Influx of serum proteins and their concentration in spinal fluid along the neuraxis

Abstract

A difference in protein concentration between cisterna magna ( 27 mg 100 ml ) and spinal subarachnoid space fluid ( 44 mg 100 ml ) has been observed in the cat. The question of whether the elevated protein concentration in spinal CSF was due to an increased permeability of the blood-spinal fluid barrier in the spinal subarachnoid space was examined. CSF formation and absorption and protein flux was studied by perfusing the ventriculocisternal and spinal subarachnoid spaces. Under the influence of acetazolamide, the rates of influx of albumin during perfusion of the ventriculocisternal system was similar to that found in spinal subarachnoid space perfusion experiments. From measurements of both surface areas, the influx of albumin/cm 2 was 3- to 5-fold less in the spinal subarachnoid region than in the ventriculocisternal system. These results indicate that the differences in protein concentration in the CSF compartments studied is not due to an increase in permeability to protein in the spinal subarachnoid space. An alternate explanation for the increased protein concentration in the spinal subarachnoid space is based on regional differences of CSF circulation and a constant protein influx in the absence of local CSF formation.