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Looft-Wilson RC, Stechmann JK, Milenski KG, Shah VM, Kulkarni PG, Arif AB, Guiot T, Beinlich NMC, Dos Santos CA, Rice SK. Myoendothelial feedback in mouse mesenteric resistance arteries is similar between the sexes, dependent on nitric oxide synthase, and independent of TPRV4. Am J Physiol Heart Circ Physiol 2024; 326:H190-H202. [PMID: 37921665 PMCID: PMC11213485 DOI: 10.1152/ajpheart.00170.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 10/17/2023] [Accepted: 10/30/2023] [Indexed: 11/04/2023]
Abstract
Myoendothelial feedback (MEF), the endothelium-dependent vasodilation following sympathetic vasoconstriction (mediated by smooth muscle to endothelium gap junction communication), has been well studied in resistance arteries of males, but not females. We hypothesized that MEF responses would be similar between the sexes, but different in the relative contribution of the underlying nitric oxide and hyperpolarization mechanisms, given that these mechanisms differ between the sexes in agonist-induced endothelium-dependent dilation. We measured MEF responses (diameter changes) of male and female first- to second-order mouse mesenteric arteries to phenylephrine (10 µM) over 30 min using isolated pressure myography ± blinded inhibition of nitric oxide synthase (NOS) using Nω-nitro-l-arginine methyl ester (l-NAME; 0.1-1.0 mM), hyperpolarization using 35 mM KCl, or transient receptor potential vanilloid 4 (TRPV4) channels using GSK219 (0.1-1.0 µM) or RN-1734 (30 µM). MEF was similar [%dilation (means ± SE): males = 26.7 ± 2.0 and females = 26.1 ± 1.9 at 15 min] and significantly inhibited by l-NAME (1.0 mM) at 15 min [%dilation (means ± SE): males = 8.2 ± 3.3, P < 0.01; females = 6.8 ± 1.9, P < 0.001] and over time (P < 0.01) in both sexes. l-NAME (0.1 mM) + 35 mM KCl nearly eliminated MEF in both sexes (P < 0.001-0.0001). Activation of TRPV4 with GSK101 (0.1-10 µM) induced similar dilation between the sexes. Inhibition of TRPV4, which is reportedly involved in the hyperpolarization mechanism, did not inhibit MEF in either sex. Similar expression of eNOS was found between the sexes with Western blot. Thus, MEF is prominent and similar in murine first- and second-order mesenteric resistance arteries of both sexes, and reliant primarily on NOS and secondarily on hyperpolarization, but not TRPV4.NEW & NOTEWORTHY We found that female mesenteric resistance arteries have similar postconstriction dilatory responses (i.e., myoendothelial feedback) to a sympathetic neurotransmitter analog as male arteries. Both sexes use nitric oxide synthase (NOS) and hyperpolarization, but not TRPV4, in this response. Moreover, the key protein involved in this pathway (eNOS) is similarly expressed in these arteries between the sexes. These similarities are surprising given that agonist-induced endothelium-dependent dilatory mechanisms differ in these arteries between the sexes.
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Affiliation(s)
- Robin C Looft-Wilson
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Jacob K Stechmann
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Katherine G Milenski
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Vishakha M Shah
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Preetika G Kulkarni
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Arusha B Arif
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | - Tanner Guiot
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
| | | | | | - Spencer K Rice
- Department of Kinesiology, William and Mary, Williamsburg, Virginia, United States
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Schmidt K, de Wit C. Endothelium-Derived Hyperpolarizing Factor and Myoendothelial Coupling: The in vivo Perspective. Front Physiol 2021; 11:602930. [PMID: 33424626 PMCID: PMC7786115 DOI: 10.3389/fphys.2020.602930] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022] Open
Abstract
The endothelium controls vascular tone adopting blood flow to tissue needs. It releases chemical mediators [e.g., nitric oxide (NO), prostaglandins (PG)] and exerts appreciable dilation through smooth muscle hyperpolarization, thus termed endothelium-dependent hyperpolarization (EDH). Initially, EDH was attributed to release of a factor, but later it was suggested that smooth muscle hyperpolarization might be derived from radial spread of an initial endothelial hyperpolarization through heterocellular channels coupling these vascular cells. The channels are indeed present and formed by connexins that enrich in gap junctions (GJ). In vitro data suggest that myoendothelial coupling underlies EDH-type dilations as evidenced by blocking experiments as well as simultaneous, merely identical membrane potential changes in endothelial and smooth muscle cells (SMCs), which is indicative of coupling through ohmic resistors. However, connexin-deficient animals do not display any attenuation of EDH-type dilations in vivo, and endothelial and SMCs exhibit distinct and barely superimposable membrane potential changes exerted by different means in vivo. Even if studied in the exact same artery EDH-type dilation exhibits distinct features in vitro and in vivo: in isometrically mounted vessels, it is rather weak and depends on myoendothelial coupling through connexin40 (Cx40), whereas in vivo as well as in vitro under isobaric conditions it is powerful and independent of myoendothelial coupling through Cx40. It is concluded that EDH-type dilations are distinct and a significant dependence on myoendothelial coupling in vitro does not reflect the situation under physiologic conditions in vivo. Myoendothelial coupling may act as a backup mechanism that is uncovered in the absence of the powerful EDH-type response and possibly reflects a situation in a pathophysiologic environment.
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Affiliation(s)
- Kjestine Schmidt
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
| | - Cor de Wit
- Institut für Physiologie, Universität zu Lübeck, Lübeck, Germany.,Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK) e.V. (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Lübeck, Germany
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Lemmey HAL, Garland CJ, Dora KA. Intrinsic regulation of microvascular tone by myoendothelial feedback circuits. CURRENT TOPICS IN MEMBRANES 2020; 85:327-355. [PMID: 32402644 DOI: 10.1016/bs.ctm.2020.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The endothelium is an important regulator of arterial vascular tone, acting to release nitric oxide (NO) and open Ca2+-activated K+ (KCa) channels to relax vascular smooth muscle cells (VSMCs). While agonists acting at endothelial cell (EC) receptors are widely used to assess the ability of the endothelium to reduce vascular tone, the intrinsic EC-dependent mechanisms are less well characterized. In small resistance arteries and arterioles, the presence of heterocellular gap junctions termed myoendothelial gap junctions (MEGJs) allows the passage of not only current, but small molecules including Ca2+ and inositol trisphosphate (IP3). When stimulated to contract, the increase in VSM Ca2+ and IP3 can therefore potentially pass through MEGJs to activate adjacent ECs. This activation releases NO and opens KCa channels, which act to limit contraction. This myoendothelial feedback (MEF) is amplified by EC Ca2+ influx and release pathways, and is dynamically modulated by processes regulating gap junction conductance. There is a remarkable localization of key signaling and regulatory proteins within the EC projection toward VSM, and the intrinsic EC-dependent signaling pathways occurring with this highly specialized microdomain are reviewed.
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Affiliation(s)
- Hamish A L Lemmey
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | | | - Kim A Dora
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
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Pogoda K, Kameritsch P. Molecular regulation of myoendothelial gap junctions. Curr Opin Pharmacol 2019; 45:16-22. [DOI: 10.1016/j.coph.2019.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 02/14/2019] [Accepted: 03/15/2019] [Indexed: 11/16/2022]
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Looft‐Wilson RC, Todd SE, Berberich KM, Wolfert MR. Flow does not alter eNOS phosphoryation at Ser1179 or Thr495 in preconstricted mouse mesenteric arteries. Physiol Rep 2018; 6:e13864. [PMID: 30247813 PMCID: PMC6129772 DOI: 10.14814/phy2.13864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 08/17/2018] [Accepted: 08/20/2018] [Indexed: 12/23/2022] Open
Abstract
In arteries, endothelium-dependent vasodilatory agonists and flow-induced shear stress cause vasodilation largely by activation of the endothelial enzyme eNOS, which generates nitric oxide that relaxes vascular smooth muscle. Agonists activate eNOS in part through increased phosphorylation at Ser1179 and decreased phosphorylation at Thr495. We previously found that preconstriction of intact, isolated mouse mesenteric arteries with phenylephrine also caused increased Ser1179 and decreased Thr495 eNOS phosphorylation, and sequential treatment with the vasodilatory agonist acetylcholine did not cause any further change in phosphorylation at these sites, despite producing vasodilation. The present study tests the hypothesis that luminal flow in these arteries preconstricted with phenylephrine also produces vasodilation without phosphorylation changes at these sites. First-order mesenteric arteries, isolated from male C57/BL6 mice (7-20 weeks of age) anesthetized with pentobarbital (50 mg/kg, i.p.), were cannulated, pressurized, and treated with stepped increases in luminal flow (15-120 μL/min). Flow resulted in dilation that plateaued at ~60 μL/min (31.3 ± 3.0% dilation) and was significantly (P < 0.001) NOS-dependent at all flow rates (determined by 10-4 mol/L L-NAME treatment). In separate arteries, preconstriction with phenylephrine (10-5 mol/L) resulted in increased eNOS phosphorylation at Ser1179 (P < 0.05) and decreased phosphorylation at Thr495, but subsequent flow at 60 μL/min for 5 or 15 min did not cause further changes in phosphorylation, despite causing dilation. Thus, flow-induced dilation does not require changes in these eNOS phosphorylation sites beyond those induced by alpha1-adrenergic stimulation with phenylephrine, indicating that eNOS is activated by other mechanisms during acute flow-induced dilation of preconstricted arteries.
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Affiliation(s)
- Robin C. Looft‐Wilson
- Department of Kinesiology and Health SciencesThe College of William & MaryWilliamsburgVirginia
| | - Sarah E. Todd
- Department of Kinesiology and Health SciencesThe College of William & MaryWilliamsburgVirginia
| | - Kristen M. Berberich
- Department of Kinesiology and Health SciencesThe College of William & MaryWilliamsburgVirginia
| | - Madeline R. Wolfert
- Department of Kinesiology and Health SciencesThe College of William & MaryWilliamsburgVirginia
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Wei R, Lunn SE, Tam R, Gust SL, Classen B, Kerr PM, Plane F. Vasoconstrictor stimulus determines the functional contribution of myoendothelial feedback to mesenteric arterial tone. J Physiol 2018; 596:1181-1197. [PMID: 29411383 DOI: 10.1113/jp274797] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/17/2018] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS In isolated resistance arteries, endothelial modulation of vasoconstrictor responses to α1 -adrenoceptor agonists occurs via a process termed myoendothelial feedback: localized inositol trisphosphate (InsP3 )-dependent Ca2+ transients activate intermediate conductance Ca2+ -activated K+ (IKCa ) channels, hyperpolarizing the endothelial membrane potential to limit further reductions in vessel diameter. We demonstrate that IKCa channel-mediated myoendothelial feedback limits responses of isolated mesenteric arteries to noradrenaline and nerve stimulation, but not to the thromboxane A2 mimetic U46619 or to increases in intravascular pressure. In contrast, in the intact mesenteric bed, although responses to exogenous noradrenaline were limited by IKCa channel-mediated myoendothelial feedback, release of NO and activation of endothelial small conductance Ca2+ -activated K+ (SKCa ) channels in response to increases in shear stress appeared to be the primary mediators of endothelial modulation of vasoconstriction. We propose that (1) the functional contribution of myoendothelial feedback to arterial tone is determined by the nature of the vasoconstrictor stimulus, and (2) although IKCa channel-mediated myoendothelial feedback may contribute to local control of arterial diameter, in the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction. ABSTRACT Constriction of isolated resistance arteries in response to α1 -adrenoceptor agonists is limited by reciprocal engagement of inhibitory endothelial mechanisms via myoendothelial feedback. In the current model of feedback, agonist stimulation of smooth muscle cells results in localized InsP3 -dependent Ca2+ transients that activate endothelial IKCa channels. The subsequent hyperpolarization of the endothelial membrane potential then feeds back to the smooth muscle to limit further reductions in vessel diameter. We hypothesized that the functional contribution of InsP3 -IKCa channel-mediated myoendothelial feedback to limiting arterial diameter may be influenced by the nature of the vasoconstrictor stimulus. To test this hypothesis, we investigated the functional role of myoendothelial feedback in modulating responses of rat mesenteric resistance arteries to the adrenoceptor agonist noradrenaline, the thromboxane A2 mimetic U46619, increases in intravascular pressure and stimulation of perivascular sympathetic nerves. In isolated arteries, responses to noradrenaline and stimulation of sympathetic nerves, but not to U46619 and increases in intravascular pressure, were modulated by IKCa channel-dependent myoendothelial feedback. In the intact mesenteric bed perfused under conditions of constant flow, responses to exogenous noradrenaline were modulated by myoendothelial feedback, but shear stress-induced release of NO and activation of endothelial SKCa channels appeared to be the primary mediators of endothelial modulation of vasoconstriction to agonists and nerve stimulation. Thus, we propose that myoendothelial feedback may contribute to local control of diameter within arterial segments, but at the level of the intact vascular bed, increases in shear stress may be the major stimulus for engagement of the endothelium during vasoconstriction.
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Affiliation(s)
- R Wei
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - S E Lunn
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - R Tam
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - S L Gust
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - B Classen
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
| | - P M Kerr
- Department of Nursing Science, Faculty of Nursing, MacEwan University, Edmonton, Alberta, T5J 4S2, Canada
| | - F Plane
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada.,Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, T6G 2H7, Canada
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