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Abstract —The influence of 1‐norepinephrine on the accumulation of [14C]choline by nuclei‐free homogenates and synaptosomes of guinea‐pig brain was studied. Kinetic analysis of choline accumulation by guinea‐pig brain resulted in both high and low affinity Michaelis constants. Norepinephrine stimulated the high affinity choline transport process but not the low and the magnitude of its stimulation in 3 different brain regions was correlated with the choline acetyltransferase activity of those regions. Depletion of norepinephrine from the brainstem by pretreatment with the catecholamine depleter alpha‐methyl‐para‐tyrosine significantly decreased the maximal velocity of choline transport. Both the alpha adrenergic receptor blocker phentolamine and the beta adrenergic receptor blocker propranalol inhibited norepinephrine induced stimulation of choline transport. Cocaine stimulated choline transport at low concentrations and pretreatment of animals with reserpine significantly antagonized cocaine's stimulation of choline transport. The results suggest that endogenous norepinephrine may modify the high affinity choline transport process in guinea‐pig brain.
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Carroll et al. (1975) studied this question.
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