Transfer of I125-albumin from blood into brain and cerebrospinal fluid in newborn and juvenile rats.

Human fetuses, rabbit fetuses and newborn rats have a relatively high concentration of protein in cerebrospinal fluid (csf) as compared with the adult. The present study was undertaken in an attempt to evaluate whether this high protein concentration in newborn rats is caused by a high permeability of the blood-brain-csf barrier to protein or by a low production rate of csf. The results suggest that the high concentration protein in csf in newborn rats is due to a low rate of production of csf rather than to an increased transfer of protein across the blood-brain-csf barrier.