Abstract:
:1. In vivo microdialysis in halothane-anaesthetized rats and synaptosomal [3H]-noradrenaline uptake studies in vitro were used to evaluate the effects of imidazole (medetomidine) and imidazoline (clonidine and UK 14,304) alpha 2-adrenoceptor agonists on extraneuronal levels of noradrenaline in the frontal cortex. 2. Levels of noradrenaline in the dialysate were increased by a depolarizing concentration of K+ (60 mM for 20 min) and substantially attenuated by reducing Ca2+ supply in the perfusate. These results suggest that spontaneous efflux of noradrenaline in the cortex is regulated predominantly by cation-dependent exocytotic mechanisms. 3. At a low perfusion concentration (0.5 microM), medetomidine, clonidine and UK 14,304 all reduced the level of noradrenaline in cortical dialysates. Continuous perfusion of the selective alpha 2-adrenoceptor antagonist, atipamezole (0.5 microM) caused a sustained increase in noradrenaline efflux and reversed the inhibitory effects of medetomidine. All these changes are consistent with drug actions at presynaptic alpha 2-adrenoceptors. 4. Higher concentrations of medetomidine (5-50 microM), but not clonidine or UK 14,304, evoked a non-desensitizing increase in noradrenaline efflux. This effect was not antagonized by 0.5 microM atipamezole. 5. The tricyclic noradrenaline reuptake inhibitor, desmethylimipramine (0.5-50 microM), increased noradrenaline efflux in a concentration-dependent manner. 6. The specific uptake of [3H]-noradrenaline into cortical synaptosomes was inhibited by medetomidine and desmethylimipramine with IC50 values of approximately 7 microM and 8 microM respectively. Neither clonidine nor UK 14,304 inhibited [3H]-noradrenaline uptake. 7. These results indicate that micromolar concentrations of the selective alpha2-adrenoceptor agonist,medetomidine, can augment extraneuronal levels of noradrenaline in the rat frontal cortex; this effect seems to involve an inhibition of noradrenaline reuptake rather than an action at alpha2-adrenoceptors.
journal_name
Br J Pharmacoljournal_title
British journal of pharmacologyauthors
Dalley JW,Stanford SCdoi
10.1111/j.1476-5381.1995.tb14962.xsubject
Has Abstractpub_date
1995-04-01 00:00:00pages
1717-23issue
8eissn
0007-1188issn
1476-5381journal_volume
114pub_type
杂志文章abstract::1. The diversity of alpha(2) and purinergic autoreceptor actions on action potential evoked calcium transients in single varicosities has been investigated using the calcium indicator Oregon Green 488 BAPTA-1. 2. During long trains of impulses (10 Hz for 30 s), the change in calcium concentration in varicosities from ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0702984
更新日期:1999-12-01 00:00:00
abstract::1. Measurements were made of the uptake, metabolism and release of [(3)H]-adrenaline by human platelets in citrated plasma or in an artificial medium.2. Radioactive adrenaline was not taken up at 0-2 degrees C. At 37 degrees C there was a slow uptake which continued for at least 5 hours.3. About half of the radioactiv...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1970.tb09903.x
更新日期:1970-08-01 00:00:00
abstract::1. We investigated the role of two conserved basic residues in the second transmembrane helix arginine 172 (R172) and lysine 179 (K179) of the VPAC(2) receptor. 2. Vasoactive intestinal polypeptide (VIP) activated VPAC(2) receptors with an EC(50) value of 7 nM, as compared to 150, 190 and 4000 nM at R172L, R172Q and K...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0704195
更新日期:2001-08-01 00:00:00
abstract::The diterpene, forskolin, is shown to produce a concentration-dependent, increase in short circuit current in two epithelial preparations, amphibian skin and rat colon. In the amphibian tissue the increase is sensitive to amiloride and due to an increase in electrogenic transepithelial sodium transport towards the ser...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1982.tb09187.x
更新日期:1982-05-01 00:00:00
abstract:BACKGROUND AND PURPOSE:The two longest C-termini of the purinergic P2X receptors occur in the P2X2 and P2X7 receptors and are thought to interact with multiple cytoplasmic proteins, among which are members of the cytoskeleton, including microtubules. In this work we asked whether disrupting the microtubule cytoskeleton...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.2011.01254.x
更新日期:2011-07-01 00:00:00
abstract::1. The potassium current in embryo spinal neurones of Xenopus consists of at least two kinetically distinct components with overlapping voltage-dependencies of activation. We investigated whether capsaicin might specifically block these components in acutely dissociated neurones from stage 37/38 embryos by use of stan...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb15680.x
更新日期:1996-09-01 00:00:00
abstract::The pharmaceutical industry is testing new potential drugs for their propensity to prolong human cardiac repolarization, and regards this as a sign of proarrhythmic risk. Many studies have dethroned the common perception that prolonged repolarization is a reliable surrogate marker for torsades de pointes (TdP) arrhyth...
journal_title:British journal of pharmacology
pub_type: 评论,杂志文章
doi:10.1038/sj.bjp.0707299
更新日期:2007-08-01 00:00:00
abstract::1. The mechanism of the inhibitory effect of dehydroemetine on the heart was investigated using (a) the spontaneously contracting isolated guinea-pig atrial preparation and (b), the electrically driven left atrial preparation.2. Dehydroemetine decreased the rate and amplitude of contraction of spontaneously contractin...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1972.tb06897.x
更新日期:1972-12-01 00:00:00
abstract::1. By use of patch-clamp techniques, the effects of SD-3212, a novel antiarrhythmic drug, on the calcium current (Ica), the sodium current (INa) and the muscarinic acetylcholine-receptor-operated potassium current (IK.ACh) were examined and compared with those of bepridil in guinea-pig single atrial cells. 2. SD-3212 ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1995.tb17237.x
更新日期:1995-11-01 00:00:00
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 effec...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1993.tb14012.x
更新日期:1993-12-01 00:00:00
abstract::Inhalation of cyclopropane in dogs, by the closed circuit method, for a fixed period, produced an emetic response during recovery from anaesthesia. Bilateral surgical ablation of the emetic chemoreceptor trigger zone of the area postrema rendered the dogs refractory to several times (3-6) the threshold emetic dose of ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1971.tb07174.x
更新日期:1971-09-01 00:00:00
abstract::1. A synthetic oxytocin analogue, [1-N-carbamoyl-hemicystine-2-O-methyltyrosine]-oxytocin (carbamoyl-methyloxytocin), has been tested as an antagonist to the actions of oxytocin and vasopressin on the uterus, the mammary gland and blood pressure.2. The analogue inhibited the response of the isolated rat uterus to both...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1970.tb09927.x
更新日期:1970-10-01 00:00:00
abstract::1. The noradrenaline (NA) concentration in the "heart" (atria and right ventricle) of male rats was estimated at different periods following adrenal demedullation. For 1-3 weeks after the operation there was, in all rats, a reduction in NA content of the tissue, whereas, after somewhat longer intervals, the concentrat...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1970.tb10335.x
更新日期:1970-01-01 00:00:00
abstract::Amyotrophic lateral sclerosis (ALS) is an adult onset disorder characterized by progressive neuromuscular junction (NMJ) dismantling and degeneration of motor neurons leading to atrophy and paralysis of voluntary muscles responsible for motion and breathing. Except for a minority of patients harbouring genetic mutatio...
journal_title:British journal of pharmacology
pub_type: 杂志文章,评审
doi:10.1111/bph.15276
更新日期:2020-09-28 00:00:00
abstract:BACKGROUND AND PURPOSE:Calu-3 cells are derived from serous cells of human lung submucosal glands, a prime target for therapy in cystic fibrosis (CF). Calu-3 cells can be cultured to form epithelia capable of transepithelial transport of chloride. A CF Calu-3 cell is not available. EXPERIMENTAL APPROACH:A retroviral v...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0707175
更新日期:2007-04-01 00:00:00
abstract::1 The effect of phenoxybenzamine on the efflux of [3H]-noradrenaline and the mechanical response to single pulse excitation of superfused guinea-pig vas deferens was determined to examine the validity of the currently accepted hypothesis of a presynaptic negative feedback system on adrenergic nerve terminals. 2 The ad...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1979.tb13686.x
更新日期:1979-06-01 00:00:00
abstract::1. The effects of prejunctional beta-adrenoceptor activation on electrically evoked noradrenaline (NA) and adenosine 5'-triphosphate (ATP) were studied by use of continuous amperometry and conventional intracellular recording techniques. Excitatory junction potentials (e.j.ps) were used as a measure of ATP release, an...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0700959
更新日期:1997-03-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Disruptions of executive function, including attentional deficits, are a hallmark of a number of diseases. ACh in the prefrontal cortex regulates attentive behaviour; however, the role of α7 nicotinic ACh receptor (α7nAChR) in attention is contentious. EXPERIMENTAL APPROACH:In order to probe att...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/bph.13260
更新日期:2015-10-01 00:00:00
abstract::1. We previously demonstrated that cyclopiazonic acid (CPA), an inhibitor of Ca(2+)-ATPase in the sarcoplasmic reticulum, induced rhythmic relaxations of active tension in the endothelium-denuded small arteries of the mesentery and the ear of the rabbit, but that this agent failed to induce rhythmic responses in the e...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb15392.x
更新日期:1996-05-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Dilatation of cerebral and dural arteries causes a throbbing, migraine-like pain, indicating that these structures are involved in migraine. Clinical trials suggest that adenosine 5'-triphosphate-sensitive K(+) (K(ATP)) channel opening may cause migraine by dilatating intracranial arteries, inclu...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/bjp.2008.86
更新日期:2008-05-01 00:00:00
abstract::Levetiracetam, the alpha-ethyl analogue of the nootropic piracetam, is a widely used antiepileptic drug (AED) that provides protection against partial seizures and is also effective in the treatment of primary generalized seizure syndromes including juvenile myoclonic epilepsy. Levetiracetam was discovered in 1992 thr...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/bjp.2008.221
更新日期:2008-08-01 00:00:00
abstract::1. Effects of KC399, an opener of ATP-sensitive K+ channels were investigated on membrane potential, isometric force and intracellular Ca2+ ([Ca2+]i) mobilization induced by acetylcholine (ACh) in smooth muscle from the rabbit trachea. 2. In these smooth muscle cells, ACh (0.1 and 1 microM) depolarized the membrane in...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1995.tb16642.x
更新日期:1995-08-01 00:00:00
abstract::1. The present study shows the effects of imipramine in a single dose (10 mg kg(-1), p.o.) or following repeated (14 days, twice a day) treatment on the level of mRNA coding for D2 dopamine receptors in the rat caudate putamen (CP). Repeated administration of imipramine resulted in the increase of the level of mRNA co...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0701681
更新日期:1998-03-01 00:00:00
abstract::1 In the guinea-pig vas deferens, grayanotoxin I (G-I), a diterpenic toxin isolated from certain ericaceous plants caused rhythmic contractions which were dose-dependent (5 x 10(-5) M - 10(-3) M); these followed an initial transient contraction.2 The G-I (3 x 10(-4) M)-induced contraction was markedly inhibited or abo...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1983.tb08806.x
更新日期:1983-03-01 00:00:00
abstract::1. We measured the effects of agonists and antagonists of metabotropic glutamate (mGlu) receptors (types 1 and 5) on NMDA-induced depolarization of mouse cortical wedges in order to characterize the mGlu receptor type responsible for modulating NMDA responses. We also characterized a number of mGlu receptor agents by ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0703904
更新日期:2001-02-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Post-operative ileus (POI) is induced by intestinal inflammation. Here, we aimed to clarify the effects of 5-HT3 receptor antagonists against POI. EXPERIMENTAL APPROACH:We administered three 5-HT3 receptor antagonists, ondansetron, tropisetron and palonosetron, to a mouse model of POI induced by...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/bph.13006
更新日期:2015-02-01 00:00:00
abstract::1. In the zymosan rat air pouch model of inflammation we have assessed the time dependence of phospholipase A2 (PLA2) accumulation in the inflammatory exudates as well as cell migration, myeloperoxidase activity, prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels. 2. A significant increase in PLA2 activity was d...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb15353.x
更新日期:1996-04-01 00:00:00
abstract::1. We studied the inhibitory effect of pituitary adenylate cyclase activating polypeptide (PACAP 1-27) on the increase in total pulmonary resistance (RL) caused either by allergen or histamine in anaesthetized, ventilated guinea-pigs. 2. PACAP 1-27 given via i.v. infusion (0.045-4.5 nmol kg-1 min-1) dose-dependently r...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1995.tb15897.x
更新日期:1995-07-01 00:00:00
abstract::1. The affinity of the alpha 1-adrenoceptor antagonist SB 216469 (also known as REC 15/2739) has been determined at native and cloned alpha 1-adrenoceptor subtypes by radioligand binding and at functional alpha 1-adrenoceptor subtypes in isolated tissues. 2. In radioligand binding studies with [3H]-prazosin, SB 216469...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb16009.x
更新日期:1996-11-01 00:00:00
abstract::1. A study has been made of the effects of cocaine and sympathetic denervation on responses of the cat spleen to (-)-noradrenaline and (-)-isoprenaline.2. Responses of isolated strips of spleen capsule to (-)-noradrenaline or to (-)-isoprenaline were not affected by reserpine-pretreatment.3. In adult cats, cocaine (1 ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1973.tb08255.x
更新日期:1973-08-01 00:00:00