scholarly journals Reduction of Functional Capillary Density in Human Brain after Stroke

1990 ◽  
Vol 10 (3) ◽  
pp. 317-326 ◽  
Author(s):  
Albert Gjedde ◽  
Hiroto Kuwabara ◽  
Antoine M. Hakim
Keyword(s):  
Blood Flow ◽  
Brain Tissue ◽  
Capillary Density ◽  
Functional Capillary Density ◽  
Functional Density ◽  
Hemodynamic Variables ◽  
Cortical Gray Matter ◽  
Cerebral Ischemic ◽  
Reduced Density

The blood flow of brain tissue often returns to normal after an ischemic episode. As “luxury” rather than “reactive” reperfusion, this hyperemia is associated with low metabolism. It is not known to what extent the high blood flow accompanies a high, normal, or low density of capillaries. The resolution of this question may indicate whether the functional capillary density is variable and, if so, whether it is coupled to blood flow or metabolism. To answer these questions, we defined functional capillaries as capillaries that transport glucose. We then calculated the density of functional capillaries ( Dcap) and the mean time of transit of blood through the capillaries ( tcap) from hemodynamic variables obtained in vivo by positron tomography of five patients afflicted by cerebral ischemic stroke. Each patient was studied twice, within 36 h of the insult and 1 week later. We identified nominally “ischemic” regions in the first study as cortical gray matter regions, contiguous with the ischemic focus, in which the magnitude of blood flow did not exceed 20 ml 100 g−1 min−1. In these regions, values of metabolism and functional capillary density were proportionately low compared with normal values obtained in the contralateral hemisphere. The studies revealed a reduction of the functional density of exchange vessels in postischemic brain tissue as soon as 36 h after the insult. In “ischemic” regions, within 36 h of the insult, the net extraction of oxygen was inversely related to the capillary transit time and appeared to be limited mainly by the low functional density of the capillaries. Contrary to expectations, the reduced density persisted, even when more than adequate perfusion of the tissue returned. For these reasons, we concluded that changes of the capillary density were associated with changes of the metabolism of the tissue rather than with blood flow.

scholarly journals Imaging of the Intestinal Microcirculation during Acute and Chronic Inflammation

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 418
Author(s):  
Kayle Dickson ◽  
Hajer Malitan ◽  
Christian Lehmann
Keyword(s):  
Blood Flow ◽  
Multiorgan Failure ◽  
Capillary Density ◽  
Intestinal Microcirculation ◽  
Inflammatory Conditions ◽  
Microcirculatory Disturbances ◽  
Vessel Integrity ◽  
Irritable Bowel ◽  
Acute And Chronic Inflammation

Because of its unique microvascular anatomy, the intestine is particularly vulnerable to microcirculatory disturbances. During inflammation, pathological changes in blood flow, vessel integrity and capillary density result in impaired tissue oxygenation. In severe cases, these changes can progress to multiorgan failure and possibly death. Microcirculation may be evaluated in superficial tissues in patients using video microscopy devices, but these techniques do not allow the assessment of intestinal microcirculation. The gold standard for the experimental evaluation of intestinal microcirculation is intravital microscopy, a technique that allows for the in vivo examination of many pathophysiological processes including leukocyte-endothelial interactions and capillary blood flow. This review provides an overview of changes in the intestinal microcirculation in various acute and chronic inflammatory conditions. Acute conditions discussed include local infections, severe acute pancreatitis, necrotizing enterocolitis and sepsis. Inflammatory bowel disease and irritable bowel syndrome are included as examples of chronic conditions of the intestine.

scholarly journals In vivo swine kidney viscoelasticity during acute gradual decrease in renal blood flow: pilot study (Viscoelasticidad renal durante la disminución gradual de flujo sanguíneo en un modelo porcino in vivo: estudio piloto)

2014 ◽  
Vol 7 (13) ◽  
Author(s):  
Carolina Amador ◽  
Matthew Urban ◽  
Randall Kinnick ◽  
Shigao Chen ◽  
James F. Greenleaf
Keyword(s):  
Blood Flow ◽  
Elastic Modulus ◽  
Renal Blood Flow ◽  
Hemodynamic Variables ◽  
Shear Elasticity ◽  
Para Determinar ◽  
Method Accuracy ◽  
The Relationship ◽  
Swine Kidney

Elasticity imaging methods have been used to study kidney mechanical properties and have demonstrated that the kidney elastic modulus increases with disease state. However, studies in swine suggest that kidney elastic modulus is also affected by hemodynamic variables. A newly emerging method called Shearwave Dispersion Ultrasound Vibrometry (SDUV) offers a tool to determine renal elasticity and viscosity in vivo. The purpose of this study was directed toward evaluating the feasibility of SDUV for in vivo measurements of healthy swine kidney during acute gradual decease of renal blood flow. In this study in vivo SDUV measurements were made on a group of 5 normal swine kidneys at baseline renal blood flow (RBF) and 25, 50, 75 and 100% decrease in RBF. The shear elastic modulus at full baseline was 7.04 ± 0.92 kPa and 3.48 ± 0.20 kPa at 100% decrease in RBF. The viscosity did not change between baseline (2.23 ± 0.33 Pa•s) and 100% decrease in RBF (2.03 ± 0.32 Pa•s). The data from this study indicates that other variables such as local blood flow, pressure and volume as well as method accuracy need to be measured to illustrate the relationship between shear elasticity and viscosity associated with acute kidney processes.Resumen: Métodos de imágenes de elasticidad se han utilizado para estudiar las propiedades mecánicas renales y han demostrado que el módulo elástico de los riñones del aumenta con el estado de enfermedades renales. Sin embargo, estudios en cerdos sugieren que el riñón módulo elástico también se ve afectada por las variables hemodinámicas. Un método emergente llamado Shearwave Dispersion Ultrasound Vibrometry (SDUV) ofrece una herramienta para determinar la elasticidad y la viscosidad renal. El propósito de este estudio se dirige a la evaluación de la viabilidad de SDUV para mediciones las propiedades viscoelasticas del riñón saludable durante variación aguda del flujo sanguíneo renal. En este estudio el método SDUV se realizó en un grupo de 5 riñones porcinos normales al inicio del flujo sanguíneo renal (RBF) basal y 25, 50, 75 y 100% de disminución en el RBF. El módulo elástico basal fue de 7,04 ± 0,92 kPa y 3,48 ± 0,20 kPa a 100% de disminución del RBF. La viscosidad no cambió entre el momento basal (2,23 ± 0,33 Pa • s) y el 100% de disminución del RBF (2,03 ± 0,32 Pa • s). Los datos de este estudio indican que variables tales como el flujo local de sangre, la presión y el volumen así como el método exactitud deben ser medidos para ilustrar la relación entre la elasticidad y la viscosidad asociada con los procesos renales agudos.

Acute pancreatitis in rats: effects of sodium taurocholate, CCK-8, and Sec on pancreatic microcirculation

1997 ◽  
Vol 272 (2) ◽  
pp. G310-G320 ◽  
Author(s):  
T. Plusczyk ◽  
S. Westermann ◽  
D. Rathgeb ◽  
G. Feifel
Keyword(s):  
Blood Flow ◽  
Pancreatic Duct ◽  
Capillary Permeability ◽  
Sodium Taurocholate ◽  
Capillary Density ◽  
Capillary Blood ◽  
Capillary Blood Flow ◽  
Biliary Pancreatitis ◽  
Acute Biliary Pancreatitis

With use of in vivo microscopy, pancreatic duct permeability, red blood cell (RBC) velocities, functional capillary density (FCD), and overall changes in capillary blood flow (perfusion index) were estimated after intraductal infusion of sodium taurocholate (0.8 ml, 4%) alone or in combination with systemic administration of cholecystokinin (CCK, 0.3 microg/100 g body wt) or secretin (Sec, 10 microg/100 g body wt). Sodium taurocholate mediated a significant increase in pancreatic duct and capillary permeability within 105 +/- 26 s followed by a transient decrease in RBC velocities and a sustained decrease in FCD, which were paralleled by dramatic flow heterogeneity. Therefore, a significant reduction in overall capillary blood flow was calculated. CCK stimulation aggravated the microcirculatory failure due to a decrease in RBC velocities, which was accompanied by an increase in acinar cellular necrosis. Sec stimulation attenuated microcirculatory failure due to a more moderate reduction of FCD. The enhanced pancreatic duct and capillary permeability, which enables free diffusion of pancreatic digestive enzymes into the parenchyma, is the initiating event in acute biliary pancreatitis, causing microcirculatory failure and tissue damage. The microcirculatory changes are secondary and a propagating factor for the development of acini necrosis. Stimulation with CCK worsened the course of acute biliary pancreatitis.

scholarly journals Imaging the injured beating heart intravitally and the vasculoprotection afforded by haematopoietic stem cells

2019 ◽  
Vol 115 (13) ◽  
pp. 1918-1932 ◽  
Author(s):  
Dean P J Kavanagh ◽  
Adam B Lokman ◽  
Georgiana Neag ◽  
Abigail Colley ◽  
Neena Kalia
Keyword(s):  
Blood Flow ◽  
Progenitor Cells ◽  
Intravital Microscopy ◽  
Causative Factor ◽  
Capillary Density ◽  
Beating Heart ◽  
Laser Speckle ◽  
Microvascular Perfusion ◽  
Contrast Imaging

Abstract Aims Adequate microcirculatory perfusion, and not just opening of occluded arteries, is critical to salvage heart tissue following myocardial infarction. However, the degree of microvascular perfusion taking place is not known, limited primarily by an inability to directly image coronary microcirculation in a beating heart in vivo. Haematopoietic stem/progenitor cells (HSPCs) offer a potential therapy but little is known about their homing dynamics at a cellular level and whether they protect coronary microvessels. This study used intravital microscopy to image the anaesthetized mouse beating heart microcirculation following stabilization. Methods and results A 3D-printed stabilizer was attached to the ischaemia–reperfusion injured (IRI) beating heart. The kinetics of neutrophil, platelet and HSPC recruitment, as well as functional capillary density (FCD), was imaged post-reperfusion. Laser speckle contrast imaging (LSCI) was used for the first time to monitor ventricular blood flow in beating hearts. Sustained hyperaemic responses were measured throughout reperfusion, initially indicating adequate flow resumption. Intravital microscopy confirmed large vessel perfusion but demonstrated poor transmission of flow to downstream coronary microvessels. Significant neutrophil adhesion and microthrombus formation occurred within capillaries with the latter occluding them, resulting in patchy perfusion and reduced FCD. Interestingly, ‘patrolling’ neutrophils were also observed in capillaries. Haematopoietic stem/progenitor cells readily trafficked through the heart but local retention was poor. Despite this, remarkable anti-thromboinflammatory effects were observed, consequently improving microvascular perfusion. Conclusion We present a novel approach for imaging multiple microcirculatory perturbations in the beating heart with LSCI assessment of blood flow. Despite deceptive hyperaemic responses, increased microcirculatory flow heterogeneity was seen, with non-perfused areas interspersed with perfused areas. Microthrombi, rather than neutrophils, appeared to be the major causative factor. We further applied this technique to demonstrate local stem cell presence is not a pre-requisite to confer vasculoprotection. This is the first detailed in vivo characterization of coronary microcirculatory responses post-reperfusion injury.

Umbilical Cord Blood CD133+ Stem Cells Exhibit Vasculogenic Capacity In Vitro and Augment Neovasculogenesis In Vivo in a Murine Model of Vascular Ischemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1790-1790
Author(s):  
M.R. Finney ◽  
L.R. Fanning ◽  
P.J. Vincent ◽  
D.G. Winter ◽  
M.A. Hoffman ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Blood Flow ◽  
Cord Blood ◽  
Umbilical Cord Blood ◽  
Hind Limb ◽  
Capillary Density ◽  
Functional Assays

Abstract Recent reports have utilized a variety of cell types for cellular therapy in mediating therapeutic angiogenesis in response to ischemia. We sought to assess the vasculogeneic potential of selected CD133+ hematopoietic stem cells (HSC) from umbilical cord blood (UCB) utilizing in vitro functional assays and an in vivo murine hind-limb ischemia model. Methods & Results: Mononuclear cells (MNC) from UCB or bone marrow (BM) were incubated with CD133+ conjugated magnetic beads, followed by automated sorting through magnetic columns (Miltenyi). Routine yield of CD133+ cells was 0.5±0.2% of UCB MNC and 0.7±0.3% of BM MNC, with a purity of 79±2% (UCB, n=30) and 84±5% (BM, n=12). Surface expression in the UCB CD133+ population was 3.6±1.5% KDR(VEGFR2), 8.7± 3.8% CXCR4 and 22.7±2.8% CD105 compared to 9.2±1.8% KDR, 14.4±1.3% CXCR4 and 23.7±2.3% CD105 in the BM CD133+ population. We measured chemotactic migration of cells towards SDF-1 (100ng/mL) compared to control wells containing media alone. The fold increase over control was 4.9±2.9 UCB MNC, 1.8±0.7 UCB CD133+ and 8.3±1.7 BM CD133+ (n=3). Angiogenic protein assays of CD133+ cells demonstrated elevated levels of IL-8 production as compared to MNC (103+/−380 pg/mL greater in CD133+ than MNC from the same UCB unit) when cultured for 24h in basal media. NOD/SCID mice underwent ligation of the right femoral artery and were given cells or vehicle control via intracardiac injection immediately following injury. Mice were given 1 x 106 MNC or 0.5 x 106 CD133+ cells. Laser Doppler flow measurements were obtained from both limbs each week for 6 weeks and the ratio of perfusion in the ischemic/healthy limb was calculated. At 28 days, perfusion ratios were statistically higher in study groups receiving UCB CD133+ cells, 0.55±0.06 (n=9), BM CD133+ cells 0.47±0.07 (n=8), BM MNC 0.48±0.8 (n=6) compared to cytokine controls 0.37±0.03 (n=12, p<0.05). Mice receiving UCB MNC did not show statistically significant improvement in measured blood flow over control animals 0.42±0.05 (n=8, p=0.34). At sacrifice, bone marrow was harvested to assess engraftment of human cells by flow cytometric analysis. Mice injected with UCB CD133+ cells showed 19±4.9% positive huCD45 cells compared to 2.5±0.6% for UCB MNC, 1.6±0.4% for BM CD133+ cells and 2.3±0.3% for BM MNC (n=3). Histological studies from day 42 tissue samples of muscle distal to arterial ligation were evaluated for capillary density. Control animals had capillary density of 131±6.9 cells/mm2. Capillary density was statistically higher that controls in animals receiving UCB CD133+ (320±18; p<0.0001), BM CD133++ (183±9.3; p<0.0001), and UCB MNC (164±10.5; p=0.011). Mice treated with BM MNC (135±9.4) did not have a statistically significant increase in capillary density from controls (p=0.73). In addition, animals treated with either UCB or BM-derived CD133+ cells had statistically higher capillary density than unselected MNC (p=<0.0001 and p=0.0004, respectively). Conclusions: In vitro functional assays showed that UCB-derived CD133+ HSC demonstrate enhanced homing capability (migration) as well as the potential for cellular recruitment (via IL-8 production) for angiogenesis in response to ischemia. Furthermore, UCB derived CD133+ HSC mediate significantly improved blood flow in an in vivo murine hind-limb injury model of ischemia, indicating the greater vasculogenic potential of selected CD133+ cells from of this stem cell source.

Evolution of a “falx lunatica” in demarcation of critically ischemic myocutaneous tissue

2005 ◽  
Vol 288 (3) ◽  
pp. H1224-H1232 ◽  
Author(s):  
Yves Harder ◽  
Michaela Amon ◽  
Mirko Georgi ◽  
Andrej Banic ◽  
Dominique Erni ◽  
...  
Keyword(s):  
Capillary Density ◽  
Functional Capillary Density ◽  
Tissue Necrosis ◽  
Capillary Perfusion ◽  
Edema Formation ◽  
Perfusion Failure ◽  
Ischemic Tissue ◽  
Flap Elevation ◽  
Observation Period

Using intravital microscopy in a chronic in vivo mouse model, we studied the demarcation of myocutaneous flaps and evaluated microvascular determinants for tissue survival and necrosis. Chronic ischemia resulted in a transition zone, characterized by a red fringe and a distally adjacent white falx, which defined the demarcation by dividing the proximally normal from the distally necrotic tissue. Tissue survival in the red zone was determined by hyperemia, as indicated by recovery of the transiently reduced functional capillary density, and capillary remodeling, including dilation, hyperperfusion, and increased tortuosity. Angiogenesis and neovascularization were not observed over the 10-day observation period. The white rim distal to the red zone, appearing as “falx lunatica,” showed a progressive decrease of functional capillary density similar to that of the necrotic distal area but without desiccation, and thus transparency, of the tissue. Development of the distinct zones of the critically ischemic tissue could be predicted by partial tissue oxygen tension (Pt[Formula: see text]) analysis by the time of flap elevation. The falx lunatica evolved at a Pt[Formula: see text] between 6.2 ± 1.3 and 3.8 ± 0.7 mmHg, whereas tissue necrosis developed at <3.8 ± 0.7 mmHg. Histological analysis within the falx lunatica revealed interstitial edema formation and muscle fiber nuclear rarefaction but an absence of necrosis. We have thus demonstrated that ischemia-induced necrosis does not demarcate sharply from normal tissue but develops beside a fringe of tissue with capillary remodeling an adjacent falx lunatica that survives despite nutritive capillary perfusion failure, probably by direct oxygen diffusion.

Vasoactive agents and splanchnic oxygen uptake

1982 ◽  
Vol 243 (1) ◽  
pp. G1-G9 ◽  
Author(s):  
P. R. Kvietys ◽  
D. N. Granger
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Oxidative Metabolism ◽  
Flow Distribution ◽  
Capillary Density ◽  
Exchange Capacity ◽  
Vasoactive Agents ◽  
Splanchnic Oxygen

Many vasoactive agents are known to alter oxygen uptake by splanchnic organs. Data from the literature indicate that, in general, vasodilators increase, whereas vasoconstrictors decrease oxygen uptake. We compare and contrast the effects of vasoactive agents on oxygen uptake observed in vivo, under constant-flow and free-flow conditions, to those observed in vitro. The discrepancies between the in vivo and in vitro data are discussed relative to the effects of vasoactive agents on blood flow, intraorgan blood flow distribution, the countercurrent exchange of oxygen, capillary exchange capacity, and oxidative metabolism. Changes in blood flow, oxidative metabolism, and capillary density appear to be the major mechanisms by which vasoactive agents alter splanchnic oxygen uptake in vivo. Experimental designs are proposed that may help minimize inconsistencies in the data in future studies.

Diaphragmatic microcirculation during halothane and isoflurane exposure in pentobarbital-anesthetized rats

1992 ◽  
Vol 73 (4) ◽  
pp. 1614-1618 ◽  
Author(s):  
A. Leon ◽  
J. Boczkowski ◽  
B. Dureuil ◽  
E. Vicaut ◽  
M. Aubier ◽  
...  
Keyword(s):  
Capillary Density ◽  
Baseline Period ◽  
Functional Capillary Density ◽  
Dependent Manner ◽  
Minimal Alveolar Concentration ◽  
Arterial Blood ◽  
Anesthetized Rats ◽  
Isoflurane Group ◽  
Dose Dependent

We investigated the effects of halothane and isoflurane on diaphragmatic microcirculation in pentobarbital-anesthetized rats by in vivo video microscopy. After a baseline period, rats were randomly allocated into three groups according to administration of 0.5, 0.75, and 1 minimal alveolar concentration (MAC) of either halothane (group Hal, n = 16), isoflurane (group Iso, n = 14), or no halogenated agent (group C, n = 20) in three succeeding steps of 15 min. Mean arterial blood pressure (MAP), arteriolar diameters, and functional capillary density were analyzed in the last 3 min of each step. MAP remained unchanged in group C but decreased in a dose-dependent manner in both halogenated receiving groups. MAP was significantly lower in rats breathing Hal compared with those breathing Iso. Arterioles were classified in second (A2, n = 39), third (A3, n = 24), and fourth (A4, n = 30) order according to their relative location in the network. No changes in A2 and A3 diameters were noted in either group. A4 diameters remained unchanged in groups C and Iso, whereas a significant reduction was found in group Hal at 0.75 and 1 MAC exposure (P < 0.05 compared with baseline and with groups C and Iso, respectively). During Iso exposure, functional capillary density was not significantly different when compared with baseline and group C, whereas in group Hal it decreased significantly at 0.5, 0.75, and 1 MAC, amounting to 61.1 +/- 9, 30.7 +/- 10.3, and 22.8 +/- 6.3%, respectively, of baseline (P < 0.01 vs. baseline and P < 0.05 vs. groups Iso and C for 0.75 and 1 MAC).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Impaired dynamics of brain precapillary sphincters and first order capillaries explains reduced neurovascular functions in aging

2021 ◽  
Author(s):  
Changsi Cai ◽  
Stefan Andreas Zambach ◽  
Soeren Grubb ◽  
Kirsten Joan Thomsen ◽  
Barbara Lykke Lind ◽  
...  
Keyword(s):  
Blood Flow ◽  
Vascular Reactivity ◽  
Brain Aging ◽  
Capillary Density ◽  
Nitric Oxide Synthase Inhibitor ◽  
First Order ◽  
Age Related ◽  
Age Dependent ◽  
Synthase Inhibitor

The microvascular inflow tract (MIT), i.e. penetrating arterioles, precapillary sphincters and first order capillaries, is the bottleneck for brain blood flow and energy supply. However, the exact structural and functional alterations during aging remain elusive. Using in vivo 4-dimensional (xyzt) two-photon imaging, we showed an age-dependent decrease in vaso-responsivity, which was accompanied by reduced sensitivity of MIT to pinacidil and papaverine, and to vasoconstrictors endothelin-1 and to L-NAME, a nitric oxide synthase inhibitor. Reduced responsivity was accompanied by an age-dependent decrease in capillary density close to the arterioles and by loss of pericyte processes, whereas the number of pericyte somas and the pericyte αSMA density were preserved. The age-related reduction in vascular reactivity was most pronounced at precapillary sphincters, highlighting its crucial role for capillary blood flow regulation. Mathematical modeling further revealed dysregulated but protected pressure and flow in aged mice towards vasoconstriction. Prevention of reduced responsivity of the MIT may ameliorate the blood flow decrease associated with brain aging and age-related brain frailty.

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