Uptake ofpara-tyramine andmeta-tyramine into slices of the caudate nucleus and hypothalamus of the rat

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Abstract
The kinetics of the uptake ofp-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 obtainedK m andV max 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 largerK m andV max values, with the velocity of uptake being in the order dopamine>m-tyramine>p-tyramine. 2,4-Dinitrophenol (DNP) and ouabain reduced all uptakes in the caudate, but reduced only the “high”-affinity uptake ofm-tyramine and the “low”-affinity uptake of dopamine in the hypothalamus.