Abstract
Quinolinic acid is a metabolite of tryptophan. It is excreted into the urine in the healthy subjects. Quinolinic acid has various pharmacological effects, such as convulsive action in mouse, inhibition of erythropoiesis and lymphocyte blast formation. We identified quinolinic acid in uremic serum by use of gas chromatography/mass spectrometry (GC/MS). 3, 5-Pyridinedicarboxylic acid was added as an internal standard. The sample was deproteinized with ethanol, the eluate from ion exchange column was methylated and applied to GC/MS. Serum concentration of quinolinic acid (1.5±0.4μg/ml) was increased in the chronic hemodialysis patients as compared with that in the healthy subjects (0.10± 0.01, μg/ml). The serum concentration of quinolinic acid decreased to 0.25±0.12 μg/ml after conventional hemodialysis. After ultrafiltration by CF-25 (Amicon), the concentration of free quinolinic acid was measured. The concentration of the free quinolinic acid was the same as the serum level. This shows that quinolinic acid is not bound to serum proteins.
