title: Effect of dexmedetomidine on the release of [3H]-noradrenaline from rat kidney cortex slices: characterization of alpha2-adrenoceptor.
abstract: The presynaptic modulation of [3H]-noradrenaline (NA) release from rat kidney cortex slices, a method used for the first time, was investigated. Rat kidney cortex slices were loaded with [3H]-NA and the release of radioactivity at rest and in response to field stimulation was determined. The alpha(2)-adrenoceptor agonist, dexmedetomidine inhibited the stimulation-evoked release of NA from kidney slices in a concentration-dependent manner, whereas alpha(2)-adrenoceptor antagonist CH-38083 (7,8-methyenedioxy-14-alpha-hydroxyalloberbane HCl), an alpha(2)-adrenoceptor antagonists, enhanced it. When dexmedetomidine and BRL-44408, a selective alpha(2A) antagonist, were added together, the effect of dexmedetomidine was significantly antagonized. In contrast, ARC-239 (2-(2,4-(o-piperazine-1-yl)-ethyl-4,4-dimethyl-1,3-(2H, 4H)disoguinolinedione chloride), a selective alpha(2B)-antagonist, had no effect on the release and failed to prevent the effect of dexmedetomidine. Prazosin, an alpha(1)- and alpha(2B/C)-adrenoceptor antagonist enhanced the release evoked by field stimulation. It is therefore suggested that there is a negative feedback modulation of NA release at the sympathetic innervation of kidney cortex, and dexmedetomidine, a clinically used anesthetic adjunct inhibits the release via activation of alpha(2C)-adrenoceptors.
authors.affiliation: Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, PO Box 67, H-1450, Budapest, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Taoda
authors.forename: Y U
authors.initials: YU
authors.lastname: Adachi
authors.forename: Y
authors.initials: Y
authors.lastname: Uchihashi
authors.forename: K
authors.initials: K
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Satoh
authors.forename: E S
authors.initials: ES
authors.lastname: Vizi
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D001599:Berberine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D020927:Dexmedetomidine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005246:Feedback; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D054833:Isoindoles; D007546:Isoquinolines / Q000494:pharmacology; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011241:Prednisone / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D014316:Tritium
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000701:Analgesics, Opioid; D007093:Imidazoles; D007211:Indoles; D054833:Isoindoles; D007546:Isoquinolines; D010879:Piperazines; D018341:Receptors, Adrenergic, alpha-2; D001599:Berberine; D014316:Tritium; C048886:7,8-(methylenedioxy)-14-hydroxyberbane; D020927:Dexmedetomidine; D009020:Morphine; C032994:AR-C239; D011241:Prednisone; D009638:Norepinephrine; D011224:Prazosin; C072125:BRL 44408