Abstract
1. The acetylcholine content of cortical slices from rat brain, was determined after incubation for 30 min in a medium containing acetylcholine (4 mug/ml.). The cholinesterase activity of the slices had been inhibited by pretreatment with 3,3-dimethyl-n-butyl 2-methylphosphonofluoridate (soman).2. Acetylcholine accumulated in the tissue slices, up to a concentration of about six times that in the medium.3. The uptake of acetylcholine was partly inhibited by potassium in high concentrations.4. Hemicholinium-3, O-ethyl S-diethylaminoethyl ethylphosphonothiolate, physostigmine, atropine and choline, in that order of potency, inhibited the accumulation of acetylcholine in the cortical slices, but soman and ethyl N,N-dimethyl phosphonoamidocyanate (tabun) had no effect on the uptake of acetylcholine.5. Substances interfering with energy metabolism, such as 2,4-dinitrophenol, oligomycin, sodium azide, amylobarbitone sodium and p-chloromercuribenzoate inhibited the uptake of acetylcholine. Ouabain had little inhibitory effect.6. In anaerobic conditions the accumulation of acetylcholine in the tissue slices was nearly blocked.7. The uptake of acetylcholine in the tissue slices was dependent on temperature. The Q(10) was about 2.8. Autoradiography of sections from slices in which (3)H-acetylcholine had accumulated showed a diffuse distribution of radioactivity in the cytoplasm of all cells. There was no visible preference for certain cells or cell structures.