Contribution of elastin and collagen to the inflation response of the pig thoracic aorta: Assessing elastin's role in mechanical homeostasis

Lillie, Margo A.; Armstrong, Ty; Gerard, SK; Shadwick, Robert E.; Gosline, John M.

doi:10.1016/j.jbiomech.2012.05.034

Cited by 28 publications

(38 citation statements)

References 37 publications

(35 reference statements)

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“…mid mid and For comparison, inflation tests were run on 12 pig thoracic aortas following the protocol of Lillie et al (Lillie et al, 2012).…”

Section: Artery Inflation Testsmentioning

confidence: 99%

“…Tissue harvesting was at times opportunistic and in situ longitudinal stretch could not be determined for all samples, but where measured, longitudinal stretches were typically around λ z =1.4. Inflating the arteries without in vivo longitudinal tethering limits the information we can derive from these tests, but it has no impact on the ability of recruited collagen to restrict circumferential stretch (Lillie et al, 2012), which is our main focus. Abundant collagen was visible on all the arteries and could be readily removed from the retial arteries.…”

Section: Artery Inflation Testsmentioning

confidence: 99%

“…The stiffness of the fin whale thoracic aorta was attributed to its unusually high collagen content (Gosline and Shadwick, 1996). Collagen is stiff, and in a terrestrial mammalian artery it is slack at low blood pressures but straightens and becomes taut around physiological pressures to prevent possible over-inflation at higher pressures (Armentano et al, 1991;Bank et al, 1996;Cox, 1978;Lillie et al, 2012). Delaying collagen recruitment for loading until physiological pressures optimizes the mechanical performance of arteries.…”

Section: Introductionmentioning

confidence: 99%

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Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Lillie

Piscitelli

Vogl

et al. 2013

Journal of Experimental Biology

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SUMMARYFin whales have an incompliant aorta, which, we hypothesize, represents an adaptation to large, depth-induced variations in arterial transmural pressures. We hypothesize these variations arise from a limited ability of tissues to respond to rapid changes in ambient ocean pressures during a dive. We tested this hypothesis by measuring arterial mechanics experimentally and modelling arterial transmural pressures mathematically. The mechanical properties of mammalian arteries reflect the physiological loads they experience, so we examined a wide range of fin whale arteries. All arteries had abundant adventitial collagen that was usually recruited at very low stretches and inflation pressures (2-3kPa), making arterial diameter largely independent of transmural pressure. Arteries withstood significant negative transmural pressures (−7 to −50kPa) before collapsing. Collapse was resisted by recruitment of adventitial collagen at very low stretches. These findings are compatible with the hypothesis of depth-induced variation of arterial transmural pressure. Because transmural pressures depend on thoracic pressures, we modelled the thorax of a diving fin whale to assess the likelihood of significant variation in transmural pressures. The model predicted that deformation of the thorax body wall and diaphragm could not always equalize thoracic and ambient pressures because of asymmetrical conditions on dive descent and ascent. Redistribution of blood could partially compensate for asymmetrical conditions, but inertial and viscoelastic lag necessarily limits tissue response rates. Without pressure equilibrium, particularly when ambient pressures change rapidly, internal pressure gradients will develop and expose arteries to transient pressure fluctuations, but with minimal hemodynamic consequence due to their low compliance.

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“…mid mid and For comparison, inflation tests were run on 12 pig thoracic aortas following the protocol of Lillie et al (Lillie et al, 2012).…”

Section: Artery Inflation Testsmentioning

confidence: 99%

Section: Artery Inflation Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Lillie

Piscitelli

Vogl

et al. 2013

Journal of Experimental Biology

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“…Enhanced vascular stiffness of resistance arteries has been attributed to increases in collagen content 20,21 , non-fibrous extracellular matrix proteins, and adhesion molecules [for review, see 22 ], as well as to alterations in elastic fiber organization in the internal elastic lamina 23 . According to this, several studies have shown a link between arterial stiffness and abnormal increase in the collagen/elastin ratio in hypertension 18,[24][25][26] .…”

Section: Introductionmentioning

confidence: 99%

Arterial stiffness is associated with adipokine dysregulation in non-hypertensive obese mice

Gil‐Ortega

Martín-Ramos

Arribas

et al. 2016

Vascular Pharmacology

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“…The outer tunica adventitia contains vasa and nervi vasorum embedded within dense or loose collagen connective tissue. The incorporation of extracellular matrix (proteoglycans) and fibers (particularly elastin and collagen) into the network of smooth muscle and connective tissue cells provides nonlinear elasticity and distributes the tensile stresses (Shadwick 1999), as well as the deformation of the aortic wall (Lillie et al 2012;Kim and Baek 2011). Although the aorta shares the basic histological and biomechanical design of other arteries, it is the largest elastic artery of the mammalian body.…”

Section: Introductionmentioning

confidence: 99%

Segmental differences in the orientation of smooth muscle cells in the tunica media of porcine aortae

Tonar

Kochová

Cimrman

et al. 2014

Biomech Model Mechanobiol

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The orientation of vascular smooth muscle cells of porcine aortae was assessed to test the widely accepted assumption that these smooth muscle cells are arranged in two helices. We used tangential histological sections of 82 samples of five anatomical segments of thoracic and abdominal porcine aortae and three age groups in animals ranging in age from 5 to 210 days. The distribution of the orientation of smooth muscle cell nuclei in five proximodistal segments of the porcine aortae was determined using an algorithm that fitted a mixture of one to five von Mises probability distributions of the data retrieved from histological micrographs. Automated tracking of the nuclei was confirmed by and consistent with manual histological analysis. The orientation of the vascular smooth muscle cells was successfully fitted using two von Mises distributions in most of the samples with different ages, wall thicknesses, and anatomical positions, which corresponds to two populations of vascular smooth muscle cells. A minor fraction of samples also required a tertiary von Mises distribution to describe the orientation of the smooth muscle cell nuclei. The distribution of vascular smooth muscle cells in five aortic segments ranging from the thoracic ascending aorta to the abdominal intrarenal aorta exhibited similar main directions but different shapes. These results are consistent with the widely used model of two muscular helices intermingling in the arterial wall. Furthermore, we calculated the central angles of symmetry and the mean value of angles between the two assumed smooth muscle directions. We also successfully approximated the orientation of the smooth muscle cells using a mixture of von Mises distributions and our open-source software named dist_mixtures. This method is openly available to researchers who are interested in mathematically assessing the orientation of cell nuclei in various tissues.

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Contribution of elastin and collagen to the inflation response of the pig thoracic aorta: Assessing elastin's role in mechanical homeostasis

Cited by 28 publications

References 37 publications

Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Arterial stiffness is associated with adipokine dysregulation in non-hypertensive obese mice

Segmental differences in the orientation of smooth muscle cells in the tunica media of porcine aortae

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