Lack of Selectivity Between the Uptake of [3H] Adrenaline and [3H]Noradrenaline into Rat Hypothalamic Slices |
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Authors: | C. Routledge C. A. Marsden |
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Affiliation: | Department of Physiology and Pharmacology, Nottingham University Medical School, Nottingham, England |
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Abstract: | 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. |
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Keywords: | Adrenaline uptake Noradrenaline uptake Hypothalamus Adrener- gicneurones |
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