Passive sensitization of human bronchi augments smooth muscle shortening velocity and capacity

1994 ◽  
Vol 267 (2) ◽  
pp. L218-L222 ◽  
Author(s):  
R. W. Mitchell ◽  
E. Ruhlmann ◽  
H. Magnussen ◽  
A. R. Leff ◽  
K. F. Rabe
Keyword(s):  
Smooth Muscle ◽  
Human Serum ◽  
Immunoglobulin E ◽  
Isometric Force ◽  
Lung Resection ◽  
Electrical Field Stimulation ◽  
Shortening Velocity ◽  
Passive Sensitization ◽  
High Concentrations

We assessed whether incubation with human serum from atopic individuals containing high concentrations of immunoglobulin E (IgE) causes augmentation of maximal contraction of human bronchial smooth muscle from non-atopic subjects in vitro. Bronchi were obtained from eight patients undergoing lung resection, and force-velocity relationships were determined for eight pairs of epithelium-intact bronchial rings of generations 6-7 using an electromagnetic lever system, which allowed isotonic shortening when load-clamps [from 0 to maximal isometric force (P0)] were applied at specific times after onset of contraction. Contractions were elicited by supramaximal electrical field stimulation (50 Hz, 10 s train duration, 25 V). Optimal length (Lo) for each tissue was determined during equilibration. After resection, tissues were sensitized passively with human sera containing high titers (> 1,000 U/ml) of IgE by incubation for 16 h at 20 degrees C. Maximal shortening velocity (Vmax) was increased for passively sensitized bronchi [0.1150 +/- 0.0240 1/2 circumferences/s (1/2Cir/s)] compared with sham-sensitized bronchi [0.0731 +/- 0.0152 1/2Cir/s, P = 0.038]. Similarly, maximal shortening (delta Lmax) was augmented in sensitized bronchial rings (11.27 +/- 1.80 %Lo) compared with sham-sensitized tissues (8.19 +/- 1.39 %Lo, P = 0.012). However, P0 did not differ between sensitized (122.5 +/- 24.4 mN/cm2) compared with sham-sensitized tissues (138.4 +/- 32.1 mN/cm2, P = 0.642). Our data are the first demonstration that Vmax and delta Lmax are augmented in sensitized but not challenged human bronchial rings after passive sensitization using human serum containing high concentrations of IgE.

Effect of airway inflammation on smooth muscle shortening and contractility in guinea pig trachealis

1993 ◽  
Vol 265 (6) ◽  
pp. L549-L554 ◽  
Author(s):  
R. W. Mitchell ◽  
I. M. Ndukwu ◽  
K. Arbetter ◽  
J. Solway ◽  
A. R. Leff
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Neurogenic Inflammation ◽  
Isometric Force ◽  
Electrical Field Stimulation ◽  
Shortening Velocity ◽  
Lever System ◽  
Force Velocity

We studied the effect of either 1) immunogenic inflammation caused by aerosolized ovalbumin or 2) neurogenic inflammation caused by aerosolized capsaicin in vivo on guinea pig tracheal smooth muscle (TSM) contractility in vitro. Force-velocity relationships were determined for nine epithelium-intact TSM strips from ovalbumin-sensitized (OAS) vs. seven sham-sensitized controls and TSM strips for seven animals treated with capsaicin aerosol (Cap-Aer) vs. eight sham controls. Muscle strips were tethered to an electromagnetic lever system, which allowed isotonic shortening when load clamps [from 0 to maximal isometric force (Po)] were applied at specific times after onset of contraction. Contractions were elicited by supramaximal electrical field stimulation (60 Hz, 10-s duration, 18 V). Optimal length for each muscle was determined during equilibration. Maximal shortening velocity (Vmax) was increased in TSM from OAS (1.72 +/- 0.46 mm/s) compared with sham-sensitized animals (0.90 +/- 0.15 mm/s, P < 0.05); Vmax for TSM from Cap-Aer (0.88 +/- 0.11 mm/s) was not different from control TSM (1.13 +/- 0.08 mm/s, P = NS). Similarly, maximal shortening (delta max) was augmented in TSM from OAS (1.01 +/- 0.15 mm) compared with sham-sensitized animals (0.72 +/- 0.14 mm, P < 0.05); delta max for TSM from Cap-Aer animals (0.65 +/- 0.11 mm) was not different from saline aerosol controls (0.71 +/- 0.15 mm, P = NS). We demonstrate Vmax and delta max are augmented in TSM after ovalbumin sensitization; in contrast, neurogenic inflammation caused by capsaicin has no effect on isolated TSM contractility in vitro. These data suggest that airway hyperresponsiveness in vivo that occurs in association with immunogenic or neurogenic inflammation may result from different effects of these types of inflammation on airway smooth muscle.

Vanadate oxidation activates contraction in skinned smooth muscle without myosin light chain phosphorylation

1997 ◽  
Vol 272 (1) ◽  
pp. C278-C288 ◽  
Author(s):  
M. J. Lalli ◽  
K. Obara ◽  
R. J. Paul
Keyword(s):  
Smooth Muscle ◽  
Light Chain ◽  
Muscle Activation ◽  
Isometric Force ◽  
Total Force ◽  
Shortening Velocity ◽  
Irreversible Damage ◽  
Initial Control ◽  
High Concentrations ◽  
Cross Bridges

Phosphorylation of the myosin regulatory light chain (LC20-P1) is the major route of smooth muscle activation. However, after prior exposure to vanadate, permeabilized guinea pig taenia coli smooth muscle contracts in the absence of LC20-P1. We characterized the vanadate-induced contraction and investigated the mechanism of this novel activation pathway. Addition of vanadate to a control contracture (6.6 microM Ca2+) inhibits force (effective dose for 50% response was approximately 100 microM). In contrast, preincubation with high concentrations of vanadate (threshold at 1-2 mM) elicited a contraction on subsequent transfer of the fiber to a vanadate-free, Ca(2+)-free solution. Maximum isometric force of approximately 60% of control was obtained in fibers preincubated in 4 mM vanadate for 10 min. Addition of Ca2+ to a vanadate-induced contracture increased force, but the total force never exceeded the initial control. After maximal thiophosphorylation of LC20 with adenosine 5'-O-(3-thiotriphosphate), treatment with vanadate did not increase force. Unloaded shortening velocity (Vmax) was similar in Ca2+ and vanadate contractures and was additive. After thiophosphorylation, preincubation in vanadate had no effect on Vmax, suggesting that vanadate affected the number of activated bridges and not cycle rate. Vanadate mechanisms likely involve oxidation, since preincubation with 4 mM vanadate and 25 mM dithiothreitol (DTT) did not produce force. DTT could reverse a vanadate-induced contracture in 30-60 min. Subsequently, fibers demonstrated control contraction/relaxation cycles. Thus vanadate treatment did not cause irreversible damage, such as the extraction of proteins. Potential oxidation sites are proteins at 17 kDa and between 30 and 40 kDa, which were not alkylated by N-ethylmaleimide if they were treated in the presence of vanadate or in the rigor state. Vanadate-induced contractures are likely mediated by a reversible oxidation that activates cross bridges similarly to that of LC20-Pi and may play an important role in oxidant injury.

scholarly journals Could an increase in airway smooth muscle shortening velocity cause airway hyperresponsiveness?

2011 ◽  
Vol 300 (1) ◽  
pp. L121-L131 ◽  
Author(s):  
Sharon R. Bullimore ◽  
Sana Siddiqui ◽  
Graham M. Donovan ◽  
James G. Martin ◽  
James Sneyd ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Airway Hyperresponsiveness ◽  
Isometric Force ◽  
Muscle Length ◽  
Shortening Velocity ◽  
Bridge Model ◽  
Generating Capacity ◽  
Cross Bridges

Airway hyperresponsiveness (AHR) is a characteristic feature of asthma. It has been proposed that an increase in the shortening velocity of airway smooth muscle (ASM) could contribute to AHR. To address this possibility, we tested whether an increase in the isotonic shortening velocity of ASM is associated with an increase in the rate and total amount of shortening when ASM is subjected to an oscillating load, as occurs during breathing. Experiments were performed in vitro using 27 rat tracheal ASM strips supramaximally stimulated with methacholine. Isotonic velocity at 20% isometric force (Fiso) was measured, and then the load on the muscle was varied sinusoidally (0.33 ± 0.25 Fiso, 1.2 Hz) for 20 min, while muscle length was measured. A large amplitude oscillation was applied every 4 min to simulate a deep breath. We found that: 1) ASM strips with a higher isotonic velocity shortened more quickly during the force oscillations, both initially ( P < 0.001) and after the simulated deep breaths ( P = 0.002); 2) ASM strips with a higher isotonic velocity exhibited a greater total shortening during the force oscillation protocol ( P < 0.005); and 3) the effect of an increase in isotonic velocity was at least comparable in magnitude to the effect of a proportional increase in ASM force-generating capacity. A cross-bridge model showed that an increase in the total amount of shortening with increased isotonic velocity could be explained by a change in either the cycling rate of phosphorylated cross bridges or the rate of myosin light chain phosphorylation. We conclude that, if asthma involves an increase in ASM velocity, this could be an important factor in the associated AHR.

Stimulus-response relationships for isotonic shortening and isometric tension generation in rabbit trachealis

1994 ◽  
Vol 77 (4) ◽  
pp. 1638-1643 ◽  
Author(s):  
A. Opazo-Saez ◽  
P. D. Pare
Keyword(s):  
Smooth Muscle ◽  
Isometric Force ◽  
Electrical Field Stimulation ◽  
Isometric Tension ◽  
Maximal Response ◽  
Field Stimulation ◽  
Electrical Field ◽  
Increased Sensitivity ◽  
Isotonic Shortening

Nonspecific bronchial hyperresponsiveness in asthma is characterized by increased maximal airway narrowing (reactivity) and increased sensitivity of the airways. A decreased load on airway smooth muscle (ASM) has been suggested as a mechanism of increased reactivity. We hypothesized that decreased ASM load can also cause a leftward shift in the dose-response curve and explain increased sensitivity. We tested this hypothesis using rabbit tracheal smooth muscle strips in vitro by measuring isotonic shortening and isometric force during electrical field stimulation (1–100 Hz) at the length at which maximal active tension developed (Lmax), 90% Lmax, and 110% Lmax The frequency-response relationships expressed as frequency vs. percent maximal shortening or tension were not different at Lmax or 110% Lmax, but at 90% Lmax the frequency vs. shortening relationship was significantly shifted leftward relative to the frequency vs. tension relationship (P < 0.05). The electrical field stimulation frequencies that produced 50% maximal response for isometric tension and for isotonic shortening, respectively, were 6.7 +/- 1.9 and 3.9 +/- 0.7 Hz at 90% Lmax, 9.2 +/- 2.1 and 7.5 +/- 1.9 Hz at 100% Lmax, and 2.8 +/- 1.0 and 1.2 +/- 0.5 Hz at 110% Lmax. We conclude that, at lengths below Lmax, isotonic shortening is facilitated compared with isometric tension and therefore decreased ASM load in vivo may result in increased sensitivity.

Passive sensitization of human airways induces myogenic contractile responses in vitro

1997 ◽  
Vol 83 (4) ◽  
pp. 1276-1281 ◽  
Author(s):  
R. W. Mitchell ◽  
K. F. Rabe ◽  
H. Magnussen ◽  
A. R. Leff
Keyword(s):  
Immunoglobulin E ◽  
Electrical Field Stimulation ◽  
Maximal Response ◽  
Myogenic Response ◽  
Contractile Responses ◽  
Force Transducers ◽  
Passive Sensitization ◽  
Human Airways ◽  
Mechanical Stretching

Mitchell, R. W., K. F. Rabe, H. Magnussen, and A. R. Leff.Passive sensitization of human airways induces myogenic contractile responses in vitro. J. Appl. Physiol. 83(4): 1276–1281, 1997.—We assessed effects of passive sensitization on human bronchial smooth muscle (BSM) response to mechanical stretching in vitro. Bronchial rings were sham (control) or passively sensitized overnight by using sera from donors demonstrating sensitivity to Dermatophagoides farinae and having immunoglobulin E (IgE) concentrations of 2,600 ± 200 U/ml. Tissues were fixed isometrically to force transducers to measure responses to electrical field stimulation (EFS) and quick stretch (QS). The myogenic response to QS was normalized to the maximal response to EFS (%EFS). The myogenic response of sensitized BSM was 47.9 ± 10.9 %EFS to a QS of ∼6.5% optimal length ( L o); sham-sensitized tissues had a myogenic response of 13.5 ± 6.4 %EFS ( P = 0.012 vs. passively sensitized). A QS of ∼13% L o in sensitized BSM caused a response of 82.8 ± 20.9 %EFS; sham-sensitized tissues developed a response of 38.2 ± 17.3 %EFS ( P = 0.004). BSM incubated with serum from nonallergic donors did not demonstrate increased QS response (4.6 ± 1.4 %EFS, P = not significant vs. tissue exposed to atopic sera). However, tissues incubated in sera from nonatopic donors supplemented with hapten-specific chimeric IgE (JW8) demonstrated augmented myogenic response to QS of ∼6.5% L o (21.9 ± 6.2 %EFS, P = 0.027 vs. nonatopic sera alone). We demonstrate that passive sensitization of human BSM preparations causes induction and augmentation of myogenic contractions to QS; this hyperresponsiveness corresponds to the IgE concentration in sensitizing sera.

Abstract 958: Cardiac MyBP-C Modulates Actomyosin Interactions: Evidence From Cardiac MyBP-c−/ − Mice

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Yves Lecarpentier ◽  
Nicolas Vignier ◽  
Patricia Oliviero ◽  
Miguel Cortes-Morichetti ◽  
Lucie Carrier ◽  
...  
Keyword(s):  
Thin Filament ◽  
Isometric Force ◽  
Binding Protein ◽  
Critical Role ◽  
Cardiac Contractility ◽  
Left Ventricular ◽  
Actin Binding ◽  
Power Stroke ◽  
Shortening Velocity

The precise role of cardiac myosin binding protein C (cMyBP-C) on actomyosin interaction (AMI) remains unknown. We hypothesized that the lack of cMyBP-C impaired cardiac AMI. Experiments were performed on 16 weeks old cMyBP-C −/− (KO) and age-matched wild-type (WT) mice (n=20/group). In vitro mechanical and energetics properties were performed on left ventricular (LV) papillary muscles and Huxley’s equations were used to characterize AMI. In vitro motility assays were performed using myosin purified from LV. Myosin-based sliding velocities of actin filaments were analyzed at baseline, after pretreatment of the myosin solution with 10 umol of the catalytic subunit of PKA and/or in the presence of increasing amount of α-actinin, an actin-binding protein that acts as an internal load thereby providing an index of relative isometric force. Western-blot analysis was used to quantify cMyBP-C and phosphorylated cMyBP-C in myosin solutions. Compared to WT, both total tension and maximum shortening velocity were lower in KO (p<0.001). The probability for myosin to be weakly bound to actin was higher in KO than in WT (8.6±0.3 vs. 5.4±0.2%, p<0.05), whereas the number of strongly bound, high-force generated state cross-bridges was lower in KO (6.4±0.9 vs. 11.6±1.0 10 9 /mm 2 , p<0.001). The unitary force per AMI was lower in KO than in WT (p<0.01). At baseline, myosin-based velocities of actin were slower in KO than in WT (1.65±0.01 vs. 1.98±0.01 um/s, p<0.01). The minimum amount of α-actinin needed to completely arrest the thin filament motility was significantly higher in WT than in KO (73.3±1.1 vs 29.1±0.1 ug/l, p<0.001). As expected, cMyBP-C was present in WT myosin solution whereas cMyBP-C was not detected in KO. In WT, PKA induced a 1.6-fold increased in cMyBP-C phosphorylation (p<0.01) associated with a 53±1% increase in the amount of α-actinin required to arrest thin filament motility (p<0.001). PKA did not modify sliding velocity in WT. In KO, PKA had no effect on myosin sliding. We conclude that cMyBP-C regulates AMI by limiting inefficient cross-bridge formation and by enhancing the power stroke step. Phosphorylation status of cMyBP-C appears to play a critical role on cardiac contractility through a direct effect on the myosin molecular motor.

Mechanical properties of human bronchial smooth muscle in vitro

1992 ◽  
Vol 73 (4) ◽  
pp. 1481-1485 ◽  
Author(s):  
K. Ishida ◽  
P. D. Pare ◽  
J. Hards ◽  
R. R. Schellenberg
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Electrical Field Stimulation ◽  
Tracheal Smooth Muscle ◽  
Cross Sectional ◽  
Velocity Of Shortening ◽  
Muscle Shortening ◽  
Tension Generation ◽  
Very High

The in vitro mechanical properties of smooth muscle strips from 10 human main stem bronchi obtained immediately after pneumonectomy were evaluated. Maximal active isometric and isotonic responses were obtained at varying lengths by use of electrical field stimulation (EFS). At the length (Lmax) producing maximal force (Pmax), resting tension was very high (60.0 +/- 8.8% Pmax). Maximal fractional muscle shortening was 25.0 +/- 9.0% at a length of 75% Lmax, whereas less shortening occurred at Lmax (12.2 +/- 2.7%). The addition of increasing elastic loads produced an exponential decrease in the shortening and velocity of shortening but increased tension generation of muscle strips stimulated by EFS. Morphometric analysis revealed that muscle accounted for 8.7 +/- 1.5% of the total cross-sectional tissue area. Evaluation of two human tracheal smooth muscle preparations revealed mechanics similar to the bronchial preparations. Passive tension at Lmax was 10-fold greater and maximal active shortening was threefold less than that previously demonstrated for porcine trachealis by us of the same apparatus. We attribute the limited shortening of human bronchial and tracheal smooth muscle to the larger load presumably provided by a connective tissue parallel elastic component within the evaluated tissues, which must be overcome for shortening to occur. We suggest that a decrease in airway wall elastance could increase smooth muscle shortening, leading to excessive responses to contractile agonists, as seen in airway hyperresponsiveness.

Myosin phosphorylation and contraction of feline esophageal smooth muscle

1985 ◽  
Vol 249 (1) ◽  
pp. C9-C14 ◽  
Author(s):  
N. W. Weisbrodt ◽  
R. A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Mechanical Activation ◽  
Smooth Muscles ◽  
Circular Muscle ◽  
Electrical Field Stimulation ◽  
Muscle Layer ◽  
Field Stimulation ◽  
Shortening Velocity ◽  
Myosin Phosphorylation ◽  
Isotonic Shortening

We tested the hypothesis that phosphorylation of the 20,000-Da light chain of myosin (LC 20) is related to mechanical activation of esophageal smooth muscle. Circular muscle layer strips of cat esophagus were taken from the lower esophageal sphincter (LES) and the distal esophageal body (EB). The LES strips developed tone spontaneously, and the EB strips were tonically contracted with carbachol. Both tissues relaxed in response to electrical-field stimulation. Phosphorylation of the LC 20 was determined in tissues quick-frozen during relaxation and during stress redevelopment after cessation of field stimulation. Stress and phosphorylation levels were low after 30 s of field stimulation, and a rapid contraction followed field stimulation. Phosphorylation in the LES increased from 0.043 +/- 0.029 to 0.328 +/- 0.043 mol Pi/mol LC 20 within 10 s after stimulation of the inhibitory nerves was terminated, while stress was still rising rapidly. Phosphorylation in the LES then declined to a steady-state value of 0.162 +/- 0.034 mol Pi/mol LC 20 after 10 min. Isotonic shortening velocities at a constant afterload following a quick release showed changes with time that were proportional to the level of phosphorylation. This was also true for values of maximal shortening velocity estimated for zero external load and for the rate of stress redevelopment after a step shortening. Comparable measurements were made in the carbachol-contracted EB. These results indicate that visceral smooth muscles, which normally function tonically (LES) or phasically (EB), exhibit an initial rapid mechanical activation associated with myosin phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

Histamine tachyphylaxis in canine airways despite prostaglandin synthesis inhibition

1988 ◽  
Vol 65 (5) ◽  
pp. 1944-1949 ◽  
Author(s):  
P. J. Antol ◽  
S. J. Gunst ◽  
R. E. Hyatt
Keyword(s):  
Smooth Muscle ◽  
Dose Response ◽  
Prostaglandin Synthesis ◽  
Response Curves ◽  
Synthesis Inhibition ◽  
High Concentrations ◽  
Alpha Chloralose ◽  
Prostaglandin Synthesis Inhibitors

Tachyphylaxis to aerosolized histamine was studied in dogs anesthetized with thiamylal after pretreatment with prostaglandin synthesis inhibitors. Three consecutive histamine dose-response curves were obtained in nine dogs pretreated with 5 mg/kg indomethacin; two of these nine were also pretreated with 10 mg/kg indomethacin. Seven of the nine dogs were pretreated with 4 mg/kg sodium meclofenamate; four of these seven were also pretreated with 12 mg/kg. All dogs had tachyphylaxis at high concentrations of histamine regardless of inhibitor used. Pretreatment with indomethacin while the dogs were under alpha-chloralose-urethan anesthesia gave similar results. Histamine tachyphylaxis was also studied both in the presence and in the absence of indomethacin in tracheal smooth muscle strips obtained from seven additional dogs. A decrease in the median effective dose to histamine was observed in the indomethacin-treated strips, but tachyphylaxis to histamine remained. We conclude that prostaglandin synthesis inhibition does not reverse histamine tachyphylaxis either in vivo or in vitro. Thus the mechanism of histamine tachyphylaxis remains unexplained.

Phosphorylation of caldesmon by ERK MAP kinases in smooth muscle

2000 ◽  
Vol 278 (4) ◽  
pp. C718-C726 ◽  
Author(s):  
Jason C. Hedges ◽  
Brian C. Oxhorn ◽  
Michael Carty ◽  
Leonard P. Adam ◽  
Ilia A. Yamboliev ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Map Kinase ◽  
Map Kinases ◽  
Isometric Force ◽  
Phosphorylation Site ◽  
Smooth Muscle Contraction ◽  
Tracheal Smooth Muscle ◽  
Muscarinic Agonists

Phosphorylation of h-caldesmon has been proposed to regulate airway smooth muscle contraction. Both extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein (MAP) kinases phosphorylate h-caldesmon in vitro. To determine whether both enzymes phosphorylate caldesmon in vivo, phosphorylation-site-selective antibodies were used to assay phosphorylation of MAP kinase consensus sites. Stimulation of cultured tracheal smooth muscle cells with ACh or platelet-derived growth factor increased caldesmon phosphorylation at Ser789 by about twofold. Inhibiting ERK MAP kinase activation with 50 μM PD-98059 blocked agonist-induced caldesmon phosphorylation completely. Inhibiting p38 MAP kinases with 25 μM SB-203580 had no effect on ACh-induced caldesmon phosphorylation. Carbachol stimulation increased caldesmon phosphorylation at Ser789 in intact tracheal smooth muscle, which was blocked by the M2 antagonist AF-DX 116 (1 μM). AF-DX 116 inhibited carbachol-induced isometric contraction by 15 ± 1.4%, thus dissociating caldesmon phosphorylation from contraction. Activation of M2 receptors leads to activation of ERK MAP kinases and phosphorylation of caldesmon with little or no functional effect on isometric force. P38 MAP kinases are also activated by muscarinic agonists, but they do not phosphorylate caldesmon in vivo.

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