Fig. 5. (A ) A typical absorbance versus  dye concentration curve, used to determine the dye concentration by spectrophotometry. Shown are the steady state plasma levels of dye (B ) determined by indicator dilution (at 2 min after bolus injection) or by spectrophotometry (2–3 min after bolus injection). Indicator dilution measurements were calibrated from the ex vivo  dye calibration method. FITC-BSA = fluorescein isothiocyanate–conjugated bovine serum albumin.