The Uptake of Acetylpyrrolidinecholine — A False Cholinergic Transmitter — Into Mammalian Cerebral Cortical Synaptic Vesicles
It is now well established that cholinergic vesicles are metabolically heterogeneous organelles. It is, however, still under discussion whether this is due to an intravesicular or an intervesicular heterogeneity. March-banks and Israel (10), supporting the hypothesis of intravesicular heterogeneity, suggested that newly formed ACh is only loosely bound to the vesicles. On the other hand, a distinct vesicle fraction obtained from the electromotor system of Torpedo marmorata after its incubation with radioisotopes shows a high specific radioactivity (12), results which favor the view that intervesicular differences do exist. Biochemical and morphological findings suggest that these vesicles have already passed through an exoendocytotic cycle. If one assumes that these vesicles are located near the presynaptic membrane, the probability that they take up newly formed ACh and release it during stimulation would be higher than that of vesicles further away.
KeywordsSynaptic Vesicle Subcellular Fraction Presynaptic Membrane Synaptosomal Membrane Intraventricular Injection
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