Ventriculocisternal Perfusion Studies in the Monkey. I. Comparison of Radioiodinated (125I) Serum Albumin and Blue Dextran as Indicators to Measure Rate of Formation of Cerebrospinal Fluid.

摘要

The characteristics of two nondiffusible indicators, 125I labeled albumin (RISA-125) and blue dextran, were compared by using them simultaneously to measure rate of formation of cerebrospinal fluid (Vf) in in vitro experiments and in a series of ventriculocisternal perfusion experiments in rhesus monkeys. Mean Vf calculated from the dilution of RISA-125 was 37.6 microliters/min; the Vf calculated from the corresponding dilution of blue dextran was 37.1 microliters/min. In the in vitro experiments, simulated Vf calculated from these counts varied around the mean by more than plus or minus 10 percent at the 95 percent confidence limits. Counting variability is probably related to the low-energy levels of the 125I isotope. Vf calculated from the dilution of blue dextran had one-tenth the coefficient of variation of the Vf calculated from the dilution of RISA-125. Blue dextran is preferable to RISA-125 to measure the rate of formation of cerebrospinal fluid because it is easier to detect accurately small changes of Vf with blue dextran.