The response of the isolated ileum of the guinea-pig to histamine is potentiated in the presence of 2-, 3-or 4-picolylamine. These compounds have been found to inhibit the histaminase and/or " diamine oxidase" of pig kidney. The three corresponding picolylmethylamines did not potentiate the response of the ileum to histamine; they were without significant affinity for the pig kidney oxidase. It is suggested that the potentiating action of the three primary amines is due to their inhibitory action on histaminase. The responses of the ileum to acetylcholine and 5-hydroxytryptamine were not potentiated.
Desipramine, a tricyclic antidepressant drug, almost completely prevents the accumulation of tritiated norepinephrine by sympathetic neurons of the rat heart after the injection of a tracer dose of the labeled amine. However, desipramine does not alter the accumulation of norepinephrine after the injection of a large dose of the neurohormone. Despite the failure of desipramine to block the neuronal uptake of norepinephrine, it still prevents exogenous norepinephrine from displacing the endogenous neurohormone (previously labeled with H(3)-norepinephrine) from intraneuronal storage sites.
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