Uptake of histamine by rabbit hypothalamic slices.

The accumulation of [-14C] histamine into slices of rabbit hypothalamus was studied. All areas of hypothalamus took up histamine against a concentration gradient. The highest accumulation was into the infundibular area and the lowest into the mamillary body. The uptake did not correlate with the level of endogenous histamine. The uptake continued for at least two hours and a maximum tissue/medium ratio of about 5.6 was reached. The major part of radioactivity was chromatographically shown to be histamine. The uptake was temperature dependent and required sodium. It was not significantly inhibited by compound 48/80, but it could be inhibited with desipramine and 5-hydroxytryptamine. Therefore, the uptake of histamine shares many characteristics of the uptake of monoamines by brain slices, even if the rate of uptake appeared to be slower.