Abstract
Our laboratory has previously characterized a high affinity choline uptake system (HAChUS) in Limulus tissues and synaptosomes. We report here on the characterization of the HAChUS in synaptosomes prepared selectively from central nervous system tissues shown to be enriched for presumed cholinergic functions; namely the protocerebrum, corpora pedunculata and abdominal ganglia. Synaptosomes were prepared from these tissues by means of a modification of the subfractionation procedure developed by Dowdall and Whittaker. In our modification, we harvested a PP 2L fraction exclusively from the S 2 fraction. Compared to the P 2L fraction, the PP 2L was greater than three times more efficient in [ 3H]choline uptake and was significantly more sensitive to inhibition with micromolar concentrations of hemicholinium-3. The PP 2L fraction HAChUS was shown to have characteristics common to the HAChUS of identified cholinergic tissues.
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