Abstract:
:1. During the past few years it has been shown that the sympatholytic effect resulting from localized microinjection of clonidine and other imidazolines into the rostral ventrolateral medulla (RVL) results from activation of 'imidazoline' receptors (I1 receptors) rather than from an alpha 2-adrenoceptor-mediated effect. 2. The relative contributions of these two receptor systems to the hypotensive action of systemically administered clonidine have not been studied. Clonidine has affinity for both I1 and alpha 2-adrenoceptors; guanabenz represents a useful pharmacological tool, since it activates only the alpha 2-adrenoceptor. 3. Antagonists acting at both I1 and alpha 2-adrenoceptors (idazoxan) and at only alpha 2-adrenoceptors (SK&F 86466; 6-chloro-3-methyl-2,3,4,5-tetrahydro-3-benzazepine) are available. Idazoxan (1 mg kg-1, i.v.) and SK&F 86466 (3 mg kg-1, i.v.) produced an equivalent degree of blockade of the pressor response to guanabenz or clonidine in the pithed rat, a response mediated by the alpha 2-adrenoceptor. 4. Guanabenz (30 micrograms kg-1, i.v.) and clonidine (10 micrograms kg-1, i.v.) lowered blood pressure in the chloralose-anaesthetized spontaneously hypertensive rat by 48 +/- 4.6 mmHg and 44 +/- 5.4 mmHg, respectively; this response, for either agonist, was blocked by both idazoxan and SK&F 86466. 5. These data show that the hypotensive effect of intravenously administered clonidine results from activation of central alpha 2-adrenoceptors, with no significant contribution from an I1-mediated effect. Thus clonidine can lower blood pressure by different receptor mechanisms, dependent on the route of administration.
journal_name
Br J Pharmacoljournal_title
British journal of pharmacologyauthors
Hieble JP,Kolpak DCdoi
10.1111/j.1476-5381.1993.tb14012.xsubject
Has Abstractpub_date
1993-12-01 00:00:00pages
1635-9issue
4eissn
0007-1188issn
1476-5381journal_volume
110pub_type
杂志文章abstract::1 The isolated perfused ear of the rabbit connected to the body only by its nerve, was used to investigate the influence of prostaglandin F2alpha on the algesic effect of bradykinin and acetylcholine. 2 Bradykinin and acetylcholine, following intra-arterial injection into the isolated perfused ear elicited a dose-rela...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1977.tb08390.x
更新日期:1977-03-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Inhaled glucocorticoid (ICS)/long-acting β2 -adrenoceptor agonist (LABA) combination therapy is a recommended treatment option for patients with moderate/severe asthma in whom adequate control cannot be achieved by an ICS alone. Previously, we discovered that LABAs can augment dexamethasone-induc...
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journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1983.tb10508.x
更新日期:1983-05-01 00:00:00
abstract::1 The effects of microiontophoretically applied morphine and its interactions with the effects of microiontophoretic applications of either acetylcholine, (-)-noradrenaline or 5-hydroxytryptamine have been studied on single neurones in the brain stem of rats anaesthetized with urethane.2 Morphine excited or inhibited ...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1974.tb09591.x
更新日期:1974-01-01 00:00:00
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pub_type: 杂志文章
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更新日期:1977-04-01 00:00:00
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更新日期:1998-10-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1993.tb12836.x
更新日期:1993-02-01 00:00:00
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pub_type: 杂志文章
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更新日期:1980-01-01 00:00:00
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journal_title:British journal of pharmacology
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更新日期:2011-01-01 00:00:00
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journal_title:British journal of pharmacology
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更新日期:1988-08-01 00:00:00
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journal_title:British journal of pharmacology
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更新日期:2002-02-01 00:00:00
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journal_title:British journal of pharmacology
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更新日期:1970-05-01 00:00:00
abstract::1. The present study was designed to investigate tolerance to several pharmacological effects of apomorphine. 2. Changes in blood pressure, heart rate, plasma noradrenaline levels, rectal temperature, respiratory rate and retching plus vomiting were compared after administration of apomorphine (200 micrograms kg-1, i....
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abstract::1. The responses of rat isolated aortae to vasoconstrictor and vasodilator agents have been studied in 14-day streptozotocin-diabetic rats. The effects of treatment with the aldose reductase inhibitor, ponalrestat, on these responses have also been investigated. 2. Maximum contractile responses and aortic sensitivity ...
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更新日期:1994-10-01 00:00:00
abstract::1. The aim of this study was to investigate the cardiovascular effects of a novel, potent and specific phosphodiesterase 5 (PDE 5) inhibitor, 1,3 dimethyl-6-(2-propoxy-5-methane sulphonylamidophenyl)-pyrazolo[3,4-d]pyrimidin-4-(5H)-one (DMPPO) in phenylephrine-precontracted rat aortic rings and different in vivo rat p...
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更新日期:1996-07-01 00:00:00
abstract::1. The modification by Bay K 8644 of the vasodilator effects of nifedipine, diltiazem, nicorandil and nitroglycerin was investigated in the femoral arterial bed of anaesthetized dogs. 2. The right femoral artery was cannulated and its arterial bed was perfused with autologous blood at a constant pressure slightly high...
journal_title:British journal of pharmacology
pub_type: 杂志文章
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更新日期:1988-01-01 00:00:00
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更新日期:2006-05-01 00:00:00
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