scholarly journals The Morphology of Villous Capillary Bed in Normal and Diabetic Placenta

10.5772/32155 ◽  
2012 ◽  
Author(s):  
Marie Jirkovsk
Keyword(s):  
Capillary Bed ◽  
Diabetic Placenta

Nitric oxide release in rat skeletal muscle capillary

1996 ◽  
Vol 270 (5) ◽  
pp. H1696-H1703 ◽  
Author(s):  
D. Mitchell ◽  
K. Tyml
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Leukocyte Adhesion ◽  
Microvascular Blood Flow ◽  
Capillary Length ◽  
Nitric Oxide Release ◽  
Longus Muscle ◽  
Potent Vasodilator ◽  
Capillary Bed ◽  
Synthase Inhibitor

Nitric oxide (NO) has been shown to be a potent vasodilator released from endothelial cells (EC) in large blood vessels, but NO release has not been examined in the capillary bed. Because the capillary bed represents the largest source of EC, it may be the largest source of vascular NO. In the present study, we used intravital microscopy to examine the effect of the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on the microvasculature of the rat extensor digitorum longus muscle. L-NAME (30 mM) applied locally to a capillary (300 micron(s) from the feeding arteriole) reduced red blood cell (RBC) velocity [VRBC; control VRBC = 238 +/- 58 (SE) micron/s; delta VRBC = -76 +/- 8%] and RBC flux (4.4 +/- 0.7 to 2.8 +/- 0.7 RBC/s) significantly in the capillary, but did not change feeding arteriole diameter (Dcon = 6.3 +/- 0.7 micron, delta D = 5 +/- 7%) or draining venule diameter (Dcon = 10.1 +/- 0.6 micron, delta D = 4 +/- 2%). Because of the VRBC change, the flux reduction was equivalent to an increased local hemoconcentration from 1.8 to 5 RBCs per 100 micron capillary length. L-NAME also caused an increase in the number of adhering leukocytes in the venule from 0.29 to 1.43 cells/100 micron. L-NAME (30 mM) applied either to arterioles or to venules did not change capillary VRBC. Bradykinin (BK) locally applied to the capillary caused significant increases in VRBC (delta VRBC = 111 +/- 23%) and in arteriolar diameter (delta D = 40 +/- 5%). This BK response was blocked by capillary pretreatment with 30 mM L-NAME (delta VRBC = -4 +/- 27%; delta D = 5 +/- 9% after BK). We concluded that NO may be released from capillary EC both basally and in response to the vasodilator BK. We hypothesize that 1) low basal levels of NO affect capillary blood flow by modulating local hemoconcentration and leukocyte adhesion, and 2) higher levels of NO (stimulated by BK) may cause a remote vasodilation to increase microvascular blood flow.

scholarly journals Vascularized organoids on a chip: strategies for engineering organoids with functional vasculature

Lab on a Chip ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 473-488
Author(s):  
Shun Zhang ◽  
Zhengpeng Wan ◽  
Roger D. Kamm
Keyword(s):  
Capillary Bed

Possible strategy to integrate pre-vascularized organoid and in vitro capillary bed on a microfluidic based platform, aiming for establishing perfused vasculature throughout organoids in vitro.

scholarly journals Fractalkine (CX3CL1) and Its Receptor CX3CR1 May Contribute to Increased Angiogenesis in Diabetic Placenta

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Dariusz Szukiewicz ◽  
Jan Kochanowski ◽  
Michal Pyzlak ◽  
Grzegorz Szewczyk ◽  
Aleksandra Stangret ◽  
...  
Keyword(s):  
Placental Tissue ◽  
Normal Pregnancy ◽  
Angiogenic Factor ◽  
Inflammatory Reactions ◽  
Ability To Act ◽  
The Mean ◽  
Class C ◽  
Diabetic Placenta ◽  
Receptor Cx3cr1 ◽  
Cx3cr1 Expression

Chemokine CX3CL1 is unique, possessing the ability to act as a dual agent: chemoattractant and adhesive compound. Acting via its sole receptor CX3CR1, CX3CL1 participates in many processes in human placental tissue, including inflammation and angiogenesis. Strongly upregulated by hypoxia and/or inflammation-induced inflammatory cytokines secretion, CX3CL1 may act locally as a key angiogenic factor. Both clinical observations and histopathological studies of the diabetic placenta have confirmed an increased incidence of hypoxia and inflammatory reactions with defective angiogenesis. In this study we examined comparatively (diabetes class C complicated versus normal pregnancy) the correlation between CX3CL1 content in placental tissue, the mean CX3CR1 expression, and density of the network of placental microvessels. A sandwich enzyme immunoassay was applied for CX3CL1 measurement in placental tissue homogenates, whereas quantitative immunohistochemical techniques were used for the assessment of CX3CR1 expression and the microvascular density. Significant differences have been observed for all analyzed parameters between the groups. The mean concentration of CX3CL1 in diabetes was increased and accompanied by augmented placental microvessel density as well as a higher expression of CX3CR1. In conclusion, we suggest involvement of CX3CL1/CX3CR1 signaling pathway in the pathomechanism of placental microvasculature remodeling in diabetes class C.

Retention of leukocytes in capillaries: role of cell size and deformability

1990 ◽  
Vol 69 (5) ◽  
pp. 1767-1778 ◽  
Author(s):  
G. P. Downey ◽  
D. E. Doherty ◽  
B. Schwab ◽  
E. L. Elson ◽  
P. M. Henson ◽  
...  
Keyword(s):  
Cell Size ◽  
Dynamic Equilibrium ◽  
Human Neutrophils ◽  
Biophysical Properties ◽  
Adhesive Properties ◽  
Pulmonary Capillaries ◽  
Size Discrepancy ◽  
Capillary Bed ◽  
Filtration Properties

Leukocytes within the circulation are in dynamic equilibrium with a marginated pool, thought to reside mainly within the pulmonary capillaries. The size discrepancy between the mean diameter of circulating leukocytes (6-8 microns) and that of the pulmonary capillaries (approximately 5.5 microns) forces the cells to deform in order to transit the capillary bed. Consequently, we investigated the hypothesis that the biophysical properties of cell size and deformability determined differential leukocyte retention in the lung. Comparison of the filtration properties of human neutrophils, lymphocytes, monocytes, platelets, and erythrocytes through polycarbonate filters (5-micron pore diameter) revealed that the largest leukocytes (neutrophils and monocytes) were retained to the greatest extent and the smaller cells (lymphocytes and platelets) the least. Undifferentiated HL-60 cells, of greater diameter than their differentiated counterparts, were also retained to a greater extent, confirming that cell size was one important determinant of retention in these model capillaries. However, compared with neutrophils, which are of similar diameter, monocytes were retained to a greater extent, suggesting that monocytes might be less deformable than neutrophils. To test this hypothesis, deformability was measured directly using the cell poker. Monocytes were found to be the stiffest, neutrophils the softest, and lymphocytes intermediate. Glutaraldehyde treatment of neutrophils markedly increased their stiffness and decreased their ability to transit the pores of the filters in vitro and the pulmonary microvasculature of rabbits without changing their adhesive properties or size. These observations support the hypothesis that biophysical properties of leukocytes (size and deformability) determine in part their ability to transit the pulmonary capillaries and may determine the magnitude of their marginated pools.

Perivascular and tissue PO2 in contracting rat spinotrapezius muscle

1987 ◽  
Vol 252 (6) ◽  
pp. H1192-H1202 ◽  
Author(s):  
J. M. Lash ◽  
H. G. Bohlen
Keyword(s):  
Skeletal Muscle ◽  
Muscle Contractions ◽  
Large Decrease ◽  
Functional Hyperemia ◽  
Biochemical Status ◽  
Tissue Po2 ◽  
Close Proximity ◽  
Exercise Hyperemia ◽  
Capillary Bed

This study evaluated the possibility that during skeletal muscle contractions tissue O2 tension (Po2) around arterioles and venules decreases substantially more than in the middle of the capillary bed and thereby influences functional hyperemia. Periarteriolar [H+] and [K+] were also measured because most large arterioles are in close proximity to venules such that the biochemical status of the periarteriolar tissue could be influenced by a large decrease in O2 availability in the annulet of tissue surrounding the venules. Stimulation frequencies in the range of 2-12 Hz were used to activate the rat spinotrapezius muscle. Periarteriolar and capillary bed Po2, [H+], and [K+] changed during the first few minutes of stimulation but were restored to near resting concentrations as the functional hyperemia developed. However, perivenular Po2 decreased rapidly to approximately 50-60% of the resting gas tension as contractions began, and only minor recovery occurred. Elevation of tissue and periarteriolar Po2 with an O2-enriched superfusion solution did not prevent dilation during contractions to the same diameter as during the response at very low superfusion Po2. Therefore, the extent to which O2 influences arteriolar dilation and exercise hyperemia in the spinotrapezius muscle of the rat may depend less on periarteriolar and capillary bed Po2 than on the release of vasoactive materials from the nearby perivenular tissues as the availability of O2 decreases.

scholarly journals Computational modeling of RBC and neutrophil transit through the pulmonary capillaries

2001 ◽  
Vol 90 (2) ◽  
pp. 545-564 ◽  
Author(s):  
Yaqi Huang ◽  
Claire M. Doerschuk ◽  
Roger D. Kamm
Keyword(s):  
Transpulmonary Pressure ◽  
Temporal Variations ◽  
Local Pressure ◽  
In Vivo Experiments ◽  
Pulmonary Capillaries ◽  
Transit Times ◽  
Capillary Bed ◽  
Pulmonary Microcirculation ◽  
Preferential Pathways

A computational model of the pulmonary microcirculation is developed and used to examine blood flow from arteriole to venule through a realistically complex alveolar capillary bed. Distributions of flow, hematocrit, and pressure are presented, showing the existence of preferential pathways through the system and of large segment-to-segment differences in all parameters, confirming and extending previous work. Red blood cell (RBC) and neutrophil transit are also analyzed, the latter drawing from previous studies of leukocyte aspiration into micropipettes. Transit time distributions are in good agreement with in vivo experiments, in particular showing that neutrophils are dramatically slowed relative to the flow of RBCs because of the need to contract and elongate to fit through narrower capillaries. Predicted neutrophil transit times depend on how the effective capillary diameter is defined. Transient blockage by a neutrophil can increase the local pressure drop across a segment by 100–300%, leading to temporal variations in flow and pressure as seen by videomicroscopy. All of these effects are modulated by changes in transpulmonary pressure and arteriolar pressure, although RBCs, neutrophils, and rigid microspheres all behave differently.

scholarly journals The state of the capillary bed in children with allergic diseases of the respiratory tract according to computer capillaroscopy of the nail bed

2020 ◽  
Vol 19 (2) ◽  
pp. 51-58
Author(s):  
Yu. L. Mizernitskiy ◽  
I. M. Melnikova ◽  
E. V. Udaltsova
Keyword(s):  
Tract Infection ◽  
Respiratory Tract ◽  
Respiratory Tract Infection ◽  
Respiratory Diseases ◽  
Allergic Diseases ◽  
Upper Respiratory Tract ◽  
Pronounced Increase ◽  
Nail Bed ◽  
Capillary Bed ◽  
Functional Features

Introduction. The actuality of children allergic respiratory diseases problem is due to the steady increase oftheir occurrence all over the world. Computerized capillaroscopy (ССS) of the nail bed is a non-invasive and highly informative method for assessing the structural and functional parameters of capillaries in real time and physiological conditions, and so it is effectively applied in pediatric practice. However, studies in this promising direction are rare. Aim. Was to determine the microcirculation peculiarities in children suffering from respiratory allergic diseases with prolonged cough, using the method of computerized capillaroscopy of the nail bed. Materials and methods. 238 children aged from 2 to 17 years with acute and chronic respiratory diseases, accompanied by prolonged (more than 4 weeks) cough, were examined and divided into 4 groups (Gr): Gr1 (n=68) – patients with acute or exacerbation of the chronic upper respiratory tract diseases of the infectious genesis; Gr2 (n=53) – patients with lower respiratory tract infection; Gr3 (n=39) – patients with allergic rhinitis; Gr4 (n=78) – patients with bronchial asthma (BA). All patients underwent history, examination and ССS of the nail bed. Results. Patients with allergic diseases of the respiratory tract, especially with BA, were found to have structural and functional disorders of the capillary bed and a pronounced increase in the length of the perivascular zone indicating an increase in the hydration degree of the interstitial space due to chronic allergic inflammation, in contrast to children with respiratory tract infection getting changed microcirculation parameters mainly in the venous part of capillaries. Conclusion. CСS of the nail bed is a highly informative method to identify functional features of the capillaries in allergic and infectious pathologies of the respiratory system, which can be successfully used as additional criteria for their differential diagnosis.

scholarly journals A nonlinear multi-scale model for blood circulation in a realistic vascular system

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Ulin Nuha A. Qohar ◽  
Antonella Zanna Munthe-Kaas ◽  
Jan Martin Nordbotten ◽  
Erik Andreas Hanson
Keyword(s):  
Blood Flow ◽  
Blood Circulation ◽  
Vascular System ◽  
Scale Model ◽  
Model Framework ◽  
Fluid Exchange ◽  
Multi Scale ◽  
Proposed Model ◽  
Porous Media Model ◽  
Capillary Bed

In the last decade, numerical models have become an increasingly important tool in biological and medical science. Numerical simulations contribute to a deeper understanding of physiology and are a powerful tool for better diagnostics and treatment. In this paper, a nonlinear multi-scale model framework is developed for blood flow distribution in the full vascular system of an organ. We couple a quasi one-dimensional vascular graph model to represent blood flow in larger vessels and a porous media model to describe flow in smaller vessels and capillary bed. The vascular model is based on Poiseuille’s Law, with pressure correction by elasticity and pressure drop estimation at vessels' junctions. The porous capillary bed is modelled as a two-compartment domain (artery and venous) using Darcy’s Law. The fluid exchange between the artery and venous capillary bed compartments is defined as blood perfusion. The numerical experiments show that the proposed model for blood circulation: (i) is closely dependent on the structure and parameters of both the larger vessels and of the capillary bed, and (ii) provides a realistic blood circulation in the organ. The advantage of the proposed model is that it is complex enough to reliably capture the main underlying physiological function, yet highly flexible as it offers the possibility of incorporating various local effects. Furthermore, the numerical implementation of the model is straightforward and allows for simulations on a regular desktop computer.

Sign in / Sign up

Export Citation Format

Share Document