Redistribution of Adenine Derivatives Among Subcellular Fractions From Guinea Pig Neocortical Tissues, on Incubation in Vitro

After the brief in vitro exposure of guinea‐pig neocortical tissue to [ 14 C]adenine, synaptosomal fractions prepared from the incubated tissue contained about 6% of its retained 14 C. On continued incubation and superfusion with or without stimulation, the synaptosomal proportion of the 14 C increased, while the protein and K content of the fraction underwent smaller changes only. Colchicine, 0.5 m m , diminished the synaptosomal enrichment in [ 14 C]adenine derivatives and also in some cases increased the 14 C effluent from tissues to superfusates. Colchicine also diminished the uptake of adenosine, but not of adenine, to the neocortical tissues. It is concluded that nerve terminal regions receive adenine derivatives from other tissue components as part of their normal metabolism, and that much of this can arrive by extracellular fluids; transport cytoplasmically is not excluded.