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Zhang Y, Su Z, An L, Li L, Wei M, Ge D, Liu H. miR‐98 acts as an inhibitor in chronic constriction injury‐induced neuropathic pain via downregulation of high‐mobility group AT‐hook 2. J Cell Biochem 2019; 120:10363-10369. [PMID: 30659647 DOI: 10.1002/jcb.28320] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 11/28/2018] [Indexed: 01/29/2023]
Affiliation(s)
- Yang Zhang
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Zhen Su
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Li‐Jun An
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Lin Li
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Meng Wei
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Dong‐Jian Ge
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
| | - Hai‐Lin Liu
- Department of Anesthesiology The Affiliated Huai'an No.1 People's Hospital of Nanjing Medical University Huai'an Jiangsu China
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Wei R, Lunn SE, Tam R, Gust SL, Classen B, Kerr PM, Plane F. Vasoconstrictor stimulus determines the functional contribution of myoendothelial feedback to mesenteric arterial tone. J Physiol 2018; 596:1181-1197. [PMID: 29411383 DOI: 10.1113/jp274797] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/17/2018] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS In isolated resistance arteries, endothelial modulation of vasoconstrictor responses to α1 -adrenoceptor agonists occurs via a process termed myoendothelial feedback: localized inositol trisphosphate (InsP3 )-dependent Ca2+ transients activate intermediate conductance Ca2+ -activated K+ (IKCa ) channels, hyperpolarizing the endothelial membrane potential to limit further reductions in vessel diameter. We demonstrate that IKCa channel-mediated myoendothelial feedback limits responses of isolated mesenteric arteries to noradrenaline and nerve stimulation, but not to the thromboxane A2 mimetic U46619 or to increases in intravascular pressure. In contrast, in the intact mesenteric bed, although responses to exogenous noradrenaline were limited by IKCa channel-mediated myoendothelial feedback, release of NO and activation of endothelial small conductance Ca2+ -activated K+ (SKCa ) channels in response to increases in shear stress appeared to be the primary mediators of endothelial modulation of vasoconstriction. We propose that (1) the functional contribution of myoendothelial feedback to arterial tone is determined by the nature of the vasoconstrictor stimulus, and (2) although IKCa channel-mediated myoendothelial feedback may contribute to local control of arterial diameter, in the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction. ABSTRACT Constriction of isolated resistance arteries in response to α1 -adrenoceptor agonists is limited by reciprocal engagement of inhibitory endothelial mechanisms via myoendothelial feedback. In the current model of feedback, agonist stimulation of smooth muscle cells results in localized InsP3 -dependent Ca2+ transients that activate endothelial IKCa channels. The subsequent hyperpolarization of the endothelial membrane potential then feeds back to the smooth muscle to limit further reductions in vessel diameter. We hypothesized that the functional contribution of InsP3 -IKCa channel-mediated myoendothelial feedback to limiting arterial diameter may be influenced by the nature of the vasoconstrictor stimulus. To test this hypothesis, we investigated the functional role of myoendothelial feedback in modulating responses of rat mesenteric resistance arteries to the adrenoceptor agonist noradrenaline, the thromboxane A2 mimetic U46619, increases in intravascular pressure and stimulation of perivascular sympathetic nerves. In isolated arteries, responses to noradrenaline and stimulation of sympathetic nerves, but not to U46619 and increases in intravascular pressure, were modulated by IKCa channel-dependent myoendothelial feedback. In the intact mesenteric bed perfused under conditions of constant flow, responses to exogenous noradrenaline were modulated by myoendothelial feedback, but shear stress-induced release of NO and activation of endothelial SKCa channels appeared to be the primary mediators of endothelial modulation of vasoconstriction to agonists and nerve stimulation. Thus, we propose that myoendothelial feedback may contribute to local control of diameter within arterial segments, but at the level of the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction.
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Affiliation(s)
- R Wei
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - S E Lunn
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - R Tam
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - S L Gust
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - B Classen
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - P M Kerr
- Department of Nursing Science, Faculty of Nursing, MacEwan University, Edmonton, Alberta, T5J 4S2, Canada
| | - F Plane
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.,Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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3
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Longo LD, Goyal R. Cerebral artery signal transduction mechanisms: developmental changes in dynamics and Ca2+ sensitivity. Curr Vasc Pharmacol 2013; 11:655-711. [PMID: 24063382 PMCID: PMC3785013 DOI: 10.2174/1570161111311050008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 06/12/2012] [Accepted: 07/12/2012] [Indexed: 11/22/2022]
Abstract
As compared to the adult, the developing fetus and newborn infant are at much greater risk for dysregulation of cerebral blood flow (CBF), with complications such as intraventricular and germinal matrix hemorrhage with resultant neurologic sequelae. To minimize this dysregulation and its consequences presents a major challenge. Although in many respects the fundamental signal transduction mechanisms that regulate relaxation and contraction pathways, and thus cerebrovascular tone and CBF in the immature organism are similar to those of the adult, the individual elements, pathways, and roles differ greatly. Here, we review aspects of these maturational changes of relaxation/contraction mechanisms in terms of both electro-mechanical and pharmaco-mechanical coupling, their biochemical pathways and signaling networks. In contrast to the adult cerebrovasculature, in addition to attenuated structure with differences in multiple cytoskeletal elements, developing cerebrovasculature of fetus and newborn differs in many respects, such as a strikingly increased sensitivity to [Ca(2+)]i and requirement for extracellular Ca(2+) for contraction. In essence, the immature cerebrovasculature demonstrates both "hyper-relaxation" and "hypo-contraction". A challenge is to unravel the manner in which these mechanisms are integrated, particularly in terms of both Ca(2+)-dependent and Ca(2+)-independent pathways to increase Ca(2+) sensitivity. Gaining an appreciation of these significant age-related differences in signal mechanisms also will be critical to understanding more completely the vulnerability of the developing cerebral vasculature to hypoxia and other stresses. Of vital importance, a more complete understanding of these mechanisms promises hope for improved strategies for therapeutic intervention and clinical management of intensive care of the premature newborn.
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Affiliation(s)
- Lawrence D Longo
- Center for Perinatal Biology, Loma Linda University, School of Medicine, Loma Linda, CA 92350, USA.
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4
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Coelho WS, Sola-Penna M. Serotonin regulates 6-phosphofructo-1-kinase activity in a PLC-PKC-CaMK II- and Janus kinase-dependent signaling pathway. Mol Cell Biochem 2012; 372:211-20. [PMID: 23010892 DOI: 10.1007/s11010-012-1462-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 09/14/2012] [Indexed: 01/08/2023]
Abstract
Serotonin (5-HT) is a hormone that has been implicated in the regulation of many physiological and pathological events. One of the most intriguing properties of this hormone is its ability to up-regulate mitosis. Moreover, 5-HT stimulates glucose uptake and up-regulates PFK activity through the 5-HT(2A) receptor, resulting in the phosphorylation of a tyrosine residue of PFK and the intracellular redistribution of PFK within skeletal muscle. The present study investigated some of the signaling intermediates involved in the effects of 5-HT on 6-phosphofructo-1-kinase (PFK) regulation from skeletal muscle using kinetic assessments, immunoprecipitation, and western blotting assays. Our results demonstrate that 5-HT stimulates PFK from skeletal muscle via phospholipase C (PLC). The activation of PLC in skeletal muscle leads to the recruitment of protein kinase C (PKC) and calmodulin and the stimulation of calmodulin kinase II, which associates with PFK upon 5-HT action. Alternatively, 5-HT loses its ability to up-regulate PFK activity when Janus kinase is inhibited, suggesting that 5-HT is able to control glycolytic flux in the skeletal muscle of mice by recruiting different pathways and controlling PFK activity.
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Affiliation(s)
- Wagner Santos Coelho
- Laboratório de Enzimologia e Controle do Metabolismo (LabECoM), Departamento de Fármacos, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ 21941-590, Brazil
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5
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ORAL COMMUNICATIONS. Br J Pharmacol 2012. [DOI: 10.1111/j.1476-5381.1995.tb16906.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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6
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Coleman DA, Khalil RA. Physiologic increases in extracellular sodium salt enhance coronary vasoconstriction and Ca2+ entry. J Cardiovasc Pharmacol 2002; 40:58-66. [PMID: 12072578 DOI: 10.1097/00005344-200207000-00008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High dietary sodium salt has been suggested to increase the risk of coronary vasospasm and coronary artery disease. However, whether high-sodium salt directly affects the mechanisms of coronary artery contraction is unclear. This study investigated whether physiologic and supraphysiologic increases in extracellular concentrations of sodium chloride ([NaCl]e) enhance the Ca2+ handling mechanisms of coronary smooth muscle contraction. Isometric contraction and 45Ca2+ influx were measured in endothelium-denuded porcine coronary artery strips incubated in Krebs solution (2.5 mM Ca2+) containing increasing [NaCl]e (120, 121, 123, 126, 130, 140, and 150 mM). Increasing [NaCl]e for 30 min did not increase the resting coronary tone or 45Ca2+ influx. 5-Hydroxytryptamine (5-HT) caused concentration-dependent increases in contraction and 45Ca2+ influx. Preincubation of coronary strips in increasing [NaCl]e for 30 min did not change the median effective dose of 5-HT. However, the magnitude of the 5-HT contraction and 45Ca2+ influx was significantly increased at 121-126 mM [NaCl]e. Preincubation with 2,4-dichlorobenzamil (10-5 M), inhibitor of the Na+/Ca2+ exchanger, or KB-R7943 (10-5 M), selective inhibitor of the reverse mode of the Na+/Ca2+ exchanger, abolished the increases in 5-HT contraction and 45Ca2+ influx at 121-126 mM [NaCl]e. Preincubation in Krebs solution containing 120 mM NaCl plus 1-6 mM LiCl or N-methyl-d-glucamine did not increase 5-HT contraction or 45Ca2+ influx. Higher [NaCl]e (140-150 mM) increased 5-HT-induced 45Ca2+ influx but inhibited 5-HT contraction. 5-HT (10-5 M)- and caffeine (25 mM)-induced contraction in Ca2+-free (2 mM EGTA) solution, a measure of Ca2+ release from the intracellular stores, was not affected by small increases in [NaCl]e (121-126 mM) but was inhibited at higher [NaCl]e (130-150 mM). Thus increases in [NaCl]e within the physiologic range enhance coronary smooth muscle contraction to 5-HT by a mechanism possibly involving Ca2+ entry via the reverse mode of the Na+/Ca2+ exchanger, but not Ca2+ release from the intracellular stores. The reduction of coronary contraction with supraphysiologic [NaCl]e in both Ca2+-containing and Ca2+-free Krebs could be related to excessive increases in ionic strength and may mask significant coronary vasoconstrictor effects of physiologic increases in [NaCl]e.
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Affiliation(s)
- Dominick A Coleman
- Department of Physiology, University of Mississippi Medical Center, Jackson, MS 39216, USA
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7
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Hill PB, Dora KA, Hughes AD, Garland CJ. The involvement of intracellular Ca(2+) in 5-HT(1B/1D) receptor-mediated contraction of the rabbit isolated renal artery. Br J Pharmacol 2000; 130:835-42. [PMID: 10864890 PMCID: PMC1572141 DOI: 10.1038/sj.bjp.0703387] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
5-Hydroxytryptamine(1B/1D) (5-HT(1B/1D)) receptor coupling to contraction was investigated in endothelium-denuded rabbit isolated renal arteries, by simultaneously measuring tension and intracellular [Ca(2+)], and tension in permeabilized smooth muscle cells. In intact arterial segments, 1 nM - 10 microM 5-HT failed to induce contraction or increase the fura-2 fluorescence ratio (in the presence of 1 microM ketanserin and prazosin to block 5-HT(2) and alpha(1)-adrenergic receptors, respectively). However, in vessels pre-exposed to either 20 mM K(+) or 30 nM U46619, 5-HT stimulated concentration-dependent increases in both tension and intracellular [Ca(2+)]. 1 nM - 10 microM U46619 induced concentration-dependent contractions. In the presence of nifedipine (0.3 and 1 microM) the maximal contraction to U46619 (10 microM) was reduced by around 70%. The residual contraction was abolished by the putative receptor operated channel inhibitor, SKF 96365 (2 microM). With 0.3 microM nifedipine present, 100 nM U46619 evoked similar contraction to 30 nM U46619 in the absence of nifedipine, but contraction to 5-HT (1 nM - 10 microM) was abolished. In permeabilized arterial segments, 10 mM caffeine, 1 microM IP(3) or 100 microM phenylephrine, each evoked transient contractions by releasing Ca(2+) from intracellular stores, whereas 5-HT had no effect. In intact arterial segments pre-stimulated with 20 mM K(+), 5-HT-evoked contractions were unaffected by 1 microM thapsigargin, which inhibits sarco- and endoplasmic reticulum calcium-ATPases. In vessels permeabilized with alpha-toxin and then pre-contracted with Ca(2+) and GTP, 5-HT evoked further contraction, reflecting increased myofilament Ca(2+)-sensitivity. Contraction linked to 5-HT(1B/1D) receptor stimulation in the rabbit renal artery can be explained by an influx of external Ca(2+) through voltage-dependent Ca(2+) channels and sensitization of the contractile myofilaments to existing levels of Ca(2+), with no release of Ca(2+) from intracellular stores.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Actin Cytoskeleton/drug effects
- Actin Cytoskeleton/physiology
- Animals
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Capillary Permeability
- Dose-Response Relationship, Drug
- Female
- Fluorescence
- Fura-2
- Imidazoles/pharmacology
- In Vitro Techniques
- Inositol 1,4,5-Trisphosphate/pharmacology
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Nifedipine/pharmacology
- Phenylephrine/pharmacology
- Potassium/pharmacology
- Rabbits
- Receptor, Serotonin, 5-HT1B
- Receptor, Serotonin, 5-HT1D
- Receptors, Serotonin/physiology
- Renal Artery/drug effects
- Renal Artery/physiology
- Serotonin/pharmacology
- Thapsigargin/pharmacology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- P B Hill
- Cardiovascular Research Laboratories, University Walk, University of Bristol, Bristol, BS8 1TD
| | - K A Dora
- Cardiovascular Research Laboratories, University Walk, University of Bristol, Bristol, BS8 1TD
| | - A D Hughes
- Clinical Pharmacology, Imperial College of Science, Technology & Medicine, St Mary's Hospital, London W2 1NY
| | - C J Garland
- Cardiovascular Research Laboratories, University Walk, University of Bristol, Bristol, BS8 1TD
- Author for correspondence:
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8
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Hinton JM, Adams D, Garland CJ. 5-hydroxytryptamine stimulation of phospholipase D activity in the rabbit isolated mesenteric artery. Br J Pharmacol 1999; 126:1601-8. [PMID: 10323592 PMCID: PMC1565947 DOI: 10.1038/sj.bjp.0702484] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/1998] [Revised: 01/19/1999] [Accepted: 01/20/1999] [Indexed: 11/09/2022] Open
Abstract
1. The involvement of phospholipase D (PLD) in the 5-hydroxytryptamine 5-HT1B/5-HT1D-signalling pathway was assessed in the rabbit isolated mesenteric artery. 2. RT-PCR analysis of mesenteric smooth muscle cells revealed a strong signal corresponding to mRNA transcript for the 5-HT1B receptor. The PCR fragment corresponded to the known sequence for the 5-HT1B receptor. No signal corresponding to 5-HT1D mRNA was detected. 3. Neither 5-HT (3 microM) nor KCl (45 mM) individually stimulated any significant increase in the smooth muscle concentration of [33P]-PtdBut to reflect PLD activity. However, in the presence of KCl (45 mM), 5-HT evoked a concentration-dependent increase in [33P]-PtdBut, to a maximum of 84% with 5-HT (3 microM). 4. [33P]-PtdBut accumulation evoked by 5-HT in the presence of KCl was abolished in nominally calcium-free Krebs-Henseleit Buffer (KHB) or with the selective protein kinase C inhibitor, Ro-31 8220 (10 microM, 20 min). 5. 5-HT (3 microM) in the presence of KCl (45 mM) failed to increase either the accumulation of [33P]-phosphatidic acid in the presence of butanol, or total [3H]-inositol phosphates ([3H]-InsP) in the presence of LiCl (10 mM). 6. 5-HT (0.1-1 microM) abolished forskolin (1 microM) stimulated increases in cyclic AMP (15 fold increase), an action which was pertussis toxin-sensitive. 7. Therefore, in the presence of raised extracellular potassium 5-HT can stimulate PLD via 5-HT1B receptors in the rabbit mesenteric artery. This action requires extracellular calcium and the activation of protein kinase C. These characteristics are identical to the profile for 5-HT1B/5-HT1D-receptor evoked contraction in vascular smooth muscle cells, suggesting a role for PLD in this response to 5-HT.
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Affiliation(s)
- J M Hinton
- Department of Pharmacology, School of Medical Sciences, University of Bristol
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9
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Iizuka K, Yoshii A, Dobashi K, Horie T, Mori M, Nakazawa T. InsP3, but not novel Ca2+ releasers, contributes to agonist-initiated contraction in rabbit airway smooth muscle. J Physiol 1998; 511 ( Pt 3):915-33. [PMID: 9714870 PMCID: PMC2231150 DOI: 10.1111/j.1469-7793.1998.915bg.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. To examine the contributions of the putative Ca2+ releasers, inositol 1,4,5-trisphosphate (InsP3), cyclic ADP ribose (cADPR), and nicotinate adenine dinucleotide phosphate (NAADP), to carbachol (CCh)-induced contraction in airway smooth muscle, we measured force development of permeabilized rabbit tracheal smooth muscle, human bronchial smooth muscle and guinea-pig ileum longitudinal smooth muscle. 2. In the presence of 50 microM GTP, CCh and InsP3 contracted alpha-toxin-permeabilized tracheal smooth muscle dose dependently; the EC50 values for CCh and InsP3 were 1.84 microM and 363 microM, and the maximum responses (normalized to the 30 mM caffeine response) to 100 microM CCh and to 800 microM InsP3 were 206 +/- 13.4 % (mean +/- S.E.M.) and 84.4 +/- 5.3 %, respectively. 3. However, cADPR (10-300 microM), beta-NAD+ (2.5 mM), FK506 (30 microM) and NAADP (100 microM) neither contracted the strip by themselves nor affected the subsequent CCh (1 microM) response. alpha-Toxin-permeabilized bronchial smooth muscle and ileum smooth muscle also responded to caffeine, InsP3 and CCh but not to cADPR. 4. Both 100 microM 8-amino-cADPR, a selective cADPR antagonist, and 100 microM thionicotinamide-NADP, a selective NAADP antagonist, failed to inhibit the CCh response, although procaine abolished the caffeine, InsP3 and CCh responses in the permeabilized tracheal smooth muscle. 5. Although inhibition of the caffeine response by 30 microM ryanodine was nearly complete, approximately 30 % of the InsP3 (300 microM) plus GTP (50 microM) response was retained, and the resultant response disappeared after the caffeine response was evoked in the presence of ryanodine. 6. Heparin (300 microg ml-1) blocked InsP3 (300 microM) and CCh (3 microM) responses in beta-escin-permeabilized tracheal smooth muscle, while Ruthenium Red (100 microM) partially inhibited the CCh response. 7. Collectively, InsP3 but not cADPR or NAADP plays a key role in CCh-initiated contraction, and InsP3 utilizes a single compartment of the caffeine/ryanodine-sensitive stored Ca2+ in airway smooth muscle.
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Affiliation(s)
- K Iizuka
- First Department of Internal Medicine, Gunma University Faculty of Medicine, School of Medicine, Gunma, Japan.
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Akopov SE, Zhang L, Pearce WJ. Regulation of Ca2+ sensitization by PKC and rho proteins in ovine cerebral arteries: effects of artery size and age. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H930-9. [PMID: 9724297 DOI: 10.1152/ajpheart.1998.275.3.h930] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
G protein-regulated Ca2+ sensitivity of vascular contractile proteins plays an important role in cerebrovascular reactivity. The present study examines the intracellular mechanisms that govern G protein-regulated Ca2+ sensitivity in cerebral arteries of different size and age. We studied beta-escin-permeabilized segments of common carotid, basilar, and middle cerebral arteries from nonpregnant adult and near-term fetal sheep. Activation of protein kinase C (PKC) by (-)-indolactam V or a phorbol ester produced receptor-independent increases in Ca2+ sensitivity. Such increases were more marked in immature arteries and were inversely correlated with artery size in both mature and immature arteries. However, inhibitors of PKC did not significantly affect increases in Ca2+ sensitivity in responses to either serotonin (5-hydroxytryptamine, 5-HT) or guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). Alternatively, deactivation of rho p21, a small G protein associated with Rho kinase, by exotoxin C3 fully prevented increases in Ca2+ sensitivity in responses to 5-HT or GTPgammaS in both adult and fetal arteries of all types. Neither inhibitors of PKC nor exotoxin C3 altered baseline Ca2+ sensitivity. We conclude that patterns of receptor- and/or G protein-mediated modulation of Ca2+ sensitivity are dependent on an intracellular pathway that involves activation of small G proteins and Rho kinase. In contrast, PKC has little, if any, role in agonist-induced Ca2+ sensitization under the present experimental conditions.
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Affiliation(s)
- S E Akopov
- Department of Physiology, Loma Linda University School of Medicine, Loma Linda, California 92350, USA
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11
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Akopov SE, Zhang L, Pearce WJ. Mechanisms of platelet-induced angiospastic reactions: potentiation of calcium sensitivity. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Hu XQ, Dyer DC. 5-Hydroxytryptamine stimulates phosphoinositide hydrolysis and contraction in the ovine umbilical artery. Eur J Pharmacol 1997; 322:107-12. [PMID: 9088878 DOI: 10.1016/s0014-2999(96)00982-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
5-Hydroxytryptamine-stimulated contraction and generation of inositol phosphates (InsPs) were investigated in isolated ovine umbilical artery from near term pregnant sheep. 5-Hydroxytryptamine produced a concentration-dependent contraction in the presence or absence of external Ca2+, however, the contractile response in Ca(2+)-free medium was depressed by 67% (P < 0.05). The initial increase of either inositol monophosphate (InsP1) or inositol bisphosphate (InsP2) was not apparent, although a significant rise in both InsP1 and InsP2 was observed at 30 min (107 and 100% over basal level, P < 0.05). The generation of inositol trisphosphate (InsP3) was rapid and reached its peak at 60-90 s (35% over basal level, P < 0.05), followed by a second rise at 30 min (96% over basal level, P < 0.05). The generation of InsPs stimulated by 5-hydroxytryptamine was also concentration-dependent. In agreement with previous contraction studies, the generation of InsPs stimulated by 5-hydroxytryptamine was blocked by 10 nM ketanserin, a specific 5-HT2A receptor antagonist. A temporal study revealed that the generation of InsP3 coincided with the phasic component of the contractile response induced by 5-hydroxytryptamine. Our results suggest that through activation of 5-HT2A receptors, the generation of InsP3 plays a critical role in the contraction induced by 5-hydroxytryptamine in the ovine umbilical artery.
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Affiliation(s)
- X Q Hu
- Department of Veterinary Physiology and Pharmacology, Iowa State University, Ames 50011, USA
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13
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POSTER COMMUNICATIONS. Br J Pharmacol 1996. [DOI: 10.1111/j.1476-5381.1996.tb16426.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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14
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Parsons SJ, Sumner MJ, Garland CJ. Phospholipase A2 and protein kinase C contribute to myofilament sensitization to 5-HT in the rabbit mesenteric artery. J Physiol 1996; 491 ( Pt 2):447-53. [PMID: 8866867 PMCID: PMC1158738 DOI: 10.1113/jphysiol.1996.sp021228] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. Calcium (Ca2+, 0.1-100 microM) stimulated concentration-dependent contractions in small strips from the rabbit mesenteric artery in which the smooth muscle cells had been permeabilized with Staphylococcus aureus alpha-toxin. 2. 5-Hydroxytryptamine (5-HT) and phenylephrine, each in the presence of 10 microM guanosine 5'-triphosphate (GTP), concentration-dependently stimulated additional contractions in strips sub-maximally contracted by the presence of a buffered concentration of calcium (0.3 microM). All the additional contraction was abolished with the selective inhibitor of protein kinase C, Ro 31-8220 (10 microM). 3. Quinacrine (10-50 microM), an inhibitor of phospholipase A2, selectively inhibited the sensitization to 5-HT, but did not alter the sensitization to either phenylephrine or GTP. 4. Myofilament sensitization to calcium was mimicked by exogenous arachidonic acid (300 microM, in the presence of indomethacin, miconazole and BW755c) and the stable analogue of arachidonic acid, 5,8,11,14-eicosatetrayonic acid (ETYA, 100 microM), and in both cases did not require the additional presence of GTP. Ro 31-8220, but not quinacrine, reduced the sensitization to arachidonic acid by around 30%. 5. These results indicate that G protein-linked myofilament sensitization to calcium in the mesenteric artery that follows the activation of 5-HT receptors, but not alpha 1-receptors, involves phospholipase A2. The sensitization stimulated by each of these different receptors, and a component of the response to arachidonic acid, also appears to involve the activation of protein kinase C.
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Affiliation(s)
- S J Parsons
- Department of Pharmacology, University of Bristol, UK
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POSTER COMMUNICATIONS. Br J Pharmacol 1995. [DOI: 10.1111/j.1476-5381.1995.tb16904.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Murphy TV, Garland CJ. Specific accumulation of inositol 1,4,5-trisphosphate in rabbit basilar artery in response to noradrenaline but not 5-hydroxytryptamine. Eur J Pharmacol 1995; 290:141-4. [PMID: 8575528 DOI: 10.1016/0922-4106(95)90026-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
This study examined the ability of 5-hydroxytryptamine and noradrenaline to stimulate inositol 1,4,5-trisphosphate (IP3) mass accumulation in segments of the rabbit basilar artery. 5-Hydroxytryptamine (5-HT, 100 microM) failed to stimulate any significant accumulation of IP3 during the 5 min period following its application. In the presence of prazosin, 5-HT (300 microM) caused a rapid, transient decrease in IP3 accumulation which was significant after 5 s but had increased to pre-stimulation levels within 15 s. In contrast, noradrenaline (10 microM) stimulated a rapid, transient accumulation of IP3 which was significant after 5 s but had declined to basal levels after 60 s. In basilar artery segments bathed in Krebs solution containing 25.7 mM K+ (normal concentration 5.7 mM), the basal IP3 concentration was significantly elevated. The IP3 accumulation stimulated by either 5-HT or raised K+ was not reduced by the presence of the alpha 1-adrenoceptor antagonist, prazosin (0.1 microM). In the presence of raised K+, 5-hydroxytryptamine caused a rapid, transient inhibition of the K(+)-induced IP3 accumulation, which was maximal after 5 s but had increased to pre-stimulation levels within 30 s in the continued presence of 5-hydroxytryptamine. Noradrenaline did not affect the IP3 accumulation induced by raised extracellular [K+]. These results provide further evidence that IP3 is not involved in 5-hydroxytryptamine-induced smooth muscle contraction in the rabbit basilar artery, but support a role for this second messenger in the contraction induced in response to noradrenaline.
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Affiliation(s)
- T V Murphy
- Department of Pharmacology, School of Medical Sciences, University of Bristol, UK
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