Cerebrospinal fluid transport of sulfate in the cat

Abstract

Clearance of sulfate-35S from the cerebrospinal fluid [CSF] was measured during ventriculocisternal perfusions in cats. Sulfate-35S was cleared from CSF against a plasma gradient, and the clearance was reduced by the addition of 4 mM sulfate or thiosulfate to the perfusate, implying a carrier mechanism for sulfate transport. From simultaneous studies of iodide-125I clearance, it appeared that sulfate and iodide were transported out of the CSF by different mechanisms, in that transport of either anion could be inhibited independently of the other. Clearance of sulfate-35s from cerebrospinal fluid was 3 times greater in the adult cat than in the newborn kitten. Steady-state CSF-to-plasma distribution ratios were 0.7 and .28 respectively. Comparable values for plasma clearance of sulfate-35S rate of penetration of sulfate-35S into brain, and choroid plexus weights were obtained at both ages. Volumes of distribution of albumin-125I were similar in adult cats and kittens. The results suggest a less efficient transport of sulfate out of the cerebrospinal fluid in the kitten as compared with the adult cat.