Heterogeneity of red blood cell perfusion in capillary networks supplied by a single arteriole in resting skeletal muscle.

Ellis, Christopher G.; Wrigley, S.; Groom, A. C.

doi:10.1161/01.res.75.2.357

Cited by 89 publications

(68 citation statements)

References 20 publications

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“…In addition to the finding in dog lungs (6), temporal heterogeneity of blood flow has been found in other organs including the brain, myocardium and skeletal muscle (23)(24)(25). The lower CV temporal results contradict our hypothesis that due to greater pulmonary vasoreactivity (2,3,6,8) temporal heterogeneity would be greater in piglets than in adult animals.…”

Section: Diverse Pulmonary Blood Flow In Pigletscontrasting

confidence: 92%

Spatial and Temporal Heterogeneity of Regional Pulmonary Blood Flow in Piglets

et al. 2007

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ABSTRACT:Regional pulmonary blood flow (PBF) in adult animals varies over space and time, following a fractal pattern. We hypothesized that PBF would follow a fractal pattern in young animals. Five, two-week old piglets were sedated and mechanically ventilated. After stabilization, fluorescent microspheres were injected via the right atrium at baseline and then again at 5, 20, 20.5, 40 and 60 min. The lungs were subsequently excised, dried, inflated, and cored into 0.12-cm 3 pieces (mean n ϭ 561 Ϯ 106 per animal) with the spatial coordinates recorded for each piece. Regional PBF was spatially and temporally heterogeneous with a spatial coefficient of variation of 43.3 Ϯ 7.9% and a temporal coefficient of variation of 14.3 Ϯ 0.4%. PBF followed a fractal pattern with a fractal dimension of 1.20 Ϯ 0.06 at 20 min, remaining stable throughout the experiment. PBF decreased with distance from the hilum but did not follow a lobar pattern. Temporal heterogeneity did not significantly increase with time but low flow regions demonstrated the greatest temporal variability throughout the study. Hence, PBF in young piglets was characterized both spatial and temporal heterogeneity. A considerable amount of information describing the structural and functional characteristics of the pulmonary circulation during postnatal lung development exists. Features such as vascular reactivity, pulmonary capillary recruitment, and metabolic capabilities of the microvasculature appear to differ between adult and immature animals (1-8). Recently, the fractal spatial distribution and isogravitational heterogeneity of pulmonary blood flow (PBF) have been delineated in adult animals using injectable microspheres that achieved greater resolution than earlier studies (9,10). The results of these studies diverge from the findings of homogeneous gravitational zones described by West et al. (11). Temporal heterogeneity also occurs in the pulmonary circulation, which may subserve the conservation of energetics rather than ventilation-perfusion relationships (12).Hitherto, these physiologic characteristics remain unstudied in newborn or very young animals. Speculation suggests that the fractal nature of PBF is based on the pulmonary anatomy, particularly of the precapillary bed (13). If true, the spatial distribution of PBF in young animals should be similar to that in adults. Furthermore, the presence of temporal heterogeneity of PBF in young animals has not been reported. Previous studies suggest a higher degree of pulmonary vascular reactivity in neonatal animals (2,3,6) compared with adults, and hence temporal heterogeneity should be greater than that previously described in adult animals.We measured spatial and temporal heterogeneity in piglets because morphometric studies of pulmonary development in the piglet suggest that the vascular and alveolar changes during the first 3 months of life are similar to those seen in humans (14,15). We hypothesized that under normoxic conditions the pulmonary blood flow would demonstrate greater spatial heteroge...

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Section: Diverse Pulmonary Blood Flow In Pigletscontrasting

confidence: 92%

Spatial and Temporal Heterogeneity of Regional Pulmonary Blood Flow in Piglets

et al. 2007

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“…In crystalloid perfusion, the functional capillary density is higher than that in blood perfusion, at least transiently, because of corpuscle-free, low coronary tone, and high-flow conditions (21,41). The functional capillary density is inversely related to flow heterogeneity (14). The possible increment of capillary diameter under crystalloid perfusion may also reduce the flow heterogeneity as conjectured from the recent in vivo microscopic observation of erythrocyte flows in canine epicardial capillaries, which showed the augmented flow homogenization in capillary beds after the increment of capillary diameter during reactive hyperemia (26).…”

Section: Discussionmentioning

confidence: 99%

“…Microvascular vasomotion, which is likely to exhibit quasiperiodic or chaotic behaviors (4,42), possibly drives such temporal flow fluctuations. In addition, stochastic flow dynamics of corpuscles in capillary beds or at microvascular bifurcations seem to contribute to temporal flow fluctuations pronouncedly in lowflow regions (14). Averaged for longer time, the difference of spatial flow patterns between blood-and Tyrode-perfused hearts would decrease because of the existence of long-term fluctuations with periods of Ͼ60 s (4,23,42).…”

Section: Discussionmentioning

confidence: 99%

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Matsumoto¹,

Tachibana²,

Asano³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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hiko Kajiya. Pattern differences between distributions of microregional myocardial flows in crystalloid-and blood-perfused rat hearts. Am J Physiol Heart Circ Physiol 286: H1331-H1338, 2004. First published December 11, 2003 10.1152/ajpheart.00120.2003.-Regional myocardial flow distributions in Langendorff rat hearts under Tyrode and blood perfusion were assessed by tracer digital radiography (100-m resolution). Flow distributions during baseline and maximal hyperemia following a 60-s flow cessation were evaluated by the coefficient of variation of regional flows (CV; related to global flow heterogeneity) and the correlation between adjacent regional flows (CA; inversely related to local flow randomness). These values were obtained for the original images (64 2 pixels) and for coarsegrained images (32 2 , 16 2 , and 8 2 blocks of nearby pixels). At a given point in time during baseline, both CV and CA were higher in blood (n ϭ 7) than in Tyrode perfusion (n ϭ 7) over all pixel aggregates (P Ͻ 0.05, two-way ANOVA). During the maximal hyperemia, CV and CA were still significantly higher in blood (n ϭ 7) than in Tyrode perfusion (n ϭ 7); however, these values decreased substantially in blood perfusion and the CV and CA differences became smaller than those at baseline accordingly. During basal blood perfusion, the 60-s average flow distribution (n ϭ 7) showed a smaller CV and CA than those at a given point in time (P Ͻ 0.05, two-way ANOVA). Coronary flow reserve was significantly higher in blood than in Tyrode perfusion. In conclusion, the flow heterogeneity and the local flow similarity are both higher in blood than in Tyrode perfusion, probably due to the different degree of coronary tone preservation and the presence or absence of blood corpuscles. Under blood perfusion, temporal flow fluctuations over 60-s order are largely involved in shaping microregional flow distributions. regional myocardial perfusion; O2 carrying capacity; blood corpuscles; coronary tone; tracer digital radiography THE ISOLATED HEART MODEL USING crystalloid perfusates has been extensively used for characterizing myocardial contractility and energetics and the distribution of regional myocardial flows as well (5, 18, 49). However, most of the knowledge on regional crystalloid flows could not be extrapolated to explain the mechanisms of local regulation and coordination of regional myocardial flows under blood perfusion. Low O 2 carrying capacity of crystalloid perfusates makes an intracellular O 2 tension inadequate or just above the threshold for impaired myocardial function (6, 38) and reduces coronary tone or reserve (12,28,34). The distribution of regional myocardial flow is greatly under the influence of coronary tone (2, 5), and therefore there will be differences between spatial flow patterns in crystalloid-and blood-perfused myocardium. Furthermore, the presence or absence of blood corpuscles will augment those differences, because rheological, stochastic, and functional behaviors of corpuscles alter regional flows greatly at micr...

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“…This nonuniform distribution of flow among vessels, which can be defined as some vessels receiving more and some less of their appropriate fraction of total flow, has been invoked to explain phenomena such as flow-limited muscular performance 14 and suboptimal capillary transport of small solutes. 15 This, with a special emphasis on insulin and glucose, will be discussed in more detail in the next section. In addition, microvascular dysfunction may contribute to various kinds of end-organ damage (eg, retinopathy, lacunar stroke, microalbuminuria en heart failure).…”

Section: Microvascular Dysfunction As a Cause Of Hypertensionmentioning

confidence: 99%

Microvascular Dysfunction

Serné

Jongh

Eringa³

et al. 2007

Hypertension

208

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O besity and a central body fat distribution, hypertension, insulin resistance, glucose intolerance, dyslipidemia, and proinflammatory and prothrombotic factors are all part of the metabolic syndrome. The metabolic syndrome defines a clustering of metabolic risk factors which confers an increased risk for type 2 diabetes and cardiovascular disease. 1 In the past years a large amount of research has been aimed at elucidating the pathophysiology underlying this clustering of risk factors, because a better understanding may lead to new therapeutic approaches that specifically target underlying causes of the metabolic syndrome.Recently, it has become clear that microvascular dysfunction, by affecting both pressure and flow patterns, may have consequences not only for peripheral vascular resistance, but also for insulin-mediated changes in muscle perfusion and glucose metabolism, providing a novel pathophysiological framework for understanding the association between hypertension, obesity, and impaired insulin-mediated glucose disposal. [2][3][4] The present article examines recent data concerning the role of microvascular dysfunction as an explanation for the associations among hypertension, obesity, and impaired insulin-mediated glucose disposal.

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Heterogeneity of red blood cell perfusion in capillary networks supplied by a single arteriole in resting skeletal muscle.

Cited by 89 publications

References 20 publications

Spatial and Temporal Heterogeneity of Regional Pulmonary Blood Flow in Piglets

Spatial and Temporal Heterogeneity of Regional Pulmonary Blood Flow in Piglets

Pattern differences between distributions of microregional myocardial flows in crystalloid- and blood-perfused rat hearts

Microvascular Dysfunction

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