title: Effects of estradiol on release and disposition of norepinephrine from nerve endings.
abstract: Studies were performed to determine whether estradiol (E2) has a direct action on the release and disposition of norepinephrine (NE) from adrenergic nerve endings in isolated superfused canine saphenous veins. [3H]NE and is labeled metabolites were separated by column chromatography with measurement by liquid scintillation spectrometry. An increase in the spontaneous overflow of total 3H, [3H]NE, and [3H]dihydroxyphenylglycol ([3H]DOPEG) that occurred with 1 and 10 microgram/ml E2 in the superfusing medium suggested that E2 either induced NE release or interfered with intraneuronal NE storage. During electrical stimulation (ES), release of [3H]NE and [3H]DOPEG exceeded controls with 1 and 10 microgram/ml E2 in the superfusate, yet total 3H was little changed. The evoked release of [3H]DOPEG showed less of an elevation over its spontaneous efflux in E2-treated veins than in nontreated veins, suggesting that E2 may block neuronal reuptake of released NE. The efflux of O-methylated deaminated metabolites during and after ES was decreased by E2 treatment, suggesting also an inhibition of extraneuronal uptake of NE.
mesh_terms: D000320:Adrenergic Fibers / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D004285:Dogs; D004558:Electric Stimulation; D004958:Estradiol / Q000494:pharmacology*; D009411:Nerve Endings / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D012501:Saphenous Vein / Q000294:innervation; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D004958:Estradiol; D009638:Norepinephrine