Abstract:
:1. In isolated detrusor strips from the guinea-pig urinary bladder, contractile responses to electrical field stimulation were mostly mediated by neurally released acetylcholine (ACh) and adenosine 5'-triphosphate (ATP). 2. 5-Hydroxytryptamine (5-HT) produced a concentration-dependent increase in the amplitude of stimulated detrusor strip contractions. The 5-HT concentration-response curve showed a biphasic profile: the high potency phase was obtained at sub-micromolar concentrations (10-300 nM), while the low potency phase in the range 1-30 microM. The maximum response of the first phase was 30% of the total 5-HT response. 3. Like 5-HT, the 5-HT3 receptor agonist, 2-methyl-5-hydroxytryptamine (2-methyl-5-HT: 0.3-100 microM), the 5-HT2 receptor agonist, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI: 30 nM-3 microM) and the 5-HT4 receptor agonist, 5-methoxytryptamine (5-MeOT: 0.1-30 microM) potentiated, though with lower potency, detrusor contractions. The resulting concentration-response curves were monophasic in nature. 2-Methyl-5-HT had a maximum effect comparable to that of 5-HT. By contrast, the maximal effects of DOI and 5-MeOT were only 20% and 30% of that elicited by 30 microM 5-HT, respectively. 4. The 5-HT3 receptor antagonist, granisetron (0.3 microM) had no effect on the high potency phase, but caused a rightward parallel shift of the low potency phase of the 5-HT curve (pKB = 7.3). Granisetron(0.3 microM) antagonized with comparable affinity (pKB = 7.1) 5-HT-induced responses after pharmacological isolation of 5-HT3 receptors with the 5-HT1/5-HT2 receptor antagonist, methiothepin (0.3 microM) and the 5-HT4 receptor antagonist, GR 125487 (30 nM). Granisetron (0.1, 0.3 and 1 microM) competitively antagonized the potentiating effect of 2-methyl-5-HT with an estimated pA2 of 7.3.5. Methiothepin (0.3 microM) and the 5-HT2A receptor antagonist, ketanserin (0.3 microM) produced a slight inhibition of the first phase of the 5-HT curve. In the presence of ketanserin, an equimolar concentration of methiothepin was ineffective in further reducing the effect of 5-HT. Similarly, the 5-HT4 receptor antagonist, GR 125487 (30 nM) slightly inhibited the first phase of the 5-HT curve. Conversely, this phase was suppressed when detrusor strips were coincubated with ketanserin (or methiothepin) and GR125487.6. In a separate set of experiments, the interactions of 5-HT with either the purinergic or cholinergic components of excitatory neuromuscular transmission were investigated. In the presence of hyoscine(1 microM), 5-HT was mostly effective at sub-micromolar concentrations, while in the presence of the P2-purinoceptor antagonist, suramin (300 microM), 5-HT-induced potentiation was mainly obtained with micromolar concentrations.7. Thus, in electrically stimulated detrusor strips from guinea-pig, 5-HT potentiated excitatory neuromuscular transmission by activating at least three separate neural 5-HT receptors. These include the 5-HT2A and 5-HT4 receptors, which mediate the 5-HT high potency phase mainly by activation of purinergic transmission. On the other hand, the potentiating effect caused by micromolar concentrations of 5-HT mostly involves cholinergic transmission and is mediated by the 5-HT3 receptors.
journal_name
Br J Pharmacoljournal_title
British journal of pharmacologyauthors
Messori E,Rizzi CA,Candura SM,Lucchelli A,Balestra B,Tonini Mdoi
10.1111/j.1476-5381.1995.tb14986.xsubject
Has Abstractpub_date
1995-06-01 00:00:00pages
677-83issue
4eissn
0007-1188issn
1476-5381journal_volume
115pub_type
杂志文章abstract::1. Immunized BP2 mice developed an acute bronchoconstriction in vivo and airway muscle contraction in vitro in response to ovalbumin (OA) and these contractions were dose dependent. 2. Methysergide or atropine inhibited OA-induced bronchoconstriction in vivo and airway muscle contraction in vitro. 3. Neostigmine poten...
journal_title:British journal of pharmacology
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abstract::1. Rat phrenic nerve preparations were used in vitro to study action potential amplitude and nerve conduction time under varying conditions of Pco(2) and sodium bicarbonate concentration in the surrounding Krebs solution.2. A correlation was found between action potential amplitude and pH but not between action potent...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1969.tb07980.x
更新日期:1969-01-01 00:00:00
abstract::1. The effects of lifarizine (RS-87476) on intracellular Ca2+ rises and the release of glutamate from rat cerebrocortical synaptosomes depolarized with 30 mM KCl were investigated by use of entrapped fura 2 and exogenous glutamate dehydrogenase. 2. Prior (1 min) addition of lifarizine decreased 30 mM KCl-induced total...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1996.tb15380.x
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abstract::1. The effects of diprafenone and propafenone on transmembrane action potential were examined and compared in papillary muscles and single ventricular myocytes isolated from guinea-pig hearts. 2. In papillary muscles, both diprafenone and propafenone > or = 10(-6) M caused a significant and dose-dependent decrease in ...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1992.tb14529.x
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abstract::The discovery of the nitric oxide/cGMP pathway was the basis for our understanding of many normal physiological functions and the pathophysiology of several diseases. Since the discovery and introduction of sildenafil, inhibitors of PDE5 have been the first-line therapy for erectile dysfunction (ED). The success of si...
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abstract:BACKGROUND AND PURPOSE:Sphingosine-1-phosphate (S1P) has been shown to be involved in the asthmatic disease as well in preclinical mouse experimental models of this disease. The aim of this study was to understand the mechanism(s) underlying S1P effects on the lung. EXPERIMENTAL APPROACH:BALB/c, mast cell-deficient an...
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doi:10.1111/bph.13033
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abstract::1. We have compared the effects of ouabain on the maintenance of gap junctional communication in rat aortic A7r5 smooth muscle cells, monkey COS-1 fibroblasts and human HeLa epithelial cells. 2. Ouabain (1 mM) interrupted dye coupling between confluent A7r5 cells within approximately 1 h, and high concentrations of ou...
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更新日期:2003-12-01 00:00:00
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doi:10.1111/j.1476-5381.1986.tb10172.x
更新日期:1986-01-01 00:00:00
abstract::1. The effects of several drugs, including antagonists of vasoactive intestinal peptide (VIP), and antisera to VIP or peptide histidine isoleucine (PHI), on relaxation responses of guinea-pig isolated trachea to electrical field stimulation (EFS) have been examined. 2. beta-Adrenoceptor blockade with propranolol only ...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1989.tb11847.x
更新日期:1989-03-01 00:00:00
abstract::1. This study was undertaken to evaluate in vivo the influence of amiodarone on the effects of triiodothyronine (T3) in brown adipose tissue (BAT) which are independent of thyroid hormone synthesis and of the conversion of thyroxine (T4) to T3. Thyroidectomized rats were given a replacement dose of T3 (0.5 mg kg(-1) p...
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doi:10.1038/sj.bjp.0702456
更新日期:1999-03-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1992.tb09036.x
更新日期:1992-03-01 00:00:00
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更新日期:2000-01-01 00:00:00
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更新日期:2015-04-01 00:00:00
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journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1985.tb11109.x
更新日期:1985-12-01 00:00:00
abstract::1 Rats treated for seven days with seryl-trihydroxybenzylhydrazine (benserazide), and inhibitor of peripheral aromatic L-amino acid decarboxylase (500 mg/kg, daily, i.p.) alone or in combination with L-DOPA methylester (500 mg/kg, daily, i.p.) for seven days showed a moderate but significant decrease of liver aldehyde...
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abstract::1. The present study was aimed to determine whether propranolol improves contractile function of the ischaemic/reperfused heart through protection of the mitochondrial function during ischaemia. 2. Isolated perfused rat hearts were subjected to 35-min ischaemia followed by 60-min reperfusion. Pre-treatment with propra...
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abstract::1. A crude preparation of toxin was extracted from a sample of mussels Mytilus edulis, part of a batch responsible for many cases of paralytic shellfish poisoning.2. The crude extract was partially purified by absorption on sodium Amberlite ion-exchange resin. Two toxins were recovered by elution from the Amberlite, a...
journal_title:British journal of pharmacology
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journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1971.tb09934.x
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abstract::1 The effects of isoprenaline, propranolol and phosphodiesterase inhibitors on (3)H-transmitter overflow elicited by low frequency nerve stimulation were determined in the isolated perfused spleen of the cat.2 (-)-Isoprenaline (0.14, 1.4, and 14 nM) produced a concentration-dependent increase in [(3)H]-transmitter ove...
journal_title:British journal of pharmacology
pub_type: 杂志文章
doi:10.1111/j.1476-5381.1978.tb07779.x
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abstract::1. The rat spinal cord in vitro has been used to assess the effect of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) on the dorsal root evoked extracellular ventral root reflex (DR-VRR) and the intracellular excitatory postsynaptic potential (e.p.s.p.) in ventral horn neurones and motoneurones. 2. CNQX (1-5 microM) produ...
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abstract::1 The effects of general anaesthetics on the responses of neurones to iontophoretically applied L-glutamate have been examined in slices of the guinea-pig olfactory cortex in vitro. 2 Concentrations of pentobarbitone, ether, methoxyflurance, trichloroethylene and alphaxalone that are known to depress synaptic transmis...
journal_title:British journal of pharmacology
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doi:
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abstract::1. The specificity of several ganglion stimulants has been tested on the isolated guinea-pig ileum by measuring the dose ratios produced by concentrations of hexamethonium.2. Most ganglion stimulants are also active at postganglionic receptors, some as blocking agents (for example, lobeline and dimethylphenylpiperazin...
journal_title:British journal of pharmacology
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doi:10.1111/j.1476-5381.1971.tb07093.x
更新日期:1971-05-01 00:00:00
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更新日期:2005-07-01 00:00:00
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journal_title:British journal of pharmacology
pub_type: 杂志文章,评审
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更新日期:2011-10-01 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
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更新日期:2001-03-01 00:00:00