A reinterpretation of tyramine sympathomimetic effect and tachyphylaxis

In this commentary, the indirect sympathomimetic effect of tyramine and the phenomenon of tyramine tachyphylaxis are reinterpreted in terms of carrier-mediated exchange processes. Extracellular tyramine would exchange with intraterminal noradrenaline and, upon repeated tyramine administration, with a mixture of noradrenaline and tyramine progressively more enriched in the pharmacologically inactive amine.