Further studies on the effect of various drugs on the uptake of tyramine-3H and formation of octopamine-3H in the rat heart

Abstract

Pretreatment with desipramine, phenindamine, cocaine, and diphenhydramine significantly inhibited the conversion of tyramine-³H to octopamine-³H by the rat heart in vivo presumably by blocking the adrenergic neuronal uptake of the latter amine. Triprolidine pretreatment had no significant effect on amine uptake. These results are compared with previously reported data from this laboratory and show that the order of efficacy obtained with the drugs for the blockade of tyramine-³H uptake correlates well with their ability to block norepinephrine uptake and to inhibit the tyramine-induced increase in phosphorylase a activity. It is concluded that tyramine and norepinephrine utilize the same uptake system.