Viscoelastic and dynamic nonlinear properties of airway smooth muscle tissue: roles of mechanical force and the cytoskeleton

2006 ◽  
Vol 290 (6) ◽  
pp. L1227-L1237 ◽  
Author(s):  
Satoru Ito ◽  
Arnab Majumdar ◽  
Hiroaki Kume ◽  
Kaoru Shimokata ◽  
Keiji Naruse ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Cultured Cells ◽  
Kinase Inhibitor ◽  
Viscoelastic Model ◽  
Harmonic Distortion ◽  
Cytochalasin D ◽  
Tracheal Smooth Muscle ◽  
Smooth Muscle Tissue ◽  
Nonlinear Properties ◽  
Dynamic Nonlinearity

The viscoelastic and dynamic nonlinear properties of guinea pig tracheal smooth muscle tissues were investigated by measuring the storage (G′) and loss (G") moduli using pseudorandom small-amplitude length oscillations between 0.12 and 3.5 Hz superimposed on static strains of either 10 or 20% of initial length. The G" and G′ spectra were interpreted using a linear viscoelastic model incorporating damping (G) and stiffness (H), respectively. Both G and H were elevated following an increase in strain from 10 to 20%. There was no change in harmonic distortion ( Kd), an index of dynamic nonlinearity, between 10 and 20% strains. Application of methacholine at 10% strain significantly increased G and H while it decreased Kd. Cytochalasin D, isoproterenol, and HA-1077, a Rho-kinase inhibitor, significantly decreased both G and H but increased Kd. Following cytochalasin D, G, H, and Kd were all elevated when mean strain increased from 10 to 20%. There were no changes in hysteresivity, G/H, under any condition. We conclude that not all aspects of the viscoelastic properties of tracheal smooth muscle strips are similar to those previously observed in cultured cells. We attribute these differences to the contribution of the extracellular matrix. Additionally, using a network model, we show that the dynamic nonlinear behavior, which has not been observed in cell culture, is associated with the state of the contractile stress and may derive from active polymerization within the cytoskeleton.

Role of Rho in Ca2+-insensitive contraction and paxillin tyrosine phosphorylation in smooth muscle

2000 ◽  
Vol 279 (2) ◽  
pp. C308-C318 ◽  
Author(s):  
Dolly Mehta ◽  
Dale D. Tang ◽  
Ming-Fang Wu ◽  
Simon Atkinson ◽  
Susan J. Gunst
Keyword(s):  
Smooth Muscle ◽  
Tyrosine Phosphorylation ◽  
Actin Polymerization ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Cytochalasin D ◽  
Cytoskeletal Proteins ◽  
Tracheal Smooth Muscle ◽  
Contractile Activation ◽  
Mlc Phosphorylation

We investigated whether Rho activation is required for Ca2+-insensitive paxillin phosphorylation, myosin light chain (MLC) phosphorylation, and contraction in tracheal muscle. Tyrosine-phosphorylated proteins have been implicated in the Ca2+-insensitive contractile activation of smooth muscle tissues. The contractile activation of tracheal smooth muscle increases tyrosine phosphorylation of the cytoskeletal proteins paxillin and focal adhesion kinase. Paxillin is implicated in integrin-mediated signal transduction pathways that regulate cytoskeletal organization and cell motility. In fibroblasts and other nonmuscle cells, paxillin tyrosine phosphorylation depends on the activation of Rho and is inhibited by cytochalasin, an inhibitor of actin polymerization. In permeabilized muscle strips, we found that ACh induced Ca2+-insensitive contraction, MLC phosphorylation, and paxillin tyrosine phosphorylation. Ca2+-insensitive contraction and MLC phosphorylation induced by ACh were inhibited by C3 transferase, an inhibitor of Rho activation; however, C3 transferase did not inhibit paxillin tyrosine phosphorylation. Ca2+-insensitive paxillin tyrosine phosphorylation was also not inhibited by the Rho kinase inhibitor Y-27632, by cytochalasin D, or by the inhibition of MLC phosphorylation. We conclude that, in tracheal smooth muscle, Rho mediates Ca2+-insensitive contraction and MLC phosphorylation but that Rho is not required for Ca2+-insensitive paxillin tyrosine phosphorylation. Paxillin phosphorylation also does not require actomyosin activation, nor is it inhibited by the actin filament capping agent cytochalasin D.

Effect of Off-Axis Cell Orientation in Smooth Muscle Tissue

2003 ◽  
Author(s):  
P. A. Sarma ◽  
Ramana M. Pidaparti ◽  
Richard A. Meiss
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Muscle Tissue ◽  
Maximum Shear Stress ◽  
Tracheal Smooth Muscle ◽  
Cell Alignment ◽  
Cell Orientation ◽  
Element Analysis ◽  
Smooth Muscle Tissue ◽  
Axis Orientation

The cell alignment in a smooth muscle tissue plays a significant role in determining its mechanical properties. In addition to shortening strain, the off-axis cell orientation θ also modify the shear stress relationship significantly. A simulation model based on finite element analysis is developed to study the effect of stresses of tracheal smooth muscle tissue when its cells are orientated off-axially. Results obtained indicate that the maximum shear stress values of tracheal smooth muscle tissue at 45% strain are 2.5 times the values at 20% strain for all three off-axis orientation values θ = 15°, 30° and 45°.

Smooth Muscle Tissue Response to Applied Vibration Following Extreme Isotonic Shortening

2002 ◽  
Author(s):  
Nandhini Dhanaraj ◽  
Ramana M. Pidaparti ◽  
Richard A. Meiss
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Smooth Muscle ◽  
Muscle Tissue ◽  
Mechanical Response ◽  
Tissue Response ◽  
Tracheal Smooth Muscle ◽  
Smooth Muscle Tissue ◽  
Vibratory Response ◽  
Isotonic Shortening

The objectives of the present study are to investigate the response of a tracheal smooth muscle tissue to an applied longitudinal vibration following isotonic shortening, and, using experimental data, to simulate the mechanical response through a non-linear finite element analysis. The response of an activated smooth muscle tissue to forced length oscillations at 33Hz for 1 second was obtained. The response in terms of stiffness change and hysteresis was estimated from the experimental data. A finite element simulation was carried out to simulate the vibratory response under experimental conditions. The results obtained indicate that the approach and the vibratory response obtained may be useful for describing the cross-bridge deattachements within the cells as well as connective tissue connections characteristics of tracheal smooth muscle tissue.

Sodium nitroprusside stimulates Ca2+ -activated K+ channels in porcine tracheal smooth muscle cells

1996 ◽  
Vol 270 (3) ◽  
pp. L338-L345 ◽  
Author(s):  
M. Yamakage ◽  
C. A. Hirshman ◽  
T. L. Croxton
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Sodium Nitroprusside ◽  
Airway Smooth Muscle ◽  
Guanylate Cyclase ◽  
Kinase Inhibitor ◽  
Muscle Cells ◽  
Tracheal Smooth Muscle ◽  
Membrane Hyperpolarization ◽  
Kca Channels

To directly investigate the possible role of large-conductance Ca2+ -activated K+ (KCa) channels in nitro-vasodilator-induced relaxation of airway smooth muscle, we used cell-attached patch-clamp techniques to test the effects of sodium nitroprusside (SNP) on KCa channels in freshly dispersed porcine tracheal smooth muscle cells. Channel open-state probability (nPo) increased approximately 13-fold with exposure to 10(-5) M SNP, and this was partially reversed by addition of the guanylate cyclase inhibitors methylene blue (3 X 10(-4) M) or LY-83583 (5 X 10(-5) M). Pretreatment with the guanosine 3',5' -cyclic monophosphate (cGMP)-dependent protein kinase (G kinase) inhibitor Rp-8-(p-chlorophenylthio) cGMP-phosphorothioate (2 X 10(-5) M) prevented activation of KCa channels by SNP. We also tested the ability of G kinase to directly activate KCa channels in inside-out patches. G kinase (2.5 U/microliter) with ATP (0.5 mM) and cGMP (0.1 mM), but not ATP and cGMP alone, increased nPo approximately 23-fold. We conclude that SNP activates KCa channels in airway smooth muscle via guanylate cyclase and G kinase. Phosphorylation of the channel protein by G kinase may account for this response. Consequent membrane hyperpolarization and inhibition of Ca2+ entry through voltage-dependent channels may contribute to SNP-induced relaxation of airway smooth muscle.

Tryptase activates phosphatidylinositol 3-kinases proteolytically independently from proteinase-activated receptor-2 in cultured dog airway smooth muscle cells

2006 ◽  
Vol 290 (2) ◽  
pp. L259-L269 ◽  
Author(s):  
James K. Brown ◽  
Morley D. Hollenberg ◽  
Cary A. Jones
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Kinase Inhibitor ◽  
Muscle Cells ◽  
Tracheal Smooth Muscle ◽  
Hydroxyl Group ◽  
Airway Smooth Muscle Cells ◽  
Cellular Mechanisms ◽  
Akt Phosphorylation ◽  
Phosphatidylinositol 3

Mast cell tryptase is a potent mitogen for many cells in the airways and lung, but the cellular mechanisms for its growth stimulatory effects are poorly understood. Our major goal was to determine whether tryptase activates phosphatidylinositol 3-kinases (PI 3-kinases) in cultured dog tracheal smooth muscle cells to induce its mitogenic effects. After exposure to tryptase, cells were lysed. Immunocomplexes prepared from the lysates using an antibody to the p85 subunit of PI 3-kinase, but not using anti-phosphotyrosine antibodies, possessed increased capacity to phosphorylate inositol on its D3 hydroxyl group. Tryptase also increased phosphorylation of Akt, a downstream target of PI 3-kinases. This effect was abolished by one PI 3-kinase inhibitor, wortmannin, and attenuated by another, LY-294004, which also blocked tryptase's mitogenic effects. Treatment of tryptase with p-amidino phenylmethanesulfonyl fluoride, to abolish its proteolytic activity irreversibly, inhibited its stimulatory effects on Akt phosphorylation. Proteinase-activated receptor-2 (PAR-2)-activating peptides failed to increase Akt phosphorylation in cultured dog tracheal smooth muscle cells, but the PAR-2-activating peptides did induce brisk increases in Akt phosphorylation in Madin-Darby canine kidney cells. We concluded that tryptase activates PI 3-kinases in cultured dog tracheal smooth muscle cells to induce its potent mitogenic effects. These effects of tryptase on PI 3-kinases appear to occur via novel proteolytic mechanisms independent from PAR-2. Also, tryptase, although comparable in mitogenic potency to platelet-derived growth factor (PDGF), induces considerably less tyrosine phosphorylation on proteins than occur in response to PDGF.

Force regulates smooth muscle actin in cardiac fibroblasts

2000 ◽  
Vol 279 (6) ◽  
pp. H2776-H2785 ◽  
Author(s):  
J. Wang ◽  
A. Seth ◽  
C. A. G. McCulloch
Keyword(s):  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Cultured Cells ◽  
Kinase Inhibitor ◽  
Cardiac Fibroblasts ◽  
Smooth Muscle Actin ◽  
Focal Adhesions ◽  
Pressure Overload ◽  
Muscle Actin ◽  
P38 Kinase

Chronic ventricular pressure overload can regulate expression of α-smooth muscle actin (SMA) in cardiac fibroblasts, but it is unclear if force alone or the concomitant activity of angiotensin II is the principal regulatory factor. To test if SMA mRNA and protein in rat cardiac fibroblasts are regulated directly by force, we first induced SMA expression in cultured cells and then applied magnetically generated perpendicular forces through focal adhesions using collagen-coated magnetite beads. Continuous static forces (0.65 pN/μm2) selectively reduced SMA but not β-actin mRNA and protein content within 4 h (to 55 ± 9% of controls); SMA returned to baseline by 8 h. There was no change in SMA content after force application with either plasma or the cellular fibronectin IIIA domain, BSA, or poly-l-lysine beads. The early loss of SMA was apparently due to selective leakage into the cell culture medium. Treatment with angiotensin II (10 nM) abrogated the force-induced reduction of SMA and increased the levels of this protein. The stress kinase p38 was phosphorylated by force, whereas extracellular signal-regulated kinase 1/2 and c-Jun NH2-terminal kinase were unaffected. The p38 kinase inhibitor SB-203580 relieved the force-induced SMA reduction. We conclude that force-induced inhibition of SMA is mediated through the p38 kinase pathway, and this pathway antagonizes angiotensin II regulation of SMA.

Active and passive components in the length-dependent stiffness of tracheal smooth muscle during isotonic shortening

2005 ◽  
Vol 98 (1) ◽  
pp. 234-241 ◽  
Author(s):  
Richard A. Meiss ◽  
Ramana M. Pidaparti
Keyword(s):  
Smooth Muscle ◽  
Structural Model ◽  
Isometric Force ◽  
Isometric Tension ◽  
Tracheal Smooth Muscle ◽  
Shortening Velocity ◽  
Muscle Contractility ◽  
Smooth Muscle Tissue ◽  
Induced Changes ◽  
Isotonic Shortening

Contraction of smooth muscle tissue involves interactions between active and passive structures within the cells and in the extracellular matrix. This study focused on a defined mechanical behavior (shortening-dependent stiffness) of canine tracheal smooth muscle tissues to evaluate active and passive contributions to tissue behavior. Two approaches were used. In one, mechanical measurements were made over a range of temperatures to identify those functions whose temperature sensitivity (Q10) identified them as either active or passive. Isotonic shortening velocity and rate of isometric force development had high Q10 values (2.54 and 2.13, respectively); isometric stiffness showed Q10 values near unity. The shape of the curve relating stiffness to isotonic shortening lengths was unchanged by temperature. In the other approach, muscle contractility was reduced by applying a sudden shortening step during the rise of isometric tension. Control contractions began with the muscle at the stepped length so that properties were measured over comparable length ranges. Under isometric conditions, redeveloped isometric force was reduced, but the ratio between force and stiffness did not change. Under isotonic conditions beginning during force redevelopment at the stepped length, initial shortening velocity and the extent of shortening were reduced, whereas the rate of relaxation was increased. The shape of the curve relating stiffness to isotonic shortening lengths was unchanged, despite the step-induced changes in muscle contractility. Both sets of findings were analyzed in the context of a quasi-structural model describing the shortening-dependent stiffness of lightly loaded tracheal muscle strips.

scholarly journals Integrin-linked kinase is responsible for Ca2+-independent myosin diphosphorylation and contraction of vascular smooth muscle

2005 ◽  
Vol 392 (3) ◽  
pp. 641-648 ◽  
Author(s):  
David P. Wilson ◽  
Cindy Sutherland ◽  
Meredith A. Borman ◽  
Jing Ti Deng ◽  
Justin A. MacDonald ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Vascular Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Kinase Inhibitors ◽  
Cultured Cells ◽  
Kinase Inhibitor ◽  
Smooth Muscle Contraction ◽  
Integrin Linked Kinase

Smooth muscle contraction is activated by phosphorylation at Ser-19 of LC20 (the 20 kDa light chains of myosin II) by Ca2+/calmodulin-dependent MLCK (myosin light-chain kinase). Diphosphorylation of LC20 at Ser-19 and Thr-18 is observed in smooth muscle tissues and cultured cells in response to various contractile stimuli, and in pathological circumstances associated with hypercontractility. MLCP (myosin light-chain phosphatase) inhibition can lead to LC20 diphosphorylation and Ca2+-independent contraction, which is not attributable to MLCK. Two kinases have emerged as candidates for Ca2+-independent LC20 diphosphorylation: ILK (integrin-linked kinase) and ZIPK (zipper-interacting protein kinase). Triton X-100-skinned rat caudal arterial smooth muscle was used to investigate the relative importance of ILK and ZIPK in Ca2+-independent, microcystin (phosphatase inhibitor)-induced LC20 diphosphorylation and contraction. Western blotting and in-gel kinase assays revealed that both kinases were retained in this preparation. Ca2+-independent contraction of calmodulin-depleted tissue in response to microcystin was resistant to MLCK inhibitors [AV25 (a 25-amino-acid peptide derived from the autoinhibitory domain of MLCK), ML-7, ML-9 and wortmannin], protein kinase C inhibitor (GF109203X) and Rho-associated kinase inhibitors (Y-27632 and H-1152), but blocked by the non-selective kinase inhibitor staurosporine. ZIPK was inhibited by AV25 (IC50 0.63±0.05 μM), whereas ILK was insensitive to AV25 (at concentrations as high as 100 μM). AV25 had no effect on Ca2+-independent, microcystin-induced LC20 mono- or di-phosphorylation, with a modest effect on force. We conclude that direct inhibition of MLCP in the absence of Ca2+ unmasks ILK activity, which phosphorylates LC20 at Ser-19 and Thr-18 to induce contraction. ILK is probably the kinase responsible for myosin diphosphorylation in vascular smooth muscle cells and tissues.

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