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Saternos HC, Almarghalani DA, Gibson HM, Meqdad MA, Antypas RB, Lingireddy A, AbouAlaiwi WA. Distribution and function of the muscarinic receptor subtypes in the cardiovascular system. Physiol Genomics 2017; 50:1-9. [PMID: 29093194 DOI: 10.1152/physiolgenomics.00062.2017] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Muscarinic acetylcholine receptors belong to the G protein-coupled receptor superfamily and are widely known to mediate numerous functions within the central and peripheral nervous system. Thus, they have become attractive therapeutic targets for various disorders. It has long been known that the parasympathetic system, governed by acetylcholine, plays an essential role in regulating cardiovascular function. Unfortunately, due to the lack of pharmacologic selectivity for any one muscarinic receptor, there was a minimal understanding of their distribution and function within this region. However, in recent years, advancements in research have led to the generation of knockout animal models, better antibodies, and more selective ligands enabling a more thorough understanding of the unique role muscarinic receptors play in the cardiovascular system. These advances have shown muscarinic receptor 2 is no longer the only functional subtype found within the heart and muscarinic receptors 1 and 3 mediate both dilation and constriction in the vasculature. Although muscarinic receptors 4 and 5 are still not well characterized in the cardiovascular system, the recent generation of knockout animal models will hopefully generate a better understanding of their function. This mini review aims to summarize recent findings and advances of muscarinic involvement in the cardiovascular system.
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Affiliation(s)
- Hannah C Saternos
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Daniyah A Almarghalani
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Hayley M Gibson
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Mahmood A Meqdad
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Raymond B Antypas
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Ajay Lingireddy
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
| | - Wissam A AbouAlaiwi
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo , Toledo, Ohio
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Fuder H, Muscholl E. Heteroreceptor-mediated modulation of noradrenaline and acetylcholine release from peripheral nerves. Rev Physiol Biochem Pharmacol 2006; 126:265-412. [PMID: 7886380 DOI: 10.1007/bfb0049778] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- H Fuder
- IKP-AKP, Professo Lücker GmbH, Grünstadt, Germany
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Toda N, Okamura T. The pharmacology of nitric oxide in the peripheral nervous system of blood vessels. Pharmacol Rev 2003; 55:271-324. [PMID: 12773630 DOI: 10.1124/pr.55.2.3] [Citation(s) in RCA: 219] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Unanticipated, novel hypothesis on nitric oxide (NO) radical, an inorganic, labile, gaseous molecule, as a neurotransmitter first appeared in late 1989 and into the early 1990s, and solid evidences supporting this idea have been accumulated during the last decade of the 20th century. The discovery of nitrergic innervation of vascular smooth muscle has led to a new understanding of the neurogenic control of vascular function. Physiological roles of the nitrergic nerve in vascular smooth muscle include the dominant vasodilator control of cerebral and ocular arteries, the reciprocal regulation with the adrenergic vasoconstrictor nerve in other arteries and veins, and in the initiation and maintenance of penile erection in association with smooth muscle relaxation of the corpus cavernosum. The discovery of autonomic efferent nerves in which NO plays key roles as a neurotransmitter in blood vessels, the physiological roles of this nerve in the control of smooth muscle tone of the artery, vein, and corpus cavernosum, and pharmacological and pathological implications of neurogenic NO have been reviewed. This nerve is a postganglionic parasympathetic nerve. Mechanical responses to stimulation of the nerve, mainly mediated by NO, clearly differ from those to cholinergic nerve stimulation. The naming "nitrergic or nitroxidergic" is therefore proposed to avoid confusion of the term "cholinergic nerve", from which acetylcholine is released as a major neurotransmitter. By establishing functional roles of nitrergic, cholinergic, adrenergic, and other autonomic efferent nerves in the regulation of vascular tone and the interactions of these nerves in vivo, especially in humans, progress in the understanding of cardiovascular dysfunctions and the development of pharmacotherapeutic strategies would be expected in the future.
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Affiliation(s)
- Noboru Toda
- Toyama Institute for Cardiovascular Pharmacology Research, Toyama Bldg., 7-13, 1-Chome, Azuchi-machi, Chuo-ku, Osaka 541-0052, Japan.
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Sauviat MP, Marquais M, Vernoux JP. Muscarinic effects of the Caribbean ciguatoxin C-CTX-1 on frog atrial heart muscle. Toxicon 2002; 40:1155-163. [PMID: 12165319 DOI: 10.1016/s0041-0101(02)00117-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effects of Caribbean ciguatoxin (C-CTX-1) isolated from horse-eye jack (Caranx latus) on the electrical and mechanical activities of frog auricle were studied. C-CTX-1 (1 pM-50 nM) dose-dependently shortened the duration of the plateau and the repolarizing phase of the action potential (AP). The AP shortening induced by C-CTX-1 (50 nM) was suppressed or prevented either by tetrodotoxin (TTX; 0.6 nM) or by atropine (0.1mM). C-CTX-1 (50 nM) prolonged the TTX (0.6 nM)-sensitive electrical response of the vagus nerve branches, which innervate the auricle. The C-CTX-1 (50 nM)-induced shortening of the plateau and of the repolarization phase were prevented or reversed by gallamine (20 microM) and pirenzepine (0.5 microM), respectively. C-CTX-1 (50 nM) decreased the amplitude of the peak contraction and shortened its duration. In the presence of gallamine (20 microM), C-CTX-1 decreased the amplitude of the peak contraction and shortened its duration in the presence of pirenzepine (0.5 microM). C-CTX-1 (50 nM) decreased the time constant of the relaxation phase of the peak contraction suggesting that it increased the Na(+)/Ca(2+) exchange activity. Acetylcholine (ACh; 1 pM) shortened APD, decreased the peak contraction and mimics the effects of C-CTX-1. In conclusion, the presented data show that C-CTX-1 released ACh from atrial cholinergic nerve terminals which activated M(1) and M(2) muscarinic receptors subtype (mAChR). Our findings suggest that M(1) and M(2) mAChR are present in frog atrial tissue and play a previously unrecognized role in the modulation of the AP duration and of the mechanical activity of cardiac tissue.
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Affiliation(s)
- Martin-Pierre Sauviat
- Laboratoire d'Optique et Biosciences, INSERM U 451, UMR CNRS 7645, Ecole Polytechnique-ENSTA, 91128, Palaiseau, France.
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Sand C, Peters SLM, Mathy MJ, Pfaffendorf M, van Zwieten PA. The effects of hypochlorite-induced oxidative stress on presynaptic M2-receptors at sympathetic nerve endings in the rat tail artery. AUTONOMIC & AUTACOID PHARMACOLOGY 2002; 22:127-32. [PMID: 12568130 DOI: 10.1046/j.1474-8673.2002.00253.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1 It was shown recently that stimulation of cardiac muscarinic M2-receptors revealed an enhanced negative inotropic response in isolated rat left atria after exposure to hypochlorite-induced oxidative stress. This phenomenon was not observed after stimulation of the cardiac A1-receptor, which like the M2-receptor is coupled to Gi-proteins. Since even the contractile response to M3-receptor stimulation was not amplified in the rat portal vein, we hypothesized a M2-receptor specificity of this hypochlorite-induced enhancement. 2 The present study was performed in order to investigate whether the sympathoinhibitory response to presynaptically located M2-receptor stimulation would also be modified after exposure to hypochlorite in the rat tail artery. We applied electrical field stimulation (EFS) in order to mimic sympathetic neurotransmission. 3 EFS increased the vascular tone frequency-dependently (0.3-4 Hz). EFS-induced vasoconstriction could be attenuated by acetylcholine (30 nM-1 microM) in a concentration-dependent manner. Hypochlorite (10 and 100 microM) did not affect the sympathoinhibitory effect of acetylcholine (100 nM). 4 In conclusion, in contrast to cardiac M2-receptors, hypochlorite did not amplify the sympathoinhibitory effects of presynaptic M2-receptors. The different responsiveness between neuronal and cardiac M2-receptors to hypochlorite may be explained by the different G-protein subunits involved in the activation of the underlying signalling cascade.
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Affiliation(s)
- C Sand
- Department of Pharmacotherapy, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, the Netherlands
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Jiang F, Li CG, Rand MJ. CHOLINERGIC PREJUNCTIONAL INHIBITION OF NITRERGIC NEUROTRANSMISSION IN THE GUINEA-PIG ISOLATED BASILAR ARTERY. Clin Exp Pharmacol Physiol 1999. [DOI: 10.1046/j.1440-1681.1999.03041.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Liu J, Lee TJ. Mechanism of prejunctional muscarinic receptor-mediated inhibition of neurogenic vasodilation in cerebral arteries. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H194-204. [PMID: 9887033 DOI: 10.1152/ajpheart.1999.276.1.h194] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) is a major transmitter in mediating cerebral neurogenic vasodilation in several species. Recent findings have suggested that acetylcholine, which is costored with NO in cerebral perivascular nerves, plays a role in modulating NO release, presumably by acting on muscarinic (M) receptors on nitric oxidergic nerve terminals. The present study was designed using an in vitro tissue bath technique to pharmacologically characterize the presynaptic muscarinic-receptor subtype(s) that mediate modulation of NO release and therefore neurogenic vasodilation and to investigate further the possible mechanisms involved in this presynaptic modulation in porcine basilar arteries. Transmural nerve stimulation (TNS) elicited a frequency-dependent, tetrodotoxin-sensitive relaxation. The relaxation was abolished by nitro-L-arginine (30 microM) and was completely reversed by L-arginine and L-citrulline, but not by their D-enantiomers. Atropine (0.01-1 microM), pirenzepine (an M1-receptor antagonist, 0. 01-1 microM), and methoctramine (an M2-receptor antagonist, 0.01-1 microM), but not 4-DAMP (an M3-receptor antagonist) or tropicamide (an M4-receptor antagonist) at concentrations as high as 10 mM, significantly increased the TNS-elicited relaxation. This relaxation, on the other hand, was significantly attenuated by arecaidine but-2-ynyl ester tosylate (an M2-receptor agonist, 0.1 microM) but was not affected by McN-A-343 (an M1-receptor agonist, 1 microM). Double-labeling immunohistochemical study demonstrated that perivascular M2 receptor-immunoreactive fibers were completely coincident with NADPH diaphorase fibers. Furthermore, the muscarinic receptor-mediated modulation of TNS-elicited relaxation was completely prevented by omega-conotoxin GVIA (0.1 microM), a specific N-type Ca2+ channel inhibitor, but was still observed in the presence of tetraethylammonium (1 mM), 8-bromo-cAMP (0.5 mM), and pertussis toxin. It is concluded that the presynaptic M2 receptors on porcine cerebral perivascular nitric oxidergic nerves mediate inhibition of NO release. The inhibition is due primarily to a decreased Ca2+ influx through N-type Ca2+ channels.
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Affiliation(s)
- J Liu
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois 62794-9629, USA
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8
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Toda N, Ayajiki K, Okamura T. Inhibition of nitroxidergic nerve function by neurogenic acetylcholine in monkey cerebral arteries. J Physiol 1997; 498 ( Pt 2):453-61. [PMID: 9032692 PMCID: PMC1159214 DOI: 10.1113/jphysiol.1997.sp021871] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. Modification by endogenous or exogenous acetylcholine and vasoactive intestinal polypeptide (VIP) of vasodilatation mediated by nitric oxide (NO) released from nitroxidergic nerves was studied in isolated monkey cerebral arteries. In arterial strips denuded of endothelium, transmural electrical stimulation (2-20 Hz) produced relaxations that were abolished by tetrodotoxin. 2. The relaxation response was attenuated by acetylcholine, and the attenuation was reversed by atropine. Attenuation was also observed with AF-DX 116, an antagonist of the muscarinic acetylcholine receptor subtype, M2. NO-induced relaxation was not affected by acetylcholine. Neurogenic relaxation was also inhibited by physostigmine and potentiated by atropine. 3. VIP in concentrations that elicited slight relaxation did not alter the response to nerve stimulation. In the strips showing tachyphylaxis to VIP, the neurogenic response was not inhibited. 4. Histochemical studies of whole-mount preparations revealed nerve fibres with NO synthase and VIP immunoreactivity, and also acetylcholinesterase, suggesting the presence of perivascular nitroxidergic, VIPergic and cholinergic innervation. 5. It is concluded that the actions of nitroxidergic nerve fibres on the monkey cerebral artery are inhibited by nerve-released acetylcholine acting on prejunctional muscarinic receptors, possibly of the M2 subtype. Despite the presence of VIP immunoreactive nerve fibres and the ability of exogenous VIP to relax the artery, there is no evidence supporting either a prejunctional modulation of nitroxidergic nerve function by VIP or a role for VIP as a vasodilatory neurotransmitter.
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Affiliation(s)
- N Toda
- Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan.
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Encabo A, Ferrer M, Salaíces M, Manso R, Marín J, Balfagón G. Effect of clenbuterol on the modulation of noradrenaline release in the rat tail artery. JOURNAL OF AUTONOMIC PHARMACOLOGY 1996; 16:243-50. [PMID: 9023668 DOI: 10.1111/j.1474-8673.1996.tb00358.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
1. Exposure of rat tail arteries to clenbuterol, a beta 2-adrenoceptor agonist, for 20 or 90 min, did not change or increase, respectively, tritium overflow induced by electrical field stimulation in arteries preincubated with [3H]-noradrenaline (NA). This facilitatory effect was antagonized by propranolol. 2. Phentolamine increased the evoked overflow four-fold, which was not modified by 90 min incubation with clenbuterol. In rats pretreated with clenbuterol for 2 weeks, the stimulated overflow was not enhanced by this beta 2-agonist, and the increase produced by phentolamine was markedly diminished. 3. Contractile responses induced by electrical field stimulation were not modified or increased (only at low frequencies) by preincubation with clenbuterol for 20 or 90 min, respectively. This effect was inhibited by propranolol. 4. In arteries precontracted with 5-hydroxytryptamine, clenbuterol (10 nM-10 microM) produced small relaxations, which were reduced by propranolol plus phentolamine and not modified by phentolamine or 90 min exposure to clenbuterol. 5. These results indicate that prolonged exposure of rat tail arteries to clenbuterol produces a facilitation of NA release mediated by activation of presynaptic beta 2-adrenoceptors, which may be involved on the enhancement of contractile responses to electrical stimulation induced by clenbuterol. However, chronic treatment with this beta-agonist desensitizes these receptors.
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Affiliation(s)
- A Encabo
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain
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10
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Drijfhout WJ, Grol CJ, Westerink BH. Parasympathetic inhibition of pineal indole metabolism by prejunctional modulation of noradrenaline release. Eur J Pharmacol 1996; 308:117-24. [PMID: 8840122 DOI: 10.1016/0014-2999(96)00283-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The role of the parasympathetic nervous system in rat pineal indole metabolism was investigated by transpineal in vivo microdialysis. On-line coupling to a high performance liquid chromatography system with fluorescence detection (HPLC-FD) allowed simultaneous analysis of three major indolic compounds from the pineal, i.e. serotonin, N-acetylserotonin and melatonin. Infusion of the muscarinic receptor agonists, carbachol and oxotremorine, during the dark period resulted in a marked decrease of melatonin release. This effect was suggested to be mediated by a decrease in N-acetyltransferase activity, since a similar decrease was seen in N-acetylserotonin release, while serotonin levels increased simultaneously. Nicotine did show a very slight effect on the three indoles under these circumstances. Neostigmine failed to influence pineal indole metabolism, indicating that the endogenous tonus of acetylcholine release is either absent or extremely low in the middle of the dark period. The involvement of sympathetic innervation in the muscarinic effects was investigated by measurement of noradrenaline release from the pineal by sensitive off-line HPLC-FD analysis of noradrenaline in the dialysates. Carbachol markedly decreased the noradrenaline input during the infusion. Noradrenaline release returned to baseline values immediately after infusion with carbachol. These data suggest that the in vivo inhibitory effect of muscarinic receptor agonists on pineal melatonin production is mediated by presynaptic muscarinic receptors, located on the sympathetic nerve endings. This prejunctional inhibition of noradrenaline release causes a reduced induction of N-acetyltransferase activity, resulting in decreased melatonin release.
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Affiliation(s)
- W J Drijfhout
- University Centre for Pharmacy, Department of Medicinal Chemistry, Groningen, Netherlands.
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11
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Sánchez-Merino JA, Marín J, Balfagón G, Ferrer M. Involvement of alpha 2-adrenoceptors and protein kinase C on nicotine-induced facilitation of noradrenaline release in bovine cerebral arteries. GENERAL PHARMACOLOGY 1995; 26:827-33. [PMID: 7635258 DOI: 10.1016/0306-3623(94)00259-p] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. Incubation of bovine cerebral vessels (previously exposed to [3H]-noradrenaline) with nicotine for 30 sec produced a facilitation of the electrically-induced noradrenaline release, which was antagonized by hexamethonium, a blocker of nicotinic receptors. This facilitation was not observed when the incubation time was increased to 20 or 75 min. 2. Rauwolscine, an alpha 2-adrenoceptor blocker, enhanced and phorbol 12, 13-dibutyrate reduced the facilitator effect produced by 30 sec exposure to nicotine. 3. These data suggest: (1) presynaptic nicotinic receptors produce a facilitation of stimulated noradrenaline release; these receptors are easily desensitized by increasing the incubation time with nicotine; (2) protein kinase C and alpha 2-adrenoceptors appear to be involved in this process.
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Affiliation(s)
- J A Sánchez-Merino
- Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain
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12
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Dauphin F, MacKenzie ET. Cholinergic and vasoactive intestinal polypeptidergic innervation of the cerebral arteries. Pharmacol Ther 1995; 67:385-417. [PMID: 8577823 DOI: 10.1016/0163-7258(95)00022-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Acetylcholine and vasoactive intestinal polypeptide are not only two vasoactive agonists that predominantly induce a vasodilatation of the cerebral arteries, but also correspond to neurotransmitters that innervate the various anatomical segments of the cerebral vasculature. The distinct patterns of the cerebrovascular cholinergic and vasoactive intestinal polypeptidergic innervation, their neurochemistry, in vitro and in vivo pharmacology, as well as the putative pathophysiological implications of these neurotransmission systems are critically summarized on the basis of the most recently published literature.
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Affiliation(s)
- F Dauphin
- Université de Caen, URA 1829 CNRS, Centre Cyceron, France
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13
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Lincoln J. Innervation of cerebral arteries by nerves containing 5-hydroxytryptamine and noradrenaline. Pharmacol Ther 1995; 68:473-501. [PMID: 8788567 DOI: 10.1016/0163-7258(95)02017-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Noradrenaline (NA)-containing nerves, mainly originating in the sympathetic superior cervical ganglia, supply large and small cerebral arteries. In large cerebral arteries, nerves containing serotonin (5-hydroxytryptamine, 5-HT) may represent neuronal uptake of circulating 5-HT by sympathetic nerves. 5-HT-containing nerves supplying small pial vessels probably have a central origin in the dorsal raphe nucleus. In most species, NA is a weak vasoconstrictor (alpha 1- or alpha 2-adrenoceptors), while 5-HT is a potent vasoconstrictor (5-HT2 or 5-HT1-like receptors) of large cerebral arteries. In contrast, both NA and 5-HT tend to cause vasodilatation in small pial vessels and arterioles. Adrenergic and serotonergic transmission can be modulated by pH, a range of putative neurotransmitters and neuromodulators, and by the endothelium. Sumatriptan, a 5-HT1-like receptor agonist, has been shown to be effective in the treatment of migraine. Changes in NA- or 5-HT-containing nerves and/or in the responses of cerebral vessels to NA and 5-HT have been observed in a variety of vascular disorders, including cerebral vasospasm following subarachnoid haemorrhage, hypertension, and atherosclerosis.
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Affiliation(s)
- J Lincoln
- Department of Anatomy and Developmental Biology, University College London, UK
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Shen A, Mitchelson F. Characterization of the muscarine receptor subtype on sympathetic nerve endings in the rat caudal artery. Eur J Pharmacol 1994; 252:167-72. [PMID: 7512503 DOI: 10.1016/0014-2999(94)90593-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The prejunctional muscarine receptor on sympathetic nerves in the rat caudal artery was characterized using several selective antagonists. The inhibitory response of carbachol on vasoconstriction elicited by sympathetic nerve stimulation was antagonized by benzhexol (trihexyphenidyl; pKB 7.1), heptane-1,7-bis(dimethyl-3'-phthalimidopropyl ammonium bromide) (C7/3-phth; pKB 6.5) and hexahydrosiladifenidol (HHSiD; apparent pKB 6.0). These pKB values suggest that the receptor most closely resembles the muscarine M2 receptor subtype rather than the muscarine M1, M3 or M4 receptor subtypes.
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Affiliation(s)
- A Shen
- School of Pharmacology, Victorian College of Pharmacy (Monash University), Parkville, Australia
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Bartolami S, Ripoll C, Planche M, Pujol R. Localisation of functional muscarinic receptors in the rat cochlea: evidence for efferent presynaptic autoreceptors. Brain Res 1993; 626:200-9. [PMID: 8281431 DOI: 10.1016/0006-8993(93)90580-g] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the rat cochlea, the activation of muscarinic receptors stimulates the hydrolysis of phosphoinositides but the importance of this muscarinic effect is still unknown. In order to find out about the role of the muscarinic receptors in the cochlea, we examined their functional distribution within this organ. This was achieved by measuring the formation of [3H]inositol phosphates induced by carbachol (1 mM) in two regions of the cochlea: the modiolus and the organ of Corti. At both sites, carbachol enhanced the accumulation of inositol phosphates in an atropine-sensitive way. These stimulations were completely antagonised by 4-diphenylacetoxy-N-methyl piperidine methiodide (1 microM) but unchanged by pirenzepine (1 microM). In cochleas depleted of outer hair cells by a treatment with amikacin, the carbachol-induced formation of inositol phosphates is not altered with respect to control, undamaged cochleas. Conversely, when the medial cholinergic axons which form synapses with the outer hair cells are destroyed by the section of the crossed olivocochlear bundle the carbachol-stimulated inositol phosphates response is reduced by 35% in the organ of Corti. This section has no effect in the modiolus, despite the degeneration of some modiolar fibers. Our results show that functional muscarinic receptors are distributed both in the organ of Corti and in the modiolus. These two structures contain presumably the same class of cholinoceptor. The effects of selective destruction clearly demonstrate that a population of muscarinic receptors is located on presynaptic membranes at the level of the medial axon-outer hair cell contacts. They also point to spiral ganglion neurons and/or the Schwann cells as sites for the functional cholinoceptors in the modiolus.
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Affiliation(s)
- S Bartolami
- Laboratoire de Neurobiologie de l'Audition, INSERM U-254, Montpellier, France
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Racké K, Brunn G, Elsner M, Wessler I. Effects of indomethacin on muscarinic inhibition of endogenous noradrenaline release from rat isolated trachea. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1993; 348:21-7. [PMID: 8377837 DOI: 10.1007/bf00168532] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The release of endogenous noradrenaline from rat isolated tracheae was evoked by electrical field stimulation (3 Hz, 540 pulses) in the presence of yohimbine, desipramine and tyrosine. The muscarine receptor agonist oxotremorine concentration-dependently inhibited the evoked release of noradrenaline by 95% at 1 mumol/l, EC50 values in two series of experiments 41 and 57 nmol/l, respectively. The effect of oxotremorine was antagonized by the non-selective muscarine receptor antagonist scopolamine (10-1000 nmol/l) in a manner suggesting a simple competitive interaction (slope of Schild plot -0.94; pA2 value 8.88). However, the M2 selective muscarine receptor antagonist methoctramine (0.1-10 mumol/l) affected the action of oxotremorine in a manner suggesting a complex interaction (slope of Schild plot -0.47). Addition of indomethacin (3 mumol/l) caused an increase of the evoked release of noradrenaline by 45% and low concentrations of oxotremorine (0.01 and 0.1 mumol/l, but not 1 mumol/l) became less effective resulting in a slight shift to the right of the concentration response curve (EC50 169 nmol/l). Moreover, in the presence of indomethacin methoctramine (0.1-10 mumol/l) antagonized the effects of oxotremorine in a manner suggesting a simple competitive interaction (slope of Schild plot -0.93, pA2 value 7.61). In the presence of indomethacin, the concentration response curve of oxotremorine was only slightly shifted to the right in the presence of the M1 receptor selective antagonist pirenzepine (1 mumol/l, -log KB 6.1) and not significantly affected by the M3 receptor selective antagonist p-fluoro-hexahydrosiladifenidol (1 mumol/l). In conclusion, the release of noradrenaline in the rat trachea is inhibited via presynaptic muscarine heteroreceptors of the M2 subtype.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Racké
- Department of Pharmacology, University of Frankfurt, Germany
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Ayajiki K, Okamura T, Toda N. Nitric oxide mediates, and acetylcholine modulates, neurally induced relaxation of bovine cerebral arteries. Neuroscience 1993; 54:819-25. [PMID: 8332264 DOI: 10.1016/0306-4522(93)90251-a] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Helical strips of bovine basilar arteries denuded of the endothelium responded to transmural electrical stimulation with frequency-dependent relaxations that were abolished or markedly attenuated by treatment with tetrodotoxin, oxyhemoglobin and Methylene Blue. Relaxations induced by vasoactive intestinal polypeptide and calcitonin gene-related peptide were not affected by oxyhemoglobin and Methylene Blue. The neurally induced relaxation was not attenuated in the artery made unresponsive to these peptides by successive application. The relaxation caused by nerve stimulation was markedly inhibited by treatment with NG-nitro-L-arginine, a nitric oxide synthase inhibitor, which did not inhibit the relaxation caused by exogenously applied nitric oxide. The inhibition was reversed by L-arginine but not by the D-enantiomer. Exogenously applied acetylcholine did not alter the tone of endothelium-denuded arteries. Neurally induced relaxations were attenuated by treatment with acetylcholine and physostigmine and were significantly potentiated by atropine. It may be concluded that the relaxation induced by nerve stimulation is mediated by nitric oxide, but not by vasoactive intestinal polypeptide or calcitonin gene-related peptide, derived from vasodilator nerves innervating the bovine basilar artery, and the nerve function is inhibited prejunctionally via muscarinic receptor activation by acetylcholine released from cholinergic nerves but is not influenced by vasoactive intestinal polypeptide.
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Affiliation(s)
- K Ayajiki
- Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan
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Casado MA, Marín J, Salaices M. Evidence for M1 muscarinic cholinoceptors mediating facilitation of noradrenaline release in guinea-pig carotid artery. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1992; 346:391-4. [PMID: 1436124 DOI: 10.1007/bf00171079] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The muscarinic agonists acetylcholine (1-50 mumol/l), carbachol (1-10 mumol/l) and McN-A-343 (1-50 mumol/l, selective for M1 receptors) increased, in a concentration-dependent manner, the electrically-evoked tritium overflow from guinea-pig carotid arteries preincubated with [3H]-noradrenaline. The increase caused by acetylcholine was not modified by hexamethonium (300 mumol/l) but was reduced by the muscarinic receptor antagonists methylatropinium (0.5 and 1 nmol/l, non-selective), pirenzepine (1 and 5 nmol/l, M1-selective), methoctramine (1 and 5 mumol/l, M2-selective) and p-fluoro-hexahydro-sila-difenidol (0.1-1 mumol/l, M3-selective). The order of potencies (expressed as negative logarithms of concentrations that reduced by 50% the facilitatory effect of acetylcholine) was: methyl-atropinium (9.93) > pirenzepine (8.83) > p-fluoro-hexahydro-siladifenidol (6.81) > or = methoctramine (6.20). These results demonstrate the existence of facilitatory M1 receptors modulating noradrenaline release in blood vessels.
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Affiliation(s)
- M A Casado
- Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma, Madrid, Spain
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