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Han YS, Delmotte P, Sieck GC. Effects of TNFα on Dynamic Cytosolic Ca 2 + and Force Responses to Muscarinic Stimulation in Airway Smooth Muscle. Front Physiol 2021; 12:730333. [PMID: 34393833 PMCID: PMC8363307 DOI: 10.3389/fphys.2021.730333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 07/09/2021] [Indexed: 11/30/2022] Open
Abstract
Previously, we reported that in airway smooth muscle (ASM), the cytosolic Ca2+ ([Ca2+]cyt) and force response induced by acetyl choline (ACh) are increased by exposure to the pro-inflammatory cytokine tumor necrosis factor α (TNFα). The increase in ASM force induced by TNFα was not associated with an increase in regulatory myosin light chain (rMLC20) phosphorylation but was associated with an increase in contractile protein (actin and myosin) concentration and an enhancement of Ca2+ dependent actin polymerization. The sensitivity of ASM force generation to elevated [Ca2+]cyt (Ca2+ sensitivity) is dynamic involving both the shorter-term canonical calmodulin-myosin light chain kinase (MLCK) signaling cascade that regulates rMLC20 phosphorylation and cross-bridge recruitment as well as the longer-term regulation of actin polymerization that regulates contractile unit recruitment and actin tethering to the cortical cytoskeleton. In this study, we simultaneously measured [Ca2+]cyt and force responses to ACh and explored the impact of 24-h TNFα on the dynamic relationship between [Ca2+]cyt and force responses. The temporal delay between the onset of [Ca2+]cyt and force responses was not affected by TNFα. Similarly, the rates of rise of [Ca2+]cyt and force responses were not affected by TNFα. The absence of an impact of TNFα on the short delay relationships between [Ca2+]cyt and force was consistent with the absence of an effect of [Ca2+]cyt and force on rMLC20 phosphorylation. However, the integral of the phase-loop plot of [Ca2+]cyt and force increased with TNFα, consistent with an impact on actin polymerization and, contractile unit recruitment and actin tethering to the cortical cytoskeleton.
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Affiliation(s)
- Young-Soo Han
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Philippe Delmotte
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
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Han YS, Delmotte PF, Arteaga GM, Sieck GC. Dynamic cytosolic Ca 2+ and force responses to muscarinic stimulation in airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 2021; 321:L91-L101. [PMID: 33908264 DOI: 10.1152/ajplung.00596.2020] [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] [Indexed: 01/15/2023] Open
Abstract
During agonist stimulation of airway smooth muscle (ASM), agonists such as ACh induce a transient increase in cytosolic Ca2+ concentration ([Ca2+]cyt), which leads to a contractile response [excitation-contraction (E-C) coupling]. Previously, the sensitivity of the contractile response of ASM to elevated [Ca2+]cyt (Ca2+ sensitivity) was assessed as the ratio of maximum force to maximum [Ca2+]cyt. However, this static assessment of Ca2+ sensitivity overlooks the dynamic nature of E-C coupling in ASM. In this study, we simultaneously measured [Ca2+]cyt and isometric force responses to three concentrations of ACh (1, 2.6, and 10 μM). Both maximum [Ca2+]cyt and maximum force responses were ACh concentration dependent, but force increased disproportionately, thereby increasing static Ca2+ sensitivity. The dynamic properties of E-C coupling were assessed in several ways. The temporal delay between the onset of ACh-induced [Ca2+]cyt and onset force responses was not affected by ACh concentration. The rates of rise of the ACh-induced [Ca2+]cyt and force responses increased with increasing ACh concentration. The integral of the phase-loop plot of [Ca2+]cyt and force from onset to steady state also increased with increasing ACh concentration, whereas the rate of relaxation remained unchanged. Although these results suggest an ACh concentration-dependent increase in the rate of cross-bridge recruitment and in the rate of rise of [Ca2+]cyt, the extent of regulatory myosin light-chain (rMLC20) phosphorylation was not dependent on ACh concentration. We conclude that the dynamic properties of [Ca2+]cyt and force responses in ASM are dependent on ACh concentration but reflect more than changes in the extent of rMLC20 phosphorylation.
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Affiliation(s)
- Young-Soo Han
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Philippe F Delmotte
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Grace M Arteaga
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
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Al-Jumaily AM, Mathur M, Cairns S. Combination of isoproterenol and length oscillations in relaxing porcine airway smooth muscles. BIOMATERIALS AND BIOMECHANICS IN BIOENGINEERING 2015. [DOI: 10.12989/bme.2015.2.4.225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Jo-Avila M, Al-Jumaily AM, Lu J. Relaxant effect of superimposed length oscillation on sensitized airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 2014; 308:L479-84. [PMID: 25480332 DOI: 10.1152/ajplung.00218.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Asthma is associated with reductions in the airway lumen and breathing difficulties that are attributed to airway smooth muscles (ASM) hyperconstriction. Pharmaceutical bronchodilators such as salbutamol and isoproterenol are normally used to alleviate this constriction. Deep inspirations and tidal oscillations (TO) have also been reported to relax ASM in healthy airways with less response in asthmatics. Little information is available on the effect of other forms of oscillation on asthmatic airways. This study investigates the effect of length oscillations (LO), with amplitude 1 and 1.5% in the frequency range 5-20 Hz superimposed on breathing equivalent LO, on contracted ASM dissected from sensitized mice. These mice are believed to show some symptoms such as airway hyperreactivity similar to those associated with asthma in humans. In the frequency range used in this work, this study shows an increase in ASM relaxation of an average of 10% for 1.5% amplitude when compared with TO, ISO, or the combination of both. No similar finding is observed with 1% amplitude. This suggests that superimposed length oscillation acting over the interaction of myosin and actin during contraction may lead to temporal rearrangement and disturbance of the cross-bridge process in asthmatic airways.
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Affiliation(s)
- Miguel Jo-Avila
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
| | - Ahmed M Al-Jumaily
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
| | - Jun Lu
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
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Estimation of airway smooth muscle stiffness changes due to length oscillation using artificial neural network. J Theor Biol 2012; 310:115-8. [DOI: 10.1016/j.jtbi.2012.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Revised: 06/07/2012] [Accepted: 06/08/2012] [Indexed: 11/24/2022]
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Al-Jumaily AM, Mbikou P, Redey PR. Effect of length oscillations on airway smooth muscle reactivity and cross-bridge cycling. Am J Physiol Lung Cell Mol Physiol 2012; 303:L286-94. [DOI: 10.1152/ajplung.00100.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Excessive airway narrowing due to airway smooth muscle (ASM) hyperconstriction is a major symptom in many respiratory diseases. In vitro imposition of length oscillations similar to those produced by tidal breathing on contracted ASM have shown to reduce muscle active forces, which is usually attributed to unconfirmed disruption of actomyosin cross-bridges. This research focuses on an in vitro investigation of the effect of mechanical oscillations on ASM reactivity and actomyosin cross-bridges. A computerized organ bath system was used to test maximally precontracted bovine ASM subjected to length oscillations at frequencies in the range of 10–100 Hz superimposed on tidal breathing oscillation. Using an immunofluorescence technique, two specific antibodies against the phospho-serine19 myosin light chain and the α-smooth muscle actin were used to analyze the colocalization between these two filaments. Data were processed using the plug-in “colocalization threshold” of ImageJ 1.43m software. The results demonstrate that both tidal and superimposed length oscillations reduce the active force in contracted ASM for a relatively long term and that the latter enhances the force reduction of the former. This reduction was also found to be frequency and time dependent. Additionally colocalization analysis indicates that length oscillations cause the detachment of the actomyosin connections and that this condition is sustained even after the cessation of the length oscillations.
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Affiliation(s)
- Ahmed M. Al-Jumaily
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
| | - Prisca Mbikou
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
| | - Prachi R. Redey
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
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Ijpma G, Lauzon AM. The rise of passive airway smooth muscle mechanics. J Appl Physiol (1985) 2011; 112:335-6. [PMID: 22052866 DOI: 10.1152/japplphysiol.01338.2011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Raqeeb A, Jiao Y, Syyong HT, Paré PD, Seow CY. Regulatable stiffness in relaxed airway smooth muscle: a target for asthma treatment? J Appl Physiol (1985) 2011; 112:337-46. [PMID: 21998272 DOI: 10.1152/japplphysiol.01036.2011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The airway smooth muscle (ASM) layer within the airway wall modulates airway diameter and distensibility. Even in the relaxed state, the ASM layer possesses finite stiffness and limits the extent of airway distension by the radial force generated by parenchymal tethers and transmural pressure. Airway stiffness has often been attributed to passive elements, such as the extracellular matrix in the lamina reticularis, adventitia, and the smooth muscle layer that cannot be rapidly modulated by drug intervention such as ASM relaxation by β-agonists. In this study, we describe a calcium-sensitive component of ASM stiffness mediated through the Rho-kinase signaling pathway. The stiffness of ovine tracheal smooth muscle was assessed in the relaxed state under the following conditions: 1) in physiological saline solution (Krebs solution) with normal calcium concentration; 2) in calcium-free Krebs with 2 mM EGTA; 3) in Krebs with calcium entry blocker (SKF-96365); 4) in Krebs with myosin light chain kinase inhibitor (ML-7); and 5) in Krebs with Rho-kinase inhibitor (Y-27632). It was found that a substantial portion of the passive stiffness could be abolished when intracellular calcium was removed; this calcium-sensitive stiffness appeared to stem from intracellular source and was not sensitive to ML-7 inhibition of myosin light chain phosphorylation, but was sensitive to Y-27632 inhibition of Rho kinase. The results suggest that airway stiffness can be readily modulated by targeting the calcium-sensitive component of the passive stiffness within the muscle layer.
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Affiliation(s)
- Abdul Raqeeb
- James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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Syyong HT, Raqeeb A, Paré PD, Seow CY. Time course of isotonic shortening and the underlying contraction mechanism in airway smooth muscle. J Appl Physiol (1985) 2011; 111:642-56. [DOI: 10.1152/japplphysiol.00085.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although the structure of the contractile unit in smooth muscle is poorly understood, some of the mechanical properties of the muscle suggest that a sliding-filament mechanism, similar to that in striated muscle, is also operative in smooth muscle. To test the applicability of this mechanism to smooth muscle function, we have constructed a mathematical model based on a hypothetical structure of the smooth muscle contractile unit: a side-polar myosin filament sandwiched by actin filaments, each attached to the equivalent of a Z disk. Model prediction of isotonic shortening as a function of time was compared with data from experiments using ovine tracheal smooth muscle. After equilibration and establishment of in situ length, the muscle was stimulated with ACh (100 μM) until force reached a plateau. The muscle was then allowed to shorten isotonically against various loads. From the experimental records, length-force and force-velocity relationships were obtained. Integration of the hyperbolic force-velocity relationship and the linear length-force relationship yielded an exponential function that approximated the time course of isotonic shortening generated by the modeled sliding-filament mechanism. However, to obtain an accurate fit, it was necessary to incorporate a viscoelastic element in series with the sliding-filament mechanism. The results suggest that a large portion of the shortening is due to filament sliding associated with muscle activation and that a small portion is due to continued deformation associated with an element that shows viscoelastic or power-law creep after a step change in force.
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Affiliation(s)
| | | | - Peter D. Paré
- James Hogg Research Centre/St. Paul's Hospital,
- Department of Medicine, and
| | - Chun Y. Seow
- James Hogg Research Centre/St. Paul's Hospital,
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Al-Jumaily A, Du Y. Fading memory model for airway smooth muscle dynamic response. J Theor Biol 2011; 283:10-3. [DOI: 10.1016/j.jtbi.2011.05.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/12/2011] [Accepted: 05/16/2011] [Indexed: 11/16/2022]
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Ijpma G, Al-Jumaily AM, Cairns SP, Sieck GC. Myosin filament polymerization and depolymerization in a model of partial length adaptation in airway smooth muscle. J Appl Physiol (1985) 2011; 111:735-42. [PMID: 21659490 DOI: 10.1152/japplphysiol.00114.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Length adaptation in airway smooth muscle (ASM) is attributed to reorganization of the cytoskeleton, and in particular the contractile elements. However, a constantly changing lung volume with tidal breathing (hence changing ASM length) is likely to restrict full adaptation of ASM for force generation. There is likely to be continuous length adaptation of ASM between states of incomplete or partial length adaption. We propose a new model that assimilates findings on myosin filament polymerization/depolymerization, partial length adaptation, isometric force, and shortening velocity to describe this continuous length adaptation process. In this model, the ASM adapts to an optimal force-generating capacity in a repeating cycle of events. Initially the myosin filament, shortened by prior length changes, associates with two longer actin filaments. The actin filaments are located adjacent to the myosin filaments, such that all myosin heads overlap with actin to permit maximal cross-bridge cycling. Since in this model the actin filaments are usually longer than myosin filaments, the excess length of the actin filament is located randomly with respect to the myosin filament. Once activated, the myosin filament elongates by polymerization along the actin filaments, with the growth limited by the overlap of the actin filaments. During relaxation, the myosin filaments dissociate from the actin filaments, and then the cycle repeats. This process causes a gradual adaptation of force and instantaneous adaptation of shortening velocity. Good agreement is found between model simulations and the experimental data depicting the relationship between force development, myosin filament density, or shortening velocity and length.
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Affiliation(s)
- Gijs Ijpma
- Institute of Biomedical Technologies, Auckland University of Technology, Auckland, New Zealand
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