Rat Brain Samples Research Articles

Acid-labile (amide) nitrogen metabolism of brain proteins.

Abstract—When the TCA‐insoluble fraction of samples of rat brain was extracted with organic (lipid) solvents, a soluble protein fraction was obtained which was metabolically active in the release and uptake of ammonia. The total nitrogen content of this fraction increased during aerobic incubation of slices of cerebral cortex and in brain samples after electrical stimulation of the rats, but under these conditions the content of protein‐bound, acid‐labile (amide) nitrogen decreased. Treatment of rats with intraperitoneally injected camphor caused a decrease in the content of acid‐labile nitrogen both in the proteins extracted into lipid solvents from the TCA precipitate of brain tissue samples and in the residual, washed TCA precipitate. By contrast, after treatment of rats with pentobarbitone, the content of proteinbound, acid‐labile nitrogen increased in the lipid solvent extract but decreased in the residual, washed TCA precipitate. After electrical stimulation of rats, the content of acid‐labile nitrogen in proteins of subcellular particles isolated from homogenates of brain exhibited dissimilar changes from control level: a pronounced decrease in the crude nuclear fraction but no change or a slight increase in the crude mitochondrial and in the combined microsomal and supernatant fractions. When slices of rat brain were incubated aerobically in the presence of glucose, ammonia was transferred from free amino acids to the acid‐labile (amide) nitrogen of protein. Evidence was obtained indicating the participation of aspartate and purine nucleotides in this transfer.

Photosorption and photodesorption of oxygen by zinc oxide: Product analyses

Caffeine and its metabolites theophylline, theobromine and paraxanthine have been determined in rat brain and serum samples by high-performance liquid chromatography with ultraviolet detection. The recovery, 85–103%, allowed quantification by external standard methods. The variability was found to be less than 3 and 7% for intra-day and inter-day assays, respectively. The detection limit, 1.57 ng of methylxanthines on column, allowed the determination of 62.5 ng/g or ml in biological material. Rats treated with 30 mg/kg caffeine (subcutaneously) were sacrificed at different times (1, 6, 12 and 24 h). Higher concentrations of methylxanthines (specially paraxanthine) were observed in the striatum than in the rest of the brain, and it was also observed that the clearance of methylxanthines was faster in serum than in brain structures.

Novel catalytic properties of yttrium oxide

Caffeine and its metabolites theophylline, theobromine and paraxanthine have been determined in rat brain and serum samples by high-performance liquid chromatography with ultraviolet detection. The recovery, 85–103%, allowed quantification by external standard methods. The variability was found to be less than 3 and 7% for intra-day and inter-day assays, respectively. The detection limit, 1.57 ng of methylxanthines on column, allowed the determination of 62.5 ng/g or ml in biological material. Rats treated with 30 mg/kg caffeine (subcutaneously) were sacrificed at different times (1, 6, 12 and 24 h). Higher concentrations of methylxanthines (specially paraxanthine) were observed in the striatum than in the rest of the brain, and it was also observed that the clearance of methylxanthines was faster in serum than in brain structures.