scholarly journals Contribution of serial and parallel microperfusion to spatial variability in pulmonary inter- and intra-acinar blood flow

2010 ◽  
Vol 108 (5) ◽  
pp. 1116-1126 ◽  
Author(s):  
A. R. Clark ◽  
K. S. Burrowes ◽  
M. H. Tawhai
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Distal Portion ◽  
Model Structure ◽  
Capillary Recruitment ◽  
Pulmonary Acinus ◽  
Acinar Structure ◽  
Computational Simplicity ◽  
Pulmonary Microcirculation ◽  
Increased Blood Flow

This study presents a theoretical model of combined series and parallel perfusion in the human pulmonary acinus that maintains computational simplicity while capturing some important features of acinar structure. The model provides a transition between existing models of perfusion in the large pulmonary blood vessels and the pulmonary microcirculation. Arterioles and venules are represented as distinct elastic vessels that follow the branching structure of the acinar airways. These vessels are assumed to be joined at each generation by capillary sheets that cover the alveoli present at that generation, forming a “ladderlike” structure. Compared with a model structure in which capillary beds connect only the most distal blood vessels in the acinus, the model with combined serial and parallel perfusion provides greater capacity for increased blood flow in the lung via capillary recruitment when the blood pressure is elevated. Stratification of acinar perfusion emerges in the model, with red blood cell transit time significantly larger in the distal portion of the acinus compared with the proximal portion. This proximal-to-distal pattern of perfusion may act in concert with diffusional screening to optimize the potential for gas exchange.

Site of recruitment in the pulmonary microcirculation

1989 ◽  
Vol 66 (5) ◽  
pp. 2079-2083 ◽  
Author(s):  
W. L. Hanson ◽  
J. D. Emhardt ◽  
J. P. Bartek ◽  
L. P. Latham ◽  
L. L. Checkley ◽  
...  
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Total Surface Area ◽  
Capillary Recruitment ◽  
Fluid Load ◽  
Pulmonary Arterial ◽  
Pulmonary Microcirculation ◽  
Adequate Oxygenation ◽  
Made In

Increasing the total surface area of the pulmonary blood-gas interface by capillary recruitment is an important factor in maintaining adequate oxygenation when metabolic demands increase. Capillaries are known to be recruited during conditions that raise pulmonary blood flow and pressure. To determine whether pulmonary arterioles and venules are part of the recruitment process, we made in vivo microscopic observations of the subpleural microcirculation (all vessels less than 100 microns) in the upper lung where blood flow is low (zone 2). To evoke recruitment, pulmonary arterial pressure was elevated either by an intravascular fluid load or by airway hypoxia. Of 209 arteriolar segments compared during low and high pulmonary arterial pressures, none recruited or derecruited. Elevated arterial pressure, however, did increase the number of perfused capillary segments by 96% with hypoxia and 165% with fluid load. Recruitment was essentially absent in venules (4 cases of recruitment in 289 segments as pressure was raised). These data support the concept that recruitment in the pulmonary circulation is exclusively a capillary event.

Injury And Inflammation Induced In The Microcirculation Of The Rabbit By Antigen-Antibody Complexes

1981 ◽  
Author(s):  
J P Crawford ◽  
H Z Movat ◽  
N S Ranadive ◽  
J B Hay
Keyword(s):  
Blood Flow ◽  
Inflammatory Response ◽  
Skin Lesions ◽  
Precipitin Test ◽  
Cork Borer ◽  
Pulmonary Microcirculation ◽  
Antigen Antibody ◽  
Kinetics Of ◽  
Increased Blood Flow ◽  
Circulating Antibody

An experimental model was used to study the morphogenesis, quantitation and kinetics of the inflammatory response in the dermis of rabbits. New Zealand White rabbits were immunized with ovalbumin, bled, the antibody precipitated by ammonium sulphate and redissolved in saline. Circulating antibody was determined by the quantitative precipitin test. The reversed passive Arthus reaction was elicited by injecting normal rabbits intravenously with antigen [1.0 gm] and intradermally with 0.9 mg of antibody, in triplicate sites. The lesions were allowed to develop for 1-8, 18 and 24 hours post-injection. To assess the inflammatory response, 5 parameters were examined: 1) Exudation of plasma using 125I-serum albumin; 2) Infiltration of leukocytes with 51Cr-labelled cells; 3) Hemorrhage with 59Fe-erythrocytes; 4) Formation of microthrombi with 111In-platelets; and 5) Blood flow with 57Co-microspheres. The animals were killed, the lesions punched out with a cork borer and counted in a gamma spectrometer. Skin lesions from rabbits not injected with tracers were fixed in glutaraldehyde-formalin and prepared for microscopic examination. With the aid of these techniques, increase of vascular permeability and the formation of microthrombi peaked in 2-hour old lesions. Increased blood flow peaked in leasions 3-4 hours postinjection. Infiltration of polymorphonuclear leukocytes reached a maximum in lesions 2-3 hours old, followed by hemorrhage, which reached a maximum and plateaued after 4 hours. Immune complexes may induce a hemorrhagic inflammation, the kinetics of which can be ascertained. Preliminary studies indicate that these techniques are applicable for the examination of experimentally-induced hypersensitivity pneumonitides and disorders of the pulmonary microcirculation.

Selected Contribution: Measuring the response time of pulmonary capillary recruitment to sudden flow changes

2000 ◽  
Vol 89 (3) ◽  
pp. 1233-1238 ◽  
Author(s):  
Eric M. Jaryszak ◽  
William A. Baumgartner ◽  
Amanda J. Peterson ◽  
Robert G. Presson ◽  
Robb W. Glenny ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Response Time ◽  
Capillary Recruitment ◽  
Lung Lobe ◽  
Pulmonary Capillaries ◽  
Pulmonary Capillary ◽  
Flow Changes ◽  
Pulmonary Microcirculation

To determine how rapidly pulmonary capillaries recruit after sudden changes in blood flow, we used an isolated canine lung lobe perfused by two pumps running in parallel. When one pump was turned off, flow was rapidly halved; when it was turned on again, flow immediately doubled. We recorded pulmonary capillary recruitment in subpleural alveoli using videomicroscopy to measure how rapidly the capillaries reached a new steady state after these step changes in blood flow. When flow was doubled, capillary recruitment reached steady state in <4 s. When flow was halved, steady state was reached in ∼8 s. We conclude that the pulmonary microcirculation responds rapidly to step changes in flow, even in the capillaries that are most distant from the hilum.

scholarly journals Ménièreés syndrome and hearing changes

2019 ◽  
Author(s):  
vernon thornton
Keyword(s):  
Blood Flow ◽  
Epithelial Cells ◽  
Inner Ear ◽  
Blood Vessels ◽  
Energy Supply ◽  
Simple Test ◽  
Sugar Levels ◽  
Ion Pumping ◽  
Increased Blood Flow ◽  
Skipping Breakfast

A simple test of hearing in the affected ear of a sufferer of Ménière's disease (me) has shown the following: a regular daily pattern of changes in hearing; the existence of three daily peaks of improvement in hearing; and that these peaks occurred about two hours after each of three daily meals. In one test, after skipping breakfast, the corresponding peak was absent. It is proposed that these changes in hearing were the result of raised blood insulin and sugar levels following a meal. This caused increased blood flow in the tiny blood vessels in the inner ear and improved the energy supply to vital ion-pumping epithelial cells.

Innervation of endoneurial microvessels in human sural nerve

1992 ◽  
Vol 50 (1) ◽  
pp. 920-921
Author(s):  
John L. Beggs ◽  
Peter C. Johnson ◽  
Astrid G. Olafsen ◽  
C. Jane Watkins
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Blood Supply ◽  
Peripheral Nerves ◽  
Sural Nerve ◽  
Nerve Fibers ◽  
Arterial Supply ◽  
Autonomic Nerve ◽  
Vasa Nervorum ◽  
Endoneurial Blood Flow

The blood supply (vasa nervorum) to peripheral nerves is composed of an interconnected dual circulation. The endoneurium of nerve fascicles is maintained by the intrinsic circulation which is composed of microvessels primarily of capillary caliber. Transperineurial arterioles link the intrinsic circulation with the extrinsic arterial supply located in the epineurium. Blood flow in the vasa nervorum is neurogenically influenced (1,2). Although a recent hypothesis proposes that endoneurial blood flow is controlled by the action of autonomic nerve fibers associated with epineurial arterioles (2), our recent studies (3) show that in addition to epineurial arterioles other segments of the vasa nervorum are also innervated. In this study, we examine blood vessels of the endoneurium for possible innervation.

COMPARISON OF ANTIHYPERTENSIVE EFFECT OF MOXONIDINE VERSUS CLONIDINE IN RENAL FAILURE PATIENTS.

2018 ◽  
Vol 6 (9) ◽  
Author(s):  
DR.MATHEW GEORGE ◽  
DR.LINCY JOSEPH ◽  
MRS.DEEPTHI MATHEW ◽  
ALISHA MARIA SHAJI ◽  
BIJI JOSEPH ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renal Failure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Blood Vessels ◽  
High Blood Pressure ◽  
Antihypertensive Effect ◽  
The Body ◽  
Ability To Work ◽  
Blood Flows

Blood pressure is the force of blood pushing against blood vessel walls as the heart pumps out blood, and high blood pressure, also called hypertension, is an increase in the amount of force that blood places on blood vessels as it moves through the body. Factors that can increase this force include higher blood volume due to extra fluid in the blood and blood vessels that are narrow, stiff, or clogged(1). High blood pressure can damage blood vessels in the kidneys, reducing their ability to work properly. When the force of blood flow is high, blood vessels stretch so blood flows more easily. Eventually, this stretching scars and weakens blood vessels throughout the body, including those in the kidneys.

Microfluidics of blood in blood vessels stenosis

2016 ◽  
Vol 11 (2) ◽  
pp. 210-217 ◽  
Author(s):  
A.T. Akhmetov ◽  
A.A. Valiev ◽  
A.A. Rakhimov ◽  
S.P. Sametov ◽  
R.R. Habibullina
Keyword(s):  
Blood Flow ◽  
Blood Vessels ◽  
Hydraulic Resistance ◽  
Microfluidic Device ◽  
Human Body ◽  
Vascular System ◽  
Hydrodynamic Conditions ◽  
Microstructure Change ◽  
Healthy Part

It is mentioned in the paper that hydrodynamic conditions of a flow in blood vessels with the stenosis are abnormal in relation to the total hemodynamic conditions of blood flow in a vascular system of a human body. A microfluidic device developed with a stepped narrowing for studying of the blood flow at abnormal conditions allowed to reveal blood structure in microchannels simulating the stenosis. Microstructure change is observed during the flow of both native and diluted blood through the narrowing. The study of hemorheological properties allowed us to determine an increasing contribution of the hydraulic resistance of the healthy part of the vessel during the stenosis formation.

Diastolic pressure and peripheral resistance during stellate ganglion stimulation

1963 ◽  
Vol 204 (1) ◽  
pp. 71-72 ◽  
Author(s):  
Edward D. Freis ◽  
Jay N. Cohn ◽  
Thomas E. Liptak ◽  
Aristide G. B. Kovach
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Total Peripheral Resistance ◽  
Diastolic Pressure ◽  
Stellate Ganglion ◽  
Peripheral Resistance ◽  
Resistance Vessels ◽  
Left Stellate Ganglion ◽  
Increased Blood Flow

The mechanism of the diastolic pressure elevation occurring during left stellate ganglion stimulation was investigated. The cardiac output rose considerably, the heart rate remained essentially unchanged, and the total peripheral resistance fell moderately. The diastolic rise appeared to be due to increased blood flow rather than to any active changes in resistance vessels.

scholarly journals Age-Dependent Dysregulation of Muscle Vasculature and Blood Flow Recovery after Hindlimb Ischemia in the mdx Model of Duchenne Muscular Dystrophy

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 481
Author(s):  
Paulina Podkalicka ◽  
Olga Mucha ◽  
Katarzyna Kaziród ◽  
Iwona Bronisz-Budzyńska ◽  
Sophie Ostrowska-Paton ◽  
...  
Keyword(s):  
Blood Flow ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Blood Vessels ◽  
Mdx Mice ◽  
Hindlimb Ischemia ◽  
Double Positive ◽  
Functional Studies ◽  
Age Dependent ◽  
Dystrophic Mice

Duchenne muscular dystrophy (DMD), caused by a lack of functional dystrophin, is characterized by progressive muscle degeneration. Interestingly, dystrophin is also expressed in endothelial cells (ECs), and insufficient angiogenesis has already been hypothesized to contribute to DMD pathology, however, its status in mdx mice, a model of DMD, is still not fully clear. Our study aimed to reveal angiogenesis-related alterations in skeletal muscles of mdx mice compared to wild-type (WT) counterparts. By investigating 6- and 12-week-old mice, we sought to verify if those changes are age-dependent. We utilized a broad spectrum of methods ranging from gene expression analysis, flow cytometry, and immunofluorescence imaging to determine the level of angiogenic markers and to assess muscle blood vessel abundance. Finally, we implemented the hindlimb ischemia (HLI) model, more biologically relevant in the context of functional studies evaluating angiogenesis/arteriogenesis processes. We demonstrated that both 6- and 12-week-old dystrophic mice exhibited dysregulation of several angiogenic factors, including decreased vascular endothelial growth factor A (VEGF) in different muscle types. Nonetheless, in younger, 6-week-old mdx animals, neither the abundance of CD31+α-SMA+ double-positive blood vessels nor basal blood flow and its restoration after HLI was affected. In 12-week-old mdx mice, although a higher number of CD31+α-SMA+ double-positive blood vessels and an increased percentage of skeletal muscle ECs were found, the abundance of pericytes was diminished, and blood flow was reduced. Moreover, impeded perfusion recovery after HLI associated with a blunted inflammatory and regenerative response was evident in 12-week-old dystrophic mice. Hence, our results reinforce the hypothesis of age-dependent angiogenic dysfunction in dystrophic mice. In conclusion, we suggest that older mdx mice constitute an appropriate model for preclinical studies evaluating the effectiveness of vascular-based therapies aimed at the restoration of functional angiogenesis to mitigate DMD severity.

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