Elastic constants of inflated lobes of dog lungs

Lai-Fook, S. J.; Wilson, Theodore A.; Hyatt, Robert E.; Rodarte, Joseph R.

doi:10.1152/jappl.1976.40.4.508

Cited by 122 publications

(145 citation statements)

References 0 publications

Supporting

Mentioning

134

Contrasting

Order By: Relevance

“…These limitations are common to all measurements made in lung tissue strips 18 . Notably, however, the median stiffness measured in the parenchyma of normal lung tissue (shear modulus ~0.5kPa) does not differ substantially from estimates based on punch-indentation of intact lungs at resting volumes 19,20 . While lung tissue is known to exhibit non-linear stiffening with increasing deformation, it is not possible to test in a rigorous fashion whether this property persists down to the micro-scale with the methods employed here.…”

Section: Discussionmentioning

confidence: 63%

“…The lung has traditionally been mechanically characterized non-invasively, for instance using pressure-volume analysis 17 or punch-indentation of whole lungs 19,20 . Invasive methods such as the one described here alter the lung architecture in important ways through the loss of the air-liquid interface that normally exists in the air-filled lung and the loss of pre-stress that maintains lung partial inflation upon relaxation of respiratory muscles.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Liu¹,

Tschumperlin²

2011

JoVE

View full text Add to dashboard Cite

Matrix stiffness strongly influences growth, differentiation and function of adherent cells [1][2][3] . On the macro scale the stiffness of tissues and organs within the human body span several orders of magnitude 4 . Much less is known about how stiffness varies spatially within tissues, and what the scope and spatial scale of stiffness changes are in disease processes that result in tissue remodeling. To better understand how changes in matrix stiffness contribute to cellular physiology in health and disease, measurements of tissue stiffness obtained at a spatial scale relevant to resident cells are needed. This is particularly true for the lung, a highly compliant and elastic tissue in which matrix remodeling is a prominent feature in diseases such as asthma, emphysema, hypertension and fibrosis. To characterize the local mechanical environment of lung parenchyma at a spatial scale relevant to resident cells, we have developed methods to directly measure the local elastic properties of fresh murine lung tissue using atomic force microscopy (AFM) microindentation. With appropriate choice of AFM indentor, cantilever, and indentation depth, these methods allow measurements of local tissue shear modulus in parallel with phase contrast and fluorescence imaging of the region of interest. Systematic sampling of tissue strips provides maps of tissue mechanical properties that reveal local spatial variations in shear modulus. Correlations between mechanical properties and underlying anatomical and pathological features illustrate how stiffness varies with matrix deposition in fibrosis. These methods can be extended to other soft tissues and disease processes to reveal how local tissue mechanical properties vary across space and disease progression. Video LinkThe video component of this article can be found at https://www.jove.com/video/2911/ Protocol 1. Lung Tissue Strip Preparation 1. Lung tissue is highly compliant and difficult to cut into strips for AFM characterization. To transiently stabilize the lung structure for cutting, inflate isolated mouse lungs intratracheally with 50 ml/kg body weight of 2% low gel point agarose (prepared in PBS) warmed to 37°C. Tie off the trachea and cool the inflated lungs in a bath of PBS at 4°C for 60 minutes. The agarose will gel and stiffen in the airspaces to gently stabilize the lung structure during this interval 5 . Higher agarose concentrations, i.e. 3-4%, may be used to further enhance tissue stabilization for cutting. 2. Cut the agarose-stabilized mouse lung tissue with a razor or scalpel blade into strips of 5 x 5 mm in length and width and 400 μm in thickness, then wash the strips in a PBS bath pre-warmed to 37°C using a 100 ml glass beaker on a bench-top heated stir plate for 5 minutes to remove residual agarose. To exclude large airways and vessels, cut strips from subpleural regions distant from main stem bronchi. If airways and large vessels are to be imaged, cut strips from lung tissue more proximal to main stem bronchi. AFM Microindentation and Fluorescenc...

show abstract

Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Liu¹,

Tschumperlin²

2011

JoVE

View full text Add to dashboard Cite

show abstract

“…To study the uniaxial response of spongy lung, Lai-Fook et al [30] inflated lobes to a preset pressure, and then compressed these lobes between a pair of parallel platens while holding the alveolar pressure constant during the compression loading cycle. This is a significantly different experiment from those just discussed; it has a history effect.…”

Section: Inflation/compressionmentioning

confidence: 99%

Viscoelastic Model for Lung Parenchyma for Multi-Scale Modeling of Respiratory System Phase I: Hypo-Elastic Model for CFD Implementation

Freed¹,

Einstein²

2011

View full text Add to dashboard Cite

An isotropic constitutive model for the parenchyma of lung has been derived from the theory of hypo-elasticity. The intent is to use it to represent the mechanical response of this soft tissue in sophisticated, computational, fluid-dynamic models of the lung. This demands that the continuum model be accurate, yet simple and efficient. An objective algorithm for its numeric integration is provided. The response of the model is determined for several boundary-value problems whose experiments are used for material characterization. The £ First annual report to Pacific Northwest National Laboratory from Saginaw Valley State University reporting on progress made under grant number 136492. The project described was supported by Award Number R01HL073598 from the National Heart, Lung, and Blood Institute to Pacific Northwest National Laboratory. The content is solely the responsibility of the author and does not necessarily reflect the official views of the National Heart, Lung, and Blood Institute or the National Institutes of Health.2 effective elastic, bulk, and shear moduli, and Poisson's ratio, as tangent functions, are also derived. The model is characterized against published experimental data for lung.A bridge between this continuum model and a dodecahedral model of alveolar geometry is investigated, with preliminary findings being reported.

show abstract

“…Our observation that the cardiac fossa of the adult lung was less distortable than the lateral surface is consistent with that of Nagao (1973) who showed that the pleura isolated from the cardiac fossa is significantly less compliant than the pleura isolated from the lateral surface of the lung. The reduced distortability of the cardiac fossa may also reflect the pleura acting as a stretched membrane on the surface of the parenchyma (Lai-Fook et al 1976). The localised forces we applied to the concave cardiac fossa would further stretch the pleura, while similar forces applied to the convex lateral surface would reduce the stretch placed on the pleura.…”

Section: Discussionmentioning

confidence: 99%

“…How lung distortability changes in response to forces applied over a larger surface area, such as the left or right ventricle in situ, is not certain. Given that the tension of the pleural membrane increases with lung size (Hajji et al 1979) and given that lung deformations are influenced less by the pleura when the force is applied over a larger area (Lai-Fook et al 1976), developmental changes in lung parenchyma and changes in the size of the heart may influence this interaction. Although we applied force over a much smaller area (1 cm 2 ) than would be the case in vivo, the depths of the distortions we observed are nonetheless in keeping with those that might be expected in vivo.…”

Section: Discussionmentioning

confidence: 99%

Age‐related differences in the distortion of the sheep lung in response to localised pleural stress

Grant

Walker

Fauchère

2001

The Journal of Physiology

View full text Add to dashboard Cite

'As a means of relief from the leaping heart when passion is excited . . . they [the engendered sons of God] contrived and implanted the form of the lung -soft and bloodless . . . as a kind of padding around the heart . . .' (Plato, (Cournand, 1982) Although our understanding of the physiology of the lung has greatly changed since the time of Plato, the interaction between the heart and the lungs is still recognised to affect both respiratory and cardiac function. For example, cardiogenic gas mixing, though partially a result of instantaneous changes in the rate of O 2 consumption and CO 2 production , largely results from direct mechanical interactions between the heart and the lung. Lung gas volume decreases during diastole and increases during systole as the filling and emptying heart displaces the lungs Lloyd, 1989). Just as the heart influences lung gas volume, the presence of the lung surrounding the heart also significantly limits ventricular filling and thus limits cardiac output via the Frank-Starling mechanism. Brookhart & Boyd (1947) observed that the interaction between the heart and the lung results in intra-thoracic pressure within the cardiac fossa exceeding that in the lateral pleural space, and that an increase in lung volume is accompanied by an increase in extra-cardiac pressure. It was subsequently recognised that this increase in extra-cardiac pressure is the mechanism whereby the application of positive endexpiratory pressure and increasing lung volume act to constrain ventricular filling and limit cardiac output (Fewell et al. 1980a,b;Kingma et al. 1987).Not only does the constraint applied to the heart by the lungs change when airway pressure and lung volume are changed, it also changes with developmental age. In the fetus, the lungs are liquid filled and significantly constrain ventricular filling (Grant et al. 1992b;Grant & Walker, 1996). However, this constraint is largely eliminated immediately following the aeration of the lungs at birth (Grant et al. 1992a(Grant et al. , 1994. Within days of birth, the lungs once again significantly constrain the heart and produce up to 50% of the total constraint experienced by the neonatal heart (Grant et al. 1994); by contrast, in the adult only 25-30% of the total cardiac constraint arises from the lung (Kingma et al. 1987).Although developmental changes in the chest wall (Agostoni, 1959) and pericardium (Naimark, 1995;Naimark et al. 1998) 1. In order for diastolic filling to occur, the heart must displace the lung. Given the changes in lung structure and compliance that follow birth, we sought to determine whether the neonatal lung resists neighbouring structures encroaching into its space more than the adult lung and whether the lung surface making up the cardiac fossa resists distortion more than the lateral surface does.2. Pleural distortions, induced by applied pressures (P appl ) of 20-120 g cm _2 at airway pressures (P aw ) of 2.5-15 cmH 2 O, were recorded in isolated lungs of adult, neonatal (4-week-old) and newborn (1-week-old) sheep...

show abstract

Elastic constants of inflated lobes of dog lungs

Cited by 122 publications

References 0 publications

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Viscoelastic Model for Lung Parenchyma for Multi-Scale Modeling of Respiratory System Phase I: Hypo-Elastic Model for CFD Implementation

Age‐related differences in the distortion of the sheep lung in response to localised pleural stress

Contact Info

Product

Resources

About