Uptake of para-tyramine and meta-tyramine into slices of the caudate nucleus and hypothalamus of the rat.

The kinetics of the uptake of p-tyramine, m-tyramine, and dopamine were investigated in slices of the hypothalamus and striatum of the rat in the presence of nialamide. When uptake was analyzed by a least-squares fit to a Lineweaver-Burk plot, each amine appeared to be concentrated by both a "low"-affinity and a "high"-affinity system in both brain regions. The obtained Km and Vmax values for the "high"-affinity uptake system for each amine in both brain regions were similar. In general terms, the uptake systems in the striatum exhibited larger Km and Vmax values, with the velocity of uptake being in the order dopamine less than m-tyramine less than p-tyramine. 2,4-Dinitrophenol (DNP) and ouabain reduced all uptakes in the caudate, but reduced only the "high"-affinity uptake of m-tyramine and the "low"-affinity uptake of dopamine in the hypothalamus.