Reserpine Metaraminol

Various sympathomimetic amines can be taken up into storage vesicles, leading to the stoichiometric displacement of part of the endogenous NA content (p-tyramine and -phenylethylamine). It is not clear that such amines are taken up by the same mechanism which is responsible for catecholamine uptake. For example, metaraminol is taken up by medullary vesicles by a process which does not require ATP. and is insensitive to inhibition by reserpine. Some amines, such as DA and -methylNA. appear to be taken up both by the reserpine-sensitive and reserpine-insensitive mechanisms. It may be that the latter mechanism can account for the uptake of exogenous catecholamines into storage vesicles in reserpine-treated animals, leading to a temporary restoration of adrenergic transmission. 

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