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Longden TA, Lederer WJ. Electro-metabolic signaling. J Gen Physiol 2024; 156:e202313451. [PMID: 38197953 PMCID: PMC10783436 DOI: 10.1085/jgp.202313451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/27/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024] Open
Abstract
Precise matching of energy substrate delivery to local metabolic needs is essential for the health and function of all tissues. Here, we outline a mechanistic framework for understanding this critical process, which we refer to as electro-metabolic signaling (EMS). All tissues exhibit changes in metabolism over varying spatiotemporal scales and have widely varying energetic needs and reserves. We propose that across tissues, common signatures of elevated metabolism or increases in energy substrate usage that exceed key local thresholds rapidly engage mechanisms that generate hyperpolarizing electrical signals in capillaries that then relax contractile elements throughout the vasculature to quickly adjust blood flow to meet changing needs. The attendant increase in energy substrate delivery serves to meet local metabolic requirements and thus avoids a mismatch in supply and demand and prevents metabolic stress. We discuss in detail key examples of EMS that our laboratories have discovered in the brain and the heart, and we outline potential further EMS mechanisms operating in tissues such as skeletal muscle, pancreas, and kidney. We suggest that the energy imbalance evoked by EMS uncoupling may be central to cellular dysfunction from which the hallmarks of aging and metabolic diseases emerge and may lead to generalized organ failure states-such as diverse flavors of heart failure and dementia. Understanding and manipulating EMS may be key to preventing or reversing these dysfunctions.
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Affiliation(s)
- Thomas A. Longden
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Neurovascular Interactions, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - W. Jonathan Lederer
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Laboratory of Molecular Cardiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA
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2
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Chen YL, Daneva Z, Kuppusamy M, Ottolini M, Baker TM, Klimentova E, Shah SA, Sokolowski JD, Park MS, Sonkusare SK. Novel Smooth Muscle Ca 2+-Signaling Nanodomains in Blood Pressure Regulation. Circulation 2022; 146:548-564. [PMID: 35758040 PMCID: PMC9378684 DOI: 10.1161/circulationaha.121.058607] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Ca2+ signals in smooth muscle cells (SMCs) contribute to vascular resistance and control blood pressure. Increased vascular resistance in hypertension has been attributed to impaired SMC Ca2+ signaling mechanisms. In this regard, transient receptor potential vanilloid 4 (TRPV4SMC) ion channels are a crucial Ca2+ entry pathway in SMCs. However, their role in blood pressure regulation has not been identified. METHODS We used SMC-specific TRPV4-/- (TRPV4SMC-/-) mice to assess the role of TRPV4SMC channels in blood pressure regulation. We determined the contribution of TRPV4SMC channels to the constrictor effect of α1 adrenergic receptor (α1AR) stimulation and elevated intraluminal pressure: 2 main physiologic stimuli that constrict resistance-sized arteries. The contribution of spatially separated TRPV4SMC channel subpopulations to elevated blood pressure in hypertension was evaluated in angiotensin II-infused mice and patients with hypertension. RESULTS We provide first evidence that TRPV4SMC channel activity elevates resting blood pressure in normal mice. α1AR stimulation activated TRPV4SMC channels through PKCα (protein kinase Cα) signaling, which contributed significantly to vasoconstriction and blood pressure elevation. Intraluminal pressure-induced TRPV4SMC channel activity opposed vasoconstriction through activation of Ca2+-sensitive K+ (BK) channels, indicating functionally opposite pools of TRPV4SMC channels. Superresolution imaging of SMCs revealed spatially separated α1AR:TRPV4 and TRPV4:BK nanodomains in SMCs. These data suggest that spatially separated α1AR-TRPV4SMC and intraluminal pressure-TRPV4SMC-BK channel signaling have opposite effects on blood pressure, with α1AR-TRPV4SMC signaling dominating under resting conditions. Furthermore, in patients with hypertension and a mouse model of hypertension, constrictor α1AR-PKCα-TRPV4 signaling was upregulated, whereas dilator pressure-TRPV4-BK channel signaling was disrupted, thereby increasing vasoconstriction and elevating blood pressure. CONCLUSIONS Our data identify novel smooth muscle Ca2+-signaling nanodomains that regulate blood pressure and demonstrate their impairment in hypertension.
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Affiliation(s)
- Yen-Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Zdravka Daneva
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Maniselvan Kuppusamy
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Matteo Ottolini
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Thomas M. Baker
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Eliska Klimentova
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
| | - Soham A. Shah
- Department of Neurosurgery, University of Virginia, Charlottesville, VA, 22908, USA
| | - Jennifer D. Sokolowski
- Department of Biomedical Engineering, University of Virginia, Charlottesville, United States, VA, 22908, USA
| | - Min S. Park
- Department of Biomedical Engineering, University of Virginia, Charlottesville, United States, VA, 22908, USA
| | - Swapnil K. Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA, 22908, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, 22908, USA
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3
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Functionally linked potassium channel activity in cerebral endothelial and smooth muscle cells is compromised in Alzheimer's disease. Proc Natl Acad Sci U S A 2022; 119:e2204581119. [PMID: 35727988 PMCID: PMC9245656 DOI: 10.1073/pnas.2204581119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Patients with Alzheimer’s disease show hypoperfusion of the brain and this may contribute to disease progression. To elucidate underlying mechanisms, we studied pial arteries from 18-mo-old mice with Alzheimer’s disease due to overexpression of amyloid precursor protein. We found enhanced pressure-induced constriction of arteries because of reduction in ryanodine receptor-mediated, local calcium-release events (“Ca2+ sparks”) in arterial smooth muscle cells and a consequent decrease in the activity of large-conductance Ca2+-activated K+ (BK) channels. This phenotype was partially recapitulated by application of an amyloid-β peptide to healthy arteries. Our results will direct further research to restore cerebrovascular function, which is damaged in Alzheimer’s disease, leading to potentially new treatment options. The brain microcirculation is increasingly viewed as a potential target for disease-modifying drugs in the treatment of Alzheimer’s disease patients, reflecting a growing appreciation of evidence that cerebral blood flow is compromised in such patients. However, the pathogenic mechanisms in brain resistance arteries underlying blood flow defects have not yet been elucidated. Here we probed the roles of principal vasodilatory pathways in cerebral arteries using the APP23 mouse model of Alzheimer’s disease, in which amyloid precursor protein is increased approximately sevenfold, leading to neuritic plaques and cerebrovascular accumulation of amyloid-β similar to those in patients with Alzheimer’s disease. Pial arteries from APP23 mice (18 mo old) exhibited enhanced pressure-induced (myogenic) constriction because of a profound reduction in ryanodine receptor-mediated, local calcium-release events (“Ca2+ sparks”) in arterial smooth muscle cells and a consequent decrease in the activity of large-conductance Ca2+-activated K+ (BK) channels. The ability of the endothelial cell inward rectifier K+ (Kir2.1) channel to cause dilation was also compromised. Acute application of amyloid-β 1-40 peptide to cerebral arteries from wild-type mice partially recapitulated the BK dysfunction seen in APP23 mice but had no effect on Kir2.1 function. If mirrored in human Alzheimer’s disease, these tandem defects in K+ channel-mediated vasodilation could account for the clinical cerebrovascular presentation seen in patients: reduced blood flow and crippled functional hyperemia. These data direct future research toward approaches that reverse this dual vascular channel dysfunction, with the ultimate aim of restoring healthy cerebral blood flow and improving clinical outcomes.
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4
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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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5
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Leo MD, Peixoto-Nieves D, Yin W, Raghavan S, Muralidharan P, Mata-Daboin A, Jaggar JH. TMEM16A channel upregulation in arterial smooth muscle cells produces vasoconstriction during diabetes. Am J Physiol Heart Circ Physiol 2021; 320:H1089-H1101. [PMID: 33449847 PMCID: PMC7988758 DOI: 10.1152/ajpheart.00690.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 12/11/2022]
Abstract
The pathological involvement of anion channels in vascular dysfunction that occurs during type 2 diabetes (T2D) is unclear. Here, we tested the hypothesis that TMEM16A, a calcium-activated chloride (Cl-) channel, contributes to modifications in arterial contractility during T2D. Our data indicate that T2D increased TMEM16A mRNA in arterial smooth muscle cells and total and surface TMEM16A protein in resistance-size cerebral and hindlimb arteries of mice. To examine vascular cell types in which TMEM16A protein increased and the functional consequences of TMEM16A upregulation during T2D, we generated tamoxifen-inducible, smooth muscle cell-specific TMEM16A knockout (TMEM16A smKO) mice. T2D increased both TMEM16A protein and Cl- current density in arterial smooth muscle cells of control (TMEM16Afl/fl) mice. In contrast, T2D did not alter arterial TMEM16A protein or Cl- current density in smooth muscle cells of TMEM16A smKO mice. Intravascular pressure stimulated greater vasoconstriction (myogenic tone) in the arteries of T2D TMEM16Afl/fl mice than in the arteries of nondiabetic TMEM16Afl/fl mice. This elevation in myogenic tone in response to T2D was abolished in the arteries of T2D TMEM16A smKO mice. T2D also reduced Akt2 protein and activity in the arteries of T2D mice. siRNA-mediated knockdown of Akt2, but not Akt1, increased arterial TMEM16A protein in nondiabetic mice. In summary, data indicate that T2D is associated with an increase in TMEM16A expression and currents in arterial smooth muscle cells that produces vasoconstriction. Data also suggest that a reduction in Akt2 function drives these pathological alterations during T2D.NEW & NOTEWORTHY We investigated the involvement of TMEM16A channels in vascular dysfunction during type 2 diabetes (T2D). TMEM16A message, protein, and currents were higher in smooth muscle cells of resistance-size arteries during T2D. Pressure stimulated greater vasoconstriction in the arteries of T2D mice that was abolished in the arteries of TMEM16A smKO mice. Akt2 protein and activity were both lower in T2D arteries, and Akt2 knockdown elevated TMEM16A protein. We propose that a decrease in Akt2 function stimulates TMEM16A expression in arterial smooth muscle cells, leading to vasoconstriction during T2D.
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MESH Headings
- Animals
- Anoctamin-1/deficiency
- Anoctamin-1/genetics
- Anoctamin-1/metabolism
- Arteries/metabolism
- Arteries/physiopathology
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/physiopathology
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/physiopathology
- Diabetic Angiopathies/etiology
- Diabetic Angiopathies/genetics
- Diabetic Angiopathies/metabolism
- Diabetic Angiopathies/physiopathology
- HEK293 Cells
- Hindlimb/blood supply
- Humans
- Insulin Resistance
- Male
- Membrane Potentials
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiopathology
- Myocytes, Smooth Muscle/metabolism
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Signal Transduction
- Streptozocin
- Up-Regulation
- Vasoconstriction
- Mice
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Affiliation(s)
- M Dennis Leo
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee
| | | | - Wen Yin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Somasundaram Raghavan
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, Tennessee
| | | | - Alejandro Mata-Daboin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
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6
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Boerman EM, Segal SS. Aging alters spontaneous and neurotransmitter-mediated Ca 2+ signaling in smooth muscle cells of mouse mesenteric arteries. Microcirculation 2020; 27:e12607. [PMID: 31994289 DOI: 10.1111/micc.12607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/30/2019] [Accepted: 01/22/2020] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Aging impairs MA dilation by reducing the ability of sensory nerves to counteract sympathetic vasoconstriction. This study tested whether altered SMC Ca2+ signals to sympathetic (NE) and sensory (CGRP) neurotransmitters underlie aging-related deficits in vasodilation. METHODS MAs from young and old mice were pressurized and loaded with Fluo-4 dye for confocal measurement of SMC Ca2+ sparks and waves. Endothelial denudation resolved the influence of ECs. SMCs were immunolabeled for RyR isoforms and compared with transcript levels for RyRs and CGRP receptor components. RESULTS SMCs from young vs old mice exhibited more spontaneous Ca2+ spark sites with no difference in Ca2+ waves. NE reduced spark sites and increased waves for both groups; addition of CGRP restored sparks and reduced waves only for young mice. Endothelial denudation attenuated Ca2+ responses to CGRP for young but not old mice, which were already attenuated, suggesting a diminished role for ECs with aging. CGRP receptor expression was similar between ages with increased serum CGRP in old mice, where RyR1 expression was replaced by RyR3. CONCLUSION With aging, we suggest that altered RyR expression in SMCs contributes to impaired ability of sensory neurotransmission to restore Ca2+ signaling underlying vasomotor control during sympathetic activation.
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Affiliation(s)
- Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA
| | - Steven S Segal
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA.,Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
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7
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To KHT, Gui P, Li M, Zawieja SD, Castorena-Gonzalez JA, Davis MJ. T-type, but not L-type, voltage-gated calcium channels are dispensable for lymphatic pacemaking and spontaneous contractions. Sci Rep 2020; 10:70. [PMID: 31919478 PMCID: PMC6952455 DOI: 10.1038/s41598-019-56953-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 12/10/2019] [Indexed: 12/28/2022] Open
Abstract
The spontaneous contractions of collecting lymphatic vessels provide an essential propulsive force to return lymph centrally. These contractions are driven by an intrinsic electrical pacemaker, working through an unknown underlying ionic mechanism that becomes compromised in some forms of lymphedema. In previous studies, T-type voltage-gated Ca2+ channels (VGCCs) were implicated in this pacemaking mechanism, based on the effects of the reputedly selective T-type VGCC inhibitors mibefradil and Ni2+. Our goal was to test this idea in a more definitive way using genetic knock out mice. First, we demonstrated through both PCR and immunostaining that mouse lymphatic muscle cells expressed Cav3.1 and Cav3.2 and produced functional T-type VGCC currents when patch clamped. We then employed genetic deletion strategies to selectively test the roles of each T-type VGCC isoform in the regulation of lymphatic pacemaking. Surprisingly, global deletion of either, or both, isoform(s) was without significant effect on either the frequency, amplitude, or fractional pump flow of lymphatic collectors from two different regions of the mouse, studied ex vivo. Further, both WT and Cav3.1-/-; 3.2-/- double knock-out lymphatic vessels responded similarly to mibefradil and Ni2+, which substantially reduced contraction amplitudes and slightly increased frequencies at almost all pressures in both strains: a pattern consistent with inhibition of L-type rather than T-type VGCCs. Neither T-type VGCC isoform was required for ACh-induced inhibition of contraction, a mechanism by which those channels in smooth muscle are thought to be targets of endothelium-derived nitric oxide. Sharp intracellular electrode measurements in lymphatic smooth muscle revealed only subtle, but not significant, differences in the resting membrane potential and action potential characteristics between vessels from wild-type and Cav3.1-/-; 3.2-/- double knock-out mice. In contrast, smooth-muscle specific deletion of the L-type VGCC, Cav1.2, completely abolished all lymphatic spontaneous contractions. Collectively our results suggest that, although T-type VGCCs are expressed in mouse lymphatic smooth muscle, they do not play a significant role in modulating the frequency of the ionic pacemaker or the amplitude of spontaneous contractions. We conclude that the effects of mibefradil and Ni2+ in other lymphatic preparations are largely or completely explained by off-target effects on L-type VGCCs, which are essential for controlling both the frequency and strength of spontaneous contractions.
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MESH Headings
- Animals
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/chemistry
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/deficiency
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Lymphatic Vessels/physiology
- Male
- Membrane Potentials/drug effects
- Mibefradil/pharmacology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/metabolism
- Nickel/pharmacology
- Pacemaker, Artificial
- Rats
- Rats, Wistar
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Affiliation(s)
- Kim H T To
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Peichun Gui
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Min Li
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Jorge A Castorena-Gonzalez
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA
| | - Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, 65212, USA.
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Hasan R, Leo MD, Muralidharan P, Mata-Daboin A, Yin W, Bulley S, Fernandez-Peña C, MacKay CE, Jaggar JH. SUMO1 modification of PKD2 channels regulates arterial contractility. Proc Natl Acad Sci U S A 2019; 116:27095-27104. [PMID: 31822608 PMCID: PMC6936352 DOI: 10.1073/pnas.1917264116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PKD2 (polycystin-2, TRPP1) channels are expressed in a wide variety of cell types and can regulate functions, including cell division and contraction. Whether posttranslational modification of PKD2 modifies channel properties is unclear. Similarly uncertain are signaling mechanisms that regulate PKD2 channels in arterial smooth muscle cells (myocytes). Here, by studying inducible, cell-specific Pkd2 knockout mice, we discovered that PKD2 channels are modified by SUMO1 (small ubiquitin-like modifier 1) protein in myocytes of resistance-size arteries. At physiological intravascular pressures, PKD2 exists in approximately equal proportions as either nonsumoylated (PKD2) or triple SUMO1-modifed (SUMO-PKD2) proteins. SUMO-PKD2 recycles, whereas unmodified PKD2 is surface-resident. Intravascular pressure activates voltage-dependent Ca2+ influx that stimulates the return of internalized SUMO-PKD2 channels to the plasma membrane. In contrast, a reduction in intravascular pressure, membrane hyperpolarization, or inhibition of Ca2+ influx leads to lysosomal degradation of internalized SUMO-PKD2 protein, which reduces surface channel abundance. Through this sumoylation-dependent mechanism, intravascular pressure regulates the surface density of SUMO-PKD2-mediated Na+ currents (INa) in myocytes to control arterial contractility. We also demonstrate that intravascular pressure activates SUMO-PKD2, not PKD2, channels, as desumoylation leads to loss of INa activation in myocytes and vasodilation. In summary, this study reveals that PKD2 channels undergo posttranslational modification by SUMO1, which enables physiological regulation of their surface abundance and pressure-mediated activation in myocytes and thus control of arterial contractility.
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Affiliation(s)
- Raquibul Hasan
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - M. Dennis Leo
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | | | - Alejandro Mata-Daboin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Wen Yin
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Simon Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Carlos Fernandez-Peña
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Charles E. MacKay
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Jonathan H. Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163
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9
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Greenstein AS, Kadir SZAS, Csato V, Sugden SA, Baylie RA, Eisner DA, Nelson MT. Disruption of Pressure-Induced Ca 2+ Spark Vasoregulation of Resistance Arteries, Rather Than Endothelial Dysfunction, Underlies Obesity-Related Hypertension. Hypertension 2019; 75:539-548. [PMID: 31865779 PMCID: PMC7055934 DOI: 10.1161/hypertensionaha.119.13540] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Supplemental Digital Content is available in the text. Obesity-related hypertension is one of the world’s leading causes of death and yet little is understood as to how it develops. As a result, effective targeted therapies are lacking and pharmacological treatment is unfocused. To investigate underlying microvascular mechanisms, we studied small artery dysfunction in a high fat–fed mouse model of obesity. Pressure-induced constriction and responses to endothelial and vascular smooth muscle agonists were studied using myography; the corresponding intracellular Ca2+ signaling pathways were examined using confocal microscopy. Principally, we observed that the enhanced basal tone of mesenteric resistance arteries was due to failure of intraluminal pressure-induced Ca2+ spark activation of the large conductance Ca2+ activated K+ potassium channel (BK) within vascular smooth muscle cells. Specifically, the uncoupling site of this mechanotransduction pathway was at the sarcoplasmic reticulum, distal to intraluminal pressure-induced oxidation of Protein Kinase G. In contrast, the vasodilatory function of the endothelium and the underlying endothelial IP-3 and TRPV4 (vanilloid 4 transient receptor potential ion channel) Ca2+ signaling pathways were not affected by the high-fat diet or the elevated blood pressure. There were no structural alterations of the arterial wall. Our work emphasizes the importance of the intricate cellular pathway by which intraluminal pressure maintains Ca2+ spark vasoregulation in the origin of obesity-related hypertension and suggests previously unsuspected avenues for pharmacological intervention.
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Affiliation(s)
- Adam S Greenstein
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | | | - Viktoria Csato
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Sarah A Sugden
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Rachael A Baylie
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - David A Eisner
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
| | - Mark T Nelson
- From the Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom
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10
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Csato V, Kadir SZSA, Khavandi K, Bennett H, Sugden S, Gurney AM, Pritchard HT, Hill‐Eubanks D, Eaton P, Nelson MT, Greenstein AS. "A Step and a Ceiling": mechanical properties of Ca 2+ spark vasoregulation in resistance arteries by pressure-induced oxidative activation of PKG. Physiol Rep 2019; 7:e14260. [PMID: 31782255 PMCID: PMC6883097 DOI: 10.14814/phy2.14260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/26/2019] [Accepted: 07/27/2019] [Indexed: 11/24/2022] Open
Abstract
We investigated the biomechanical relationship between intraluminal pressure within small mesenteric resistance arteries, oxidant activation of PKG, Ca2+ sparks, and BK channel vasoregulation. Mesenteric resistance arteries from wild type (WT) and genetically modified mice with PKG resistance to oxidative activation were studied using wire and pressure myography. Ca2+ sparks and Ca2+ transients within vascular smooth muscle cells of intact arteries were characterized using high-speed confocal microscopy of intact arteries. Arteries were studied under conditions of varying intraluminal pressure and oxidation. Intraluminal pressure specifically, rather than the generic stretch of the artery, was necessary to activate the oxidative pathway. We demonstrated a graded step activation profile for the generation of Ca2+ sparks and also a functional "ceiling" for this pressure --sensitive oxidative pathway. During steady state pressure - induced constriction, any additional Ca2+ sensitive-K+ channel functional availability was independent of oxidant activated PKG. There was an increase in the amplitude, but not the Area under the Curve (AUC) of the caffeine-induced Ca2+ transient in pressurized arteries from mice with oxidant-resistant PKG compared with wild type. Overall, we surmise that intraluminal pressure within resistance arteries controls Ca2+ spark vasoregulation through a tightly controlled pathway with a graded onset switch. The pathway, underpinned by oxidant activation of PKG, cannot be further boosted by additional pressure or oxidation once active. We propose that these restrictive characteristics of pressure-induced Ca2+ spark vasoregulation confer stability for the artery in order to provide a constant flow independent of additional pressure fluctuations or exogenous oxidants.
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Affiliation(s)
- Viktoria Csato
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Division of Clinical PhysiologyInstitute of CardiologyResearch Centre for Molecular MedicineFaculty of MedicineUniversity of DebrecenDebrecenHungary
| | - Sharifah Z. S. A. Kadir
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Department of PharmacologyFaculty of MedicineUniversity of MalayaKuala LumpurMalaysia
| | - Kaivan Khavandi
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Hayley Bennett
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Sarah Sugden
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Alison M. Gurney
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | - Harry T. Pritchard
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
| | | | - Philip Eaton
- Centre for Clinical PharmacologyWilliam Harvey Research InstituteQueen Mary University of LondonLondonUnited Kingdom
- Present address:
Centre for Clinical PharmacologyWilliam Harvey Research InstituteQueen Mary University of LondonLondonUnited Kingdom
| | - Mark T. Nelson
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
- Department of PharmacologyUniversity of VermontBurlingtonVermont
| | - Adam S. Greenstein
- Division of Cardiovascular SciencesFaculty of Biology, Medicine and HealthUniversity of ManchesterHealth Innovation Manchester NetworkManchesterUnited Kingdom
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11
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Leo MD, Zhai X, Yin W, Jaggar JH. Impaired Trafficking of β1 Subunits Inhibits BK Channels in Cerebral Arteries of Hypertensive Rats. Hypertension 2019; 72:765-775. [PMID: 30012867 DOI: 10.1161/hypertensionaha.118.11147] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hypertension is a risk factor for cerebrovascular diseases, including stroke and dementia. During hypertension, arteries become constricted and are less responsive to vasodilators, including nitric oxide (NO). The regulation of arterial contractility by smooth muscle cell (myocyte) large-conductance calcium (Ca2+)-activated potassium (BK) channels is altered during hypertension, although mechanisms involved are unclear. We tested the hypothesis that dysfunctional trafficking of pore-forming BK channel (BKα) and auxiliary β1 subunits contributes to changes in cerebral artery contractility of stroke-prone spontaneously hypertensive rats (SP-SHRs). Our data indicate that the amounts of total and surface BKα and β1 proteins are similar in unstimulated arteries of age-matched SP-SHRs and normotensive Wistar-Kyoto rats. In contrast, stimulated surface-trafficking of β1 subunits by NO or membrane depolarization is inhibited in SP-SHR myocytes. PKCα (protein kinase C α) and PKCβII total protein and activity were both higher in SP-SHR than in Wistar-Kyoto rat arteries. NO or depolarization robustly activated Rab11, a small trafficking GTPase, in Wistar-Kyoto rat arteries but weakly activated Rab11 in SP-SHRs. Bisindolylmaleimide, a PKC inhibitor, and overexpression of a PKC phosphorylation-deficient Rab11A mutant (Rab11A S177A) restored stimulated β1 subunit surface-trafficking in SP-SHR myocytes. BK channel activation by NO was inhibited in SP-SHR myocytes and restored by Rab11A S177A expression. Vasodilation to NO and lithocholate, a BKα/β1 channel activator, was inhibited in pressurized SP-SHR arteries and reestablished by bisindolylmaleimide. In summary, data indicate that spontaneously active PKC inhibits Rab11A-mediated β1 subunit trafficking in arterial myocytes of SP-SHRs, leading to dysfunctional NO-induced BK channel activation and vasodilation.
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Affiliation(s)
- M Dennis Leo
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Xue Zhai
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Wen Yin
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Jonathan H Jaggar
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
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12
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Yip KP, Balasubramanian L, Kan C, Wang L, Liu R, Ribeiro-Silva L, Sham JSK. Intraluminal pressure triggers myogenic response via activation of calcium spark and calcium-activated chloride channel in rat renal afferent arteriole. Am J Physiol Renal Physiol 2018; 315:F1592-F1600. [PMID: 30089032 DOI: 10.1152/ajprenal.00239.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Myogenic contraction of renal arterioles is an important regulatory mechanism for renal blood flow autoregulation. We have previously demonstrated that integrin-mediated mechanical force increases the occurrence of Ca2+ sparks in freshly isolated renal vascular smooth muscle cells (VSMCs). To further test whether the generation of Ca2+ sparks is a downstream signal of mechanotransduction in pressure-induced myogenic constriction, the relationship between Ca2+ sparks and transmural perfusion pressure was investigated in intact VSMCs of pressurized rat afferent arterioles. Spontaneous Ca2+ sparks were found in VSMCs when afferent arterioles were perfused at 80 mmHg. The spark frequency was significantly increased when perfusion pressure was increased to 120 mmHg. A similar increase of spark frequency was also observed in arterioles stimulated with β1-integrin-activating antibody. Moreover, spark frequency was significantly higher in arterioles of spontaneous hypertensive rats at 80 and 120 mmHg. Spontaneous membrane current recorded using whole cell perforated patch in renal VSMCs showed predominant activity of spontaneous transient inward currents instead of spontaneous transient outward currents when holding potential was set close to physiological resting membrane potential. Real-time PCR and immunohistochemistry confirmed the expression of Ca2+-activated Cl- channel (ClCa) TMEM16A in renal VSMCs. Inhibition of TMEM16A with T16Ainh-A01 impaired the pressure-induced myogenic contraction in perfused afferent arterioles. Our study, for the first time to our knowledge, detected Ca2+ sparks in VSMCs of intact afferent arterioles, and their frequencies were positively modulated by the perfusion pressure. Our results suggest that Ca2+ sparks may couple to ClCa channels and trigger pressure-induced myogenic constriction via membrane depolarization.
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Affiliation(s)
- Kay-Pong Yip
- Department of Molecular Pharmacology and Physiology, University of South Florida , Tampa, Florida
| | - Lavanya Balasubramanian
- Department of Molecular Pharmacology and Physiology, University of South Florida , Tampa, Florida
| | - Chen Kan
- Department of Industrial, Manufacturing, and System Engineering, University of Texas at Arlington , Arlington, Texas
| | - Lei Wang
- Department of Molecular Pharmacology and Physiology, University of South Florida , Tampa, Florida
| | - Ruisheng Liu
- Department of Molecular Pharmacology and Physiology, University of South Florida , Tampa, Florida
| | - Luisa Ribeiro-Silva
- Department of Molecular Pharmacology and Physiology, University of South Florida , Tampa, Florida
| | - James S K Sham
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine , Baltimore, Maryland
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13
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Evanson KW, Goldsmith JA, Ghosh P, Delp MD. The G protein-coupled estrogen receptor agonist, G-1, attenuates BK channel activation in cerebral arterial smooth muscle cells. Pharmacol Res Perspect 2018; 6:e00409. [PMID: 29938113 PMCID: PMC6011940 DOI: 10.1002/prp2.409] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 05/22/2018] [Indexed: 11/07/2022] Open
Abstract
The G protein-coupled estrogen receptor (GPER) is a significant modulator of arterial contractility and blood flow. The GPER-specific activator, G-1, has been widely used to characterize GPER function in a variety of tissue types. Large conductance, calcium (Ca2+)-activated K+ (BK) channels are sensitive to 17β-estradiol (17β-E2) and estrogenic compounds (e.g., tamoxifen, ICI 182 780) that target estrogen receptors. The purpose of this study was to investigate the effects of G-1 on BK channel activation and function in cerebral arterial myocytes. Inside-out and perforated patch clamp were utilized to assess the effects of G-1 (50 nmol·L-1-5 μmol·L-1) on BK channel activation and currents in cerebral arterial myocytes. Pressurized artery myography was used to investigate the effects of G-1 on vasodilatory response and BK channel function of cerebral resistance size arteries. G-1 reduced BK channel activation in cerebral arterial myocytes through elevations in BK channel mean close times. Depressed BK channel activation following G-1 application resulted in attenuated physiological BK currents (transient BK currents). G-1 elicited vasodilation, but reduced BK channel function, in pressurized, endothelium-denuded cerebral arteries. These data suggest that G-1 directly suppresses BK channel activation and currents in cerebral arterial myocytes, BK channels being critically important in the regulation of myocyte membrane potential and arterial contractility. Thus, GPER-mediated vasodilation using G-1 to activate the receptor may underestimate the physiological function and relevance of GPER in the cardiovascular system.
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Affiliation(s)
- Kirk W. Evanson
- Department of Nutrition, Food, and Exercise SciencesFlorida State UniversityTallahasseeFlorida
| | - Jacob A. Goldsmith
- Department of Nutrition, Food, and Exercise SciencesFlorida State UniversityTallahasseeFlorida
| | - Payal Ghosh
- Department of Nutrition, Food, and Exercise SciencesFlorida State UniversityTallahasseeFlorida
| | - Michael D. Delp
- Department of Nutrition, Food, and Exercise SciencesFlorida State UniversityTallahasseeFlorida
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14
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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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15
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Aleksandrowicz M, Dworakowska B, Dolowy K, Kozniewska E. Restoration of the response of the middle cerebral artery of the rat to acidosis in hyposmotic hyponatremia by the opener of large-conductance calcium sensitive potassium channels (BK Ca). J Cereb Blood Flow Metab 2017; 37:3219-3230. [PMID: 28058990 PMCID: PMC5584697 DOI: 10.1177/0271678x16685575] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Hyposmotic hyponatremia (the decrease of extracellular concentration of sodium ions from 145 to 121 mM and the decrease of hyposmolality from 300 to 250 mOsm/kg H2O) impairs response of the middle cerebral artery (MCA) to acetylcholine and NO donor (S-nitroso-N-acetyl-DL-penicillamine). Since acidosis activates a similar intracellular signaling pathway, the present study was designed to verify the hypothesis that the response of the MCA to acidosis is impaired during acute hyposmotic hyponatremia due to abnormal NO-related signal transduction in vascular smooth muscle cells. Studies performed on isolated, cannulated, and pressurized rat MCA revealed that hyposmotic hyponatremia impaired the response of the MCA to acidosis and this was associated with hyposmolality rather than with decreased sodium ion concentration. Response to acidosis was restored by the BKCa but not by the KATP channel activator. Patch-clamp electrophysiology performed on myocytes freshly isolated from MCAs, demonstrated that hyposmotic hyponatremia does not affect BKCa currents but decreases the voltage-dependency of the activation of the BKCa channels in the presence of a specific opener of these channels. Our study suggests that reduced sensitivity of BKCa channels in the MCA to agonists results in the lack of response of this artery to acidosis during acute hyposmotic hyponatremia.
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Affiliation(s)
- Marta Aleksandrowicz
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Dworakowska
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Krzysztof Dolowy
- 2 Department of Biophysics, Warsaw University of Life Sciences, Warsaw, Poland
| | - Ewa Kozniewska
- 1 Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.,3 Department of Experimental and Clinical Physiology, Medical University of Warsaw, Warsaw, Poland
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16
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Zhai X, Leo MD, Jaggar JH. Endothelin-1 Stimulates Vasoconstriction Through Rab11A Serine 177 Phosphorylation. Circ Res 2017; 121:650-661. [PMID: 28696251 DOI: 10.1161/circresaha.117.311102] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/06/2017] [Accepted: 07/07/2017] [Indexed: 01/18/2023]
Abstract
RATIONALE Large-conductance calcium-activated potassium channels (BK) are composed of pore-forming BKα and auxiliary β1 subunits in arterial smooth muscle cells (myocytes). Vasoconstrictors, including endothelin-1 (ET-1), inhibit myocyte BK channels, leading to contraction, but mechanisms involved are unclear. Recent evidence indicates that BKα is primarily plasma membrane localized, whereas the cellular location of β1 can be rapidly altered by Rab11A-positive recycling endosomes. Whether vasoconstrictors regulate the multisubunit composition of surface BK channels to stimulate contraction is unclear. OBJECTIVE Test the hypothesis that ET-1 inhibits BK channels by altering BKα and β1 surface trafficking in myocytes, identify mechanisms involved, and determine functional significance in myocytes of small cerebral arteries. METHODS AND RESULTS ET-1, through activation of PKC (protein kinase C), reduced surface β1 abundance and the proximity of β1 to surface BKα in myocytes. In contrast, ET-1 did not alter surface BKα, total β1, or total BKα proteins. ET-1 stimulated Rab11A phosphorylation, which reduced Rab11A activity. Rab11A serine 177 was identified as a high-probability PKC phosphorylation site. Expression of a phosphorylation-incapable Rab11A construct (Rab11A S177A) blocked the ET-1-induced Rab11A phosphorylation, reduction in Rab11A activity, and decrease in surface β1 protein. ET-1 inhibited single BK channels and transient BK currents in myocytes and stimulated vasoconstriction via a PKC-dependent mechanism that required Rab11A S177. In contrast, NO-induced Rab11A activation, surface trafficking of β1 subunits, BK channel and transient BK current activation, and vasodilation did not involve Rab11A S177. CONCLUSIONS ET-1 stimulates PKC-mediated phosphorylation of Rab11A at serine 177, which inhibits Rab11A and Rab11A-dependent surface trafficking of β1 subunits. The decrease in surface β1 subunits leads to a reduction in BK channel calcium-sensitivity, inhibition of transient BK currents, and vasoconstriction. We describe a unique mechanism by which a vasoconstrictor inhibits BK channels and identify Rab11A serine 177 as a modulator of arterial contractility.
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Affiliation(s)
- Xue Zhai
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - M Dennis Leo
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Jonathan H Jaggar
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis.
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17
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Leo MD, Zhai X, Muralidharan P, Kuruvilla KP, Bulley S, Boop FA, Jaggar JH. Membrane depolarization activates BK channels through ROCK-mediated β1 subunit surface trafficking to limit vasoconstriction. Sci Signal 2017; 10:10/478/eaah5417. [PMID: 28487419 DOI: 10.1126/scisignal.aah5417] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Membrane depolarization of smooth muscle cells (myocytes) in the small arteries that regulate regional organ blood flow leads to vasoconstriction. Membrane depolarization also activates large-conductance calcium (Ca2+)-activated potassium (BK) channels, which limits Ca2+ channel activity that promotes vasoconstriction, thus leading to vasodilation. We showed that in human and rat arterial myocytes, membrane depolarization rapidly increased the cell surface abundance of auxiliary BK β1 subunits but not that of the pore-forming BKα channels. Membrane depolarization stimulated voltage-dependent Ca2+ channels, leading to Ca2+ influx and the activation of Rho kinase (ROCK) 1 and 2. ROCK1/2-mediated activation of Rab11A promoted the delivery of β1 subunits to the plasma membrane by Rab11A-positive recycling endosomes. These additional β1 subunits associated with BKα channels already at the plasma membrane, leading to an increase in apparent Ca2+ sensitivity and activation of the channels in pressurized arterial myocytes and vasodilation. Thus, membrane depolarization activates BK channels through stimulation of ROCK- and Rab11A-dependent trafficking of β1 subunits to the surface of arterial myocytes.
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Affiliation(s)
- M Dennis Leo
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Xue Zhai
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Padmapriya Muralidharan
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Korah P Kuruvilla
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Simon Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Frederick A Boop
- Department of Neurosurgery, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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18
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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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19
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Hashad AM, Mazumdar N, Romero M, Nygren A, Bigdely-Shamloo K, Harraz OF, Puglisi JL, Vigmond EJ, Wilson SM, Welsh DG. Interplay among distinct Ca 2+ conductances drives Ca 2+ sparks/spontaneous transient outward currents in rat cerebral arteries. J Physiol 2016; 595:1111-1126. [PMID: 27805790 DOI: 10.1113/jp273329] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/30/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Distinct Ca2+ channels work in a coordinated manner to grade Ca2+ spark/spontaneous transient outward currents (STOCs) in rat cerebral arteries. The relative contribution of each Ca2+ channel to Ca2+ spark/STOC production depends upon their biophysical properties and the resting membrane potential of smooth muscle. Na+ /Ca2+ exchanger, but not TRP channels, can also facilitate STOC production. ABSTRACT Ca2+ sparks are generated in a voltage-dependent manner to initiate spontaneous transient outward currents (STOCs), events that moderate arterial constriction. In this study, we defined the mechanisms by which membrane depolarization increases Ca2+ sparks and subsequent STOC production. Using perforated patch clamp electrophysiology and rat cerebral arterial myocytes, we monitored STOCs in the presence and absence of agents that modulate Ca2+ entry. Beginning with CaV 3.2 channel inhibition, Ni2+ was shown to decrease STOC frequency in cells held at hyperpolarized (-40 mV) but not depolarized (-20 mV) voltages. In contrast, nifedipine, a CaV 1.2 inhibitor, markedly suppressed STOC frequency at -20 mV but not -40 mV. These findings aligned with the voltage-dependent profiles of L- and T-type Ca2+ channels. Furthermore, computational and experimental observations illustrated that Ca2+ spark production is intimately tied to the activity of both conductances. Intriguingly, this study observed residual STOC production at depolarized voltages that was independent of CaV 1.2 and CaV 3.2. This residual component was insensitive to TRPV4 channel modulation and was abolished by Na+ /Ca2+ exchanger blockade. In summary, our work highlights that the voltage-dependent triggering of Ca2+ sparks/STOCs is not tied to a single conductance but rather reflects an interplay among multiple Ca2+ permeable pores with distinct electrophysiological properties. This integrated orchestration enables smooth muscle to grade Ca2+ spark/STOC production and thus precisely tune negative electrical feedback.
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Affiliation(s)
- Ahmed M Hashad
- Department of Physiology and Pharmacology, Hotchkiss Brain and Libin Cardiovascular Institute, University of Calgary, Alberta, Canada
| | - Neil Mazumdar
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
| | - Monica Romero
- Department of Basic Sciences, Division of Pharmacology, Loma Linda University, CA, USA
| | - Anders Nygren
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Kamran Bigdely-Shamloo
- Department of Physiology and Pharmacology, Hotchkiss Brain and Libin Cardiovascular Institute, University of Calgary, Alberta, Canada.,Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada
| | - Osama F Harraz
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Jose L Puglisi
- California Northstate University College of Medicine, CA, USA
| | - Edward J Vigmond
- Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada.,LIRYC Institute and Lab IMB, University of Bordeaux, Bordeaux, France
| | - Sean M Wilson
- Department of Basic Sciences, Division of Pharmacology, Loma Linda University, CA, USA
| | - Donald G Welsh
- Department of Physiology and Pharmacology, Hotchkiss Brain and Libin Cardiovascular Institute, University of Calgary, Alberta, Canada.,Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
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20
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Krishnamoorthy G, Reimann K, Wangemann P. Ryanodine-induced vasoconstriction of the gerbil spiral modiolar artery depends on the Ca 2+ sensitivity but not on Ca 2+ sparks or BK channels. BMC PHYSIOLOGY 2016; 16:6. [PMID: 27806708 PMCID: PMC5093982 DOI: 10.1186/s12899-016-0026-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/13/2016] [Indexed: 01/26/2023]
Abstract
Background In many vascular smooth muscle cells (SMCs), ryanodine receptor-mediated Ca2+ sparks activate large-conductance Ca2+-activated K+ (BK) channels leading to lowered SMC [Ca2+]i and vasodilation. Here we investigated whether Ca2+ sparks regulate SMC global [Ca2+]i and diameter in the spiral modiolar artery (SMA) by activating BK channels. Methods SMAs were isolated from adult female gerbils, loaded with the Ca2+-sensitive flourescent dye fluo-4 and pressurized using a concentric double-pipette system. Ca2+ signals and vascular diameter changes were recorded using a laser-scanning confocal imaging system. Effects of various pharmacological agents on Ca2+ signals and vascular diameter were analyzed. Results Ca2+ sparks and waves were observed in pressurized SMAs. Inhibition of Ca2+ sparks with ryanodine increased global Ca2+ and constricted SMA at 40 cmH2O but inhibition of Ca2+ sparks with tetracaine or inhibition of BK channels with iberiotoxin at 40 cmH2O did not produce a similar effect. The ryanodine-induced vasoconstriction observed at 40 cmH2O was abolished at 60 cmH2O, consistent with a greater Ca2+-sensitivity of constriction at 40 cmH2O than at 60 cmH2O. When the Ca2+-sensitivity of the SMA was increased by prior application of 1 nM endothelin-1, ryanodine induced a robust vasoconstriction at 60 cmH2O. Conclusions The results suggest that Ca2+ sparks, while present, do not regulate vascular diameter in the SMA by activating BK channels and that the regulation of vascular diameter in the SMA is determined by the Ca2+-sensitivity of constriction.
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Affiliation(s)
- Gayathri Krishnamoorthy
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, 228 Coles Hall, Manhattan, Kansas, 66506-5802, USA
| | - Katrin Reimann
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, 228 Coles Hall, Manhattan, Kansas, 66506-5802, USA.,Department of Otolaryngology-Head and Neck Surgery, Tübingen Hearing Research Centre, and Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
| | - Philine Wangemann
- Anatomy & Physiology Department, Cell Physiology Laboratory, Kansas State University, 228 Coles Hall, Manhattan, Kansas, 66506-5802, USA.
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21
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Ghosh D, Syed AU, Prada MP, Nystoriak MA, Santana LF, Nieves-Cintrón M, Navedo MF. Calcium Channels in Vascular Smooth Muscle. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:49-87. [PMID: 28212803 DOI: 10.1016/bs.apha.2016.08.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Calcium (Ca2+) plays a central role in excitation, contraction, transcription, and proliferation of vascular smooth muscle cells (VSMs). Precise regulation of intracellular Ca2+ concentration ([Ca2+]i) is crucial for proper physiological VSM function. Studies over the last several decades have revealed that VSMs express a variety of Ca2+-permeable channels that orchestrate a dynamic, yet finely tuned regulation of [Ca2+]i. In this review, we discuss the major Ca2+-permeable channels expressed in VSM and their contribution to vascular physiology and pathology.
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Affiliation(s)
- D Ghosh
- University of California, Davis, CA, United States
| | - A U Syed
- University of California, Davis, CA, United States
| | - M P Prada
- University of California, Davis, CA, United States
| | - M A Nystoriak
- Diabetes and Obesity Center, University of Louisville, Louisville, KY, United States
| | - L F Santana
- University of California, Davis, CA, United States
| | | | - M F Navedo
- University of California, Davis, CA, United States.
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22
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Khavandi K, Baylie RA, Sugden SA, Ahmed M, Csato V, Eaton P, Hill-Eubanks DC, Bonev AD, Nelson MT, Greenstein AS. Pressure-induced oxidative activation of PKG enables vasoregulation by Ca2+ sparks and BK channels. Sci Signal 2016; 9:ra100. [PMID: 27729550 DOI: 10.1126/scisignal.aaf6625] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Activation of Ca2+-sensitive, large-conductance potassium (BK) channels in vascular smooth muscle cells (VSMCs) by local, ryanodine receptor-mediated Ca2+ signals (Ca2+ sparks) acts as a brake on pressure-induced (myogenic) vasoconstriction-a fundamental mechanism that regulates blood flow in small resistance arteries. We report that physiological intraluminal pressure within resistance arteries activated cGMP-dependent protein kinase (PKG) in VSMCs through oxidant-induced formation of an intermolecular disulfide bond between cysteine residues. Oxidant-activated PKG was required to trigger Ca2+ sparks, BK channel activity, and vasodilation in response to pressure. VSMCs from arteries from mice expressing a form of PKG that could not be activated by oxidants showed reduced Ca2+ spark frequency, and arterial preparations from these mice had decreased pressure-induced activation of BK channels. Thus, the absence of oxidative activation of PKG disabled the BK channel-mediated negative feedback regulation of vasoconstriction. Our results support the concept of a negative feedback control mechanism that regulates arterial diameter through mechanosensitive production of oxidants to activate PKG and enhance Ca2+ sparks.
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Affiliation(s)
- Kaivan Khavandi
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | - Rachael A Baylie
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Sarah A Sugden
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
| | - Majid Ahmed
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Viktoria Csato
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Debrecen 4012, Hungary
| | - Philip Eaton
- King's College London, Cardiovascular Division, The British Heart Foundation Centre of Excellence, The Rayne Institute, Saint Thomas' Hospital, London, SE1 7EH, UK
| | | | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Mark T Nelson
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK.,Department of Pharmacology, University of Vermont, Vermont, 05405-0068, USA
| | - Adam S Greenstein
- Institute of Cardiovascular Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Center, Manchester, M13 9NT, UK
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Hill MA, Braun AP. Oxidant signaling underlies PKGIα modulation of Ca2+ sparks and BKCa in myogenically active arterioles. Sci Signal 2016; 9:fs15. [PMID: 27729549 DOI: 10.1126/scisignal.aak9385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Local blood flow autoregulation in response to intraluminal pressure requires small artery myogenic vasoconstriction, the extent of which is thought to be governed by a feedback process that depends on Ca2+ signaling. In this issue of Science Signaling, Khavandi et al suggest a role for cyclic guanosine monophosphate (cGMP)-dependent protein kinase G Iα (PKGIα) activated by oxidants in a cGMP-independent manner.
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Affiliation(s)
- Michael A Hill
- Dalton Cardiovascular Research Center and Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO 65211, USA.
| | - Andrew P Braun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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24
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Bannister JP, Bulley S, Leo MD, Kidd MW, Jaggar JH. Rab25 influences functional Cav1.2 channel surface expression in arterial smooth muscle cells. Am J Physiol Cell Physiol 2016; 310:C885-93. [PMID: 27076616 DOI: 10.1152/ajpcell.00345.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 03/24/2016] [Indexed: 11/22/2022]
Abstract
Plasma membrane-localized CaV1.2 channels are the primary calcium (Ca(2+)) influx pathway in arterial smooth muscle cells (myocytes). CaV1.2 channels regulate several cellular functions, including contractility and gene expression, but the trafficking pathways that control the surface expression of these proteins are unclear. Similarly, expression and physiological functions of small Rab GTPases, proteins that control vesicular trafficking in arterial myocytes, are poorly understood. Here, we investigated Rab proteins that control functional surface abundance of CaV1.2 channels in cerebral artery myocytes. Western blotting indicated that Rab25, a GTPase previously associated with apical recycling endosomes, is expressed in cerebral artery myocytes. Immunofluorescence Förster resonance energy transfer (immunoFRET) microscopy demonstrated that Rab25 locates in close spatial proximity to CaV1.2 channels in myocytes. Rab25 knockdown using siRNA reduced CaV1.2 surface and intracellular abundance in arteries, as determined using arterial biotinylation. In contrast, CaV1.2 was not located nearby Rab11A or Rab4 and CaV1.2 protein was unaltered by Rab11A or Rab4A knockdown. Rab25 knockdown resulted in CaV1.2 degradation by a mechanism involving both lysosomal and proteasomal pathways and reduced whole cell CaV1.2 current density but did not alter voltage dependence of current activation or inactivation in isolated myocytes. Rab25 knockdown also inhibited depolarization (20-60 mM K(+)) and pressure-induced vasoconstriction (myogenic tone) in cerebral arteries. These data indicate that Rab25 is expressed in arterial myocytes where it promotes surface expression of CaV1.2 channels to control pressure- and depolarization-induced vasoconstriction.
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Affiliation(s)
- John P Bannister
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Simon Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - M Dennis Leo
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Michael W Kidd
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Jonathan H Jaggar
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
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25
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Jackson-Weaver O, Osmond JM, Naik JS, Gonzalez Bosc LV, Walker BR, Kanagy NL. Intermittent hypoxia in rats reduces activation of Ca2+ sparks in mesenteric arteries. Am J Physiol Heart Circ Physiol 2015; 309:H1915-22. [PMID: 26408536 DOI: 10.1152/ajpheart.00179.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 09/17/2015] [Indexed: 01/25/2023]
Abstract
Ca(+) sparks are vascular smooth muscle cell (VSMC) Ca(2+)-release events that are mediated by ryanodine receptors (RyR) and promote vasodilation by activating large-conductance Ca(2+)-activated potassium channels and inhibiting myogenic tone. We have previously reported that exposing rats to intermittent hypoxia (IH) to simulate sleep apnea augments myogenic tone in mesenteric arteries through loss of hydrogen sulfide (H2S)-induced dilation. Because we also observed that H2S can increase Ca(2+) spark activity, we hypothesized that loss of H2S after IH exposure reduces Ca(2+) spark activity and that blocking Ca(2+) spark generation reduces H2S-induced dilation. Ca(2+) spark activity was lower in VSMC of arteries from IH compared with sham-exposed rats. Furthermore, depolarizing VSMC by increasing luminal pressure (from 20 to 100 mmHg) or by elevating extracellular [K(+)] increased spark activity in VSMC of arteries from sham rats but had no effect in arteries from IH rats. Inhibiting endogenous H2S production in sham arteries prevented these increases. NaHS or phosphodiesterase inhibition increased spark activity to the same extent in sham and IH arteries. Depolarization-induced increases in Ca(2+) spark activity were due to increased sparks per site, whereas H2S increases in spark activity were due to increased spark sites per cell. Finally, inhibiting Ca(2+) spark activity with ryanodine (10 μM) enhanced myogenic tone in arteries from sham but not IH rats and blocked dilation to exogenous H2S in arteries from both sham and IH rats. Our results suggest that H2S regulates RyR activation and that H2S-induced dilation requires Ca(2+) spark activation. IH exposure decreases endogenous H2S-dependent Ca(2+) spark activation to cause membrane depolarization and enhance myogenic tone in mesenteric arteries.
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Affiliation(s)
- Olan Jackson-Weaver
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Jessica M Osmond
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Jay S Naik
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Laura V Gonzalez Bosc
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Benjimen R Walker
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
| | - Nancy L Kanagy
- Vascular Physiology Group, Department of Cell Biology and Physiology, School of Medicine, University of New Mexico, Albuquerque, New Mexico
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26
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Burris SK, Wang Q, Bulley S, Neeb ZP, Jaggar JH. 9-Phenanthrol inhibits recombinant and arterial myocyte TMEM16A channels. Br J Pharmacol 2015; 172:2459-68. [PMID: 25573456 DOI: 10.1111/bph.13077] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 12/19/2014] [Accepted: 12/23/2014] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE In arterial smooth muscle cells (myocytes), intravascular pressure stimulates membrane depolarization and vasoconstriction (the myogenic response). Ion channels proposed to mediate pressure-induced depolarization include several transient receptor potential (TRP) channels, including TRPM4, and transmembrane protein 16A (TMEM16A), a Ca(2+) -activated Cl(-) channel (CaCC). 9-Phenanthrol, a putative selective TRPM4 channel inhibitor, abolishes myogenic tone in cerebral arteries, suggesting that either TRPM4 is essential for pressure-induced depolarization, upstream of activation of other ion channels or that 9-phenanthrol is non-selective. Here, we tested the hypothesis that 9-phenanthrol is also a TMEM16A channel blocker, an ion channel for which few inhibitors have been identified. EXPERIMENTAL APPROACH Patch clamp electrophysiology was used to measure rat cerebral artery myocyte and human recombinant TMEM16A (rTMEM16A) currents or currents generated by recombinant bestrophin-1, another Ca(2+) -activated Cl(-) channel, expressed in HEK293 cells. KEY RESULTS 9-Phenanthrol blocked myocyte TMEM16A currents activated by either intracellular Ca(2+) or Eact , a TMEM16A channel activator. In contrast, 9-phenanthrol did not alter recombinant bestrophin-1 currents. 9-Phenanthrol reduced arterial myocyte TMEM16A currents with an IC50 of ∼12 μM. Cell-attached patch recordings indicated that 9-phenanthrol reduced single rTMEM16A channel open probability and mean open time, and increased mean closed time without affecting the amplitude. CONCLUSIONS AND IMPLICATIONS These data identify 9-phenanthrol as a novel TMEM16A channel blocker and provide an explanation for the previous observation that 9-phenanthrol abolishes myogenic tone when both TRPM4 and TMEM16A channels contribute to this response. 9-Phenanthrol may be a promising candidate from which to develop TMEM16A channel-specific inhibitors.
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Affiliation(s)
- Sarah K Burris
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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27
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Moreno-Domínguez A, El-Yazbi AF, Zhu HL, Colinas O, Zhong XZ, Walsh EJ, Cole DM, Kargacin GJ, Walsh MP, Cole WC. Cytoskeletal reorganization evoked by Rho-associated kinase- and protein kinase C-catalyzed phosphorylation of cofilin and heat shock protein 27, respectively, contributes to myogenic constriction of rat cerebral arteries. J Biol Chem 2014; 289:20939-52. [PMID: 24914207 PMCID: PMC4110300 DOI: 10.1074/jbc.m114.553743] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Revised: 06/03/2014] [Indexed: 12/31/2022] Open
Abstract
Our understanding of the molecular events contributing to myogenic control of diameter in cerebral resistance arteries in response to changes in intravascular pressure, a fundamental mechanism regulating blood flow to the brain, is incomplete. Myosin light chain kinase and phosphatase activities are known to be increased and decreased, respectively, to augment phosphorylation of the 20-kDa regulatory light chain subunits (LC20) of myosin II, which permits cross-bridge cycling and force development. Here, we assessed the contribution of dynamic reorganization of the actin cytoskeleton and thin filament regulation to the myogenic response and serotonin-evoked constriction of pressurized rat middle cerebral arteries. Arterial diameter and the levels of phosphorylated LC(20), calponin, caldesmon, cofilin, and HSP27, as well as G-actin content, were determined. A decline in G-actin content was observed following pressurization from 10 mm Hg to between 40 and 120 mm Hg and in three conditions in which myogenic or agonist-evoked constriction occurred in the absence of a detectable change in LC20 phosphorylation. No changes in thin filament protein phosphorylation were evident. Pressurization reduced G-actin content and elevated the levels of cofilin and HSP27 phosphorylation. Inhibitors of Rho-associated kinase and PKC prevented the decline in G-actin; reduced cofilin and HSP27 phosphoprotein content, respectively; and blocked the myogenic response. Furthermore, phosphorylation modulators of HSP27 and cofilin induced significant changes in arterial diameter and G-actin content of myogenically active arteries. Taken together, our findings suggest that dynamic reorganization of the cytoskeleton involving increased actin polymerization in response to Rho-associated kinase and PKC signaling contributes significantly to force generation in myogenic constriction of cerebral resistance arteries.
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Affiliation(s)
| | - Ahmed F. El-Yazbi
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Hai-Lei Zhu
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Olaia Colinas
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - X. Zoë Zhong
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Emma J. Walsh
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Dylan M. Cole
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Gary J. Kargacin
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
| | - Michael P. Walsh
- Biochemistry & Molecular Biology, Libin Cardiovascular Institute and Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - William C. Cole
- From the Smooth Muscle Research Group, Departments of Physiology & Pharmacology and
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28
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Evanson KW, Bannister JP, Leo MD, Jaggar JH. LRRC26 is a functional BK channel auxiliary γ subunit in arterial smooth muscle cells. Circ Res 2014; 115:423-31. [PMID: 24906643 DOI: 10.1161/circresaha.115.303407] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Smooth muscle cell (myocyte) large-conductance calcium (Ca)(2+)-activated potassium (BK) channels are functionally significant modulators of arterial contractility. Arterial myocytes express both pore-forming BKα and auxiliary β1 subunits, which increase channel Ca(2+) sensitivity. Recently, several leucine-rich repeat containing (LRRC) proteins have been identified as auxiliary γ subunits that elevate the voltage sensitivity of recombinant and prostate adenocarcinoma BK channels. LRRC expression and physiological functions in native cell types are unclear. OBJECTIVE Investigate the expression and physiological functions of leucine-rich repeat containing protein 26 (LRRC26) in arterial myocytes. METHODS AND RESULTS Reverse transcription polymerase chain reaction and Western blotting detected LRRC26 mRNA and protein in cerebral artery myocytes. Biotinylation, immunofluorescence resonance energy transfer microscopy, and coimmunoprecipitation indicated that LRRC26 was located in close spatial proximity to, and associated with, plasma membrane BKα subunits. LRRC26 knockdown (RNAi) reduced total and surface LRRC26, but did not alter BKα or β1, proteins in arteries. LRRC26 knockdown did not alter Ca(2+) sparks but reduced BK channel voltage sensitivity, which decreased channel apparent Ca(2+) sensitivity and transient BK current frequency and amplitude in myocytes. LRRC26 knockdown also increased myogenic tone over a range (40-100 mm Hg) of intravascular pressures, and reduced vasoconstriction to iberiotoxin and vasodilation to NS1619, BK channel inhibitors and activators, respectively. In contrast, LRRC26 knockdown did not alter depolarization (60 mmol/L K(+))-induced vasoconstriction. CONCLUSIONS LRRC26 is expressed, associates with BKα subunits, and elevates channel voltage- and apparent Ca(2+) sensitivity in arterial myocytes to induce vasodilation. This study indicates that arterial myocytes express a functional BK channel γ subunit.
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Affiliation(s)
- Kirk W Evanson
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - John P Bannister
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - M Dennis Leo
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis
| | - Jonathan H Jaggar
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis.
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29
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Effect of diet-induced obesity on BKCa function in contraction and dilation of rat isolated middle cerebral artery. Vascul Pharmacol 2014; 61:10-5. [DOI: 10.1016/j.vph.2014.02.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 02/13/2014] [Accepted: 02/16/2014] [Indexed: 01/09/2023]
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30
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Billaud M, Lohman AW, Johnstone SR, Biwer LA, Mutchler S, Isakson BE. Regulation of cellular communication by signaling microdomains in the blood vessel wall. Pharmacol Rev 2014; 66:513-69. [PMID: 24671377 DOI: 10.1124/pr.112.007351] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.
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Affiliation(s)
- Marie Billaud
- Dept. of Molecular Physiology and Biophysics, University of Virginia School of Medicine, PO Box 801394, Charlottesville, VA 22902.
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31
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Osmond JM, Gonzalez Bosc LV, Walker BR, Kanagy NL. Endothelin-1-induced vasoconstriction does not require intracellular Ca²⁺ waves in arteries from rats exposed to intermittent hypoxia. Am J Physiol Heart Circ Physiol 2014; 306:H667-73. [PMID: 24414066 DOI: 10.1152/ajpheart.00643.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sleep apnea is associated with cardiovascular disease, and patients with sleep apnea have elevated plasma endothelin (ET)-1 concentrations. Rats exposed to intermittent hypoxia (IH), a model of sleep apnea, also have increased plasma ET-1 concentrations and heightened constriction to ET-1 in mesenteric arteries without an increase in global vascular smooth muscle cell Ca(2+) concentration ([Ca(2+)]). Because ET-1 has been shown to increase the occurrence of propagating Ca(2+) waves, we hypothesized that ET-1 increases Ca(2+) wave activity in mesenteric arteries, rather than global [Ca(2+)], to mediate enhanced vasoconstriction after IH exposure. Male Sprague-Dawley rats were exposed to sham or IH conditions for 7 h/day for 2 wk. Mesenteric arteries from sham- and IH-exposed rats were isolated, cannulated, and pressurized to 75 mmHg to measure ET-1-induced constriction as well as changes in global [Ca(2+)] and Ca(2+) wave activity. A low concentration of ET-1 (1 nM) elicited similar vasoconstriction and global Ca(2+) responses in the two groups. Conversely, ET-1 had no effect on Ca(2+) wave activity in arteries from sham rats but significantly increased wave frequency in arteries from IH-exposed rats. The ET-1-induced increase in Ca(2+) wave frequency in arteries from IH rats was dependent on phospholipase C and inositol 1,4,5-trisphosphate receptor activation, yet inhibition of phospholipase C and the inositol 1,4,5-trisphosphate receptor did not prevent ET-1-mediated vasoconstriction. These results suggest that although ET-1 elevates Ca(2+) wave activity after IH exposure, increases in wave activity are not associated with increased vasoconstriction.
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Affiliation(s)
- Jessica M Osmond
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico
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32
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Krishnamoorthy G, Sonkusare SK, Heppner TJ, Nelson MT. Opposing roles of smooth muscle BK channels and ryanodine receptors in the regulation of nerve-evoked constriction of mesenteric resistance arteries. Am J Physiol Heart Circ Physiol 2014; 306:H981-8. [PMID: 24508642 DOI: 10.1152/ajpheart.00866.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In depolarized smooth muscle cells of pressurized cerebral arteries, ryanodine receptors (RyRs) generate "Ca2+ sparks" that activate large-conductance, Ca2+ -, and voltage-sensitive potassium (BK) channels to oppose pressure-induced (myogenic) constriction. Here, we show that BK channels and RyRs have opposing roles in the regulation of arterial tone in response to sympathetic nerve activation by electrical field stimulation. Inhibition of BK channels with paxilline increased both myogenic and nerve-induced constrictions of pressurized, resistance-sized mesenteric arteries from mice. Inhibition of RyRs with ryanodine increased myogenic constriction, but it decreased nerve-evoked constriction along with a reduction in the amplitude of nerve-evoked increases in global intracellular Ca2+. In the presence of L-type voltage-dependent Ca2+ channel (VDCC) antagonists, nerve stimulation failed to evoke a change in arterial diameter, and BK channel and RyR inhibitors were without effect, suggesting that nerve- induced constriction is dependent on activation of VDCCs. Collectively, these results indicate that BK channels and RyRs have different roles in the regulation of myogenic versus neurogenic tone: whereas BK channels and RyRs act in concert to oppose myogenic vasoconstriction, BK channels oppose neurogenic vasoconstriction and RyRs augment it. A scheme for neurogenic vasoregulation is proposed in which RyRs act in conjunction with VDCCs to regulate nerve-evoked constriction in mesenteric resistance arteries.
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Navarro-Dorado J, Garcia-Alonso M, van Breemen C, Tejerina T, Fameli N. Calcium oscillations in human mesenteric vascular smooth muscle. Biochem Biophys Res Commun 2014; 445:84-8. [PMID: 24508261 DOI: 10.1016/j.bbrc.2014.01.150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 01/22/2023]
Abstract
Phenylephrine (PE)-induced oscillatory fluctuations in intracellular Ca(2+) concentration ([Ca(2+)]i) of vascular smooth muscle have been observed in many blood vessels isolated from a wide variety of mammals. Paradoxically, until recently similar observations in humans have proven elusive. In this study, we report for the first time observations of adrenergically-stimulated [Ca(2+)]i oscillations in human mesenteric artery smooth muscle. In arterial segments preloaded with Fluo-4 AM and mounted on a myograph on the stage of a confocal microscope, we observed PE-induced oscillations in [Ca(2+)]i, which initiated and maintained vasoconstriction. These oscillations present some variability, possibly due to compromised health of the tissue. This view is corroborated by our ultrastructural analysis of the cells, in which we found only (5 ± 2)% plasma membrane-sarcoplasmic reticulum apposition, markedly less than measured in healthy tissue from laboratory animals. We also partially characterized the oscillations by using the inhibitory drugs 2-aminoethoxydiphenyl borate (2-APB), cyclopiazonic acid (CPA) and nifedipine. After PE contraction, all drugs provoked relaxation of the vessel segments, sometimes only partial, and reduced or inhibited oscillations, except CPA, which rarely caused relaxation. These preliminary results point to a potential involvement of the sarcoplasmic reticulum Ca(2+) and inositol 1,4,5-trisphosphate receptor (IP3R) in the maintenance of the Ca(2+) oscillations observed in human blood vessels.
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Affiliation(s)
- Jorge Navarro-Dorado
- Departamento de Farmacología, Universidad Complutense, av. Séneca 2, 28040 Madrid, Spain
| | - Mauricio Garcia-Alonso
- Departamento de Farmacología, Universidad Complutense, av. Séneca 2, 28040 Madrid, Spain
| | - Cornelis van Breemen
- Department of Anesthesiology, Pharmacology, and Therapeutics, The University of British Columbia, 2176 Health Sciences Mall, Medical Block C, Vancouver, BC V6T 1Z3, Canada
| | - Teresa Tejerina
- Departamento de Farmacología, Universidad Complutense, av. Séneca 2, 28040 Madrid, Spain
| | - Nicola Fameli
- Department of Anesthesiology, Pharmacology, and Therapeutics, The University of British Columbia, 2176 Health Sciences Mall, Medical Block C, Vancouver, BC V6T 1Z3, Canada.
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Dynamic regulation of β1 subunit trafficking controls vascular contractility. Proc Natl Acad Sci U S A 2014; 111:2361-6. [PMID: 24464482 DOI: 10.1073/pnas.1317527111] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Ion channels composed of pore-forming and auxiliary subunits control physiological functions in virtually all cell types. A conventional view is that channels assemble with their auxiliary subunits before anterograde plasma membrane trafficking of the protein complex. Whether the multisubunit composition of surface channels is fixed following protein synthesis or flexible and open to acute and, potentially, rapid modulation to control activity and cellular excitability is unclear. Arterial smooth muscle cells (myocytes) express large-conductance Ca(2+)-activated potassium (BK) channel α and auxiliary β1 subunits that are functionally significant modulators of arterial contractility. Here, we show that native BKα subunits are primarily (∼95%) plasma membrane-localized in human and rat arterial myocytes. In contrast, only a small fraction (∼10%) of total β1 subunits are located at the cell surface. Immunofluorescence resonance energy transfer microscopy demonstrated that intracellular β1 subunits are stored within Rab11A-postive recycling endosomes. Nitric oxide (NO), acting via cGMP-dependent protein kinase, and cAMP-dependent pathways stimulated rapid (≤1 min) anterograde trafficking of β1 subunit-containing recycling endosomes, which increased surface β1 almost threefold. These β1 subunits associated with surface-resident BKα proteins, elevating channel Ca(2+) sensitivity and activity. Our data also show that rapid β1 subunit anterograde trafficking is the primary mechanism by which NO activates myocyte BK channels and induces vasodilation. In summary, we show that rapid β1 subunit surface trafficking controls functional BK channel activity in arterial myocytes and vascular contractility. Conceivably, regulated auxiliary subunit trafficking may control ion channel activity in a wide variety of cell types.
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Amberg GC, Navedo MF. Calcium dynamics in vascular smooth muscle. Microcirculation 2013; 20:281-9. [PMID: 23384444 DOI: 10.1111/micc.12046] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 01/31/2013] [Indexed: 12/31/2022]
Abstract
Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells. These signals vary with respect to their mechanisms of generation, temporal properties, and spatial distributions. The calcium signals discussed include calcium waves, junctional calcium transients, calcium sparks, calcium puffs, and L-type calcium channel sparklets. For each calcium signal we address underlying mechanisms, general properties, physiological importance, and regulation.
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Affiliation(s)
- Gregory C Amberg
- Vascular Physiology Research Group, Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
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36
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Kur J, Bankhead P, Scholfield CN, Curtis TM, McGeown JG. Ca(2+) sparks promote myogenic tone in retinal arterioles. Br J Pharmacol 2013; 168:1675-86. [PMID: 23126272 DOI: 10.1111/bph.12044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 10/30/2012] [Accepted: 10/30/2012] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca(2+) imaging reveals subcellular Ca(2+) sparks and global Ca(2+) waves/oscillations in vascular smooth muscle. It is well established that Ca(2+) sparks can relax arteries, but we have previously reported that sparks can summate to generate Ca(2+) waves/oscillations in unpressurized retinal arterioles, leading to constriction. We have extended these studies to test the functional significance of Ca(2+) sparks in the generation of myogenic tone in pressurized arterioles. EXPERIMENTAL APPROACH Isolated retinal arterioles (25-40 μm external diameter) were pressurized to 70 mmHg, leading to active constriction. Ca(2+) signals were imaged from arteriolar smooth muscle in the same vessels using Fluo4 and confocal laser microscopy. KEY RESULTS Tone development was associated with an increased frequency of Ca(2+) sparks and oscillations. Vasomotion was observed in 40% of arterioles and was associated with synchronization of Ca(2+) oscillations, quantifiable as an increased cross-correlation coefficient. Inhibition of Ca(2+) sparks with ryanodine, tetracaine, cyclopiazonic acid or nimodipine, or following removal of extracellular Ca(2+) , resulted in arteriolar relaxation. Cyclopiazonic acid-induced dilatation was associated with decreased Ca(2+) sparks and oscillations but with a sustained rise in the mean global cytoplasmic [Ca(2+) ] ([Ca(2+) ]c ), as measured using Fura2 and microfluorimetry. CONCLUSIONS AND IMPLICATIONS This study provides direct evidence that Ca(2+) sparks can play an excitatory role in pressurized arterioles, promoting myogenic tone. This contrasts with the generally accepted model in which sparks promote relaxation of vascular smooth muscle. Changes in vessel tone in the presence of cyclopiazonic acid correlated more closely with changes in spark and oscillation frequency than global [Ca(2+) ]c , underlining the importance of frequency-modulated signalling in vascular smooth muscle.
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Affiliation(s)
- J Kur
- Centre for Vision and Vascular Science, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, UK
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Bannister JP, Leo MD, Narayanan D, Jangsangthong W, Nair A, Evanson KW, Pachuau J, Gabrick KS, Boop FA, Jaggar JH. The voltage-dependent L-type Ca2+ (CaV1.2) channel C-terminus fragment is a bi-modal vasodilator. J Physiol 2013; 591:2987-98. [PMID: 23568894 DOI: 10.1113/jphysiol.2013.251926] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Voltage-dependent L-type Ca(2+) channels (CaV1.2) are the primary Ca(2+) entry pathway in vascular smooth muscle cells (myocytes). CaV1.2 channels control systemic blood pressure and organ blood flow and are pathologically altered in vascular diseases, which modifies vessel contractility. The CaV1.2 distal C-terminus is susceptible to proteolytic cleavage, which yields a truncated CaV1.2 subunit and a cleaved C-terminal fragment (CCt). Previous studies in cardiac myocytes and neurons have identified CCt as both a transcription factor and CaV1.2 channel inhibitor, with different signalling mechanisms proposed to underlie some of these effects. CCt existence and physiological functions in arterial myocytes are unclear, but important to study given the functional significance of CaV1.2 channels. Here, we show that CCt exists in myocytes of both rat and human resistance-size cerebral arteries, where it locates to both the nucleus and plasma membrane. Recombinant CCt expression in arterial myocytes inhibited CaV1.2 transcription and reduced CaV1.2 protein. CCt induced a depolarizing shift in the voltage dependence of both CaV1.2 current activation and inactivation, and reduced non-inactivating current in myocytes. Recombinant truncated CCt lacking a putative nuclear localization sequence (92CCt) did not locate to the nucleus and had no effect on arterial CaV1.2 transcription or protein. However, 92CCt shifted the voltage dependence of CaV1.2 activation and inactivation similarly to CCt. CCt and 92CCt both inhibited pressure- and depolarization-induced vasoconstriction, although CCt was a far more effective vasodilator. These data demonstrate that endogenous CCt exists and reduces both CaV1.2 channel expression and voltage sensitivity in arterial myocytes. Thus, CCt is a bi-modal vasodilator.
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Affiliation(s)
- John P Bannister
- Department of Physiology, University of Tennessee Health Science Centre, 894 Union Avenue, Suite 426, Memphis, TN 38163, USA
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Abstract
The myogenic response has a critical role in regulation of blood flow to the brain. Increased intraluminal pressure elicits vasoconstriction, whereas decreased intraluminal pressure induces vasodilatation, thereby maintaining flow constant over the normal physiologic blood pressure range. Improved understanding of the molecular mechanisms underlying the myogenic response is crucial to identify deficiencies with pathologic consequences, such as cerebral vasospasm, hypertension, and stroke, and to identify potential therapeutic targets. Three mechanisms have been suggested to be involved in the myogenic response: (1) membrane depolarization, which induces Ca(2+) entry, activation of myosin light chain kinase, phosphorylation of the myosin regulatory light chains (LC(20)), increased actomyosin MgATPase activity, cross-bridge cycling, and vasoconstriction; (2) activation of the RhoA/Rho-associated kinase (ROCK) pathway, leading to inhibition of myosin light chain phosphatase by phosphorylation of MYPT1, the myosin targeting regulatory subunit of the phosphatase, and increased LC(20) phosphorylation; and (3) activation of the ROCK and protein kinase C pathways, leading to actin polymerization and the formation of enhanced connections between the actin cytoskeleton, plasma membrane, and extracellular matrix to augment force transmission. This review describes these three mechanisms, emphasizing recent developments regarding the importance of dynamic actin polymerization in the myogenic response of the cerebral vasculature.
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Bannister JP, Bulley S, Narayanan D, Thomas-Gatewood C, Luzny P, Pachuau J, Jaggar JH. Transcriptional upregulation of α2δ-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension. Hypertension 2012; 60:1006-15. [PMID: 22949532 DOI: 10.1161/hypertensionaha.112.199661] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2α1 with auxiliary α2δ and β subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of α2δ subunits in vasoconstriction associated with hypertension. Age-dependent development of hypertension in spontaneously hypertensive rats was associated with an unequal elevation in α2δ-1 and CaV1.2α1 mRNA and protein in cerebral artery myocytes, with α2δ-1 increasing more than CaV1.2α1. Other α2δ isoforms did not emerge in hypertension. Myocytes and arteries of hypertensive spontaneously hypertensive rats displayed higher surface-localized α2δ-1 and CaV1.2α1 proteins, surface α2δ-1:CaV1.2α1 ratio, CaV1.2 current density and noninactivating current, and pressure- and depolarization-induced vasoconstriction than those of Wistar-Kyoto controls. Pregabalin, an α2δ-1 ligand, did not alter α2δ-1 or CaV1.2α1 total protein but normalized α2δ-1 and CaV1.2α1 surface expression, surface α2δ-1:CaV1.2α1, CaV1.2 current density and inactivation, and vasoconstriction in myocytes and arteries of hypertensive rats to control levels. Genetic hypertension is associated with an elevation in α2δ-1 expression that promotes surface trafficking of CaV1.2 channels in cerebral artery myocytes. This leads to an increase in CaV1.2 current-density and a reduction in current inactivation that induces vasoconstriction. Data also suggest that α2δ-1 targeting is a novel strategy that may be used to reverse pathological CaV1.2 channel trafficking to induce cerebrovascular dilation in hypertension.
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Affiliation(s)
- John P Bannister
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, 894 Union Ave, Suite 426, Memphis, TN 38163, USA
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Bulley S, Neeb ZP, Burris SK, Bannister JP, Thomas-Gatewood CM, Jangsangthong W, Jaggar JH. TMEM16A/ANO1 channels contribute to the myogenic response in cerebral arteries. Circ Res 2012; 111:1027-36. [PMID: 22872152 DOI: 10.1161/circresaha.112.277145] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Pressure-induced arterial depolarization and constriction (the myogenic response) is a smooth muscle cell (myocyte)-specific mechanism that controls regional organ blood flow and systemic blood pressure. Several different nonselective cation channels contribute to pressure-induced depolarization, but signaling mechanisms involved are unclear. Similarly uncertain is the contribution of anion channels to the myogenic response and physiological functions and mechanisms of regulation of recently discovered transmembrane 16A (TMEM16A), also termed Anoctamin 1, chloride (Cl(-)) channels in arterial myocytes. OBJECTIVE To investigate the hypothesis that myocyte TMEM16A channels control membrane potential and contractility and contribute to the myogenic response in cerebral arteries. METHODS AND RESULTS Cell swelling induced by hyposmotic bath solution stimulated Cl(-) currents in arterial myocytes that were blocked by TMEM16A channel inhibitory antibodies, RNAi-mediated selective TMEM16A channel knockdown, removal of extracellular calcium (Ca(2+)), replacement of intracellular EGTA with BAPTA, a fast Ca(2+) chelator, and Gd(3+) and SKF-96365, nonselective cation channel blockers. In contrast, nimodipine, a voltage-dependent Ca(2+) channel inhibitor, or thapsigargin, which depletes intracellular Ca(2+) stores, did not alter swelling-activated TMEM16A currents. Pressure-induced (-40 mm Hg) membrane stretch activated ion channels in arterial myocyte cell-attached patches that were inhibited by TMEM16A antibodies and were of similar amplitude to recombinant TMEM16A channels. TMEM16A knockdown reduced intravascular pressure-induced depolarization and vasoconstriction but did not alter depolarization-induced (60 mmol/L K(+)) vasoconstriction. CONCLUSIONS Membrane stretch activates arterial myocyte TMEM16A channels, leading to membrane depolarization and vasoconstriction. Data also provide a mechanism by which a local Ca(2+) signal generated by nonselective cation channels stimulates TMEM16A channels to induce myogenic constriction.
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Affiliation(s)
- Simon Bulley
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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41
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Liang GH, Xi Q, Leffler CW, Jaggar JH. Hydrogen sulfide activates Ca²⁺ sparks to induce cerebral arteriole dilatation. J Physiol 2012; 590:2709-20. [PMID: 22508960 DOI: 10.1113/jphysiol.2011.225128] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Hydrogen sulfide (H₂S) is a gaseous vasodilator produced by endothelial cells. Mechanisms by which H₂S induces vasodilatation are unclear. We tested the hypothesis that H₂S dilates cerebral arterioles by modulating local and global intracellular Ca²⁺ signals in smooth muscle cells. High-speed confocal imaging revealed that Na₂S, an H₂S donor, increased Ca²⁺ spark frequency ∼1.43-fold and decreased global intracellular Ca²⁺ concentration ([Ca²⁺]i) by ∼37 nM in smooth muscle cells of intact piglet cerebral arterioles. In contrast, H₂S did not alter Ca²⁺ wave frequency. In voltage-clamped (-40 mV) cells, H₂S increased the frequency of iberiotoxin-sensitive, Ca²⁺ spark-induced transient Ca²⁺-activated K⁺ (KCa) currents ∼1.83-fold, but did not alter the amplitude of these events. H₂S did not alter the activity of single KCa channels recorded in the absence of Ca²⁺ sparks in arteriole smooth muscle cells. H₂S increased SR Ca²⁺ load ([Ca²⁺]SR), measured as caffeine (10 and 20mM)-induced [Ca²⁺]i transients, ∼1.5-fold. H₂S hyperpolarized (by ∼18 mV) and dilated pressurized (40 mmHg) cerebral arterioles. Iberiotoxin, a KCa channel blocker, reduced H₂S-induced hyperpolarization by ∼51%. Iberiotoxin and ryanodine, a ryanodine receptor channel inhibitor, reduced H₂S-induced vasodilatation by ∼38 and ∼37%, respectively. In summary, our data indicate that H₂S elevates [Ca²⁺]SR, leading to Ca²⁺ spark activation in cerebral arteriole smooth muscle cells. The subsequent elevation in transient KCa current frequency leads to membrane hyperpolarization, a reduction in global [Ca²⁺]i and vasodilatation.
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Affiliation(s)
- Guo Hua Liang
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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42
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Narayanan D, Adebiyi A, Jaggar JH. Inositol trisphosphate receptors in smooth muscle cells. Am J Physiol Heart Circ Physiol 2012; 302:H2190-210. [PMID: 22447942 DOI: 10.1152/ajpheart.01146.2011] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) are a family of tetrameric intracellular calcium (Ca(2+)) release channels that are located on the sarcoplasmic reticulum (SR) membrane of virtually all mammalian cell types, including smooth muscle cells (SMC). Here, we have reviewed literature investigating IP(3)R expression, cellular localization, tissue distribution, activity regulation, communication with ion channels and organelles, generation of Ca(2+) signals, modulation of physiological functions, and alterations in pathologies in SMCs. Three IP(3)R isoforms have been identified, with relative expression and cellular localization of each contributing to signaling differences in diverse SMC types. Several endogenous ligands, kinases, proteins, and other modulators control SMC IP(3)R channel activity. SMC IP(3)Rs communicate with nearby ryanodine-sensitive Ca(2+) channels and mitochondria to influence SR Ca(2+) release and reactive oxygen species generation. IP(3)R-mediated Ca(2+) release can stimulate plasma membrane-localized channels, including transient receptor potential (TRP) channels and store-operated Ca(2+) channels. SMC IP(3)Rs also signal to other proteins via SR Ca(2+) release-independent mechanisms through physical coupling to TRP channels and local communication with large-conductance Ca(2+)-activated potassium channels. IP(3)R-mediated Ca(2+) release generates a wide variety of intracellular Ca(2+) signals, which vary with respect to frequency, amplitude, spatial, and temporal properties. IP(3)R signaling controls multiple SMC functions, including contraction, gene expression, migration, and proliferation. IP(3)R expression and cellular signaling are altered in several SMC diseases, notably asthma, atherosclerosis, diabetes, and hypertension. In summary, IP(3)R-mediated pathways control diverse SMC physiological functions, with pathological alterations in IP(3)R signaling contributing to disease.
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Affiliation(s)
- Damodaran Narayanan
- Department of Physiology, University of Tennessee Health Science Center, Memphis, 38163, USA
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43
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Thomas-Gatewood C, Neeb ZP, Bulley S, Adebiyi A, Bannister JP, Leo MD, Jaggar JH. TMEM16A channels generate Ca²⁺-activated Cl⁻ currents in cerebral artery smooth muscle cells. Am J Physiol Heart Circ Physiol 2011; 301:H1819-27. [PMID: 21856902 DOI: 10.1152/ajpheart.00404.2011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transmembrane protein (TMEM)16A channels are recently discovered membrane proteins that display electrophysiological properties similar to classic Ca(2+)-activated Cl(-) (Cl(Ca)) channels in native cells. The molecular identity of proteins that generate Cl(Ca) currents in smooth muscle cells (SMCs) of resistance-size arteries is unclear. Similarly, whether cerebral artery SMCs generate Cl(Ca) currents is controversial. Here, using molecular biology and patch-clamp electrophysiology, we examined TMEM16A channel expression and characterized Cl(-) currents in arterial SMCs of resistance-size rat cerebral arteries. RT-PCR amplified transcripts for TMEM16A but not TMEM16B-TMEM16H, TMEM16J, or TMEM16K family members in isolated pure cerebral artery SMCs. Western blot analysis using an antibody that recognized recombinant (r)TMEM16A channels detected TMEM16A protein in cerebral artery lysates. Arterial surface biotinylation and immunofluorescence indicated that TMEM16A channels are located primarily within the arterial SMC plasma membrane. Whole cell Cl(Ca) currents in arterial SMCs displayed properties similar to those generated by rTMEM16A channels, including Ca(2+) dependence, current-voltage relationship linearization by an elevation in intracellular Ca(2+) concentration, a Nerstian shift in reversal potential induced by reducing the extracellular Cl(-) concentration, and a negative reversal potential shift when substituting extracellular I(-) for Cl(-). A pore-targeting TMEM16A antibody similarly inhibited both arterial SMC Cl(Ca) and rTMEM16A currents. TMEM16A knockdown using small interfering RNA also inhibited arterial SMC Cl(Ca) currents. In summary, these data indicate that TMEM16A channels are expressed, insert into the plasma membrane, and generate Cl(Ca) currents in cerebral artery SMCs.
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Affiliation(s)
- Candice Thomas-Gatewood
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Adebiyi A, McNally EM, Jaggar JH. Vasodilation induced by oxygen/glucose deprivation is attenuated in cerebral arteries of SUR2 null mice. Am J Physiol Heart Circ Physiol 2011; 301:H1360-8. [PMID: 21784985 DOI: 10.1152/ajpheart.00406.2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Physiological functions of arterial smooth muscle cell ATP-sensitive K(+) (K(ATP)) channels, which are composed of inwardly rectifying K(+) channel 6.1 and sulfonylurea receptor (SUR)-2 subunits, during metabolic inhibition are unresolved. In the present study, we used a genetic model to investigate the physiological functions of SUR2-containing K(ATP) channels in mediating vasodilation to hypoxia, oxygen and glucose deprivation (OGD) or metabolic inhibition, and functional recovery following these insults. Data indicate that SUR2B is the only SUR isoform expressed in murine cerebral artery smooth muscle cells. Pressurized SUR2 wild-type (SUR2(wt)) and SUR2 null (SUR2(nl)) mouse cerebral arteries developed similar levels of myogenic tone and dilated similarly to hypoxia (<10 mmHg Po(2)). In contrast, vasodilation induced by pinacidil, a K(ATP) channel opener, was ∼71% smaller in SUR2(nl) arteries. Human cerebral arteries also expressed SUR2B, developed myogenic tone, and dilated in response to hypoxia and pinacidil. OGD, oligomycin B (a mitochondrial ATP synthase blocker), and CCCP (a mitochondrial uncoupler) all induced vasodilations that were ∼39-61% smaller in SUR2(nl) than in SUR2(wt) arteries. The restoration of oxygen and glucose following OGD or removal of oligomycin B and CCCP resulted in partial recovery of tone in both SUR2(wt) and SUR2(nl) cerebral arteries. However, SUR(nl) arteries regained ∼60-82% more tone than did SUR2(wt) arteries. These data indicate that SUR2-containing K(ATP) channels are functional molecular targets for OGD, but not hypoxic, vasodilation in cerebral arteries. In addition, OGD activation of SUR2-containing K(ATP) channels may contribute to postischemic loss of myogenic tone.
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Affiliation(s)
- Adebowale Adebiyi
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Role of myosin light chain kinase and myosin light chain phosphatase in the resistance arterial myogenic response to intravascular pressure. Arch Biochem Biophys 2011; 510:160-73. [DOI: 10.1016/j.abb.2011.02.024] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 02/24/2011] [Accepted: 02/28/2011] [Indexed: 12/19/2022]
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Liang GH, Adebiyi A, Leo MD, McNally EM, Leffler CW, Jaggar JH. Hydrogen sulfide dilates cerebral arterioles by activating smooth muscle cell plasma membrane KATP channels. Am J Physiol Heart Circ Physiol 2011; 300:H2088-95. [PMID: 21421823 DOI: 10.1152/ajpheart.01290.2010] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hydrogen sulfide (H(2)S) is a gaseous signaling molecule that appears to contribute to the regulation of vascular tone and blood pressure. Multiple potential mechanisms of vascular regulation by H(2)S exist. Here, we tested the hypothesis that piglet cerebral arteriole smooth muscle cells generate ATP-sensitive K(+) (K(ATP)) currents and that H(2)S induces vasodilation by activating K(ATP) currents. Gas chromatography/mass spectrometry data demonstrated that after placing Na(2)S, an H(2)S donor, in solution, it rapidly (1 min) converts to H(2)S. Patch-clamp electrophysiology indicated that pinacidil (a K(ATP) channel activator), Na(2)S, and NaHS (another H(2)S donor) activated K(+) currents at physiological steady-state voltage (-50 mV) in isolated cerebral arteriole smooth muscle cells. Glibenclamide, a selective K(ATP) channel inhibitor, fully reversed pinacidil-induced K(+) currents and partially reversed (∼58%) H(2)S-induced K(+) currents. Western blot analysis indicated that piglet arterioles expressed inwardly rectifying K(+) 6.1 (K(ir)6.1) channel and sulfonylurea receptor 2B (SUR2B) K(ATP) channel subunits. Pinacidil dilated pressurized (40 mmHg) piglet arterioles, and glibenclamide fully reversed this effect. Na(2)S also induced reversible and repeatable vasodilation with an EC(50) of ∼30 μM, and this effect was partially reversed (∼55%) by glibenclamide. Vasoregulation by H(2)S was also studied in pressurized resistance-size cerebral arteries of mice with a genetic deletion in the gene encoding SUR2 (SUR2 null). Pinacidil- and H(2)S-induced vasodilations were smaller in arterioles of SUR2 null mice than in wild-type controls. These data indicate that smooth muscle cell K(ATP) currents control newborn cerebral arteriole contractility and that H(2)S dilates cerebral arterioles by activating smooth muscle cell K(ATP) channels containing SUR2 subunits.
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Affiliation(s)
- Guo Hua Liang
- Dept. of Physiology, Univ. of Tennessee Health Science Ctr., Memphis, TN 38163, USA
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Bannister JP, Thomas-Gatewood CM, Neeb ZP, Adebiyi A, Cheng X, Jaggar JH. Ca(V)1.2 channel N-terminal splice variants modulate functional surface expression in resistance size artery smooth muscle cells. J Biol Chem 2011; 286:15058-66. [PMID: 21357696 DOI: 10.1074/jbc.m110.182816] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Voltage-dependent Ca(2+) (Ca(V)1.2) channels are the primary Ca(2+) influx pathway in arterial smooth muscle cells and are essential for contractility regulation by a variety of stimuli, including intravascular pressure. Arterial smooth muscle cell Ca(V)1.2 mRNA is alternatively spliced at exon 1 (e1), generating e1b or e1c variants, with e1c exhibiting relatively smooth muscle-specific expression in the cardiovascular system. Here, we examined physiological functions of Ca(V)1.2e1 variants and tested the hypothesis that targeting Ca(V)1.2e1 modulates resistance size cerebral artery contractility. Custom antibodies that selectively recognize Ca(V)1.2 channel proteins containing sequences encoded by either e1b (Ca(V)1.2e1b) or e1c (Ca(V)1.2e1c) both detected Ca(V)1.2 in rat and human cerebral arteries. shRNA targeting e1b or e1c reduced expression of that Ca(V)1.2 variant, induced compensatory up-regulation of the other variant, decreased total Ca(V)1.2, and reduced intravascular pressure- and depolarization-induced vasoconstriction. Ca(V)1.2e1b and Ca(V)1.2e1c knockdown reduced whole cell Ca(V)1.2 currents, with Ca(V)1.2e1c knockdown most effectively reducing total Ca(V)1.2 and inducing the largest vasodilation. Knockdown of α(2)δ-1, a Ca(V)1.2 auxiliary subunit, reduced surface expression of both Ca(V)1.2e1 variants, inhibiting Ca(V)1.2e1c more than Ca(V)1.2e1b. e1b or e1c overexpression reduced Ca(V)1.2 surface expression and whole cell currents, leading to vasodilation, with e1c overexpression inducing the largest effect. In summary, data indicate that arterial smooth muscle cells express Ca(V)1.2 channels containing e1b or e1c-encoded N termini that contribute to Ca(V)1.2 surface expression, α(2)δ-1 preferentially traffics the Ca(V)1.2e1c variant to the plasma membrane, and targeting of Ca(V)1.2e1 message or the Ca(V)1.2 channel proximal N terminus induces vasodilation.
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Affiliation(s)
- John P Bannister
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA
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Westcott EB, Jackson WF. Heterogeneous function of ryanodine receptors, but not IP3 receptors, in hamster cremaster muscle feed arteries and arterioles. Am J Physiol Heart Circ Physiol 2011; 300:H1616-30. [PMID: 21357503 DOI: 10.1152/ajpheart.00728.2010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The roles played by ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate receptors (IP₃Rs) in vascular smooth muscle in the microcirculation remain unclear. Therefore, the function of both RyRs and IP₃Rs in Ca(²+) signals and myogenic tone in hamster cremaster muscle feed arteries and downstream arterioles were assessed using confocal imaging and pressure myography. Feed artery vascular smooth muscle displayed Ca(²+) sparks and Ca(²+) waves, which were inhibited by the RyR antagonists ryanodine (10 μM) or tetracaine (100 μM). Despite the inhibition of sparks and waves, ryanodine or tetracaine increased global intracellular Ca(²+) and constricted the arteries. The blockade of IP₃Rs with xestospongin D (5 μM) or 2-aminoethoxydiphenyl borate (100 μM) or the inhibition of phospholipase C using U-73122 (10 μM) also attenuated Ca(2+) waves without affecting Ca(²+) sparks. Importantly, the IP₃Rs and phospholipase C antagonists decreased global intracellular Ca(2+) and dilated the arteries. In contrast, cremaster arterioles displayed only Ca(²+) waves: Ca(²+) sparks were not observed, and neither ryanodine (10-50 μM) nor tetracaine (100 μM) affected either Ca(²+) signals or arteriolar tone despite the presence of functional RyRs as assessed by responses to the RyR agonist caffeine (10 mM). As in feed arteries, arteriolar Ca(²+) waves were attenuated by xestospongin D (5 μM), 2-aminoethoxydiphenyl borate (100 μM), and U-73122 (10 μM), accompanied by decreased global intracellular Ca(²+) and vasodilation. These findings highlight the contrasting roles played by RyRs and IP₃Rs in Ca(²+) signals and myogenic tone in feed arteries and demonstrate important differences in the function of RyRs between feed arteries and downstream arterioles.
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Affiliation(s)
- Erika B Westcott
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA.
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Bilirubin oxidation end products directly alter K+ channels important in the regulation of vascular tone. J Cereb Blood Flow Metab 2011; 31:102-12. [PMID: 20424637 PMCID: PMC2970662 DOI: 10.1038/jcbfm.2010.54] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The exact etiology of delayed cerebral vasospasm following cerebral hemorrhage is not clear, but a family of compounds termed 'bilirubin oxidation end products (BOXes)' derived from heme has been implicated. As proper regulation of vascular smooth muscle tone involves large-conductance Ca(2+)- and voltage-dependent Slo1 K(+) (BK, maxiK, K(Ca)1.1) channels, we examined whether BOXes altered functional properties of the channel. Electrophysiological measurements of Slo1 channels heterologously expressed in a human cell line and of native mouse BK channels in isolated cerebral myocytes showed that BOXes markedly diminished open probability. Biophysically, BOXes specifically stabilized the conformations of the channel with its ion conduction gate closed. The results of chemical amino-acid modifications and molecular mutagenesis together suggest that two specific lysine residues in the structural element linking the transmembrane ion-permeation domain to the carboxyl cytosolic domain of the Slo1 channel are critical in determining the sensitivity of the channel to BOXes. Inhibition of Slo1 BK channels by BOXes may contribute to the development of delayed cerebral vasospasm following brain hemorrhage.
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