebased transport studies, the normalised fractional fluorescence or luminescence intensity (If) data at either t = 200 s or t = 600 s, respectively, was graphed against the tested transporter concentration (mol%). The graphed data was then fitted using the Hill equation (Equation ):