scholarly journals Homogenization of capillary flow and oxygenation in deeper cortical layers correlates with increased oxygen extraction

2018 ◽  
Author(s):  
Baoqiang Li ◽  
Tatiana V. Esipova ◽  
Ikbal Sencan ◽  
Kivilcim Kilic ◽  
Buyin Fu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Delivery ◽  
Capillary Flow ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cortical Layers ◽  
Microvascular Network ◽  
Local Brain

ABSTRACTOur understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice at rest. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that homogenization of physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to a local brain metabolism increase. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of diseases that affect the cerebral microcirculation.IMPACT STATEMENTHomogenization of cortical capillary blood flow and oxygenation underpins an important mechanism, by which the microvascular network adapts to an increase in the local brain oxidative metabolism.

scholarly journals More homogeneous capillary flow and oxygenation in deeper cortical layers correlate with increased oxygen extraction

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Baoqiang Li ◽  
Tatiana V Esipova ◽  
Ikbal Sencan ◽  
Kıvılcım Kılıç ◽  
Buyin Fu ◽  
...  
Keyword(s):  
Oxygen Delivery ◽  
Barrel Cortex ◽  
Capillary Flow ◽  
Oxygen Demand ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Homogeneous Distribution ◽  
Metabolic Demand ◽  
Cortical Layers ◽  
Network Adaptation

Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.

Partition of capillary blood flow in rumen, reticulum, and omasum of sheep.

1977 ◽  
Vol 232 (1) ◽  
pp. E53 ◽  
Author(s):  
W Von Engelhardt ◽  
J R Hales
Keyword(s):  
Spinal Cord ◽  
Blood Flow ◽  
Capillary Flow ◽  
Unit Area ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Radioactive Microspheres ◽  
Mucosal Epithelium ◽  
Warm Environment ◽  
Conscious Sheep

Using radioactive microspheres, mucosal and muscular capillary blood flow have been measured in the rumen, reticulum, and omasum of conscious sheep. Total forestomach capillary blood flow (7.7 ml min(-1) kg body wt(-1)) was about 7% of cardiac output; 95% of the flow was in the mucosa and only 5% in muscle layers. Blood flow in the rumen was 6 times higher than in the reticulum and 4.4 times higher than in the omasum. Mucosal capillary flow per unit area of mucosal epithelium in the omassum (disregarding the increment in area due to papillae) was only one-third of that in the ventral rumen (long papillae); flow in the dorsal rumen (short papillae) was about half the flow in the ventral rumen. Mucosal flow seems to provide a convenient, indirect estimate of the increase in mucosal surface due to papillae and, thereby, of the functional forestomach surface area. Heat stimuli resulted in decreased capillary blood flow--primarily in mucosa during exposure to a warm environment and, also, in muscle during hypothalamic or spinal cord heating.

Effect of postural change and thermoregulatory stress on the capillary microcirculation of the human toe

1989 ◽  
Vol 76 (3) ◽  
pp. 231-236 ◽  
Author(s):  
M. D. Flynn ◽  
A. A. K. Hassan ◽  
J. E. Tooke
Keyword(s):  
Blood Flow ◽  
Capillary Flow ◽  
Standing Position ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Quiet Standing ◽  
Compensatory Mechanisms ◽  
Oedema Formation ◽  
Arteriovenous Shunts ◽  
Indirect Heating

1. We have applied the technique of television capillary microscopy to make direct measurements of nutritional capillary flow in the toe nailfold (i) at heart level and (ii) in a near standing position, with the foot 96 cm below heart level. By indirect heating we have examined the relationship between posture-related changes and thermoregulation in the capillary circulation of the toe. 2. Capillary blood flow in 14 male subjects with their feet at heart level showed a positive correlation with increasing skin temperature. 3. On quiet standing, capillary blood flow decreased to 11.3% of supine values, achieved both by a reduction in capillary blood velocity and the duration of flow. 4. Indirect heating of the trunk led to a partial release of sympathetic tone and induced a significant increase in capillary blood flow in both the supine and dependent positions. However during heating, the percentage fall in capillary blood flow associated with dependency remained unchanged. 5. In conclusion, it appears that in the dependent foot, compensatory mechanisms exist to limit nutritional capillary blood flow by regulating both erythrocyte velocity and the duration of flow. These mechanisms fulfil a physiological requirement to limit the rate of oedema formation. The preservation of this response during the partial sympathetic release induced by indirect heating suggests a mechanism independent of that controlling flow through arteriovenous shunts. Our results are compatible with the hypothesis that a local vasoconstrictor mechanism is operative in the vascular resistance elements in closest relation with the capillary bed, and distal to that regulating arteriovenous shunt flow.

Capillary Blood Flow in the Endometrium and Myometrium of Conscious Sheep: Effect of Catheterization of Uterine Arteries

1985 ◽  
Vol 38 (1) ◽  
pp. 209 ◽  
Author(s):  
BW Brown ◽  
IS Fraser ◽  
PE Mattner
Keyword(s):  
Blood Flow ◽  
Capillary Flow ◽  
Capillary Blood ◽  
Oestrous Cycle ◽  
Capillary Blood Flow ◽  
Uterine Arteries ◽  
Conscious Sheep

Measures of capillary blood flow in the uterine tissues of conscious ewes were obtained by the use of microspheres. Total uterine capillary blood flow was significantly greater (P < 0'01) at oestrus than at day 8 of the oestrous cycle [69' 5 � (s.e.m.) 11' 9, cf. 15' 3 � I' 2 ml min -1, n = 7], reflecting increases of a similar order in both the endometrium and the myometrium. At these stages of the oestrous cycle, endometrial capillary blood flow constituted 83' 6 and 80' 5%, respectively, of the total uterine capillary flow.

Lutein Complex Supplementation Increases Ocular Blood Flow Biomarkers in Healthy Subjects

2019 ◽  
Vol 89 (1-2) ◽  
pp. 5-12
Author(s):  
Alon Harris ◽  
Brent Siesky ◽  
Amelia Huang ◽  
Thai Do ◽  
Sunu Mathew ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Diastolic Blood Pressure ◽  
Healthy Subjects ◽  
Ocular Blood Flow ◽  
Capillary Blood ◽  
Post Treatment ◽  
Capillary Blood Flow ◽  
Doppler Imaging ◽  
Retinal Capillary

Abstract. Introduction: To investigate the effects of a lutein complex supplementation on ocular blood flow in healthy subjects. Materials and Methods: Sixteen healthy female patients (mean age 36.8 ± 12.1 years) were enrolled in this randomized, placebo-controlled, double-blinded, two-period crossover study. Subjects received daily an oral dose of the lutein with synergistic phytochemicals complex (lutein (10 mg), ascorbic acid (500 mg), tocopherols (364 mg), carnosic acid (2.5 mg), zeaxanthin (2 mg), copper (2 mg), with synergistic effects in reducing pro-inflammatory mediators and cytokines when administered together in combination) and placebo during administration periods. Measurements were taken before and after three-week supplementation periods, with crossover visits separated by a three-week washout period. Data analysis included blood pressure, heart rate, intraocular pressure, visual acuity, contrast sensitivity detection, ocular perfusion pressure, confocal scanning laser Doppler imaging of retinal capillary blood flow, and Doppler imaging of the retrobulbar blood vessels. Results: Lutein complex supplementation produced a statistically significant increase in mean superior retinal capillary blood flow, measured in arbitrary units (60, p = 0.0466) and a decrease in the percentage of avascular area in the superior (−0.029, p = 0.0491) and inferior (−0.023, p = 0.0477) retina, as well as reduced systolic (−4.06, p = 0.0295) and diastolic (−3.69, p = 0.0441) blood pressure measured in mmHg from baseline. Data comparison between the two supplement groups revealed a significant decrease in systemic diastolic blood pressure (change from pre- to post-treatment with lutein supplement (mean (SE)): −3.69 (1.68); change from pre- to post-treatment with placebo: 0.31 (2.57); p = 0.0357) and a significant increase in the peak systolic velocity (measured in cm/sec) in the central retinal artery (change from pre- to post-treatment with lutein supplement: 0.36 (0.19); change from pre- to post-treatment with placebo: −0.33 (0.21); p = 0.0384) with lutein complex supplement; data analyses from the placebo group were all non-significant. Discussion: In healthy participants, oral administration of a lutein phytochemicals complex for three weeks produced increased ocular blood flow biomarkers within retinal vascular beds and reduced diastolic blood pressure compared to placebo.

Reversal of Focal Misery Perfusion after Intracranial Angioplasty: Case Report

Neurosurgery ◽  
2001 ◽  
Vol 48 (2) ◽  
pp. 436-440 ◽  
Author(s):  
Colin P. Derdeyn ◽  
DeWitte T. Cross ◽  
Christopher J. Moran ◽  
Ralph G. Dacey
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Carotid Artery ◽  
Intracranial Stenosis ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Positron Emission ◽  
Misery Perfusion ◽  
Before And After ◽  
Hemodynamic Measurements

Abstract OBJECTIVE AND IMPORTANCE The presence of reduced blood flow and increased oxygen extraction fraction (OEF) (misery perfusion) in the hemisphere distal to an occluded carotid artery is a proven risk factor for subsequent stroke. Whether angioplasty of intracranial stenosis is sufficient to reverse this condition has not been documented. CLINICAL PRESENTATION A 67-year-old man exhibited progressive right hemispheric ischemic symptoms despite maximal antiplatelet and antithrombotic therapy. Angiography demonstrated focal 80% stenosis of the supraclinoid segment of the ipsilateral internal carotid artery. TECHNIQUE 15O positron emission tomographic measurements of cerebral blood flow and OEF were made before and after transfemoral percutaneous angioplasty. OEF values measured before angioplasty were elevated in the middle cerebral artery distal to the stenosis. Angioplasty reduced the degree of luminal stenosis to 40% (linear diameter). OEF values measured 36 hours after angioplasty were normal. CONCLUSION Angioplasty of intracranial stenosis can restore normal cerebral blood flow and oxygen extraction, despite mild residual stenosis after the procedure. Hemodynamic measurements may be useful for the identification of patients with the greatest potential to benefit from angioplasty.

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