Choline Uptake and Metabolism in Affinity‐Purified Cholinergic Nerve Terminals from Rat Brain

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Abstract
Cholinergic nerve terminals were affinity purified from rat caudate nucleus. These terminals possessed both high-(KT= 2.7 μM) and low- (KT= 58 μM) affinity uptake mechanisms for exogenous [3H]choline. The proportion of [3H]choline acetylated was reduced from 75 to 30% under conditions of anoxia and hypoglycaemia, whereas the phosphorylation of choline increased from 4 to 52%. Choline phosphorylation was also increased when the terminals were preloaded with choline. The affinity-purified terminals were shown to release acetylcholine in a Ca2+-dependent manner on depolarization. The relationship between choline acetylation and phosphorylation in the cholinergic nerve terminal is discussed.