ON THE BRAIN BARRIER SYSTEM FUNCTION AND CHANGES OF CEREBROSPINAL-FLUID CONCENTRATIONS OF PHENYLALANINE AND TYROSINE IN HUMAN PHENYLKETONURIA

  • 1 January 1984
    • journal article
    • research article
    • Vol. 43  (2) , 197-204
Abstract
In 6 patients with classic phenylketonuria (PKU) the plasma and CSF concentrations of phenylalanine and tyrosine were measured fluorimetrically. The results of the PKU group were compared with data obtained from 17 children without abnormal CSF parameters and free of metabolic or central nervous disorders, in whom a diagnostic lumbal puncture was performed. The PKU patients showed statistically significant differences in comparison while the controls: plasma and CSF phenylalanine contents were markedly higher (on an average 6.4 and 4.6 times, respectively) in PKU patients. Plasma tyrosine was 1.8 times lower, but CSF tyrosine was .apprx. 2.2 times higher in comparison to the controls. The plasma CSF-ratio (PLR) of phenylalanine did not change in PKU and could be found in the same range as in the normal controls. The PLR of tyrosine was significantly lower in PKU patients. The results are discussed with respect to an altered function of the brain barrier systems for the amino acid transport in PKU, and that increased CSF tyrosine contents in PKU may rather reflect disturbances of the intracellular metabolism of the brain cells than changes of the amino acid transport through the brain barrier produced by hyperphenylalaninemia.