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Revilla-González G, Ureña J, González-Montelongo MDC, Castellano A. Changes in arterial myocyte excitability induced by subarachnoid hemorrhage in a rat model. Vascul Pharmacol 2024; 155:107287. [PMID: 38408532 DOI: 10.1016/j.vph.2024.107287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/05/2024] [Accepted: 02/23/2024] [Indexed: 02/28/2024]
Abstract
Aneurismal subarachnoid hemorrhage (aSAH) is a neurovascular disease produced by the rupture of the cerebral arteries and the extravasation of blood to the subarachnoid space and is accompanied by severe comorbidities. Secondarily associated vasospasm is one of the main side effects after hydrocephalus and possible rebleeding. Here, we analyze the alterations in function in the arteries of a rat model of SAH. For this, autologous blood was injected into the cisterna magna. We performed electrophysiological, microfluorimetric, and molecular biology experiments at different times after SAH to determine the functional and molecular changes induced by the hemorrhage. Our results confirmed that in SAH animals, arterial myocytes were depolarized on days 5 and 7, had higher [Ca2+]i on baseline, peaks and plateaus, and were more excitable at low levels of depolarization on day 7, than in the control and sham animals. Microarray analysis showed that, on day 7, the sets of genes related to voltage-dependent Ca2+ channels and K+ dynamics in SAH animals decreased, while the voltage-independent Ca2+ dynamics genes were over-represented. In conclusion, after SAH, several mechanisms involved in arterial reactivity were altered in our animal model, suggesting that there is no unique cause of vasospasm and alterations in several signaling pathways are involved in its development.
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MESH Headings
- Animals
- Subarachnoid Hemorrhage/physiopathology
- Subarachnoid Hemorrhage/metabolism
- Subarachnoid Hemorrhage/pathology
- Disease Models, Animal
- Male
- Vasospasm, Intracranial/physiopathology
- Vasospasm, Intracranial/metabolism
- Vasospasm, Intracranial/etiology
- Vasospasm, Intracranial/pathology
- Calcium Signaling
- Time Factors
- Cerebral Arteries/metabolism
- Cerebral Arteries/physiopathology
- Cerebral Arteries/pathology
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiopathology
- Muscle, Smooth, Vascular/pathology
- Rats, Sprague-Dawley
- Gene Expression Regulation
- Calcium Channels/metabolism
- Calcium Channels/genetics
- Rats
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Affiliation(s)
- Gonzalo Revilla-González
- Instituto de Biomedicina de Sevilla, IBIS/ Hospital Universitario Virgen del Rocío/CSIC/ Universidad de Sevilla, Sevilla, Spain; Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain
| | - Juan Ureña
- Instituto de Biomedicina de Sevilla, IBIS/ Hospital Universitario Virgen del Rocío/CSIC/ Universidad de Sevilla, Sevilla, Spain; Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain
| | - María Del Carmen González-Montelongo
- Instituto de Biomedicina de Sevilla, IBIS/ Hospital Universitario Virgen del Rocío/CSIC/ Universidad de Sevilla, Sevilla, Spain; Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain.
| | - Antonio Castellano
- Instituto de Biomedicina de Sevilla, IBIS/ Hospital Universitario Virgen del Rocío/CSIC/ Universidad de Sevilla, Sevilla, Spain; Dpto. Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain.
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Gutiérrez A, Gómez Del Val A, Contreras C, Olmos L, Sánchez A, Prieto D. Calcium handling coupled to the endothelin ET A and ET B receptor-mediated vasoconstriction in resistance arteries: Differential regulation by PI3K, PKC and RhoK. Eur J Pharmacol 2023; 956:175948. [PMID: 37541372 DOI: 10.1016/j.ejphar.2023.175948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/14/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023]
Abstract
Abnormal endothelin-1 (ET-1) activity is involved in the pathogenesis of vascular diseases such as essential and pulmonary arterial hypertension, coronary artery disease, and cerebrovascular disease, blockade of ET receptors having shown efficacy in clinical assays and experimental models of hypertension. Augmented Ca2+ influx and changes in Ca2+ sensitization associated with arterial vasoconstriction underlie increased systemic vascular resistance in hypertension. Since peripheral resistance arteries play a key role in blood pressure regulation, we aimed to determine here the specific Ca2+ signaling mechanisms linked to the ET receptor-mediated vasoconstriction in resistance arteries and their selective regulation by protein kinase C (PKC), Rho kinase (RhoK), the phosphatidylinositol 3-kinase (PI3K) and the mitogen-activated protein kinase (MAPK). ET-1-induced contraction was mediated by the endothelin ETA receptor with a minor contribution of vascular smooth muscle (VSM) endothelin ETB receptors. ET receptor activation elicited Ca2+ mobilization from intracellular stores, extracellular Ca2+ influx and Ca2+ sensitization associated with contraction in resistance arteries. Vasoconstriction induced by ET-1 was largely dependent on activation of canonical transient receptor potential channel 3 (TRPC3) and extracellular Ca2+ influx through nifedipine-sensitive voltage-dependent Ca2+ channels. PI3K inhibition reduced intracellular Ca2+ mobilization and Ca2+ entry without altering vasoconstriction elicited by ET-1, while PKC has dual opposite actions by enhancing Ca2+ influx associated with contraction, and by inhibiting Ca2+ release from intracellular stores. RhoK was a major determinant of the enhanced sensitivity of the contractile filaments underlying ET-1 vasoconstriction, with also a modulatory positive action on Ca2+ influx and intracellular Ca2+ release. Augmented RhoK and PKC activities are involved in vascular dysfunction in hypertension and vascular complications of insulin-resistant states, and these kinases are thus potential pharmacological targets in vascular diseases in which the ET pathway is impaired.
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Affiliation(s)
- Alejandro Gutiérrez
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Alfonso Gómez Del Val
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Cristina Contreras
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Lucia Olmos
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Ana Sánchez
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Dolores Prieto
- Departamento de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040, Madrid, Spain.
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Jackson WF. Calcium-Dependent Ion Channels and the Regulation of Arteriolar Myogenic Tone. Front Physiol 2021; 12:770450. [PMID: 34819877 PMCID: PMC8607693 DOI: 10.3389/fphys.2021.770450] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/11/2021] [Indexed: 11/25/2022] Open
Abstract
Arterioles in the peripheral microcirculation regulate blood flow to and within tissues and organs, control capillary blood pressure and microvascular fluid exchange, govern peripheral vascular resistance, and contribute to the regulation of blood pressure. These important microvessels display pressure-dependent myogenic tone, the steady state level of contractile activity of vascular smooth muscle cells (VSMCs) that sets resting arteriolar internal diameter such that arterioles can both dilate and constrict to meet the blood flow and pressure needs of the tissues and organs that they perfuse. This perspective will focus on the Ca2+-dependent ion channels in the plasma and endoplasmic reticulum membranes of arteriolar VSMCs and endothelial cells (ECs) that regulate arteriolar tone. In VSMCs, Ca2+-dependent negative feedback regulation of myogenic tone is mediated by Ca2+-activated K+ (BKCa) channels and also Ca2+-dependent inactivation of voltage-gated Ca2+ channels (VGCC). Transient receptor potential subfamily M, member 4 channels (TRPM4); Ca2+-activated Cl− channels (CaCCs; TMEM16A/ANO1), Ca2+-dependent inhibition of voltage-gated K+ (KV) and ATP-sensitive K+ (KATP) channels; and Ca2+-induced-Ca2+ release through inositol 1,4,5-trisphosphate receptors (IP3Rs) participate in Ca2+-dependent positive-feedback regulation of myogenic tone. Calcium release from VSMC ryanodine receptors (RyRs) provide negative-feedback through Ca2+-spark-mediated control of BKCa channel activity, or positive-feedback regulation in cooperation with IP3Rs or CaCCs. In some arterioles, VSMC RyRs are silent. In ECs, transient receptor potential vanilloid subfamily, member 4 (TRPV4) channels produce Ca2+ sparklets that activate IP3Rs and intermediate and small conductance Ca2+ activated K+ (IKCa and sKCa) channels causing membrane hyperpolarization that is conducted to overlying VSMCs producing endothelium-dependent hyperpolarization and vasodilation. Endothelial IP3Rs produce Ca2+ pulsars, Ca2+ wavelets, Ca2+ waves and increased global Ca2+ levels activating EC sKCa and IKCa channels and causing Ca2+-dependent production of endothelial vasodilator autacoids such as NO, prostaglandin I2 and epoxides of arachidonic acid that mediate negative-feedback regulation of myogenic tone. Thus, Ca2+-dependent ion channels importantly contribute to many aspects of the regulation of myogenic tone in arterioles in the microcirculation.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, United States
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Sghari S, Davies WIL, Gunhaga L. Elucidation of Cellular Mechanisms That Regulate the Sustained Contraction and Relaxation of the Mammalian Iris. Invest Ophthalmol Vis Sci 2020; 61:5. [PMID: 32882011 PMCID: PMC7476664 DOI: 10.1167/iovs.61.11.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/19/2020] [Indexed: 12/15/2022] Open
Abstract
Purpose In mammals, pupil constriction and dilation form the pupillary light reflex (PLR), which is mediated by both brain-regulated (parasympathetic) and local iris-driven reflexes. To better understand the cellular mechanisms that regulate pupil physiological dynamics via central and local photoreception, we have examined the regulation of the PLR via parasympathetic and local activation, respectively. Methods In this study, the PLR was examined in mouse enucleated eyes ex vivo in real-time under different ionic conditions in response to acetylcholine and/or blue light (480 nm). The use of pupillometry recordings captured the relaxation, contraction, and pupil escape (redilation) processes for 10 minutes up to 1 hour. Results Among others, our results show that ryanodine receptor channels are the main driver for iridal stimulation-contraction coupling, in which extracellular influx of Ca2+ is required for amplification of pupil constriction. Both local and parasympathetic iridal activations are necessary, but not sufficient for sustained pupil constriction. Moreover, the degree of membrane potential repolarization in the dark is correlated with the latency and velocity of iridal constriction. Furthermore, pupil escape is driven by membrane potential hyperpolarization where voltage-gated potassium channels play a crucial role. Conclusions Together, this study presents new mechanisms regulating synchronized pupil dilation and contraction, sustained pupil constriction, iridal stimulation-contraction coupling, and pupil escape.
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Affiliation(s)
- Soufien Sghari
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Wayne I. L. Davies
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine (UCMM), Umeå University, Umeå, Sweden
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Jackson WF. Introduction to ion channels and calcium signaling in the microcirculation. CURRENT TOPICS IN MEMBRANES 2020; 85:1-18. [PMID: 32402636 DOI: 10.1016/bs.ctm.2020.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The microcirculation is the network of feed arteries, arterioles, capillaries and venules that supply and drain blood from every tissue and organ in the body. It is here that exchange of heat, oxygen, carbon dioxide, nutrients, hormones, water, cytokines, and immune cells takes place; essential functions necessary to maintenance of homeostasis throughout the life span. This chapter will outline the structure and function of each microvascular segment highlighting the critical roles played by ion channels in the microcirculation. Feed arteries upstream from the true microcirculation and arterioles within the microcirculation contribute to systemic vascular resistance and blood pressure control. They also control total blood flow to the downstream microcirculation with arterioles being responsible for distribution of blood flow within a tissue or organ dependent on the metabolic needs of the tissue. Terminal arterioles control blood flow and blood pressure to capillary units, the primary site of diffusional exchange between blood and tissues due to their large surface area. Venules collect blood from capillaries and are important sites for fluid exchange and immune cell trafficking. Ion channels in microvascular smooth muscle cells, endothelial cells and pericytes importantly contribute to all of these functions through generation of intracellular Ca2+ and membrane potential signals in these cells.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI, United States.
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Zhou ZY, Zhao WR, Shi WT, Xiao Y, Ma ZL, Xue JG, Zhang LQ, Ye Q, Chen XL, Tang JY. Endothelial-Dependent and Independent Vascular Relaxation Effect of Tetrahydropalmatine on Rat Aorta. Front Pharmacol 2019; 10:336. [PMID: 31057398 PMCID: PMC6477965 DOI: 10.3389/fphar.2019.00336] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 03/19/2019] [Indexed: 02/06/2023] Open
Abstract
Tetrahydropalmatine (THP) is an active natural alkaloid isolated from Corydalis yanhusuo W.T. Wang which has been widely used for treating pain and cardiovascular disease in traditional Chinese medicine. Previous studies suggested THP have various pharmacological effects in neural and cardio tissue while the vascular reactivity of THP was not fully established. The present study found that THP relaxed rat aorta which contracted by phenylephrine (Phe), KCl, and U46619. The vascular relaxation effect of THP was partially attenuated by PI3K inhibitor wortmannin, Akt inhibitor IV, endothelial nitric oxide synthetase (eNOS) inhibitor L-NAME, guanylate cyclase inhibitors and the mechanical removal of endothelium. Also, the eNOS substrate L-arginine reversed the inhibition effect of L-NAME on THP-induced vascular relaxation. THP also induced intracellular NO production in human umbilical vein endothelial cells. However, Pre-incubation with β-adrenergic receptor blocker propranolol, angiotensin II receptor 1 (AT1) inhibitor losartan, angiotensin II receptor 2 (AT1) inhibitor PD123319 or angiotensin converting enzyme inhibitor enalapril enhanced the vascular relaxation effect of THP. THP did not affect the angiotensin II induced vascular contraction. Cyclooxygenase-2 (COX2) inhibitor indomethacin did not affect the vascular relaxation effect of THP. Furthermore, pre-treatment THP attenuated KCl and Phe induced rat aorta contraction in standard Krebs solution. In Ca2+ free Krebs solution, THP inhibited the Ca2+ induced vascular contraction under KCl or Phe stress and reduced KCl stressed Ca2+ influx in rat vascular smooth muscle cells. THP also inhibited intracellular Ca2+ release induced vascular contraction by blocking Ryr or IP3 receptors. In addition, the voltage-dependent K+ channel (Kv) blocker 4-aminopyridine, ATP-sensitive K+ channel (KATP) blocker glibenclamide and inward rectifying K+ channel blocker BaCl2 attenuated THP induced vascular relaxation regardless of the Ca2+-activated K+ channel (KCa) blocker tetraethylammonium. Thus, we could conclude that THP relaxed rat aorta in an endothelium-dependent and independent manner. The underlying mechanism of THP relaxing rat aorta involved PI3K/Akt/eNOS/NO/cGMP signaling path-way, Ca2+ channels and K+ channels rather than COX2, β-adrenergic receptor and renin-angiotensin system (RAS). These findings indicated that THP might be a potent treatment of diseases with vascular dysfunction like hypertension.
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Affiliation(s)
- Zhong-Yan Zhou
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China
| | - Wai-Rong Zhao
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Wen-Ting Shi
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Ying Xiao
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zi-Lin Ma
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jin-Gui Xue
- Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Lun-Qing Zhang
- Faculty of Health Sciences, University of Macau, Macau, China
| | - Qing Ye
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xin-Lin Chen
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jing-Yi Tang
- Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Cardiac Rehabilitation Center of Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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7
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Jackson WF. K V channels and the regulation of vascular smooth muscle tone. Microcirculation 2018; 25. [PMID: 28985443 DOI: 10.1111/micc.12421] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/01/2017] [Indexed: 12/31/2022]
Abstract
VSMCs in resistance arteries and arterioles express a diverse array of KV channels with members of the KV 1, KV 2 and KV 7 families being particularly important. Members of the KV channel family: (i) are highly expressed in VSMCs; (ii) are active at the resting membrane potential of VSMCs in vivo (-45 to -30 mV); (iii) contribute to the negative feedback regulation of VSMC membrane potential and myogenic tone; (iv) are activated by cAMP-related vasodilators, hydrogen sulfide and hydrogen peroxide; (v) are inhibited by increases in intracellular Ca2+ and vasoconstrictors that signal through Gq -coupled receptors; (vi) are involved in the proliferative phenotype of VSMCs; and (vii) are modulated by diseases such as hypertension, obesity, the metabolic syndrome and diabetes. Thus, KV channels participate in every aspect of the regulation of VSMC function in both health and disease.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI, USA
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8
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Semenov I, Brenner R. Voltage effects on muscarinic acetylcholine receptor-mediated contractions of airway smooth muscle. Physiol Rep 2018; 6:e13856. [PMID: 30187663 PMCID: PMC6125245 DOI: 10.14814/phy2.13856] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/11/2018] [Accepted: 08/17/2018] [Indexed: 01/31/2023] Open
Abstract
Studies have shown that the activity of muscarinic receptors and their affinity to agonists are sensitive to membrane potential. It was reported that in airway smooth muscle (ASM) depolarization evoked by high K+ solution increases contractility through direct effects on M3 muscarinic receptors. In this study, we assessed the physiological relevance of voltage sensitivity of muscarinic receptors on ASM contractility. Our findings reveal that depolarization by high K+ solution induces contraction in intact mouse trachea predominantly through activation of acetylcholine release from embedded nerves, and to a lesser extent by direct effects on M3 receptors. We therefore devised a pharmacological approach to depolarize tissue to various extents in an organ bath preparation, and isolate contraction due exclusively to ASM muscarinic receptors within range of physiological voltages. Our results indicate that unliganded muscarinic receptors do not contribute to contraction regardless of voltage. Utilizing low K+ solution to hyperpolarize membrane potentials during contractions had no effect on liganded muscarinic receptor-evoked contractions, although it eliminated the contribution of voltage-gated calcium channels. However, we found that muscarinic signaling was potentiated by at least 42% at depolarizing voltages (average -12 mV) induced by high K+ solution (20 mmol/L K+ ). In summary, we conclude that contractions evoked by direct activation of muscarinic receptors have negligible sensitivity to physiological voltages. However, contraction activated by cholinergic stimulation can be potentiated by membrane potentials occurring beyond the physiological range of ASM.
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Affiliation(s)
- Iurii Semenov
- Frank Reidy Research Center for BioelectricsOld Dominion UniversityNorfolkVirginia
| | - Robert Brenner
- Department of Cell and Integrative PhysiologyUniversity of Texas Health Science Center San AntonioSan AntonioTexas
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9
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Schubert R. The second life of ion transporters as signal transducers. Acta Physiol (Oxf) 2018; 224:e13155. [PMID: 29938912 DOI: 10.1111/apha.13155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- R Schubert
- Cardiovascular Physiology, Centre for Biomedicine and Medical Technology Mannheim (CBTM), European Center of Angioscience (ECAS), Ruprecht-Karls-University Heidelberg, Mannheim, Germany
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10
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Contribution of L-type Ca2+ channel-sarcoplasmic reticulum coupling to depolarization-induced arterial contraction in spontaneously hypertensive rats. Hypertens Res 2018; 41:730-737. [DOI: 10.1038/s41440-018-0076-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/24/2018] [Accepted: 02/25/2018] [Indexed: 11/08/2022]
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Jackson WF, Boerman EM. Voltage-gated Ca 2+ channel activity modulates smooth muscle cell calcium waves in hamster cremaster arterioles. Am J Physiol Heart Circ Physiol 2018; 315:H871-H878. [PMID: 29957015 DOI: 10.1152/ajpheart.00292.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cremaster muscle arteriolar smooth muscle cells (SMCs) display inositol 1,4,5-trisphosphate receptor-dependent Ca2+ waves that contribute to global myoplasmic Ca2+ concentration and myogenic tone. However, the contribution made by voltage-gated Ca2+ channels (VGCCs) to arteriolar SMC Ca2+ waves is unknown. We tested the hypothesis that VGCC activity modulates SMC Ca2+ waves in pressurized (80 cmH2O/59 mmHg, 34°C) hamster cremaster muscle arterioles loaded with Fluo-4 and imaged by confocal microscopy. Removal of extracellular Ca2+ dilated arterioles (32 ± 3 to 45 ± 3 μm, n = 15, P < 0.05) and inhibited the occurrence, amplitude, and frequency of Ca2+ waves ( n = 15, P < 0.05), indicating dependence of Ca2+ waves on Ca2+ influx. Blockade of VGCCs with nifedipine (1 μM) or diltiazem (10 μM) or deactivation of VGCCs by hyperpolarization of smooth muscle with the K+ channel agonist cromakalim (10 μM) produced similar inhibition of Ca2+ waves ( P < 0.05). Conversely, depolarization of SMCs with the K+ channel blocker tetraethylammonium (1 mM) constricted arterioles from 26 ± 3 to 14 ± 2 μm ( n = 11, P < 0.05) and increased wave occurrence (9 ± 3 to 16 ± 3 waves/SMC), amplitude (1.6 ± 0.07 to 1.9 ± 0.1), and frequency (0.5 ± 0.1 to 0.9 ± 0.2 Hz, n = 10, P < 0.05), effects that were blocked by nifedipine (1 μM, P < 0.05). Similarly, the VGCC agonist Bay K8644 (5 nM) constricted arterioles from 14 ± 1 to 8 ± 1 μm and increased wave occurrence (3 ± 1 to 10 ± 1 waves/SMC) and frequency (0.2 ± 0.1 to 0.6 ± 0.1 Hz, n = 6, P < 0.05), effects that were unaltered by ryanodine (50 μM, n = 6, P > 0.05). These data support the hypothesis that Ca2+ waves in arteriolar SMCs depend, in part, on the activity of VGCCs. NEW & NOTEWORTHY Arterioles that control blood flow to and within skeletal muscle depend on Ca2+ influx through voltage-gated Ca2+ channels and release of Ca2+ from internal stores through inositol 1,4,5-trisphosphate receptors in the form of Ca2+ waves to maintain pressure-induced smooth muscle tone.
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Affiliation(s)
- William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
| | - Erika M Boerman
- Department of Pharmacology and Toxicology, Michigan State University , East Lansing, Michigan
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12
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Shen CP, Romero M, Brunelle A, Wolfe C, Dobyns A, Francis M, Taylor MS, Puglisi JL, Longo LD, Zhang L, Wilson CG, Wilson SM. Long-term high-altitude hypoxia influences pulmonary arterial L-type calcium channel-mediated Ca 2+ signals and contraction in fetal and adult sheep. Am J Physiol Regul Integr Comp Physiol 2017; 314:R433-R446. [PMID: 29167165 DOI: 10.1152/ajpregu.00154.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Long-term hypoxia (LTH) has a profound effect on pulmonary arterial vasoconstriction in the fetus and adult. Dysregulation in Ca2+ signaling is important during the development of LTH-induced pulmonary hypertension. In the present study, we tested the hypothesis that L-type Ca2+ channels (CaL), which are voltage dependent and found in smooth, skeletal, and cardiac muscle, are important in the adaptation of pulmonary arterial contractions in postnatal maturation and in response to LTH. Pulmonary arteries were isolated from fetal or adult sheep maintained at low or high altitude (3,801 m) for >100 days. The effects were measured using an L-type Ca2+ channel opener FPL 64176 (FPL) in the presence or absence of an inhibitor, Nifedipine (NIF) on arterial contractions, intracellular Ca2+ oscillations, and ryanodine receptor-driven Ca2+ sparks. FPL induced pulmonary arterial contractions in all groups were sensitive to NIF. However, when compared with 125 mM K+, FPL contractions were greater in fetuses than in adults. FPL reduced Ca2+ oscillations in myocytes of adult but not fetal arteries, independently of altitude. The FPL effects on Ca2+ oscillations were reversed by NIF in myocytes of hypoxic but not normoxic adults. FPL failed to enhance Ca2+ spark frequency and had little impact on spatiotemporal firing characteristics. These data suggest that CaL-dependent contractions are largely uncoupled from intracellular Ca2+ oscillations and the development of Ca2+ sparks. This raises questions regarding the coupling of pulmonary arterial contractility to membrane depolarization, attendant CaL facilitation, and the related associations with the activation of Ca2+ oscillations and Ca2+ sparks.
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Affiliation(s)
- Christine P Shen
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Monica Romero
- Advanced Imaging and Microscopy Core, Loma Linda University School of Medicine , Loma Linda, California
| | - Alexander Brunelle
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Craig Wolfe
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Abigail Dobyns
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Michael Francis
- Department of Physiology, University of South Alabama College of Medicine , Mobile, Alabama
| | - Mark S Taylor
- Department of Physiology, University of South Alabama College of Medicine , Mobile, Alabama
| | - Jose L Puglisi
- Department of Biostatistics, California Northstate University School of Medicine , Elk Grove, California
| | - Lawrence D Longo
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Lubo Zhang
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Christopher G Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
| | - Sean M Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda University School of Medicine , Loma Linda, California
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Nagaraj C, Tabeling C, Nagy BM, Jain PP, Marsh LM, Papp R, Pienn M, Witzenrath M, Ghanim B, Klepetko W, Weir EK, Heschl S, Kwapiszewska G, Olschewski A, Olschewski H. Hypoxic vascular response and ventilation/perfusion matching in end-stage COPD may depend on p22phox. Eur Respir J 2017; 50:50/1/1601651. [PMID: 28729471 DOI: 10.1183/13993003.01651-2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 04/10/2017] [Indexed: 11/05/2022]
Abstract
Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease in which the amount of emphysema and airway disease may be very different between individuals, even in end-stage disease. Emphysema formation may be linked to the involvement of the small pulmonary vessels. The NAPDH oxidase (Nox) family is emerging as a key disease-related factor in vascular diseases, but currently its role in hypoxia-induced pulmonary remodelling in COPD remains unclear.Here we investigate the role of p22phox, a regulatory subunit of Nox, in COPD lungs, hypoxic pulmonary vasoconstriction (HPV), hypoxia-induced pulmonary vascular remodelling and pulmonary hypertension.In COPD, compared to control lungs, p22phox expression was significantly reduced. The expression was correlated positively with mean pulmonary arterial pressure and oxygenation index and negatively with the diffusing capacity of the lung for carbon monoxide (p<0.02). This suggests a role of p22phox in ventilation/perfusion ratio matching, vascular remodelling and loss of perfused lung area. In p22phox-/- mice, HPV was significantly impaired. In the chronic hypoxic setting, lack of p22phox was associated with improved right ventricular function and decreased pulmonary vascular remodelling.p22phox-dependent Nox plays an important role in the COPD phenotype, by its action on phase II HPV and chronic vascular remodelling.
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Affiliation(s)
- Chandran Nagaraj
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.,Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Christoph Tabeling
- Dept of Infectious Diseases and Pulmonary Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Bence M Nagy
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.,Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Pritesh P Jain
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Leigh M Marsh
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Rita Papp
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Michael Pienn
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria
| | - Martin Witzenrath
- Dept of Infectious Diseases and Pulmonary Medicine, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Bahil Ghanim
- Dept of Thoracic Surgery, Division of Surgery, Medical University Vienna, Vienna, Austria
| | - Walter Klepetko
- Dept of Thoracic Surgery, Division of Surgery, Medical University Vienna, Vienna, Austria
| | - E Kenneth Weir
- Dept of Medicine, University of Minnesota, Minneapolis, MN, USA
| | - Stefan Heschl
- Dept of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria
| | - Grazyna Kwapiszewska
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.,Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Andrea Olschewski
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria .,Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Horst Olschewski
- Ludwig Boltzmann Institute for Lung Vascular Research, Graz, Austria.,Division of Pulmonology, Dept of Internal Medicine, Medical University of Graz, Graz, Austria
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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16
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Mauban JRH, Zacharia J, Fairfax S, Wier WG. PC-PLC/sphingomyelin synthase activity plays a central role in the development of myogenic tone in murine resistance arteries. Am J Physiol Heart Circ Physiol 2015; 308:H1517-24. [PMID: 25888510 DOI: 10.1152/ajpheart.00594.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 04/03/2015] [Indexed: 11/22/2022]
Abstract
Myogenic tone is an intrinsic property of the vasculature that contributes to blood pressure control and tissue perfusion. Earlier investigations assigned a key role in myogenic tone to phospholipase C (PLC) and its products, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). Here, we used the PLC inhibitor, U-73122, and two other, specific inhibitors of PLC subtypes (PI-PLC and PC-PLC) to delineate the role of PLC in myogenic tone of pressurized murine mesenteric arteries. U-73122 inhibited depolarization-induced contractions (high external K(+) concentration), thus confirming reports of nonspecific actions of U-73122 and its limited utility for studies of myogenic tone. Edelfosine, a specific inhibitor of PI-PLC, did not affect depolarization-induced contractions but modulated myogenic tone. Because PI-PLC produces IP3, we investigated the effect of blocking IP3 receptor-mediated Ca(2+) release on myogenic tone. Incubation of arteries with xestospongin C did not affect tone, consistent with the virtual absence of Ca(2+) waves in arteries with myogenic tone. D-609, an inhibitor of PC-PLC and sphingomyelin synthase, strongly inhibited myogenic tone and had no effect on depolarization-induced contraction. D-609 appeared to act by lowering cytoplasmic Ca(2+) concentration to levels below those that activate contraction. Importantly, incubation of pressurized arteries with a membrane-permeable analog of DAG induced vasoconstriction. The results therefore mandate a reexamination of the signaling pathways activated by the Bayliss mechanism. Our results suggest that PI-PLC and IP3 are not required in maintaining myogenic tone, but DAG, produced by PC-PLC and/or SM synthase, is likely through multiple mechanisms to increase Ca(2+) entry and promote vasoconstriction.
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Affiliation(s)
- Joseph R H Mauban
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Joseph Zacharia
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Seth Fairfax
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
| | - Withrow Gil Wier
- Department of Physiology, School of Medicine, University of Maryland Baltimore, Baltimore, Maryland
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Sukhanova KY, Bouryi VA, Gordienko DV. Convergence of Ionotropic and Metabotropic Signal Pathways upon Activation of P2X Receptors in Vascular Smooth Muscle Cells. NEUROPHYSIOLOGY+ 2015. [DOI: 10.1007/s11062-015-9464-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Protective Effect and Mechanism of Total Flavones from Rhododendron simsii Planch on Endothelium-Dependent Dilatation and Hyperpolarization in Cerebral Ischemia-Reperfusion and Correlation to Hydrogen Sulphide Release in Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:904019. [PMID: 25050128 PMCID: PMC4090445 DOI: 10.1155/2014/904019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 05/12/2014] [Accepted: 05/12/2014] [Indexed: 12/26/2022]
Abstract
We for the first time investigated the effect and mechanism of the total flavones of Rhododendron simsii Planch (TFR), a widely-used Chinese herb for a thousand years, on vasodilatation and hyperpolarization in middle cerebral artery (MCA) of rats subject to global cerebral ischemia-reperfusion (CIR). TFR (11~2700 mg/L) evoked dose-dependent vasodilation and hyperpolarization in MCA of both sham and CIR that were partially inhibited by 30 μM N-nitro-L-arginine-methyl-ester and 10 μM indomethacin and further attenuated by endogenous H2S synthese-CSE inhibitor PPG (100 μM) or Ca2+-activated potassium channel (Kca) inhibitor TEA (1 mM). In whole-cell patch clamp recording, TFR remarkably enhanced the outward current that was inhibited by TEA. CIR increased CSE mRNA expression and the contents of H2S that were further increased by TFR. We conclude that, in MCA of CIR rats, TFR induces non-NO and non-PGI2-mediated effects of vasodilatation and hyperpolarization involving Kca and increases CSE mRNA expression level in endothelial cells and H2S content in the cerebrum. These findings suggest that the response induced by TFR is potentially related to endothelium-derived hyperpolarizing factor mediated by the endogenous H2S and promote the use of TFR in protection of brain from ischemia-reperfusion injury.
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Hofmann F, Flockerzi V, Kahl S, Wegener JW. L-type CaV1.2 calcium channels: from in vitro findings to in vivo function. Physiol Rev 2014; 94:303-26. [PMID: 24382889 DOI: 10.1152/physrev.00016.2013] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The L-type Cav1.2 calcium channel is present throughout the animal kingdom and is essential for some aspects of CNS function, cardiac and smooth muscle contractility, neuroendocrine regulation, and multiple other processes. The L-type CaV1.2 channel is built by up to four subunits; all subunits exist in various splice variants that potentially affect the biophysical and biological functions of the channel. Many of the CaV1.2 channel properties have been analyzed in heterologous expression systems including regulation of the L-type CaV1.2 channel by Ca(2+) itself and protein kinases. However, targeted mutations of the calcium channel genes confirmed only some of these in vitro findings. Substitution of the respective serines by alanine showed that β-adrenergic upregulation of the cardiac CaV1.2 channel did not depend on the phosphorylation of the in vitro specified amino acids. Moreover, well-established in vitro phosphorylation sites of the CaVβ2 subunit of the cardiac L-type CaV1.2 channel were found to be irrelevant for the in vivo regulation of the channel. However, the molecular basis of some kinetic properties, such as Ca(2+)-dependent inactivation and facilitation, has been approved by in vivo mutagenesis of the CaV1.2α1 gene. This article summarizes recent findings on the in vivo relevance of well-established in vitro results.
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20
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Sukhanova KY, Harhun MI, Bouryi VA, Gordienko DV. Mechanisms of [Ca2+]i elevation following P2X receptor activation in the guinea-pig small mesenteric artery myocytes. Pharmacol Rep 2013; 65:152-63. [PMID: 23563033 DOI: 10.1016/s1734-1140(13)70973-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 09/24/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND There is growing evidence suggesting involvement of L-type voltage-gated Ca2+ channels (VGCCs) in purinergic signaling mechanisms. However, detailed interplay between VGCCs and P2X receptors in intracellular Ca2+ mobilization is not well understood. This study examined relative contribution of the Ca2+ entry mechanisms and induced by this entry Ca2+ release from the intracellular stores engaged by activation of P2X receptors in smooth muscle cells (SMCs) from the guinea-pig small mesenteric arteries. METHODS P2X receptors were stimulated by the brief local application of αβ-meATP and changes in [Ca2+]i were monitored in fluo-3 loaded SMCs using fast x-y confocal Ca2+ imaging. The effects of the block of L-type VGCCs and/or depletion of the intracellular Ca2+ stores on αβ-meATP-induced [Ca2+]i transients were analyzed. RESULTS Our analysis revealed that Ca2+ entry via L-type VGCCs is augmented by the Ca2+-induced Ca2+ release significantly more than Ca2+ entry via P2X receptors, even though net Ca2+ influxes provided by the two mechanisms are not significantly different. CONCLUSIONS Thus, arterial SMCs upon P2X receptor activation employ an effective mechanism of the Ca2+ signal amplification, the major component of which is the Ca2+ release from the SR activated by Ca2+ influx via L-type VGCCs. This signaling pathway is engaged by depolarization of the myocyte membrane resulting from activation of P2X receptors, which, being Ca2+ permeable, per se form less effective Ca2+ signaling pathway. This study, therefore, rescales potential targets for therapeutic intervention in purinergic control of vascular tone.
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Affiliation(s)
- Khrystyna Yu Sukhanova
- Laboratory of Molecular Pharmacology and Biophysics of Cell Signalling, A.A. Bogomoletz, Institute of Physiology, Bogomoletz 4, Kiev, 01024, Ukraine.
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21
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Ozkan MH, Ozturk EI, Uma S. Electrical field stimulation (EFS)-induced relaxations turn into contractions upon removal of extracellular calcium in rat mesenteric artery. Pharmacol Res 2013; 70:60-5. [DOI: 10.1016/j.phrs.2013.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 12/03/2012] [Accepted: 01/04/2013] [Indexed: 10/27/2022]
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Tykocki NR, Thompson JM, Jackson WF, Watts SW. Ryanodine receptors are uncoupled from contraction in rat vena cava. Cell Calcium 2012. [PMID: 23177664 DOI: 10.1016/j.ceca.2012.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ryanodine receptors (RyR) are Ca(2+)-sensitive ion channels in the sarcoplasmic reticulum (SR) membrane, and are important effectors of SR Ca(2+) release and smooth muscle excitation-contraction coupling. While the relationship between RyR activation and contraction is well characterized in arteries, little is known about the role of RyR in excitation-contraction coupling in veins. We hypothesized that RyR are present and directly coupled to contraction in rat aorta (RA) and vena cava (RVC). RA and RVC expressed mRNA for all 3 RyR subtypes, and immunofluorescence showed RyR protein was present in RA and RVC smooth muscle cells. RA and RVC rings contracted when Ca(2+) was re-introduced after stores depletion with thapsigargin (1μM), indicating both tissues contained intracellular Ca(2+) stores. To assess RyR function, contraction was then measured in RA and RVC exposed to the RyR activator caffeine (20mM). In RA, caffeine caused contraction that was attenuated by the RyR antagonists ryanodine (10μM) and tetracaine (100μM). However, caffeine (20mM) did not contract RVC. We next measured contraction and intracellular Ca(2+) (Ca(2+)(i)) simultaneously in RA and RVC exposed to caffeine. While caffeine increased Ca(2+)(i) and contracted RA, it had no significant effect on Ca(2+)(i) or contraction in RVC. These data suggest that ryanodine receptors, while present in both RA and RVC, are inactive and uncoupled from Ca(2+) release and contraction in RVC.
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Affiliation(s)
- N R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University, 1355 Bogue St. Room B-445, East Lansing, MI 48824, USA.
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Fernández-Tenorio M, Porras-González C, Castellano A, López-Barneo J, Ureña J. Tonic arterial contraction mediated by L-type Ca2+ channels requires sustained Ca2+ influx, G protein-associated Ca2+ release, and RhoA/ROCK activation. Eur J Pharmacol 2012; 697:88-96. [PMID: 23051677 DOI: 10.1016/j.ejphar.2012.09.047] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 09/20/2012] [Accepted: 09/21/2012] [Indexed: 11/25/2022]
Abstract
KCl-evoked sustained contraction requires L-type Ca(2+) channel activation, metabotropic Ca(2+) release from the sarcoplasmic reticulum (mechanism denoted calcium channel-induced Ca(2+) release) and RhoA/Rho associated kinase activation. Although high K(+) solutions are used to depolarize myocytes, these solutions can stimulate other signaling pathways such as those triggered by the activation of muscarinic and purinergic receptors. The present study examines the functional role of calcium channel-induced Ca(2+) release under pharmacological activation of L-type Ca(2+) channel without significant membrane depolarization. It also analyzes the role of the "steady-state" Ca(2+) influx through L-type Ca(2+) channels on myocyte sustained contraction. Measurement of contractility in arterial rings was done on a vessel myograph. Membrane potential was measured by fluorescence techniques loading intact myocytes with a membrane potential sensitive dye, and a reversible permeabilization method was used to load myocytes in intact arteries with GDPβS and Ca(v)1.2 siRNA. Application of an L-type Ca(2+) channel agonist, without effect on membrane potential, evoked sustained contraction via G-protein induced Ca(2+) release from the sarcoplasmic reticulum and RhoA/Rho associated kinase activation. Tonic myocyte contractions mediated by L-type Ca(2+) channel activation required sustained Ca(2+) influx through the channels and Ca(2+) uptake by the sarcoplasmic reticulum. Because L-type Ca(2+) channels participate in numerous pathophysiological processes mediated by maintained arterial contraction, our data could help to optimize therapeutic treatment of arterial vasospasm.
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Affiliation(s)
- Miguel Fernández-Tenorio
- Instituto de Biomedicina de Sevilla and Dpto. Fisiología Médica y Biofísica, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Spain
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Ureña J, López-Barneo J. Metabotropic regulation of RhoA/Rho-associated kinase by L-type Ca2+ channels. Trends Cardiovasc Med 2012; 22:155-60. [PMID: 22902183 DOI: 10.1016/j.tcm.2012.07.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 01/17/2023]
Abstract
Sustained vascular smooth muscle contraction can be mediated by several mechanisms, including the influx of extracellular Ca(2+) through L-type voltage-gated Ca(2+) channels (LTCCs) and by RhoA/Rho-associated kinase (ROCK)-dependent Ca(2+) sensitization of the contractile machinery. Conformational changes in the LTCC following depolarization can also trigger an ion-independent metabotropic pathway that involves G protein/phospholipase C activation, giving rise to inositol 1,4,5-trisphosphate synthesis and subsequent Ca(2+) release from the sarcoplasmic reticulum (SR) (calcium channel-induced Ca(2+) release or calcium channel-induced calcium release [CCICR]). In this review, we summarize recent data suggesting that LTCC activation and subsequent metabotropic Ca(2+) release from the SR participate in depolarization-evoked RhoA/ROCK activity and sustained arterial contraction. During protracted depolarizations, refilling of the SR stores by a residual influx of extracellular Ca(2+) through LTCCs helps maintain RhoA activity and contractile activation. These findings suggest that CCICR plays a major role in tonic vascular smooth muscle contraction, providing a link between membrane depolarization-induced LTCC activation and metabotropic Ca(2+) release and RhoA/ROCK stimulation.
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Affiliation(s)
- Juan Ureña
- Instituto de Biomedicina de Sevilla (IBiS) and Departamento de Fisiología Médica y Biofísica, Hospital Universitario Virgen de Rocío/CSIC/Universidad de Sevilla, 41013 Seville, Spain.
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Yamamura H, Ohya S, Muraki K, Imaizumi Y. Involvement of inositol 1,4,5-trisphosphate formation in the voltage-dependent regulation of the Ca(2+) concentration in porcine coronary arterial smooth muscle cells. J Pharmacol Exp Ther 2012; 342:486-96. [PMID: 22588257 DOI: 10.1124/jpet.112.194233] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The involvement of inositol 1,4,5-trisphosphate (IP(3)) formation in the voltage-dependent regulation of intracellular Ca(2+) concentration ([Ca(2+)](i)) was examined in smooth muscle cells of the porcine coronary artery. Slow ramp depolarization from -90 to 0 mV induced progressive [Ca(2+)](i) increase. The slope was reduced or increased in the presence of Cd(2+) or (±)-1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-[trifluoromethyl]-phenyl)pyridine-3-carboxlic acid methyl ester (Bay K 8644), respectively. The decrease in [Ca(2+)](i) via the membrane hyperpolarization induced by K(+) channel openers (levcromakalim and Evans blue) under current clamp was identical to that under voltage clamp. The step hyperpolarization from -40 to -80 mV reduced [Ca(2+)](i) uniformly over the whole-cell area with a time constant of ∼10 s. The [Ca(2+)](i) at either potential was unaffected by heparin, an inhibitor of IP(3) receptors. Alternatively, [Ca(2+)](i) rapidly increased in the peripheral regions by depolarization from -80 to 0 mV and stayed at that level (∼400 nM) during a 60-s pulse. When the pipette solution contained IP(3) pathway blockers [heparin, 2-aminoethoxydiphenylborate, xestospongin C, or 1-[6-[((17β)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione (U73122)], the peak [Ca(2+)](i) was unchanged, but the sustained [Ca(2+)](i) was gradually reduced by ∼250 nM within 30 s. In the presence of Cd(2+), a long depolarization period slightly increased the [Ca(2+)](i), which was lower than that in the presence of heparin alone. In coronary arterial myocytes, the sustained increase in the [Ca(2+)](i) during depolarization was partly caused by the Ca(2+) release mediated by the enhanced formation of IP(3). The initial [Ca(2+)](i) elevation triggered by the Ca(2+) influx though voltage-dependent Ca(2+) channels may be predominantly responsible for the activation of phospholipase C for IP(3) formation.
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Affiliation(s)
- Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan
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Westcott EB, Goodwin EL, Segal SS, Jackson WF. Function and expression of ryanodine receptors and inositol 1,4,5-trisphosphate receptors in smooth muscle cells of murine feed arteries and arterioles. J Physiol 2012; 590:1849-69. [PMID: 22331418 DOI: 10.1113/jphysiol.2011.222083] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We tested the hypothesis that vasomotor control is differentially regulated between feed arteries and downstream arterioles from the cremaster muscle of C57BL/6 mice. In isolated pressurized arteries, confocal Ca(2+) imaging of smooth muscle cells (SMCs) revealed Ca(2+) sparks and Ca(2+) waves. Ryanodine receptor (RyR) antagonists (ryanodine and tetracaine) inhibited both sparks and waves but increased global Ca(2+) and myogenic tone. In arterioles, SMCs exhibited only Ca(2+) waves that were insensitive to ryanodine or tetracaine. Pharmacological interventions indicated that RyRs are functionally coupled to large-conductance, Ca(2+)-activated K(+) channels (BK(Ca)) in SMCs of arteries, whereas BK(Ca) appear functionally coupled to voltage-gated Ca2+ channels in SMCs of arterioles. Inositol 1,4,5-trisphosphate receptor (IP3R) antagonists (xestospongin D or 2-aminoethoxydiphenyl borate) or a phospholipase C inhibitor (U73122) attenuated Ca(2+) waves, global Ca(2+) and myogenic tone in arteries and arterioles but had no effect on arterial sparks. Real-time PCR of isolated SMCs revealed RyR2 as the most abundant isoform transcript; arteries expressed twice the RyR2 but only 65% the RyR3 of arterioles and neither vessel expressed RyR1. Immunofluorescent localisation of RyR protein indicated bright, clustered staining of arterial SMCs in contrast to diffuse staining in arteriolar SMCs. Expression of IP(3)R transcripts and protein immunofluorescence were similar in SMCs of both vessels with IP(3)R1>>IP(3)R2>IP(3)R3. Despite similar expression of IP(3)Rs and dependence of Ca(2+) waves on IP(3)Rs, these data illustrate pronounced regional heterogeneity in function and expression of RyRs between SMCs of the same vascular resistance network. We conclude that vasomotor control is differentially regulated in feed arteries vs. downstream arterioles.
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Affiliation(s)
- Erika B Westcott
- Department of Pharmacology & Toxicology, Michigan State University, East Lansing, MI 48824, USA
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Functional and transcriptional induction of aquaporin-1 gene by hypoxia; analysis of promoter and role of Hif-1α. PLoS One 2011; 6:e28385. [PMID: 22174795 PMCID: PMC3233559 DOI: 10.1371/journal.pone.0028385] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 11/07/2011] [Indexed: 01/11/2023] Open
Abstract
Aquaporin-1 (AQP1) is a water channel that is highly expressed in tissues with rapid O2 transport. It has been reported that this protein contributes to gas permeation (CO2, NO and O2) through the plasma membrane. We show that hypoxia increases Aqp1 mRNA and protein levels in tissues, namely mouse brain and lung, and in cultured cells, the 9L glioma cell line. Stopped-flow light-scattering experiments confirmed an increase in the water permeability of 9L cells exposed to hypoxia, supporting the view that hypoxic Aqp1 up-regulation has a functional role. To investigate the molecular mechanisms underlying this regulatory process, transcriptional regulation was studied by transient transfections of mouse endothelial cells with a 1297 bp 5′ proximal Aqp1 promoter-luciferase construct. Incubation in hypoxia produced a dose- and time-dependent induction of luciferase activity that was also obtained after treatments with hypoxia mimetics (DMOG and CoCl2) and by overexpressing stabilized mutated forms of HIF-1α. Single mutations or full deletions of the three putative HIF binding domains present in the Aqp1 promoter partially reduced its responsiveness to hypoxia, and transfection with Hif-1α siRNA decreased the in vitro hypoxia induction of Aqp1 mRNA and protein levels. Our results indicate that HIF-1α participates in the hypoxic induction of AQP1. However, we also demonstrate that the activation of Aqp1 promoter by hypoxia is complex and multifactorial and suggest that besides HIF-1α other transcription factors might contribute to this regulatory process. These data provide a conceptual framework to support future research on the involvement of AQP1 in a range of pathophysiological conditions, including edema, tumor growth, and respiratory diseases.
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Félétou M. The Endothelium, Part I: Multiple Functions of the Endothelial Cells -- Focus on Endothelium-Derived Vasoactive Mediators. ACTA ACUST UNITED AC 2011. [DOI: 10.4199/c00031ed1v01y201105isp019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Fernández-Tenorio M, Porras-González C, Castellano A, Del Valle-Rodríguez A, López-Barneo J, Ureña J. Metabotropic regulation of RhoA/Rho-associated kinase by L-type Ca2+ channels: new mechanism for depolarization-evoked mammalian arterial contraction. Circ Res 2011; 108:1348-57. [PMID: 21493898 DOI: 10.1161/circresaha.111.240127] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Sustained vascular smooth muscle contraction is mediated by extracellular Ca(2+) influx through L-type voltage-gated Ca(2+) channels (VGCC) and RhoA/Rho-associated kinase (ROCK)-dependent Ca(2+) sensitization of the contractile machinery. VGCC activation can also trigger an ion-independent metabotropic pathway that involves G-protein/phospholipase C activation, inositol 1,4,5-trisphosphate synthesis, and Ca(2+) release from the sarcoplasmic reticulum (calcium channel-induced Ca(2+) release). We have studied the functional role of calcium channel-induced Ca(2+) release and the inter-relations between Ca(2+) channel and RhoA/ROCK activation. METHODS AND RESULTS We have used normal and genetically modified animals to study single myocyte electrophysiology and fluorimetry as well as cytosolic Ca(2+) and diameter in intact arteries. These analyses were complemented with measurement of tension and RhoA activity in normal and reversibly permeabilized arterial rings. We have found that, unexpectedly, L-type Ca(2+) channel activation and subsequent metabotropic Ca(2+) release from sarcoplasmic reticulum participate in depolarization-evoked RhoA/ROCK activity and sustained arterial contraction. We show that these phenomena do not depend on the change in the membrane potential itself, or the mere release of Ca(2+) from the sarcoplasmic reticulum, but they require the simultaneous activation of VGCC and the downstream metabotropic pathway with concomitant Ca(2+) release. During protracted depolarizations, refilling of the stores by a residual extracellular Ca(2+) influx through VGCC helps maintaining RhoA activity and sustained arterial contraction. CONCLUSIONS These findings reveal that calcium channel-induced Ca(2+) release has a major role in tonic vascular smooth muscle contractility because it links membrane depolarization and Ca(2+) channel activation with metabotropic Ca(2+) release and sensitization (RhoA/ROCK stimulation).
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Affiliation(s)
- Miguel Fernández-Tenorio
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain
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Abstract
The 21-amino-acid peptide ET-1 (endothelin-1) regulates a diverse array of physiological processes, including vasoconstriction, angiogenesis, nociception and cell proliferation. Most of the effects of ET-1 are associated with an increase in intracellular calcium concentration. The calcium influx and mobilization pathways activated by ET-1, however, vary immensely. The present review begins with the basics of calcium signalling and investigates the different ways intracellular calcium concentration can increase in response to a stimulus. The focus then shifts to ET-1, and discusses how ET receptors mobilize calcium. We also examine how disease alters calcium-dependent responses to ET-1 by discussing changes to ET-1-mediated calcium signalling in hypertension, as there is significant interest in the role of ET-1 in this important disease. A list of unanswered questions regarding ET-mediated calcium signals are also presented, as well as perspectives for future research of calcium mobilization by ET-1.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA.
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Fernández-Tenorio M, González-Rodríguez P, Porras C, Castellano A, Moosmang S, Hofmann F, Ureña J, López-Barneo J. Short communication: genetic ablation of L-type Ca2+ channels abolishes depolarization-induced Ca2+ release in arterial smooth muscle. Circ Res 2010; 106:1285-9. [PMID: 20299662 DOI: 10.1161/circresaha.109.213967] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE In arterial myocytes, membrane depolarization-induced Ca(2+) release (DICR) from the sarcoplasmic reticulum (SR) occurs through a metabotropic pathway that leads to inositol trisphosphate synthesis independently of extracellular Ca(2+) influx. Despite the fundamental functional relevance of DICR, its molecular bases are not well known. OBJECTIVE Biophysical and pharmacological data have suggested that L-type Ca(2+) channels could be the sensors coupling membrane depolarization to SR Ca(2+) release. This hypothesis was tested using smooth muscle-selective conditional Ca(v)1.2 knockout mice. METHODS AND RESULTS In aortic myocytes, the decrease of Ca(2+) channel density was paralleled by the disappearance of SR Ca(2+) release induced by either depolarization or Ca(2+) channel agonists. Ca(v)1.2 channel deficiency resulted in almost abolition of arterial ring contraction evoked by DICR. Ca(2+) channel-null cells showed unaltered caffeine-induced Ca(2+) release and contraction. CONCLUSION These data suggest that Ca(v)1.2 channels are indeed voltage sensors coupled to the metabolic cascade, leading to SR Ca(2+) release. These findings support a novel, ion-independent, functional role of L-type Ca(2+) channels linked to intracellular signaling pathways in vascular myocytes.
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Affiliation(s)
- Miguel Fernández-Tenorio
- Instituto de Biomedicina de Sevilla, Edificio de Laboratorios, 2 planta, Hospital Universitario Virgen del Rocío, Avenida Manuel Siurot s/n, 41013 Sevilla, Spain
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Kawaguchi T, Satoh KI, Kuji A, Joh S. Features of distinct contractions induced with a high and a low concentration of KCl, noradrenaline, and histamine in swine lingual artery. Naunyn Schmiedebergs Arch Pharmacol 2010; 381:107-20. [PMID: 20054523 DOI: 10.1007/s00210-009-0486-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Accepted: 12/11/2009] [Indexed: 12/23/2022]
Abstract
We investigated the features of swine lingual artery contraction induced with different strengths of stimulation. Endothelium-denuded artery rings were contracted with two concentrations of KCl, noradrenaline, and histamine with or without Y-27632, sodium nitroprusside (SNP), 2,2-diphenyl-1,3,2-oxaza-borolidine internal salt (2- APB), and extracellular Ca2+. While stored at 5 degrees C up to 3 days, artery rings remained active to strong stimulation but became inactive to weak stimulation if prior warming was lacking. Artery rings contracted slowly and progressively to weak stimulation but rapidly to strong stimulation and then kept a plateau or slightly relaxed. Y-27632, SNP, and 2-APB, irrespective of extracellular Ca2+, attenuated weak-stimulation-induced contractions to much greater extents except that 2-APB similarly diminished contractions to both noradrenaline concentrations. Without extracellular Ca2+, transitory contractions occurred with one peak to strong stimulation and two small peaks to weak stimulation, though one full peak to both noradrenaline concentrations. Artery rings lost stimulant responsiveness when extracellular Ca2+ was absent, but subsequent Ca2+ reintroduction without coexisting stimulant triggered transient contractions, which were as large as contractions to weak stimulation with extracellular Ca2+ and ceased with Y-27632, SNP, and 2-APB. These results collectively suggest that, in the lingual artery, its contraction properties shift coupling with strengths of both receptor- and voltage-mediated stimulation, with the tonic-like component being dominant in weak-stimulation-induced contraction.
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Affiliation(s)
- Takaki Kawaguchi
- Department of Biochemistry, School of Dentistry, Iwate Medical University, Morioka 020-8505, Japan.
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The role of ion channels in hypoxic pulmonary vasoconstriction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 661:3-14. [PMID: 20204720 DOI: 10.1007/978-1-60761-500-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hypoxic pulmonary vasoconstriction (HPV) is an important mechanism by which localized flow of blood in small resistance pulmonary arteries is matched to alveolar ventilation. This chapter discusses the role of several potassium and calcium channels in HPV, both in enhancing calcium influx into smooth muscle cells (SMCs) and in stimulating the release of calcium from the sarcoplasmic reticulum, thus increasing cytosolic calcium. The increase in calcium sensitivity caused by hypoxia is reviewed in Chapter 19. Particular attention is paid to the activity of the L-type calcium channels which increase calcium influx as a result of membrane depolarization and also increase calcium influx at any given membrane potential in response to hypoxia. In addition, activation of the L-type calcium channel may, in the absence of any calcium influx, cause calcium release from the sarcoplasmic reticulum. Many of these mechanisms have been reported to be involved in both HPV and in normoxic contraction of the ductus arteriosus.
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Broughton BRS, Jernigan NL, Norton CE, Walker BR, Resta TC. Chronic hypoxia augments depolarization-induced Ca2+ sensitization in pulmonary vascular smooth muscle through superoxide-dependent stimulation of RhoA. Am J Physiol Lung Cell Mol Physiol 2009; 298:L232-42. [PMID: 19897743 DOI: 10.1152/ajplung.00276.2009] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rho kinase (ROCK)-dependent vasoconstriction has been implicated as a major factor in chronic hypoxia (CH)-induced pulmonary hypertension. This component of pulmonary hypertension is associated with arterial myogenicity and increased vasoreactivity to receptor-mediated agonists and depolarizing stimuli resulting from ROCK-dependent myofilament Ca(2+) sensitization. On the basis of separate lines of evidence that CH increases pulmonary arterial superoxide (O(2)(-)) generation and that O(2)(-) stimulates RhoA/ROCK signaling in vascular smooth muscle (VSM), we hypothesized that depolarization-induced O(2)(-) generation mediates enhanced RhoA-dependent Ca(2+) sensitization in pulmonary VSM following CH. To test this hypothesis, we determined effects of the ROCK inhibitor HA-1077 and the O(2)(-)-specific spin trap tiron on vasoconstrictor reactivity to depolarizing concentrations of KCl in isolated lungs and Ca(2+)-permeabilized, pressurized small pulmonary arteries from control and CH (4 wk at 0.5 atm) rats. Using the same vessel preparation, we examined effects of CH on KCl-dependent VSM membrane depolarization and O(2)(-) generation using sharp electrodes and the fluorescent indicator dihydroethidium, respectively. Finally, using a RhoA-GTP pull-down assay, we investigated the contribution of O(2)(-) to depolarization-induced RhoA activation. We found that CH augmented KCl-dependent vasoconstriction through a Ca(2+) sensitization mechanism that was inhibited by HA-1077 and tiron. Furthermore, CH caused VSM membrane depolarization that persisted with increasing concentrations of KCl, enhanced KCl-induced O(2)(-) generation, and augmented depolarization-dependent RhoA activation in a O(2)(-)-dependent manner. These findings reveal a novel mechanistic link between VSM membrane depolarization, O(2)(-) generation, and RhoA activation that mediates enhanced myofilament Ca(2+) sensitization and pulmonary vasoconstriction following CH.
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Affiliation(s)
- Brad R S Broughton
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
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Kirschstein T, Rehberg M, Bajorat R, Tokay T, Porath K, Köhling R. High K+-induced contraction requires depolarization-induced Ca2+ release from internal stores in rat gut smooth muscle. Acta Pharmacol Sin 2009; 30:1123-31. [PMID: 19578389 DOI: 10.1038/aps.2009.98] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
AIM Depolarization-induced contraction of smooth muscle is thought to be mediated by Ca2+ influx through voltage-gated L-type Ca2+channels. We describe a novel contraction mechanism that is independent of Ca2+ entry. METHODS Pharmacological experiments were carried out on isolated rat gut longitudinal smooth muscle preparations, measuring isometric contraction strength upon high K+-induced depolarization. RESULTS Treatment with verapamil, which presumably leads to a conformational change in the channel, completely abolished K+-induced contraction, while residual contraction still occurred when Ca2+ entry was blocked with Cd2+. These results were further confirmed by measuring intracellular Ca2+ transients using Fura-2. Co-application of Cd2+ and the ryanodine receptor blocker DHBP further reduced contraction, albeit incompletely. Additional blockage of either phospholipase C (U 73122) or inositol 1,4,5-trisphophate (IP3)receptors (2-APB) abolished most contractions, while sole application of these blockers and Cd2+ (without parallel ryanodine receptor manipulation) also resulted in incomplete contraction block. CONCLUSION We conclude that there are parallel mechanisms of depolarization-induced smooth muscle contraction via (a) Ca2+ entry and (b) Ca2+ entry-independent, depolarization-induced Ca2+-release through ryanodine receptors and IP3, with the latter being dependent on phospholipase C activation.
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Abstract
The endothelium controls vascular tone not only by releasing NO and prostacyclin, but also by other pathways causing hyperpolarization of the underlying smooth muscle cells. This characteristic was at the origin of the term 'endothelium-derived hyperpolarizing factor' (EDHF). However, this acronym includes different mechanisms. Arachidonic acid metabolites derived from the cyclo-oxygenases, lipoxygenases and cytochrome P450 pathways, H(2)O(2), CO, H(2)S and various peptides can be released by endothelial cells. These factors activate different families of K(+) channels and hyperpolarization of the vascular smooth muscle cells contribute to the mechanisms leading to their relaxation. Additionally, another pathway associated with the hyperpolarization of both endothelial and vascular smooth muscle cells contributes also to endothelium-dependent relaxations (EDHF-mediated responses). These responses involve an increase in the intracellular Ca(2+) concentration of the endothelial cells, followed by the opening of SK(Ca) and IK(Ca) channels (small and intermediate conductance Ca(2+)-activated K(+) channels respectively). These channels have a distinct subcellular distribution: SK(Ca) are widely distributed over the plasma membrane, whereas IK(Ca) are preferentially expressed in the endothelial projections toward the smooth muscle cells. Following SK(Ca) activation, smooth muscle hyperpolarization is preferentially evoked by electrical coupling through myoendothelial gap junctions, whereas, following IK(Ca) activation, K(+) efflux can activate smooth muscle Kir2.1 and/or Na(+)/K(+)-ATPase. EDHF-mediated responses are altered by aging and various pathologies. Therapeutic interventions can restore these responses, suggesting that the improvement in the EDHF pathway contributes to their beneficial effect. A better characterization of EDHF-mediated responses should allow the determination of whether or not new drugable targets can be identified for the treatment of cardiovascular diseases.
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Membrane depolarization causes a direct activation of G protein-coupled receptors leading to local Ca2+ release in smooth muscle. Proc Natl Acad Sci U S A 2009; 106:11418-23. [PMID: 19549818 DOI: 10.1073/pnas.0813307106] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane depolarization activates voltage-dependent Ca(2+) channels (VDCCs) inducing Ca(2+) release via ryanodine receptors (RyRs), which is obligatory for skeletal and cardiac muscle contraction and other physiological responses. However, depolarization-induced Ca(2+) release and its functional importance as well as underlying signaling mechanisms in smooth muscle cells (SMCs) are largely unknown. Here we report that membrane depolarization can induce RyR-mediated local Ca(2+) release, leading to a significant increase in the activity of Ca(2+) sparks and contraction in airway SMCs. The increased Ca(2+) sparks are independent of VDCCs and the associated extracellular Ca(2+) influx. This format of local Ca(2+) release results from a direct activation of G protein-coupled, M(3) muscarinic receptors in the absence of exogenous agonists, which causes activation of Gq proteins and phospholipase C, and generation of inositol 1,4,5-triphosphate (IP(3)), inducing initial Ca(2+) release through IP(3) receptors and then further Ca(2+) release via RyR2 due to a local Ca(2+)-induced Ca(2+) release process. These findings demonstrate an important mechanism for Ca(2+) signaling and attendant physiological function in SMCs.
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Félétou M. Calcium-activated potassium channels and endothelial dysfunction: therapeutic options? Br J Pharmacol 2009; 156:545-62. [PMID: 19187341 DOI: 10.1111/j.1476-5381.2009.00052.x] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The three subtypes of calcium-activated potassium channels (K(Ca)) of large, intermediate and small conductance (BK(Ca), IK(Ca) and SK(Ca)) are present in the vascular wall. In healthy arteries, BK(Ca) channels are preferentially expressed in vascular smooth muscle cells, while IK(Ca) and SK(Ca) are preferentially located in endothelial cells. The activation of endothelial IK(Ca) and SK(Ca) contributes to nitric oxide (NO) generation and is required to elicit endothelium-dependent hyperpolarizations. In the latter responses, the hyperpolarization of the smooth muscle cells is evoked either via electrical coupling through myo-endothelial gap junctions or by potassium ions, which by accumulating in the intercellular space activate the inwardly rectifying potassium channel Kir2.1 and/or the Na(+)/K(+)-ATPase. Additionally, endothelium-derived factors such as cytochrome P450-derived epoxyeicosatrienoic acids and under some circumstances NO, prostacyclin, lipoxygenase products and hydrogen peroxide (H(2)O(2)) hyperpolarize and relax the underlying smooth muscle cells by activating BK(Ca). In contrast, cytochrome P450-derived 20-hydroxyeicosatetraenoic acid and various endothelium-derived contracting factors inhibit BK(Ca). Aging and cardiovascular diseases are associated with endothelial dysfunctions that can involve a decrease in NO bioavailability, alterations of EDHF-mediated responses and/or enhanced production of endothelium-derived contracting factors. Because potassium channels are involved in these endothelium-dependent responses, activation of endothelial and/or smooth muscle K(Ca) could prevent the occurrence of endothelial dysfunction. Therefore, direct activators of these potassium channels or compounds that regulate their activity or their expression may be of some therapeutic interest. Conversely, blockers of IK(Ca) may prevent restenosis and that of BK(Ca) channels sepsis-dependent hypotension.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France.
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Calderón-Sánchez E, Fernández-Tenorio M, Ordóñez A, López-Barneo J, Ureña J. Hypoxia inhibits vasoconstriction induced by metabotropic Ca2+ channel-induced Ca2+ release in mammalian coronary arteries. Cardiovasc Res 2009; 82:115-24. [DOI: 10.1093/cvr/cvp006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Mahaut-Smith MP, Martinez-Pinna J, Gurung IS. A role for membrane potential in regulating GPCRs? Trends Pharmacol Sci 2008; 29:421-9. [PMID: 18621424 DOI: 10.1016/j.tips.2008.05.007] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 05/16/2008] [Accepted: 05/28/2008] [Indexed: 10/21/2022]
Abstract
G-protein-coupled receptors (GPCRs) have ubiquitous roles in transducing extracellular signals into cellular responses. Therefore, the concept that members of this superfamily of surface proteins are directly modulated by changes in membrane voltage could have widespread consequences for cell signalling. Although several studies have indicated that GPCRs can be voltage dependent, particularly P2Y(1) receptors in the non-excitable megakaryocyte, the evidence has been mostly indirect. Recent work on muscarinic receptors has stimulated substantial interest in this field by reporting the first voltage-dependent charge movements for a GPCR. An underlying mechanism is proposed whereby a voltage-induced conformational change in the receptor alters its ability to couple to the G protein and thereby influences its affinity for an agonist. We discuss the strength of the evidence behind this hypothesis and include suggestions for future work. We also describe other examples in which direct voltage control of GPCRs can account for effects of membrane potential on downstream signals and highlight the possible physiological consequences of this phenomenon.
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Affiliation(s)
- Martyn P Mahaut-Smith
- Department of Cell Physiology and Pharmacology, University of Leicester, LE1 9HN, UK.
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Siddiqui RA, Harvey KA, Zaloga GP. Modulation of enzymatic activities by n-3 polyunsaturated fatty acids to support cardiovascular health. J Nutr Biochem 2008; 19:417-37. [PMID: 17904342 DOI: 10.1016/j.jnutbio.2007.07.001] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 06/14/2007] [Accepted: 07/03/2007] [Indexed: 12/13/2022]
Abstract
Epidemiological evidence from Greenland Eskimos and Japanese fishing villages suggests that eating fish oil and marine animals can prevent coronary heart disease. Dietary studies from various laboratories have similarly indicated that regular fish oil intake affects several humoral and cellular factors involved in atherogenesis and may prevent atherosclerosis, arrhythmia, thrombosis, cardiac hypertrophy and sudden cardiac death. The beneficial effects of fish oil are attributed to their n-3 polyunsaturated fatty acid (PUFA; also known as omega-3 fatty acids) content, particularly eicosapentaenoic acid (EPA; 20:5, n-3) and docosahexaenoic acid (DHA; 22:6, n-3). Dietary supplementation of DHA and EPA influences the fatty acid composition of plasma phospholipids that, in turn, may affect cardiac cell functions in vivo. Recent studies have demonstrated that long-chain omega-3 fatty acids may exert beneficial effects by affecting a wide variety of cellular signaling mechanisms. Pathways involved in calcium homeostasis in the heart may be of particular importance. L-type calcium channels, the Na+-Ca2+ exchanger and mobilization of calcium from intracellular stores are the most obvious key signaling pathways affecting the cardiovascular system; however, recent studies now suggest that other signaling pathways involving activation of phospholipases, synthesis of eicosanoids, regulation of receptor-associated enzymes and protein kinases also play very important roles in mediating n-3 PUFA effects on cardiovascular health. This review is therefore focused on the molecular targets and signaling pathways that are regulated by n-3 PUFAs in relation to their cardioprotective effects.
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Affiliation(s)
- Rafat A Siddiqui
- Cellular Biochemistry Laboratory, Methodist Research Institute, Clarian Health, Indianapolis, IN 46202, USA.
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Ryglewski S, Pflueger HJ, Duch C. Expanding the neuron's calcium signaling repertoire: intracellular calcium release via voltage-induced PLC and IP3R activation. PLoS Biol 2007; 5:e66. [PMID: 17341135 PMCID: PMC1808487 DOI: 10.1371/journal.pbio.0050066] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Accepted: 12/29/2006] [Indexed: 01/30/2023] Open
Abstract
Neuronal calcium acts as a charge carrier during information processing and as a ubiquitous intracellular messenger. Calcium signals are fundamental to numerous aspects of neuronal development and plasticity. Specific and independent regulation of these vital cellular processes is achieved by a rich bouquet of different calcium signaling mechanisms within the neuron, which either can operate independently or may act in concert. This study demonstrates the existence of a novel calcium signaling mechanism by simultaneous patch clamping and calcium imaging from acutely isolated central neurons. These neurons possess a membrane voltage sensor that, independent of calcium influx, causes G-protein activation, which subsequently leads to calcium release from intracellular stores via phospholipase C and inositol 1,4,5-trisphosphate receptor activation. This allows neurons to monitor activity by intracellular calcium release without relying on calcium as the input signal and opens up new insights into intracellular signaling, developmental regulation, and information processing in neuronal compartments lacking calcium channels.
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Affiliation(s)
- Stefanie Ryglewski
- Institute of Biology/Neurobiology, Free University of Berlin, Berlin, Germany
| | - Hans J Pflueger
- Institute of Biology/Neurobiology, Free University of Berlin, Berlin, Germany
| | - Carsten Duch
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- * To whom correspondence should be addressed. E-mail:
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Thai TL, Fellner SK, Arendshorst WJ. ADP-ribosyl cyclase and ryanodine receptor activity contribute to basal renal vasomotor tone and agonist-induced renal vasoconstriction in vivo. Am J Physiol Renal Physiol 2007; 293:F1107-14. [PMID: 17652368 DOI: 10.1152/ajprenal.00483.2006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
An important role for the enzyme ADP-ribosyl cyclase (ADPR cyclase) and its downstream targets, the ryanodine receptors (RyR), is emerging for a variety of vascular systems. We hypothesized that the ADPR cyclase/RyR pathway contributes to regulation of renal vasomotor tone in vivo. To test this, we continuously measured renal blood flow (RBF) in anesthetized Sprague-Dawley rats. Infusion of the ADPR cyclase inhibitor nicotinamide intrarenally at low doses inhibits angiotensin II (ANG II)- and norepinephrine (NE)-induced vasoconstriction by 72 and 67%, respectively ( P < 0.001). RBF studies in rats were extended to mice lacking the predominant form of ADPR cyclase (CD38). Acute renal vasoconstrictor responses to ANG II and NE are impaired by 59 and 52%, respectively, in anesthetized CD38−/− mice compared with wild-type controls ( P < 0.05). Intrarenal injection of the RyR activator FK506 decreases RBF by 22% ( P > 0.03). Furthermore, RyR inhibition with ruthenium red attenuates ANG II and NE responses by 50 and 59%, respectively ( P ≤ 0.01). Given at higher doses, nicotinamide increases basal RBF by 22% ( P > 0.001). Non-receptor-mediated renal vasoconstriction by L-type voltage-gated Ca2+channels is also dependent on ADPR cyclase and RyRs. Nicotinamide and ruthenium red inhibit constriction by the L-type channel agonist BAY K 8644 by 59% ( P > 0.02) and 63% ( P > 0.001). We conclude that 1) ADPR cyclase activity contributes to regulation of renal vasomotor tone under resting conditions, 2) renal vasoconstriction induced by G protein-coupled receptor agonists ANG II and NE is mediated in part by ADPR cyclase and RyRs, and 3) ADPR cyclase and RyRs participate in L-type channel-mediated renal vasoconstriction in vivo.
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Affiliation(s)
- Tiffany L Thai
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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Kim S, Yun HM, Baik JH, Chung KC, Nah SY, Rhim H. Functional interaction of neuronal Cav1.3 L-type calcium channel with ryanodine receptor type 2 in the rat hippocampus. J Biol Chem 2007; 282:32877-89. [PMID: 17823125 DOI: 10.1074/jbc.m701418200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal L-type Ca(2+) channels do not support synaptic transmission, but they play an essential role in synaptic activity-dependent gene expression. Ca(v)1.2 and Ca(v)1.3 are the two most widely expressed L-type Ca(2+) channels in neurons and have different biophysical and subcellular distributions. The function of the Ca(v) 1.3 L-type Ca(2+) channel and its cellular mechanisms in the central nervous system are poorly understood. In this study, using a yeast two-hybrid assay, we found that the N terminus of the rat Ca(v)1.3 alpha(1) subunit interacts with a partial N-terminal amino acid sequence of ryanodine receptor type 2 (RyR2). Reverse transcription-PCR and Western blot assays revealed high expression of both Ca(v)1.3 and RyR2 in the rat hippocampus. We also demonstrate a physical association of Ca(v)1.3 with RyR2 using co-immunoprecipitation assays. Moreover, immunocytochemistry revealed prominent co-localization between Ca(v)1.3 and RyR2 in hippocampal neurons. Depolarizing cells by an acute treatment of a high concentration of KCl (high-K, 60 mm) showed that the activation of L-type Ca(2+) channels induced RyR opening and led to RyR-dependent Ca(2+) release, even in the absence of extracellular Ca(2+). Furthermore, we found that RyR2 mRNA itself is increased by long term treatment of high-K via activation of L-type Ca(2+) channels. These acute and long term effects of high-K on RyRs were selectively blocked by small interfering RNA-mediated silencing of Ca(v)1.3. These results suggest a physical and functional interaction between Ca(v)1.3 and RyR2 and important implications of Ca(v)1.3/RyR2 clusters in translating synaptic activity into alterations in gene expression.
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Affiliation(s)
- Sunoh Kim
- Life Sciences Division, Korea Institute of Science and Technology, 39-1 Hawholgok-dong, Sungbuk-gu, Seoul, Korea
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47
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Abstract
Endothelium-dependent relaxations are attributed to the release of various factors, such as nitric oxide, carbon monoxide, reactive oxygen species, adenosine, peptides and arachidonic acid metabolites derived from the cyclooxygenases, lipoxygenases, and cytochrome P450 monooxygenases pathways. The hyperpolarization of the smooth muscle cell can contribute to or be an integral part of the mechanisms underlying the relaxations elicited by virtually all these endothelial mediators. These endothelium-derived factors can activate different families of K(+) channels of the vascular smooth muscle. Other events associated with the hyperpolarization of both the endothelial and the vascular smooth muscle cells (endothelium-derived hyperpolarizing factor (EDHF)-mediated responses) contribute also to endothelium-dependent relaxations. These responses involve an increase in the intracellular Ca(2+) concentration of the endothelial cells followed by the opening of Ca(2+)-activated K(+) channels of small and intermediate conductance and the subsequent hyperpolarization of these cells. Then, the endothelium-dependent hyperpolarization of the underlying smooth muscle cells can be evoked by direct electrical coupling through myoendothelial junctions and/or the accumulation of K(+) ions in the intercellular space between the two cell types. These various mechanisms are not necessarily mutually exclusive and, depending on the vascular bed and the experimental conditions, can occur simultaneously or sequentially, or also may act synergistically.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France
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48
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Morita H, Honda A, Inoue R, Ito Y, Abe K, Nelson MT, Brayden JE. Membrane Stretch-Induced Activation of a TRPM4-Like Nonselective Cation Channel in Cerebral Artery Myocytes. J Pharmacol Sci 2007; 103:417-26. [PMID: 17420615 DOI: 10.1254/jphs.fp0061332] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Stretch-activated cation channels (SACs) have been observed in many types of smooth muscle cells. However, the molecular identity and activation mechanisms of SACs remain poorly understood. We report that TRPM4-like cation channels are activated by membrane stretch in rat cerebral artery myocytes (CAMs). Negative pressure (> or =20 mmHg, cell-attached mode) activated single channels (approximately 20 pS) in isolated CAMs. These channels were permeable to Na(+) and Cs(+) and inhibited by Gd(3+) (30 microM) and DIDS (100 microM). The effect of negative pressure was abolished by membrane excision, but subsequent application of Ca(2+) (>100 nM) to the intracellular side of the membrane restored single channel activity that was indistinguishable from SACs. Caffeine (5 mM), which depletes SR Ca(2+)-stores, first activated and then abolished SACs. Tetracaine (100 microM), a ryanodine receptor antagonist, inhibited SACs. Overexpression of hTRPM4B in HEK293 cells resulted in the appearance of cation channels that were activated by both negative pressure and Ca(2+) and which had very similar biophysical and pharmacological properties as compared with SACs in CAMs. These studies indicate that TRPM4-like channels in CAMs can be activated by membrane stretch, possibly through ryanodine receptor activation, and this may contribute to the depolarization and concomitant vasoconstriction of intact cerebral arteries following mechanical stimulation.
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MESH Headings
- 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid/pharmacology
- Animals
- Boron Compounds/pharmacology
- Calcium Channels/genetics
- Calcium Channels/physiology
- Cell Line
- Cell Membrane/physiology
- Cells, Cultured
- Cerebral Arteries/cytology
- Cerebral Arteries/metabolism
- Cerebral Arteries/physiology
- Female
- Gadolinium/pharmacology
- Gene Expression/drug effects
- Humans
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/physiology
- Patch-Clamp Techniques
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Stress, Mechanical
- TRPC Cation Channels/genetics
- TRPC Cation Channels/physiology
- TRPM Cation Channels/genetics
- TRPM Cation Channels/physiology
- TRPV Cation Channels/genetics
- TRPV Cation Channels/physiology
- Transient Receptor Potential Channels/genetics
- Transient Receptor Potential Channels/physiology
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Affiliation(s)
- Hiromitsu Morita
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA.
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49
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Billups D, Billups B, Challiss RAJ, Nahorski SR. Modulation of Gq-protein-coupled inositol trisphosphate and Ca2+ signaling by the membrane potential. J Neurosci 2006; 26:9983-95. [PMID: 17005862 PMCID: PMC2266565 DOI: 10.1523/jneurosci.2773-06.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Gq-protein-coupled receptors (GqPCRs) are widely distributed in the CNS and play fundamental roles in a variety of neuronal processes. Their activation results in phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis and Ca2+ release from intracellular stores via the phospholipase C (PLC)-inositol 1,4,5-trisphosphate (IP3) signaling pathway. Because early GqPCR signaling events occur at the plasma membrane of neurons, they might be influenced by changes in membrane potential. In this study, we use combined patch-clamp and imaging methods to investigate whether membrane potential changes can modulate GqPCR signaling in neurons. Our results demonstrate that GqPCR signaling in the human neuronal cell line SH-SY5Y and in rat cerebellar granule neurons is directly sensitive to changes in membrane potential, even in the absence of extracellular Ca2+. Depolarization has a bidirectional effect on GqPCR signaling, potentiating thapsigargin-sensitive Ca2+ responses to muscarinic receptor activation but attenuating those mediated by bradykinin receptors. The depolarization-evoked potentiation of the muscarinic signaling is graded, bipolar, non-inactivating, and with no apparent upper limit, ruling out traditional voltage-gated ion channels as the primary voltage sensors. Flash photolysis of caged IP3/GPIP2 (glycerophosphoryl-myo-inositol 4,5-bisphosphate) places the voltage sensor before the level of the Ca2+ store, and measurements using the fluorescent bioprobe eGFP-PH(PLCdelta) (enhanced green fluorescent protein-pleckstrin homology domain-PLCdelta) directly demonstrate that voltage affects muscarinic signaling at the level of the IP3 production pathway. The sensitivity of GqPCR IP3 signaling in neurons to voltage itself may represent a fundamental mechanism by which ionotropic signals can shape metabotropic receptor activity in neurons and influence processes such as synaptic plasticity in which the detection of coincident signals is crucial.
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Affiliation(s)
- Daniela Billups
- Department of Cell Physiology and Pharmacology, Medical Sciences Building, University of Leicester, Leicester LE1 9HN, United Kingdom.
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50
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Tirosh R, Resnik ER, Herron J, Sukovich DJ, Hong Z, Weir EK, Cornfield DN. Acute normoxia increases fetal pulmonary artery endothelial cell cytosolic Ca2+ via Ca2+-induced Ca2+ release. Pediatr Res 2006; 60:258-63. [PMID: 16857761 DOI: 10.1203/01.pdr.0000233077.29866.f0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
To test the hypothesis that an acute increase in O(2) tension increases cytosolic calcium ([Ca(2+)](i)) in fetal pulmonary artery endothelial cells (PAECs) via entry of extracellular calcium and subsequent calcium-induced calcium release (CICR) and nitric oxide release, low-passage PAECs (<10 passages) were isolated from the intralobar pulmonary artery (PA) of fetal sheep and maintained under hypoxic conditions (Po(2), 25 Torr). Using the calcium-sensitive dye fura-2, we demonstrated that acute normoxia (Po(2) = 120 Torr) increased PAECs [Ca(2+)](i) by increasing the rate of entry of extracellular calcium. In the presence of either ryanodine or 2-aminoethoxy-diphenylborate (2APB), normoxia did not lead to a sustained increase in PAECs [Ca(2+)](i) Whole-cell patch clamp studies demonstrated that acute normoxia causes PAEC membrane depolarization. When loaded with the nitric oxide (NO)-sensitive dye, DAF - FM, acute normoxia increased PAEC fluorescence. In PAECs derived from fetal lambs with pulmonary hypertension, an acute increase in O(2) tension had no effect on either [Ca(2+)](i) or NO production. Hypoxia increases loading of acetylcholine-sensitive calcium stores, as hypoxia potentiated the response to acetylcholine We conclude that acute normoxia increases [Ca(2+)](i) and NO production in normotensive but not hypertensive fetal PAECs via extracellular calcium entry and calcium release from calcium-sensitive intracellular stores.
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Affiliation(s)
- Raz Tirosh
- Department of Pediatrics, Division of Pediatric Pulmonary and Critical Care Medicine, University of Minnesota, Minneapolis, MN 55455, USA
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