Search results for "Muscarinic Agonists"
showing 10 items of 15 documents
Muscarinic inhibition of endogenous noradrenaline release from rabbit isolated trachea: receptor subtype and receptor reserve.
1994
The aim of the present study was to characterize putative muscarine receptors on sympathetic nerve terminals in the rabbit trachea. Release of endogenous noradrenaline from in vitro incubated rabbit trachea was evoked by electrical field stimulation (3 Hz, 540 pulses) and quantified by high performance liquid chromatography with electrochemical detection. The muscarine receptor agonist oxotremorine inhibited the evoked release of noradrenaline completely at 1 mumol/l (EC50: 64 nmol/l). The concentration response curve was very steep (Hill coefficient of 2.3). Scopolamine shifted the concentration response curve of oxotremorine to the right (-log KB 8.48) demonstrating specific, inhibitory m…
The use of pilocarpine in opioid-induced xerostomia
2001
Oral dryness can be a symptom of asystemic disease, an adverse effect of anticholin-ergic, antiadrenergic or cytotoxic drug treatment, orit can be due to local radiotherapy. Opioid use isstrongly associated with xerostomia, although themechanism for this remains unclear; in one studypatients receiving morphine were four times morelikely to have a dry mouth than patients taking otherdrugs known to cause xerostomia.
Inhibition of human detrusor contraction by a urothelium derived factor.
2003
Stimulating muscarinic receptors in pig bladder urothelium causes the release of a diffusable factor that inhibits contractions of the underlying detrusor muscle. We investigated whether the contractions of human detrusor strips elicited by the muscarinic agonist carbachol, electrical field stimulation, KCl or the neurokinin receptor agonist neurokinin A are affected by the urothelium.Paired intact and urothelium denuded muscle strips were placed in modified gassed Tyrode's solution at 37C. Cumulative concentration-response curves to carbachol or KCl were constructed. In other tissues the strips were stimulated electrically (1 to 40 Hz) with trains of square wave pulses 20 seconds in durati…
Release of acetylcholine from murine embryonic stem cells: Effect of nicotinic and muscarinic receptors and blockade of organic cation transporter
2012
The non-neuronal cholinergic system is widely expressed in nature. The present experiments were performed to characterize the non-neuronal cholinergic system in murine embryonic stem cells (CGR8 cell line).CGR8 cells were cultured in gelatinized flasks with Glasgow's buffered minimal essential medium (Gibco, Germany). Acetylcholine was measured by HPLC combined with bioreactor and electrochemical detection.CGR8 cells contained 1.08±0.12 pmol acetylcholine/10(6) cells (n=7) which was reduced to 0.50±0.06 pmol/10(6) cells (n=6; p0.05) in the presence (4h) of 30μM bromoacetylcholine to block choline acetyltransferase. A time-dependent release of acetylcholine into the incubation medium was dem…
Adrenoceptor- and cholinoceptor-mediated mechanisms in the regulation of 5-hydroxytryptamine release from isolated tracheae of newborn rabbits
1996
Abstract 1. Isolated tracheae of newborn rabbits were incubated in vitro and the outflow of 5-hydroxytryptamine (5-HT) was determined by h.p.l.c. with electrochemical detection. Evidence has previously been provided that this 5-HT outflow derives from neuroendocrine epithelial (NEE) cells of the airway mucosa. 2. Phenylephrine (1, 10 and 30 microM) enhanced the outflow of 5-HT by 80, 290 and 205%, respectively. 5-HT outflow evoked by 10 microM phenylephrine was not affected by the presence of the neurotoxin tetrodotoxin (1 microM). 3. Rauwolscine, ARC 239 (an alpha(2B)-adrenoceptor preferring antagonist), yohimbine and prazosin antagonized the effect of 10 microM phenylephrine in a concentr…
The Sources of Ca2+ for Muscarinic Receptor-induced Contraction in the Rat Ileum
1996
Abstract The contractile responses obtained by activation of different muscarinic receptor subtypes in the longitudinal muscle of the rat ileum and especially the responses of this muscle to acetylcholine in a Ca2+-free medium have been investigated. In Ca2+-containing solution, acetylcholine elicited similar concentration-dependent contractile responses in the duodenum, jejunum and ileum strips of the rat intestine. The response to a maximal concentration of the agonist (1 μM) consisted of a rapid phasic response followed by a slower tonic one. Nifedipine completely relaxes or inhibits the sustained response and only partially diminishes the phasic one, which suggests that the phasic contr…
Gastric relaxation induced by apigenin and quercetin: Analysis of the mechanism of action
2009
Abstract Aims Recently, flavonoids have been shown to cause murine gastric relaxation. In the present study we examined the mechanism of action underlying gastric relaxation induced by apigenin and quercetin in isolated mouse stomach. Main methods The mechanical activity from the whole stomach was detected as changes in the endoluminal pressure and the response to increasing concentrations of both flavonoids were tested before and after different pharmacological treatments. Key findings Apigenin and quercetin-induced a concentration-dependent gastric relaxation, apigenin being more potent than quercetin. The responses were unaffected by 2′5′dideoxyadenosine, an inhibitor of adenylate cyclas…
In vitro tracheal hyperresponsiveness to muscarinic receptor stimulation by carbachol in a rat model of bleomycin-induced pulmonary fibrosis
2006
Summary 1 Bleomycin-induced lung injury is widely used as an experimental model to investigate the pathophysiology of pulmonary fibrosis but the alterations in the pharmacological responsiveness of airways isolated from bleomycin-exposed animals has been scarcely investigated. The aim of this study was to examine the in vitro tracheal responses to muscarinic receptor stimulation with carbachol in a rat bleomycin model. 2 Concentration–response curves to carbachol (10 nm to 0.1 mm) were obtained in tracheal rings isolated from Sprague–Dawley rats 14 days after endotracheal bleomycin or saline. The intracellular calcium signal in response to carbachol (10 μm) was measured by epifluorescence m…
Anti-inflammatory and antioxidant effects of muscarinic acetylcholine receptor (mAChR) activation in the rat hippocampus
2019
AbstractRecently we found that acute treatment with Oxotremorine (Oxo), a non-selective mAChRs agonist, up-regulates heat shock proteins and activates their transcription factor heat shock factor 1 in the rat hippocampus. Here we aimed to investigate: a) if acute treatment with Oxo may regulate pro-inflammatory or anti-inflammatory cytokines and oxidative stress in the rat hippocampus; b) if chronic restraint stress (CRS) induces inflammatory or oxidative alterations in the hippocampus and whether such alterations may be affected by chronic treatment with Oxo. In the acute experiment, rats were injected with single dose of Oxo (0.4 mg/kg) and sacrificed at 24 h, 48 h and 72 h. In the CRS ex…
Receptor phosphorylation does not mediate cross talk between muscarinic M(3) and bradykinin B(2) receptors.
1999
This study examined cross talk between phospholipase C-coupled muscarinic M3and bradykinin B2receptors coexpressed in Chinese hamster ovary (CHO) cells. Agonists of either receptor enhanced phosphoinositide signaling (which rapidly desensitized) and caused protein kinase C (PKC)-independent, homologous receptor phosphorylation. Muscarinic M3but not bradykinin B2receptors were also phosphorylated after phorbol ester activation of PKC. Consistent with this, muscarinic M3receptors were phosphorylated in a PKC-dependent fashion after bradykinin B2receptor activation, but muscarinic M3receptor activation did not influence bradykinin B2receptor phosphorylation. Despite heterologous phosphorylatio…