scholarly journals Mechanopharmacology and Synergistic Relaxation of Airway Smooth Muscle

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Lu Wang ◽  
Pasquale Chitano ◽  
Peter D. Paré ◽  
Chun Y. Seow
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Intracellular Signaling ◽  
Rho Kinase ◽  
Passive Stiffness ◽  
Rock Inhibitor ◽  
Drug Induced ◽  
Intracellular Signaling Pathways ◽  
Combination Treatments ◽  
Β2 Agonist

Asthmatic airways are stiffer than normal. We have shown that the cytoskeletal passive stiffness of airway smooth muscle (ASM) can be regulated by intracellular signaling pathways, especially those associated with Rho kinase (ROCK). We have also shown that an oscillatory strain reduces the passive stiffness of ASM and its ability to generate force. Here, we investigated the combined effect of inhibiting the ASM contraction with β2 agonist and decreasing the ASM cytoskeletal stiffness with ROCK inhibitor and/or force oscillation (FO) on the relaxation of contracted ASM. We hypothesize that the ASM relaxation can be synergistically enhanced by the combination of these interventions, because drug-induced softening of the cytoskeleton enhances the FO-induced relaxation and vice versa. Sheep tracheal strips were isotonically contracted to acetylcholine (3 × 10−5 M). At the plateau of shortening, β2 agonist salbutamol (10−7 M), ROCK inhibitor H1152 (10−7 M), and FO (square wave, 1 Hz, amplitude 6% maximal active force) were applied either alone or in combination. After adjusting for nonspecific time-dependent variation, relengthening by individual interventions with low-dose salbutamol or H1152, or small amplitude FO was not significantly different from zero. However, significant relengthening was observed in all combination treatments. The relengthening was greater than the mathematical sum of relengthening caused by individual treatments thereby demonstrating synergistic relaxation. The ASM stiffness did not change with salbutamol or H1152 treatments, but was lower with FO in combination with H1152. The results suggest that the mechanopharmacological treatment can be an effective therapy for asthma.

Increase in passive stiffness at reduced airway smooth muscle length: potential impact on airway responsiveness

2010 ◽  
Vol 298 (3) ◽  
pp. L277-L287 ◽  
Author(s):  
Ynuk Bossé ◽  
Dennis Solomon ◽  
Leslie Y. M. Chin ◽  
Kevin Lian ◽  
Peter D. Paré ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Muscle Length ◽  
Passive Stiffness ◽  
Tidal Breathing ◽  
Reference Length ◽  
Length Reduction

The amplitude of strain in airway smooth muscle (ASM) produced by oscillatory perturbations such as tidal breathing or deep inspiration (DI) influences the force loss in the muscle and is therefore a key determinant of the bronchoprotective and bronchodilatory effects of these breathing maneuvers. The stiffness of unstimulated ASM (passive stiffness) directly influences the amplitude of strain. The nature of the passive stiffness is, however, not clear. In this study, we measured the passive stiffness of ovine ASM at different muscle lengths (relative to in situ length, which was used as a reference length, Lref) and states of adaptation to gain insights into the origin of this muscle property. The results showed that the passive stiffness was relatively independent of muscle length, possessing a constant plateau value over a length range from 0.62 to 1.25 Lref. Following a halving of ASM length, passive stiffness decreased substantially (by 71%) but redeveloped over time (∼30 min) at the shorter length to reach 65% of the stiffness value at Lref, provided that the muscle was stimulated to contract at least once over a ∼30-min period. The redevelopment and maintenance of passive stiffness were dependent on the presence of Ca2+ but unaffected by latrunculin B, an inhibitor of actin filament polymerization. The maintenance of passive stiffness was also not affected by blocking myosin cross-bridge cycling using a myosin light chain kinase inhibitor or by blocking the Rho-Rho kinase (RhoK) pathway using a RhoK inhibitor. Our results suggest that the passive stiffness of ASM is labile and capable of redevelopment following length reduction. Redevelopment and maintenance of passive stiffness following muscle shortening could contribute to airway hyperresponsiveness by attenuating the airway wall strain induced by tidal breathing and DI.

Regulatable stiffness in relaxed airway smooth muscle: a target for asthma treatment?

2012 ◽  
Vol 112 (3) ◽  
pp. 337-346 ◽  
Author(s):  
Abdul Raqeeb ◽  
Yuekan Jiao ◽  
Harley T. Syyong ◽  
Peter D. Paré ◽  
Chun Y. Seow
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Kinase Inhibitor ◽  
Rho Kinase ◽  
Muscle Layer ◽  
Radial Force ◽  
Calcium Entry Blocker ◽  
Passive Stiffness

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.

scholarly journals ROCK1 Translocates From Non-Caveolar to Caveolar Regions Upon KCl Stimulation in Airway Smooth Muscle

2014 ◽  
pp. 179-187 ◽  
Author(s):  
B. SOMMER ◽  
L. M. MONTAÑO ◽  
J. CHÁVEZ ◽  
V. CARBAJAL ◽  
L. M. GARCÍA-HERNANDEZ ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Rho Kinase ◽  
Rock Inhibitor ◽  
Western Blots ◽  
Voltage Dependent ◽  
Membrane Compartment ◽  
Second Messenger Pathways ◽  
Assembly Site ◽  
Ca2 Channels

Airway smooth muscle (ASM) membrane depolarization through KCl opens L-type voltage dependent Ca2+ channels (Cav1.2); its opening was considered the cause of KCl contraction. This substance is used to bypass intracellular second messenger pathways. It is now clear that KCl also activates RhoA/Rho kinase (ROCK) pathway. ROCK isoforms are characterized as ROCK1 and ROCK2. Because ROCK1 seems the most abundant isotype in lung, we studied its participation in KCl stimulated bovine ASM. With methyl-β-cyclodextrin (MβCD) we disrupted caveolae, a membrane compartment considered as the RhoA/ROCK assembly site, and found that KCl contraction was reduced to the same extent (~26 %) as Y-27632 (ROCK inhibitor) treated tissues. We confirmed that KCl induces ROCK activation and this effect was annulled by Y-27632 or MβCD. In isolated plasmalemma, ROCK1 was localized in non-caveolar membrane fractions in Western blots from control tissues, but it transferred to caveolae in samples from tissues stimulated with KCl. Cav1.2 was found at the non-caveolar membrane fractions in control and MβCD treated tissues. In MβCD treated tissues stimulated with KCl, contraction was abolished by nifedipine; only the response to Cav1.2 opening remained as the ROCK component disappeared. Our results show that, in ASM, the KCl contraction involves the translocation of ROCK1 from non-caveolar to caveolar regions and that the proper physiological response depends on this translocation.

Qualitative immunoblot analysis of PKC isoforms expressed in airway smooth muscle

1997 ◽  
Vol 272 (4) ◽  
pp. L603-L607 ◽  
Author(s):  
H. Togashi ◽  
C. A. Hirshman ◽  
C. W. Emala
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Airway Smooth Muscle ◽  
Intracellular Signaling ◽  
Immunoblot Analysis ◽  
Calcium Dependent ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Dependent Activity ◽  
Trachealis Muscle

Protein kinase C (PKC) was originally identified as a single serine/ threonine protein kinase with calcium- and phospholipid-dependent activity, but more recently PKC has been found to consist of a family of multiple isoenzymes with different biochemical characteristics, substrates, and cofactor requirements. PKC is particularly important in regulating airway smooth muscle (ASM) tone. Although a previous investigation has demonstrated PKC-beta, -delta, -epsilon, -theta and -zeta in canine trachealis muscle, additional PKC isoforms have not been characterized in ASM. Therefore, immunoblot analysis using nine isotype-specific antibodies was used to further characterize the expression of PKC isoforms in porcine ASM. In addition to the previously described beta-, delta-, epsilon-, and zeta-isoforms in ASM, the calcium-dependent alpha-isoform, and the calcium- and diacylglycerol-independent isoforms iota/lambda and mu were identified. This study demonstrates multiple PKC isoforms in porcine ASM that can participate in intracellular signaling pathways in this tissue.

scholarly journals Force maintenance and myosin filament assembly regulated by Rho-kinase in airway smooth muscle

2015 ◽  
Vol 308 (1) ◽  
pp. L1-L10 ◽  
Author(s):  
Bo Lan ◽  
Linhong Deng ◽  
Graham M. Donovan ◽  
Leslie Y. M. Chin ◽  
Harley T. Syyong ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Initial Phase ◽  
Rho Kinase ◽  
Myosin Filament ◽  
Second Phase ◽  
Minimal Effect ◽  
Kinase Inhibition ◽  
Myosin Filaments ◽  
Force Maintenance

Smooth muscle contraction can be divided into two phases: the initial contraction determines the amount of developed force and the second phase determines how well the force is maintained. The initial phase is primarily due to activation of actomyosin interaction and is relatively well understood, whereas the second phase remains poorly understood. Force maintenance in the sustained phase can be disrupted by strains applied to the muscle; the strain causes actomyosin cross-bridges to detach and also the cytoskeletal structure to disassemble in a process known as fluidization, for which the underlying mechanism is largely unknown. In the present study we investigated the ability of airway smooth muscle to maintain force after the initial phase of contraction. Specifically, we examined the roles of Rho-kinase and protein kinase C (PKC) in force maintenance. We found that for the same degree of initial force inhibition, Rho-kinase substantially reduced the muscle's ability to sustain force under static conditions, whereas inhibition of PKC had a minimal effect on sustaining force. Under oscillatory strain, Rho-kinase inhibition caused further decline in force, but again, PKC inhibition had a minimal effect. We also found that Rho-kinase inhibition led to a decrease in the myosin filament mass in the muscle cells, suggesting that one of the functions of Rho-kinase is to stabilize myosin filaments. The results also suggest that dissolution of myosin filaments may be one of the mechanisms underlying the phenomenon of fluidization. These findings can shed light on the mechanism underlying deep inspiration induced bronchodilation.

scholarly journals Allergic sensitization enhances the contribution of Rho-kinase to airway smooth muscle contraction

2004 ◽  
Vol 143 (4) ◽  
pp. 477-484 ◽  
Author(s):  
Dedmer Schaafsma ◽  
Reinoud Gosens ◽  
I Sophie T Bos ◽  
Herman Meurs ◽  
Johan Zaagsma ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Airway Smooth Muscle ◽  
Allergic Sensitization ◽  
Rho Kinase ◽  
Smooth Muscle Contraction

Direct and indirect actions of histamine on airway smooth muscle in guinea pigs

1984 ◽  
Vol 62 (6) ◽  
pp. 727-733 ◽  
Author(s):  
D. F. Biggs
Keyword(s):  
Smooth Muscle ◽  
Sodium Cromoglycate ◽  
Airway Smooth Muscle ◽  
Muscarinic Receptors ◽  
Guinea Pigs ◽  
The Other ◽  
Glossopharyngeal Nerve ◽  
Drug Induced ◽  
Afferent Pathways

Studies in guinea pigs showed that some forms of drug-induced bronchospasm are reflexogenic involving afferents in the glossopharyngeal nerve. At least two pathways appear to be involved. One pathway contains H1 receptors and is blocked by mepyramine and sodium cromoglycate (SCG), and its pharmacological characteristics are similar to those of active reflex vasodilation. The other appears to involve peripheral muscarinic receptors. The findings also indicate that SCG may act on efferent as well as afferent pathways.

Sign in / Sign up

Export Citation Format

Share Document