N-acetyl aspartic acid (NAA) and N-acetyl aspartylglutamic acid (NAAG) in human ventricular, subarachnoid, and lumbar cerebrospinal fluid

N-Acetylaspartic and N-acetylaspartylglutamic acid concentrations in human ventricular, subarachnoid and lumbar cerebrospinal fluid were measured by c ombined gas chromatography-mass spectrometry using selected ion monitoring with deuterated internal standards. N-Acetylaspartate concentrations were i n the range 55, 9, and 1 mu M, respectively; N-acetylas partylglutamate con centrations in the same fluids were in the range 8, 3 and 4 mu M, respectiv ely. There did not appear to be any difference in lumbar fluid concentratio ns of either compound between control subjects, schizophrenic patients, Alz heimer's disease patients and a pooled group of patients with neurological degeneration. Ventricular concentrations of both compounds were greatly inc reased in deceased patients suggesting that maintenance of their intracellu lar concentrations is probably energy dependent. The concentrations of thes e compounds in lumbar cerebrospinal fluid from living, and ventricular cere brospinal fluid from deceased subjects were weakly correlated with one anot her. In lumbar fluid neither compound appeared to be correlated with age. A nalysis of serially collected lumbar samples from two subjects showed a wea k concentration gradient for both compounds. Neither antipsychotic medicati on nor the acid transport inhibitor probenecid had any effect on lumbar con centrations of either compound. Attempts to use anion exchange high pressur e liquid chromatography with UV detection for measurement of the low concen trations of N-acetylaspartate found in cerebrospinal fluid from living subj ects were unsuccessful.