Transport of quinolinic acid into rabbit and rat brain

The transport metabolism of ³H]quinolinic acid in the central nervous system of rabbits and rats were studied. In vitro ³H]quinolinic acid was not readily accumulated by isolated choroid plexus. After the intraventricular injection of tracer quantities of ³H]quinolinic acid, the ³H]quinolinic acid did not enter the brain as readily as concurrently injected ¹⁴C]mannitol and was not metabolized, The permeability-surface area constant for ³H]quinolinic acid at the rat blood-brain barrier was 1.5±1.3×10^–5 sec^–1 compared to 2.8±0.4×10^–5 sec^–1 for ³H]mannitol. Our results suggest that: 1) ³H]quinolinic acid is transported in the CNS by passive diffusion and 2) is not metabolized.