Mechanical equilibrium of blood vessel walls

Azuma, Takehiko; Oka, Syôten

doi:10.1152/ajplegacy.1971.221.5.1310

Cited by 68 publications

(35 citation statements)

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“…Lame's approximation has been used to calculate the circumferential wall stress and this equation is strictly applicable only when the wall forces are in equilibrium (Azuma & Oka, 1971;Chuong & Fung, 1983;Dobrin, 1983). Consequently emphasis has been placed on those measurements where the diameter was changing slowly or not at all.…”

Section: Discussionmentioning

confidence: 99%

The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

Speden¹,

Warren²

1986

The Journal of Physiology

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4. Most of the force-generating capacity was available for counteracting the distension of moderately constricted arteries (< 40 % of maximal) produced by a 60-90 mmHg jump. More than 78 % ofthe maximum capacity was used in attempting to overcome the distension when it was maintained by computer-controlled increases in transmural pressure. The moderate constrictions were produced with noradrenaline concentrations which were 500-10000 times lower than that used to maximally activate the arteries.5. The rabbit ear artery possesses a powerful, distension-sensitive mechanism that acts to minimize diameter changes initiated by transmural pressure jumps. The diameter of the active artery was determined by a combination of noradrenaline activation and distension activation for constrictions up to at least 75 % of maximal.

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Section: Discussionmentioning

confidence: 99%

The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

Speden¹,

Warren²

1986

The Journal of Physiology

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“…If the active tension rises above a critical level or if the transmural pressure falls below a critical level, then equilibrium becomes impossible and occlusion of the vascular lumen occurs, in part because of infolding of the internal elastic membrane and endothelial cells. Although the concept of critical closure has been challenged (Azuma et al, 1971;Johnson, 1976;Alexander, 1977), closure of small resistance vessels has been observed following intense vasoconstriction (Burton, 1954;VanCitters et al, 1962;VanCitters, 1966;Nichol et al, 1951). It has been argued that the active tension required for critical closure is greater than that predicted from the Laplacian relationship and that the maximum capacity of vascular muscle for shortening is inadequate to achieve closure at positive pressures.…”

Section: Discussionmentioning

confidence: 99%

Interpretation and physiological significance of diastolic coronary artery pressure-flow relationships in the canine coronary bed.

Dole¹,

Alexander²,

Campbell³

et al. 1984

Circulation Research

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SUMMARY. We analyzed the relationship between diastolic coronary artery pressure and flow in the canine coronary bed, using an electrical analog model of the coronary circulation based on the theory of critical closure. The model contains a voltage-dependent nonlinear resistance and capacitance. The behavior of the resistive element was described using experimental diastolic pressure-flow curves obtained in the absence of compliance effects. Compliance free zero flow pressure intercepts (Pf 0 ) exceeded coronary venous pressure (P v ) by 2-to 5-fold and were related to initial diastolic coronary artery pressure P a (0) and flow F(0), and P v by: P f0 = 14.3 [(P a (0) -P v )/F(0)] + P V + 4.0 (r = 0.93). When coronary artery pressure was suddently lowered to values less than or equal to the compliance-free P ra , diastolic flow abruptly decreased and, after a transient reversal, remained at zero for up to 8 seconds. In the model, zero flow pressure represents critical closing pressure and the resistance regulating flow is the difference between coronary artery and venous pressure divided by flow. Theoretically predicted pressure-flow curves were in good agreement with existing experimental data, including the effects of elevating coronary venous pressure on zero flow pressure. Differences between compliance-free pressure-flow curves and those obtained with pressure gradually decreasing were explained by a coronary arterial compliance whose magnitude varies inversely with pressure and is dependent on vasomotor tone. In conclusion, the results of this study demonstrate the existence of a diastolic pressure gradient across the canine coronary bed at zero flow which is dependent on coronary vasomotor tone. A theoretical model of the coronary circulation based on the concept of critical closure describes the observed relationship between diastolic coronary artery pressure and flow during various experimental conditions. (Circ Res 55: 215-226, 1984)

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“…Roach & Burton (1959) studied arteries by differential digestion of elastin or collagen in the artery and measured the resulting mechanical changes of the artery after digestion. Based on this idea, Oka (1972) formulated a theoretical analysis of arterial wall which resulted in several important studies by Oka & Azuma (1970), Azuma & Oka (1971) and Azuma & Hasagawa (1971). Azuma & Hasegawa discussed the rheological properties of arteries and veins in terms of the networks of collagen, elastin and smooth muscles in the wall.…”

Section: Wall Micro-structurementioning

confidence: 99%

Biomechanics of the cardiovascular system: the aorta as an illustratory example

Kassab

2006

J. R. Soc. Interface.

100

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Biomechanics relates the function of a physiological system to its structure. The objective of biomechanics is to deduce the function of a system from its geometry, material properties and boundary conditions based on the balance laws of mechanics (e.g. conservation of mass, momentum and energy). In the present review, we shall outline the general approach of biomechanics. As this is an enormously broad field, we shall consider a detailed biomechanical analysis of the aorta as an illustration. Specifically, we will consider the geometry and material properties of the aorta in conjunction with appropriate boundary conditions to formulate and solve several well-posed boundary value problems. Among other issues, we shall consider the effect of longitudinal pre-stretch and surrounding tissue on the mechanical status of the vessel wall. The solutions of the boundary value problems predict the presence of mechanical homeostasis in the vessel wall. The implications of mechanical homeostasis on growth, remodelling and postnatal development of the aorta are considered.

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Mechanical equilibrium of blood vessel walls

Cited by 68 publications

References 0 publications

The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

The interaction between noradrenaline activation and distension activation of the rabbit ear artery.

Interpretation and physiological significance of diastolic coronary artery pressure-flow relationships in the canine coronary bed.

Biomechanics of the cardiovascular system: the aorta as an illustratory example

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