Lack of selectivity between the uptake of [3H]adrenaline and [3H]noradrenaline into rat hypothalamic slices.
The uptake of [3H]adrenaline and [3H]noradrenaline into rat hypothalamic slices was compared for determination of whether adrenaline uptake was independent of uptake into noradrenergic neurones. Kinetic analysis revealed a similar high-affinity uptake process for both adrenaline and noradrenaline, with Km and Vmax values within similar ranges. These uptakes were inhibited by desipramine and maprotiline in a dose-dependent manner, but the selective dopamine and 5-hydroxytryptamine uptake inhibitors benztropine and fluoxetine, respectively, were without effect. Competition for uptake sites by unlabelled adrenaline with [3H]adrenaline and [3H]-noradrenaline and by unlabelled noradrenaline with [3H]-adrenaline and [3H]noradrenaline was very similar. Lesioning of the major adrenaline-containing cell group (C1 cell group) decreased the hypothalamic adrenaline concentration but had no effect on hypothalamic [3H]adrenaline or [3H]noradrenaline uptake. The results suggest that exogenous adrenaline is largely taken up by high-affinity sites on noradrenergic nerve terminals.
D000818:Animals; D001590:Benztropine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D004837:Epinephrine / Q000378:metabolism*; D005473:Fluoxetine / Q000494:pharmacology; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008376:Maprotiline / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D005473:Fluoxetine; D001590:Benztropine; D008376:Maprotiline; D003891:Desipramine; D009638:Norepinephrine; D004837:Epinephrine