Myogenic reactivity and resistance distribution  in the coronary arterial tree: a model study

Cornelissen, Annemiek J. M.; Dankelman, Jenny; vanBavel, Ed; Stassen, H.G.; Spaan, Jos A. E.

doi:10.1152/ajpheart.2000.278.5.h1490

Cited by 56 publications

(49 citation statements)

References 25 publications

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“…The advantage of an assumption of symmetry is that, e.g., pressure distribution over the tree can simply be described by a chain of resistances, each resistance having the equivalent magnitude of the vessels of certain order in parallel [3,12]. Our results show that the predicted inflow and also the pressure distribution in such symmetric trees differ from those in stochastic branching trees.…”

Section: Deterministic Versus Stochastic Treesmentioning

confidence: 83%

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees

et al. 2007

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Biological variation in branching patterns is likely to affect perfusion of tissue. To assess the fundamental consequences of branching characteristics, 50 stochastic asymmetrical coronary trees and one nonstochastic symmetrical branching tree were generated. In the stochastic trees, area growth, A, at branching points was varied: A = random; 1.00; 1.10; 1.13 and 1.15 and symmetry, S, was varied: S = random; 1.00; 0.70; 0.58; 0.50 and 0.48. With random S and A values, a large variation in flow and volume was found, linearly related to the number of vessels in the trees. Large A values resulted in high number of vessels and high flow and volume values, indicating vessels connected in parallel. Lowering symmetry values increased the number of vessels, however, without changing flow, indicating a dominant connection of vessels in series. Both large A and small S values gave more realistic gradual pressure drops compared to the symmetrical non-stochastic branching tree. This study showed large variations in tree realizations, which may reflect real biological variations in tree anatomies. Furthermore, perfusion of tissue clearly depends on the branching rules applied.

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Section: Deterministic Versus Stochastic Treesmentioning

confidence: 83%

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees

et al. 2007

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“…This creates a unique situation that during the systolic phase the entire epicardial segments of coronary arteries, including small arteries just before their entering the myocardium, are exposed to a very high pressure, because there is little outflow. Studies have shown that coronary arteries (particularly small-sized segments) exhibit myogenic responses, 80,81 so that when intraluminal pressure is elevated, they would contract strongly in order to maintain vascular integrity. Therefore, although coronary arteries do not provide a pressure gradient, they would still be under high-pressure hemodynamic conditions with a strong vascular tone, which would be similar, though not the same, to those of strain vessels in the kidney and central nervous system.…”

Section: Albuminuria As An Early Marker Of Strain Vessel Injuriesmentioning

confidence: 99%

Strain vessel hypothesis: a viewpoint for linkage of albuminuria and cerebro-cardiovascular risk

et al. 2009

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Albuminuria is closely associated with stroke and cardiovascular diseases (CVDs) as well as the salt sensitivity of blood pressure (BP). Although albuminuria may reflect generalized endothelial dysfunction, there may be more specific hemodynamic mechanisms underlying these associations. Cerebral hemorrhage and infarction occur most frequently in the area of small perforating arteries that are exposed to high pressure and that have to maintain strong vascular tone in order to provide large pressure gradients from the parent vessels to the capillaries. Analogous to the perforating arteries are the glomerular afferent arterioles of the juxtamedullary nephrons. Hypertensive vascular damage occurs first and more severely in the juxtamedullary glomeruli. Therefore, albuminuria may be an early sign of vascular damages imposed on 'strain vessels' such as perforating arteries and juxtamedullary afferent arterioles. Coronary circulation also occurs under unique hemodynamic conditions, in which the entire epicardial segments are exposed to very high pressure with little flow during systolic phases. From the evolutionary point of view, we speculate that such circulatory systems in the vital organs are mandatory for survival under the danger of hypoperfusion due to difficult access to salt and water as well as high risks of wound injuries. In addition, albuminuria would indicate an impairment of renal medullary circulation, downstream from the juxtamedullary glomeruli, and therefore an impaired pressure natriuresis, which would lead to salt sensitivity of BP. Our 'strain vessel hypothesis' may explain why hypertension and diabetes, unforeseen in the concept of evolution, preferentially affect vital organs such as the brain, heart and kidney.

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“…Although the model implicitly included all mechanisms acting in vivo, such as myogenic, shear-dependent, and metabolic responses, it did not allow analysis of the relative contributions of these mechanisms to autoregulation. In the model of Cornelissen et al (5) for the coronary circulation, the myogenic response was included by assuming pressure-diameter relationships in vasoactive segments based on experimental observations on isolated segments. Liao and Kuo (20) considered the effects of only myogenic and shear-dependent responses in an empirically based model.…”

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confidence: 99%

Theoretical model of blood flow autoregulation: roles of myogenic, shear-dependent, and metabolic responses

Carlson¹,

Arciero²,

Secomb³

2008

American Journal of Physiology-Heart and Circulatory Physiology

151

160

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Carlson BE, Arciero JC, Secomb TW. Theoretical model of blood flow autoregulation: roles of myogenic, shear-dependent, and metabolic responses. Am J Physiol Heart Circ Physiol 295: H1572-H1579, 2008. First published August 22, 2008; doi:10.1152/ajpheart.00262.2008The autoregulation of blood flow, the maintenance of almost constant blood flow in the face of variations in arterial pressure, is characteristic of many tissue types. Here, contributions to the autoregulation of pressure-dependent, shear stress-dependent, and metabolic vasoactive responses are analyzed using a theoretical model. Seven segments, connected in series, represent classes of vessels: arteries, large arterioles, small arterioles, capillaries, small venules, large venules, and veins. The large and small arterioles respond actively to local changes in pressure and wall shear stress and to the downstream metabolic state communicated via conducted responses. All other segments are considered fixed resistances. The myogenic, shear-dependent, and metabolic responses of the arteriolar segments are represented by a theoretical model based on experimental data from isolated vessels. To assess autoregulation, the predicted flow at an arterial pressure of 130 mmHg is compared with that at 80 mmHg. If the degree of vascular smooth muscle activation is held constant at 0.5, there is a fivefold increase in blood flow. When myogenic variation of tone is included, flow increases by a factor of 1.66 over the same pressure range, indicating weak autoregulation. The inclusion of both myogenic and shear-dependent responses results in an increase in flow by a factor of 2.43. A further addition of the metabolic response produces strong autoregulation with flow increasing by a factor of 1.18 and gives results consistent with experimental observation. The model results indicate that the combined effects of myogenic and metabolic regulation overcome the vasodilatory effect of the shear response and lead to the autoregulation of blood flow. conducted response; microcirculation; blood flow regulation; vascular smooth muscle; vascular tone THE ABILITY OF VASCULAR BEDS to maintain a relatively constant blood flow over a large range of arterial pressures is known as vascular autoregulation. With increasing arterial pressure, the degree of vascular smooth muscle (VSM) activation, VSM tone, increases in arterioles, resulting in decreased vessel diameter and increased flow resistance. Several mechanisms contribute to changes in vascular tone, including responses to intraluminal pressure (myogenic response), shear stress on the endothelial lining of vessels (shear-dependent response), metabolite concentrations in vessels and/or tissue (metabolic response), and neural stimuli. The cerebral and renal vasculature show the most stable flow over a wide range of arterial pressures (2, 25), whereas in other beds, such as those in the mesentery, autoregulation is less effective.Several theoretical models for the autoregulation of blood flow have been developed using a multicompartmen...

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Myogenic reactivity and resistance distribution in the coronary arterial tree: a model study

Cited by 56 publications

References 25 publications

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees

Relation between branching patterns and perfusion in stochastic generated coronary arterial trees

Strain vessel hypothesis: a viewpoint for linkage of albuminuria and cerebro-cardiovascular risk

Theoretical model of blood flow autoregulation: roles of myogenic, shear-dependent, and metabolic responses

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