Release of radiolabeled dopamine, p-tyramine, and m-tyramine from rat striatal slices by some aminotetralins.

The effect of several 2-aminotetralins (2ATs) on the uptake and release of [14C] dopamine and [2H]m- or [3H]p-tyramine by rat striatal slices was examined. 6,7-Dihydroxy-2AT (6,7OHAT) and 5,6-dihydroxy-2-methyl-AT (5,6OHMeAT) were the most potent uptake inhibitors as well as the most potent releasers of the three labeled amines. The 5-, 6-, and 7-hydroxy-2-N, N-dipropyl-ATs (5-, 6-, and 7OHdiPrAT) and 5,6-dihydroxy-2-N,N-dipropyl-AT (5,6OHdiPrAT) significantly inhibited the uptakes of the three labeled amines, but they released only the tyramines. The dipropyl substitutions of a 2AT appeared to confer a tyraminergic specificity to its release properties. To verify this supposition, 2AT was compared to 2-N,N-dipropyl-AT (diPrAT). Although 2AT released both [3H]p-tyramine and [14C]dopamine, diPrAT released only [3H]p-tyramine. None of the compounds, however, differentiated between m- and p-tyramine. It was concluded that the release of tyramines could be implicated in the actions of some of the 2ATs and that the tyramines can be transported independently from dopamine.