Contribution of Collagen, Elastin, and Smooth Muscle to In Vivo Human Brachial Artery Wall Stress and Elastic Modulus

Bank, Alan J.; Wang, Hongyu; Holte, J.; Mullen, K.; Shammas, Roger A.; Kubo, Spencer H.

doi:10.1161/01.cir.94.12.3263

Cited by 229 publications

(208 citation statements)

References 26 publications

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“…24 The mean elastic modulus of elastin (E inc at 0 stress) in this study was approximately 1.0ϫ10 6 dyne/cm 2 . This value is consistent with in vivo data from our laboratory using intravascular ultrasound 12 and from animal studies which estimate the elastic modulus of elastin to be between 1 and 10ϫ10 6 dynes/cm 2 . 24 -26 Measuring brachial artery wall mechanics over a wide pressure range provides the opportunity to compare the vessel isometrically under different levels of smooth muscle tone.…”

Section: Bank Et Al Brachial Artery Elasticity 45supporting

confidence: 90%

“…Application of arterial wall models to determine constitutive equations for the contributions of the different wall components to total measured wall mechanics has been performed in vitro, 23,24 in conscious dogs, 10 and in human subjects in vivo using intravascular ultrasound. 12 The technique described in this study is the first noninvasive tool (to our knowledge) that can be used for this purpose in human subjects in vivo.…”

Section: Bank Et Al Brachial Artery Elasticity 45mentioning

confidence: 99%

“…10,11 Although smooth muscle relaxation increases stiffness by tensing the collagen and elastin fibers in parallel with the smooth muscle, it decreases stiffness by reducing tension in the smooth muscle itself and in the series elastic component. 12 The net effect of smooth muscle relaxation on arterial stiffness depends on the balance of these competing effects. With this new technique, we can measure the E inc of the arterial wall under baseline conditions and, following nitroglycerin (NTG), to determine the direct effects of smooth muscle relaxation on in vivo arterial stiffness.…”

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In Vivo Human Brachial Artery Elastic Mechanics

et al. 1999

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Background--The effects of smooth muscle relaxation on arterial wall mechanics are controversial. We used a new, in vivo, noninvasive technique to measure brachial artery wall mechanics under baseline conditions and following smooth muscle relaxation with nitroglycerin (NTG). Methods and Results-Eight healthy, normal subjects (6 male, 2 female; age 30Ϯ3.1 years) participated in the study. The nondominant brachial artery was imaged through a water-filled blood pressure cuff using an external ultrasound wall-tracking system at baseline and following 0.4 mg sublingual NTG. Simultaneous radial artery pressure waveforms were recorded by tonometry. Transmural pressure (TP) was reduced by increasing water pressure in the cuff. Brachial artery area, unstressed area, compliance, stress, strain, incremental elastic modulus (E inc ), and pulse wave velocity (PWV) were measured over a TP range from 0 to 100 mm Hg. Baseline area versus TP curves generated 30 minutes apart were not significantly different. NTG significantly shifted area versus TP (PϽ0.0001) and compliance versus TP (PϽ0.001) curves upward, whereas the E inc versus TP (PϽ0.05) and PWV versus TP (PϽ0.01) curves were shifted downward. NTG also significantly shifted stress versus strain (PϽ0.01) and E inc versus strain (PϽ0.01) curves to the right. Conclusions-We conclude that brachial artery elastic mechanics can be reproducibly measured over a wide range of TP and smooth muscle tone using a new noninvasive ultrasound technique. Smooth muscle relaxation with NTG increases isobaric compliance and decreases isobaric E inc and PWV in the human brachial artery. (Circulation. 1999;100:41-47.)

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Section: Bank Et Al Brachial Artery Elasticity 45supporting

confidence: 90%

Section: Bank Et Al Brachial Artery Elasticity 45mentioning

confidence: 99%

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confidence: 99%

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In Vivo Human Brachial Artery Elastic Mechanics

et al. 1999

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“…16,17 In the brachial artery, transmural pressure can be modulated by the application of an external blood pressure cuff, thus allowing effects of vasoactive drugs to be determined independently from the effects on MAP. 17 Studies with this technique show that, independent of transmural pressure, brachial artery elasticity is sensitive to changes in smooth muscle tone induced by NO: the NO donor nitroglycerine decreases stiffness, 17 and inhibition of basal NO synthesis by L-NMMA increases stiffness.…”

Section: Discussionmentioning

confidence: 99%

Effects of Inhibition of Basal Nitric Oxide Synthesis on Carotid-Femoral Pulse Wave Velocity and Augmentation Index in Humans

et al. 2003

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Abstract-Aortic stiffness, as measured by carotid-femoral pulse wave velocity (PWV), is a powerful, independent predictor of vascular risk. PWV in muscular arteries is influenced by basal nitric oxide (NO) release. It is not known whether NO also influences carotid-femoral PWV. We examined the effects of an NO synthase inhibitor, N G -monomethyl-L-arginine (L-NMMA), on carotid-femoral PWV and aortic augmentation index (AIx, an indirect measure of arterial stiffness). To control for effects of L-NMMA on distending pressure, we used doses of norepinephrine and dobutamine that caused similar changes in mean arterial blood pressure (MAP). Healthy men (32 to 48 years old, nϭ8) were studied on 4 occasions and received, in random order, vehicle, L-NMMA (3 mg · kg Ϫ1 by intravenous bolus followed by 3 mg · kg), and dobutamine (2.5 to 10 g · kg Ϫ1 · min Ϫ1), each for 30 minutes. PWV and AIx were measured by carotid-femoral PWV and radial tonometry, respectively. L-NMMA and norepinephrine increased MAP by 7.8Ϯ1.7 and 9.7Ϯ2.1 mm Hg, respectively (each PϽ0.05 vs vehicle) and increased PWV by 0.7Ϯ0.2 and 1.0Ϯ0.3 m · s Ϫ1 (each PϽ0.01 vs vehicle). Dobutamine, at doses that produced a similar increase in MAP (9.6Ϯ2.9 mm Hg), increased PWV by 0.8Ϯ0.2 m · s Ϫ1 (PϽ0.01 vs vehicle). Changes in PWV caused by the 3 pressor agents were closely correlated with changes in MAP (RϾ0.99, PϽ0.0001). L-NMMA and norepinephrine increased AIx, but dobutamine decreased AIx (PϽ0.01 vs norepinephrine and L-NMMA). Effects of inhibition of basal NO release on carotid-femoral PWV can be explained by the change in MAP that this causes rather than any specific effect of NO inhibition within the aorta. Key Words: aorta Ⅲ elasticity Ⅲ endothelium Ⅲ nitric oxide Ⅲ nitric oxide synthase C arotid-femoral pulse wave velocity (PWV), a measure of aortic stiffness, 1 is a powerful, independent predictor of cardiovascular events and mortality. 2-4 Aortic stiffening increases peak systolic pressure at the aortic root as a result of diminished systemic compliance and early return of pressure waves reflected from the periphery. 5,6 This provides a possible mechanism for the increased event rate and mortality associated with aortic stiffening. In addition, carotid-femoral PWV might serve as an integrated measure of the impact of cardiovascular risk factors on age-related changes in aortic structure. 4,7,8 In muscular arteries, stiffness is influenced by mean arterial blood pressure (MAP, a determinant of transmural distending pressure) and by the tone of arterial smooth muscle (which influences the elastic properties of the arterial wall). In the ovine iliac artery, basal release of nitric oxide (NO) contributes to the functional regulation of stiffness. 9 The human aorta is rich in elastin, and with advancing age, increasing relative amounts of collagen, but it also contain vascular smooth muscle, especially in the abdomen. 10 The extent to which aortic stiffness is influenced by vascular tone and in particular, by basal NO, has not previously been examined in the...

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“…The 3 principal elastic component materials of the artery wall-collagen, elastin, and smooth muscles-have values of K in descending order of Ϸ10 7 to 10 6 , 10 5 , and 10 4 N ⅐ m Ϫ2 , respectively. [11][12][13] Furthermore, these components are influenced both in physiology and pathology by changes in the mucopolysaccharide matrix, or "ground substance," in which they are embedded. The result is that the value of K for any artery varies nonlinearly with pressure (eg, Berry and Greenwald 1976 14 ; Figure 1), and with the frequency of the applied stress (eg, Bergel 15 and O'Rourke and Taylor 16 ).…”

Section: Path To Consensus In Terminologymentioning

confidence: 99%