Abstract:
:1. The aim of this study was to determine the conditions under which the alpha2-adrenoceptor agonist UK14304 produces vasoconstriction in the porcine isolated ear artery. 2. UK14304 (0.3 microM) produced a small contraction of porcine isolated ear arteries which was 7.8+/-3.3% of the response to 60 mM KCl. Similar sized contractions were obtained after precontraction with either 30 nM angiotensin II, or 0.1 microM U46619 (8.2+/-1.8% and 10.2+/-2.6% of 60 mM KCl response, respectively). However, an enhanced alpha2-adrenoceptor response was uncovered if the tissue was precontracted with U46619, and relaxed back to baseline with 1-2 microM forskolin before the addition of UK14304 (46.9+/-9.6% of 60 mM KCl response). 3. The enhanced responses to UK14304 in the presence of U46619 and forskolin were not inhibited by the alpha1-adrenoceptor antagonist prazosin (0.1 microM), but were inhibited by the alpha2-adrenoceptor antagonist rauwolscine (1 microM), indicating that the enhanced responses were mediated via postjunctional alpha2-adrenoceptors. 4. In the presence of 0.1 microM U46619 and 1 mM isobutylmethylxanthine (IBMX), 1 microM forskolin produced an increase in [3H]-cyclic AMP levels in porcine isolated ear arteries. Addition of 0.3 microM UK14304 prevented this increase. 5. The enhanced UK14304 response was dependent upon the agent used to relax the tissue. After relaxation of ear arteries precontracted with 10 nM U46619 and relaxed with forskolin the UK14304 response was 46.9+/-9.6% of the 60 mM KCl response, and after relaxation with sodium nitroprusside (SNP) the response was 24.8+3.3%. However, after relaxation of the tissue with levcromakalim the UK14304 response was only 8.2+/-1.7%, which was not different from the control response in the same tissues (12.2+/-5.6%). An enhanced contraction was also obtained after relaxation of the tissue with the cyclic AMP analogue dibutyryl cyclic AMP (23.2+/-1.3%) indicating that at least part of the enhanced response to UK14304 is independent of the ability of the agonist to inhibit cyclic AMP production. 6. Relaxation of U46619 contracted ear arteries with SNP could be inhibited by the NO-sensitive guanylyl-cyclase inhibitor 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) indicating that production of cyclic GMP is necessary for the relaxant effect of SNP. However, ODQ had no effect on the relaxation of tissue by forskolin, suggesting that this compound does not act via production of cyclic GMP. Biochemical studies showed that while forskolin increases the levels of cyclic AMP in the tissues, SNP had no effect on the levels of this cyclic nucleotide. 7. In conclusion, enhanced contractions to the alpha2-adrenoceptor agonist UK14304 can be uncovered in porcine isolated ear arteries by precontracting the tissue with U46619, followed by relaxation back to baseline with forskolin, SNP or dibutyryl cyclic AMP before addition of UK14304. There was a greater contractile response to UK14304 after relaxation with forskolin than with SNP or dibutyryl cyclic AMP, suggesting that cyclic AMP-dependent and- independent mechanisms are involved in the enhancement of the UK14304 response.
journal_name
Br J Pharmacoljournal_title
British journal of pharmacologyauthors
Roberts RE,Tomlinson AE,Kendall DA,Wilson VGdoi
10.1038/sj.bjp.0701935subject
Has Abstractpub_date
1998-07-01 00:00:00pages
1107-14issue
6eissn
0007-1188issn
1476-5381journal_volume
124pub_type
杂志文章abstract::1. Neural crest material from neurula stage Xenopus embryos was tissue cultured as small aggregates of cells or a single cell suspension. Isolated pigment cells differentiated after 2 days in culture. 2. Melatonin (10(-15) to 10(-13) M) induced pigment granule condensation; it was 10,000 times more effective than any ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1977.tb07554.x
更新日期:1977-12-01 00:00:00
abstract::1. Nociceptin, the endogenous ORL(1) receptor agonist inhibited the motor response to electrical-field stimulation in the rat anococcygeus muscle. This effect was characterized using the peptide ligands acetyl-Arg-Tyr-Tyr-Arg-Trp-Lys-NH(2) (Ac-RYYRWK-NH(2)), acetyl-Arg-Tyr-Tyr-Arg-Ile-Lys-NH(2) (Ac-RYYRIK-NH(2)) and [...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0703583
更新日期:2000-09-01 00:00:00
abstract::1. The possible involvement of nitric oxide (NO) in the induction and expression of morphine tolerance and dependence was studied in mice. A two-day repeated injection regimen was used to induce morphine tolerance and dependence. Tolerance was assessed by the tail flick test and physical dependence by naloxone challen...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb15280.x
更新日期:1996-03-01 00:00:00
abstract::Allergic inflammatory responses contribute to the symptoms of a number of diseases including atopic dermatitis, asthma and rhinitis. Cationic proteins are released from inflammatory cells and levels are known to be raised in disease states. Using an in vivo model of acute inflammation, we investigated the characterist...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0704172
更新日期:2001-08-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Inflammasomes are multimeric complexes that facilitate caspase-1-mediated processing of the pro-inflammatory cytokines IL-1β and IL-18. Clinical hypertension is associated with renal inflammation and elevated circulating levels of IL-1β and IL-18. Therefore, we investigated whether hypertension i...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/bph.13230
更新日期:2016-02-01 00:00:00
abstract::1. Neurally-evoked output of newly synthesized [3H]-acetylcholine from the rat phrenic nerve was measured in the absence of cholinesterase inhibitors. 2. Noradrenaline and isoprenaline enhanced neurally-evoked transmitter output markedly. Moreover, immediately after the application of noradrenaline the basal tritium e...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1988.tb11574.x
更新日期:1988-07-01 00:00:00
abstract::1. The effects of balloon injury on the reactivity of ipsilateral and contralateral carotid arteries were compared to those observed in arteries from intact animals (control arteries). 2. Carotid arteries were obtained from Wistar rats 2, 4, 7, 15, 30 or 45 days after injury and mounted in an isolated organ bath. Reac...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0705732
更新日期:2004-05-01 00:00:00
abstract::1. A series of 5-hydroxytryptamine (5-HT) receptor agonists including 5-HT, 5-carboxamidotryptamine (5-CT) and sumatriptan produced little or no contraction of rabbit isolated mesenteric arteries under resting tone conditions, even at concentrations up to 10(-4) M. 2. When the same agonists were retested in mesenteric...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1995.tb13228.x
更新日期:1995-01-01 00:00:00
abstract::Prostaglandin E(2) (PGE(2)) increased adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation in tracheal epithelial cells and concomitantly decreased the production/secretion of immunoreactive endothelin (irET). Naturally occurring prostanoids and selective and non-selective EP receptor agonists showed the foll...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0703886
更新日期:2001-03-01 00:00:00
abstract:BACKGROUND AND PURPOSE:Calcitonin gene-related peptide (CGRP) is a potent vasodilator, implicated in the pathogenesis of migraine. CGRP activates a receptor complex comprising, calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1). In vitro studies indicate recycling of CLR●RAMP1 is ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.2012.02129.x
更新日期:2012-12-01 00:00:00
abstract::1. Inhibition of human polymorphonuclear leucocyte (PMN) function by adenosine was studied with respect to effects of adenosine on intracellular cyclic AMP and calcium during the PMN respiratory burst. 2. The adenosine analogue 5'-N-ethylcarboxamide-adenosine (NECA) and L-N6-phenyl-isopropyl-adenosine (L-PIA) inhibite...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1989.tb12028.x
更新日期:1989-07-01 00:00:00
abstract::The effects of aconitine, an Aconitum alkaloid, on spontaneous inhibitory and excitatory postsynaptic currents (IPSCs and EPSCs respectively) were investigated in the mechanically dissociated rat ventromedial hypothalamic (VMH) neurons in which native presynaptic nerve terminals remained intact. Under current-clamp co...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0704517
更新日期:2002-02-01 00:00:00
abstract::1 This study investigated the effects of soluble complement receptor type 1 (sCR1) or sCR1sLex, agents which function as a complement inhibitor or as a combined complement inhibitor and selectin adhesion molecule antagonist, respectively, on the infarct size and cardiac troponin T (cTnT) release caused by regional myo...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0702889
更新日期:1999-11-01 00:00:00
abstract:BACKGROUND AND PURPOSE:(-)-Englerin A (EA) is a potent cytotoxic agent against renal carcinoma cells. It achieves its effects by activation of transient receptor potential canonical (TRPC)4/TRPC1 heteromeric channels. It is also an agonist at channels formed by the related protein, TRPC5. Here, we sought an EA analogue...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/bph.14128
更新日期:2018-03-01 00:00:00
abstract::1. Unique among the phospholipids, phosphatidylserine depresses brain energy metabolism when injected intravenously into mice in the form of sonicated liposomes. The possibility that this effect results from a metabolic transformation of phosphatidylserine is examined in this paper. 2. A strong enhancement of the phos...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1979.tb08708.x
更新日期:1979-12-01 00:00:00
abstract::1 Adenosine, adenosine monophosphate and adenosine triphosphate (ATP) depressed the firing rate of neurones in the rat cerebral cortex when applied by microinontophoresis. 2 4-Aminopyridine, also applied iontophoretically blocked the depressant effects of the purines, without affecting responses to gamma-aminobutyric ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1980.tb08720.x
更新日期:1980-11-01 00:00:00
abstract::Chronic heart failure (HF) is characterized by left ventricular (LV) structural remodeling, impaired function, increased circulating noradrenaline (NA) levels and impaired responsiveness of the myocardial beta-adrenoceptor (betaAR)-adenylyl cyclase (AC) system. In failing hearts, inhibition of the sodium/proton-exchan...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0706714
更新日期:2006-05-01 00:00:00
abstract::1. The effector mechanism of intestinal necrosis in rat anaphylaxis was studied following several complementary approaches: (i) the use of monoclonal antibodies (mAb) belonging to different classes (IgG1, IgG2b and IgE anti-DNP), (ii) the assay of mediators, and (iii) the use of pharmacological tools. 2. Lethality and...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1994.tb13197.x
更新日期:1994-08-01 00:00:00
abstract::1. The expression of hepatocyte growth factor (HGF) is essential for normal placental development although its function is unknown. In this study we examined the effect of HGF on trophoblast cell motility and invasion of fibrin gels and investigated the possible role of nitric oxide (NO) in this process. 2. The human ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0702757
更新日期:1999-09-01 00:00:00
abstract::1 The D3 dopamine receptor presumably activates Gi/Go subtypes of G-proteins, like the structurally analogous D2 receptor, but its signalling targets have not been clearly established due to weak functional signals from cloned receptors as heterologously expressed in mostly non-neuronal cell lines. 2 In this study, re...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0702905
更新日期:1999-11-01 00:00:00
abstract:BACKGROUND AND PURPOSE:We previously reported that NCX 2057, a compound comprising a nitric oxide (NO)-releasing moiety and the natural antioxidant, ferulic acid (FA), inhibits pro-inflammatory mediators through NO-mediated gene regulation. Here, we have assessed the activities of NCX 2057 in models of inflammatory and...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.2009.00324.x
更新日期:2009-09-01 00:00:00
abstract::1. Ezetimibe potently inhibits the transport of cholesterol across the intestinal wall, thereby reducing plasma cholesterol in preclinical animal models of hypercholesterolemia. The effect of ezetimibe on known absorptive processes was determined in the present studies. 2. Experiments were conducted in the hamster and...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0704260
更新日期:2001-09-01 00:00:00
abstract:BACKGROUND AND PURPOSE:In the setting of nitrate tolerance, endothelium-dependent relaxation is reduced in several types of peripheral vessels. However, it is unknown whether chronic in vivo administration of nitroglycerine modulates such relaxation in cerebral arteries. EXPERIMENTAL APPROACH:Isometric force and smoot...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0707562
更新日期:2008-01-01 00:00:00
abstract::The effects of pretreatment with 16,16-dimethyl prostaglandin E2 (DmPGE2) on the recovery of gastric mucosal 'barrier' parameters after ethanol-induced damage were studied using an ex vivo chamber preparation in the rat. DmPGE2 (4-40 micrograms kg-1) significantly reduced the extent of haemorrhagic damage to the gastr...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1985.tb11105.x
更新日期:1985-12-01 00:00:00
abstract::The response to vasoactive agents of microvessels of the rat was tested in vivo by direct microscopic observation of the exteriorized mesentery and assessment of cutaneous vascular permeability changes with Evans blue. The constrictor response to a standard amount of noradrenaline in mesenteric microvessels was fully ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1984.tb16217.x
更新日期:1984-11-01 00:00:00
abstract::1. Voltage-operated calcium channel (VOCC) antagonists are effective antihypertensive and antianginal agents but they also depress myocardial contractility. 2. We compared four L-type calcium channel antagonists, felodipine, nifedipine, amlodipine and verapamil and a relatively T-type selective calcium channel antagon...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0702045
更新日期:1998-09-01 00:00:00
abstract::Homocysteine is a sulphur-containing non-proteinogenic amino acid. Hyperhomocysteinaemia (HHcy), the pathogenic elevation of plasma homocysteine as a result of an imbalance of its metabolism, is an independent risk factor for various vascular diseases, such as atherosclerosis, hypertension, vascular calcification and ...
journal_title:British journal of pharmacology
pub_type: 杂志文章,评审
doi:10.1111/bph.13988
更新日期:2018-04-01 00:00:00
abstract::1 The ability of drugs to inhibit noradrenaline accumulation and to release noradrenaline was studied in the isolated anococcygeus muscle of the rat. 2 Noradrenaline, tyramine, 2-amino,6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (ADTN), 2-amino,6,7-dimethoxy-1,2,3,4-tetrahydronaphthalene (dimethyl ADTN), and 5-hydroxy...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1978.tb07798.x
更新日期:1978-07-01 00:00:00
abstract::1. Leptin, a pleiotropic hormone believed to regulate body weight, has recently been associated with inflammatory states and immune activity. Here we have studied the effect of leptin on expression of IFN-gamma-induced nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2), both prominent markers of macrophage act...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1038/sj.bjp.0704903
更新日期:2002-11-01 00:00:00
abstract::1. Extracellular recording of the stimulus-evoked population spike in the CA1 region of rat hippocampal slices in vitro was performed in order to investigate whether lappaconitine affects neuronal excitability. Lappaconitine is a diterpene alkaloid of plants of the Aconitum genus and has analgesic properties. 2. The r...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1996.tb15440.x
更新日期:1996-06-01 00:00:00