Quantitative study of bromophenol blue diffusion in the rabbit brain

A quantitative analysis of bromophenol blue diffusion in the rabbit brain was conducted. Cannulas were stereotaxically implanted into the brains of rabbits. One month later, 0.5 μl of bromophenol blue was injected into the brain and allowed to diffuse for 2 hours. Then the rabbit was decapitated, and the brain was fixed, removed, and sectioned. The sections were scanned microspectrophotometrically across the area of dye. A theoretical curve was fitted to the data, and the diffusion coefficient for the bromophenol blue was calculated as 4.5 (±0.3) × 10 −8 cm 2/sec in the thalamus and 5.4 (±0.7) × 10 −8 cm 2/sec in the internal capsule. The diffusion of bromophenol blue in 1% agar gel was also measured, and the diffusion coefficient was calculated as 4.58 (±0.30) × 10 −6 cm 2/sec in this medium.