scholarly journals Reduced biomechanical models for precision-cut lung-slice stretching experiments

2020 ◽  
Author(s):  
Hannah J. Pybus ◽  
Lowell T. Edgar ◽  
Reuben D. O’Dea ◽  
Bindi S. Brook

AbstractPrecision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.

2021 ◽  
Vol 82 (5) ◽  
Author(s):  
Hannah J. Pybus ◽  
Amanda L. Tatler ◽  
Lowell T. Edgar ◽  
Reuben D. O’Dea ◽  
Bindi S. Brook

AbstractPrecision-cut lung-slices (PCLS), in which viable airways embedded within lung parenchyma are stretched or induced to contract, are a widely used ex vivo assay to investigate bronchoconstriction and, more recently, mechanical activation of pro-remodelling cytokines in asthmatic airways. We develop a nonlinear fibre-reinforced biomechanical model accounting for smooth muscle contraction and extracellular matrix strain-stiffening. Through numerical simulation, we describe the stresses and contractile responses of an airway within a PCLS of finite thickness, exposing the importance of smooth muscle contraction on the local stress state within the airway. We then consider two simplifying limits of the model (a membrane representation and an asymptotic reduction in the thin-PCLS-limit), that permit analytical progress. Comparison against numerical solution of the full problem shows that the asymptotic reduction successfully captures the key elements of the full model behaviour. The more tractable reduced model that we develop is suitable to be employed in investigations to elucidate the time-dependent feedback mechanisms linking airway mechanics and cytokine activation in asthma.


2021 ◽  
Vol 8 (6) ◽  
pp. 91
Author(s):  
Katrin Röhm ◽  
Martin Diener ◽  
Korinna Huber ◽  
Jana Seifert

The ceca play an important role in the physiology of the gastrointestinal tract in chickens. Nevertheless, there is a gap of knowledge regarding the functionality of the ceca in poultry, especially with respect to physiological cecal smooth muscle contraction. The aim of the current study is the ex vivo characterization of cecal smooth muscle contraction in laying hens. Muscle strips of circular cecal smooth muscle from eleven hens are prepared to investigate their contraction ex vivo. Contraction is detected using an isometric force transducer, determining its frequency, height and intensity. Spontaneous contraction of the chicken cecal smooth muscle and the influence of buffers (calcium-free buffer and potassium-enriched buffer) and drugs (carbachol, nitroprusside, isoprenaline and Verapamil) affecting smooth muscle contraction at different levels are characterized. A decrease in smooth muscle contraction is observed when a calcium-free buffer is used. Carbachol causes an increase in smooth muscle contraction, whereas atropine inhibits contraction. Nitroprusside, isoprenaline and Verapamil result in a depression of smooth muscle contraction. In conclusion, the present results confirm a similar contraction behavior of cecal smooth muscles in laying hens as shown previously in other species.


2013 ◽  
Vol 26 (1) ◽  
pp. 24-36 ◽  
Author(s):  
David Wright ◽  
Pawan Sharma ◽  
Min-Hyung Ryu ◽  
Paul-Andre Rissé ◽  
Melanie Ngo ◽  
...  

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 147
Author(s):  
Romuald Brice Babou Kammoe ◽  
Gilles Kauffenstein ◽  
Julie Pelletier ◽  
Bernard Robaye ◽  
Jean Sévigny

Nucleotides released by smooth muscle cells (SMCs) and by innervating nerve terminals activate specific P2 receptors and modulate bladder contraction. We hypothesized that cell surface enzymes regulate SMC contraction in mice bladder by controlling the concentration of nucleotides. We showed by immunohistochemistry, enzymatic histochemistry, and biochemical activities that nucleoside triphosphate diphosphohydrolase-1 (NTPDase1) and ecto-5′-nucleotidase were the major ectonucleotidases expressed by SMCs in the bladder. RT-qPCR revealed that, among the nucleotide receptors, there was higher expression of P2X1, P2Y1, and P2Y6 receptors. Ex vivo, nucleotides induced a more potent contraction of bladder strips isolated from NTPDase1 deficient (Entpd1−/−) mice compared to wild type controls. The strongest responses were obtained with uridine 5′-triphosphate (UTP) and uridine 5′-diphosphate (UDP), suggesting the involvement of P2Y6 receptors, which was confirmed with P2ry6−/− bladder strips. Interestingly, this response was reduced in female bladders. Our results also suggest the participation of P2X1, P2Y2 and/or P2Y4, and P2Y12 in these contractions. A reduced response to the thromboxane analogue U46619 was also observed in wild type, Entpd1−/−, and P2ry6−/− female bladders showing another difference due to sex. In summary, NTPDase1 modulates the activation of nucleotide receptors in mouse bladder SMCs, and contractions induced by P2Y6 receptor activation were weaker in female bladders.


1992 ◽  
Vol 267 (13) ◽  
pp. 8719-8722 ◽  
Author(s):  
K Hirata ◽  
A Kikuchi ◽  
T Sasaki ◽  
S Kuroda ◽  
K Kaibuchi ◽  
...  

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