[A method for measurement of circulating blood volume with fluorescein isothiocyanate labeled red blood cells].

We developed a new method to measure the total circulating blood volume using fluorescein isothiocyanate (FITC) labeled autologous red blood cell as an indicator. Red blood cells were labeled by incubation with 0.1 mg.ml-1 FITC in PBS (pH 7.2) for 30 min at 37 degrees C. Eighteen dogs were given an intravenous injection of FITC labeled red blood cells, which were approximately 0.1% of the total circulating red blood cells estimated from the body weight. The ratio of labeled cells to the normal circulating red blood cells was determined by a flow cytometry. The total blood volume was calculated from its dilution rate. The average circulating blood volume determined by this method was 76.8 +/- 9.2 ml.kg-1 (mean +/- SD). This result coincides well with the values reported previously. This method using non radioactive tracers enables a reproducible measurement of circulating blood volume and its change with time.