Modeling the dynamics of lung tissue with pulsating blood-flow in pulmonary arteries for bioimpedance simulation

2015 ◽  
pp. 29-34
Keyword(s):  
Blood Flow ◽  
Lung Tissue ◽  
Pulmonary Arteries

Endogenous Hydrogen Sulfide Regulates Pulmonary Artery Collagen Remodeling in Rats with High Pulmonary Blood Flow

2009 ◽  
Vol 234 (5) ◽  
pp. 504-512 ◽  
Author(s):  
Xiaohui Li ◽  
Hongfang Jin ◽  
Geng Bin ◽  
Li Wang ◽  
Chaoshu Tang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Hydrogen Sulfide ◽  
Pulmonary Artery ◽  
Lung Tissue ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Tissue Growth ◽  
Pulmonary Vasculature ◽  
Collagen Remodeling ◽  
Collagen Iii

The mechanisms responsible for the structural remodeling of pulmonary vasculature induced by increased pulmonary blood flow are not fully understood. This study explores the effect of endogenous hydrogen sulfide (H2S), a novel gasotransmitter, on collagen remodeling of the pulmonary artery in rats with high pulmonary blood flow. Thirty-two Sprague-Dawley rats were randomly divided into sham, shunt, sham+PPG (D,L-propargylglycine, an inhibitor of cystathionine-γ-lyase), and shunt+PPG groups. After 4 weeks of shunting, the relative medial thickness (RMT) of pulmonary arteries and H2S concentration in lung tissues were investigated. Collagen I and collagen III were evaluated by hydroxyproline assay, sirius-red staining, and immunohistochemistry. Pulmonary artery matrix metalloproteinase-13 (MMP-13), tissue inhibitor of metalloproteinase-1 (TIMP-1), and connective tissue growth factor (CTGF) were evaluated by immunohistochemistry. After 4 weeks of aortocaval shunting, resulting in an elevation of lung tissue H2S to 116.4%, rats exhibited collagen remodeling and increased CTGF expression in the pulmonary arteries. Compared with those of the shunt group, lung tissue H2S production was lowered by 23.4%, RMT of the pulmonary artery further increased by 39.5%, pulmonary artery collagen accumulation became obvious, and pulmonary artery CTGF expression elevated ( P < 0.01) in the shunted rats treated with PPG. However, pulmonary artery MMP-13 and TIMP-1 expressions decreased significantly in rats of shunt+PPG group ( P < 0.01). This study suggests that endogenous H2S exerts an important regulatory effect on pulmonary collagen remodeling induced by high pulmonary blood flow.

scholarly journals A STUDY OF THE RELATION OF PULMONARY AND BRONCHIAL CIRCULATION

1913 ◽  
Vol 18 (5) ◽  
pp. 500-506 ◽  
Author(s):  
Albert A. Ghoreyeb ◽  
Howard T. Karsner
Keyword(s):  
Pulmonary Artery ◽  
Lung Tissue ◽  
Bronchial Artery ◽  
Venous Blood ◽  
Pulmonary Arteries ◽  
The Other ◽  
Main Trunk ◽  
Intimate Contact ◽  
Bronchial Arteries ◽  
Bronchial Circulation

The most striking point brought out in this study is that as long as a definite pressure is maintained in either the pulmonary or bronchial circulations, the admixture of bloods is extremely limited. It is easily conceivable that more mixture occurs normally than under the conditions of the experiment, but there is no reason for considering this to be a large difference. If, however, in either system the pressure sinks to zero the possibility of supply by the other system becomes evident. It takes much longer for the mass injected through the bronchial arteries to penetrate to all parts of the lung than when the mass is injected through the pulmonary artery; but when accomplished, the injection reaches to all capillaries including those of the pleura, the only vessels remaining uninjected being the larger trunks of the pulmonary artery. On the other hand, the injection of the bronchial vessels by way of the pulmonary arteries is not complete with normal pressure, but occurs rapidly when a high pulmonary pressure is employed. It is therefore probable that either circulation can suffice for the simple nutritive demands of the lung if the other system is interfered with. It has been shown that embolism of the pulmonary artery, without other circulatory disturbance, does not lead to necrosis of the affected area of the lung, but it is probable that the preservation of circulation is not due to collateral bronchial circulation so much as to the free anastomosis and early division into capillaries of the pulmonary artery. In support of this statement is the fact that the appearance is not altered when the bronchials are ligated at their origin. The same ligation shows no subsequent interference with the nutrition of the bronchi up to a period of five weeks, demonstrating that the pulmonary circulation is sufficient to provide for the nutrition of the bronchi. If, however, as Virchow has shown, the pulmonary artery supplying an entire lobe be occluded, the bronchial circulation can and does suffice for the nutrition of the lobe. In the case of the occlusion of a branch of the pulmonary artery the pressure in the area interfered with does not sink to zero because of the collateral circulation in this area; whereas, if the main trunk is occluded no collateral supply is available, the pressure sinks to zero, and the bronchial artery becomes available as a source of blood supply. It must be remembered that the lung tissue, as a whole, has ready access to oxygen and this gas is the nutritive element acquired by the blood in the lungs. From these studies it would appear that the part of the lung tissue not in intimate contact with oxygen in the air is supplied by oxygenated blood of the bronchial arteries, and that the tissues through which the pulmonary blood circulates take up whatever organized nutriment they need from the pulmonary blood and possibly provide for their oxygen and carbon dioxide interchange (which must be very slight) either directly with the alveolar air, or by finding sufficient oxygen in the venous blood of the pulmonary artery. The studies of the injected specimens confirm Küttner's findings of a very rapid breaking up of the pulmonary artery into capillaries. In all the specimens studied it was found that although the pleural vessels can be injected by way of the bronchial arteries when there is zero pressure in the pulmonary arteries, yet when the two sets of vessels are injected simultaneously in the dog, the pleural vessels invariably derive their supply of injection mass from the pulmonary artery.

scholarly journals Mechanisms of calcitonin gene-related peptide-induced increases of pulmonary blood flow in fetal sheep

2000 ◽  
Vol 279 (4) ◽  
pp. H1654-H1660 ◽  
Author(s):  
Yasushi Takahashi ◽  
Maartje De Vroomen ◽  
Christine Roman ◽  
Michael A. Heymann
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Calcitonin Gene Related Peptide ◽  
Fetal Sheep ◽  
Nitric Oxide Synthase Inhibitor ◽  
Flow Transducer ◽  
Related Peptide ◽  
Calcitonin Gene

Fetal pulmonary blood flow is regulated by various vasoactive substances. One, calcitonin gene-related peptide (CGRP), increases pulmonary blood flow. We examined four key physiological mechanisms underlying this response using the blocker drugs CGRP receptor blocker (CGRP8–37), nitric oxide synthase inhibitor [ N ω-nitro-l-arginine (l-NNA)], adenosine triphosphate-dependent potassium (KATP) channel blocker (glibenclamide), and cyclooxygenase inhibitor (indomethacin) in 17 near-term fetal sheep. Catheters were placed in the left (LPA) and main pulmonary arteries, and an ultrasonic flow transducer was placed around the LPA to measure flow continuously. CGRP was injected directly into the LPA (mean 1.02 μg/kg) before and after blockade, and responses to CGRP were statistically compared. Before blockade, CGRP increased LPA blood flow from 23 ± 25 to 145 ± 77 ml/min (means ± SD), and these increases were significantly attenuated by CGRP8–37( n = 6; 91% inhibition), l-NNA ( n = 6; 86% inhibition), and glibenclamide ( n = 6; 69% inhibition). No significant changes were found with indomethacin ( n = 6; 4% inhibition). Thus, in the fetal pulmonary circulation, CGRP increases pulmonary blood flow not only through its specific receptor but also, in part, through nitric oxide release and KATP channel activation.

scholarly journals Progressive dysfunction of nitric oxide synthase in a lamb model of chronically increased pulmonary blood flow: a role for oxidative stress

2008 ◽  
Vol 295 (5) ◽  
pp. L756-L766 ◽  
Author(s):  
Peter E. Oishi ◽  
Dean A. Wiseman ◽  
Shruti Sharma ◽  
Sanjiv Kumar ◽  
Yali Hou ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Blood Flow ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Lung Tissue ◽  
Pulmonary Blood Flow ◽  
Artery Pressure ◽  
Oxide Synthase ◽  
Inhaled No

Cardiac defects associated with increased pulmonary blood flow result in pulmonary vascular dysfunction that may relate to a decrease in bioavailable nitric oxide (NO). An 8-mm graft (shunt) was placed between the aorta and pulmonary artery in 30 late gestation fetal lambs; 27 fetal lambs underwent a sham procedure. Hemodynamic responses to ACh (1 μg/kg) and inhaled NO (40 ppm) were assessed at 2, 4, and 8 wk of age. Lung tissue nitric oxide synthase (NOS) activity, endothelial NOS (eNOS), neuronal NOS (nNOS), inducible NOS (iNOS), and heat shock protein 90 (HSP90), lung tissue and plasma nitrate and nitrite (NOx), and lung tissue superoxide anion and nitrated eNOS levels were determined. In shunted lambs, ACh decreased pulmonary artery pressure at 2 wk ( P < 0.05) but not at 4 and 8 wk. Inhaled NO decreased pulmonary artery pressure at each age ( P < 0.05). In control lambs, ACh and inhaled NO decreased pulmonary artery pressure at each age ( P < 0.05). Total NOS activity did not change from 2 to 8 wk in control lambs but increased in shunted lambs (ANOVA, P < 0.05). Conversely, NOxlevels relative to NOS activity were lower in shunted lambs than controls at 4 and 8 wk ( P < 0.05). eNOS protein levels were greater in shunted lambs than controls at 4 wk of age ( P < 0.05). Superoxide levels increased from 2 to 8 wk in control and shunted lambs (ANOVA, P < 0.05) and were greater in shunted lambs than controls at all ages ( P < 0.05). Nitrated eNOS levels were greater in shunted lambs than controls at each age ( P < 0.05). We conclude that increased pulmonary blood flow results in progressive impairment of basal and agonist-induced NOS function, in part secondary to oxidative stress that decreases bioavailable NO.

Blood Flow Velocity Profiles in Pulmonary Branch Arteries in Lambs

1995 ◽  
Vol 117 (2) ◽  
pp. 237-241
Author(s):  
H. Katayama ◽  
G. W. Henry ◽  
C. L. Lucas ◽  
B. Ha ◽  
J. I. Ferreiro ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Maximum Velocity ◽  
Left Pulmonary Artery ◽  
Control Group ◽  
Pulsed Doppler Ultrasound ◽  
Right Pulmonary Artery ◽  
Blood Flow Velocities ◽  
The Right

We studied the detailed profiles of blood flow in the right and left pulmonary arteries using 20 MHz pulsed Doppler ultrasound equipment in a lamb model. Fourteen lambs aged four to six weeks were selected. In six lambs, monocrotaline pyrrole was injected parenterally to create pulmonary hypertension (PH group). Eight other lambs served as unaltered controls (control group). The blood flow velocities were sampled in 1mm increments along the anterior—posterior axis of the branch arteries. The maximum velocity of the forward flow in the left pulmonary artery was higher than that in the right pulmonary artery in the control group (71.7 ± 15.9cm/s vs 60.2 ± 13.5; p < 0.05). The fastest backward flow was located at the posterior position of the vessel in the right pulmonary artery in the control group. No significant bias in location was shown in the left pulmonary artery. Using indices of P90, acceleration time, P90*AcT, the velocity waveforms in the PH group were compared with those in the control group. In the left pulmonary artery, every index in the control group showed a significantly greater value that in the PH group. On the other hand, no significant differences were found between either group in the right pulmonary artery.

Solubility of inert gases in homogenates of canine lung tissue

1979 ◽  
Vol 46 (6) ◽  
pp. 1207-1210 ◽  
Author(s):  
I. H. Young ◽  
P. D. Wagner
Keyword(s):  
Blood Flow ◽  
Diethyl Ether ◽  
Lung Tissue ◽  
Sulfur Hexafluoride ◽  
Inert Gases ◽  
Tissue Volume ◽  
Dog Blood

The solubility of sulfur hexafluoride (SF6), ethane, cyclopropane, halothane, diethyl ether, and acetone in homogenates of dog lung tissue were measured and compared with values obtained in dog blood. The measurements were made to provide data for a method for determining distribution of ventilation, blood flow, and tissue volume (Physiologist 20: 95, 1977) and for reasons discussed, the blood was not washed from the tissue prior to homogenization. All gases except SF6 were significantly more soluble in blood than lung tissue, whereas SF6 was 3.7 times more soluble in tissue than blood. It was further found that SF6 is 5 times more soluble, and ethane is twice as soluble in tissue obtained from lungs containing blood than in tissue obtained from rinsed lungs, suggesting that measurements of parenchymal solubility made on tissue from sinsed lungs may be considerably in error for some lipid-soluble gases.

Posture primarily affects lung tissue distribution with minor effect on blood flow and ventilation

2007 ◽  
Vol 156 (3) ◽  
pp. 293-303 ◽  
Author(s):  
Johan Petersson ◽  
Malin Rohdin ◽  
Alejandro Sánchez-Crespo ◽  
Sven Nyrén ◽  
Hans Jacobsson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Tissue Distribution ◽  
Lung Tissue ◽  
Minor Effect

Effect of baroreceptor reflex stimulation on blood flow to an atelectatic lung

1982 ◽  
Vol 52 (5) ◽  
pp. 1128-1132 ◽  
Author(s):  
W. B. Strawn ◽  
S. M. Hall ◽  
M. G. Levitzky
Keyword(s):  
Blood Flow ◽  
Carotid Sinus ◽  
Initial Period ◽  
Pulmonary Arteries ◽  
Baroreceptor Reflex ◽  
Physiological Salt Solution ◽  
Vascular Response ◽  
Left And Right ◽  
Reflex Stimulation ◽  
Stimulation Of

The effect of baroreceptor reflex stimulation by carotid sinus hypotension on the pulmonary vascular response to atelectasis was studied in eight dogs anesthetized with chloralose. Closed-chest dogs with electromagnetic flow probes previously implanted on their left (QL) and main (QT) pulmonary arteries had their left and right lungs ventilated separately. Their carotid sinuses were isolated bilaterally and perfused by a pulsatile pump with a physiological salt solution. After an initial period of bilateral 100% O2 ventilation with carotid sinus perfusion pressures (CSPP) set at each animal's initial mean arterial pressure (98 +/- 19 Torr), the left airway was occluded, QL/QT fell from 0.33 +/- 0.01 to 0.24 +/- 0.02 and PO2 fell from 323 +/- 35 Torr to 74 + 7 Torr. When CSPP was lowered to 21 +/- 3 Torr, there were no changes in QL/QT and PO2. These results suggest that stimulation of the baroreceptor reflex by carotid sinus hypotension does not interfere with the diversion of pulmonary blood flow away from a unilaterally atelectatic lung.

Expression of VEGF and its receptors Flt-1 and Flk-1/KDR is altered in lambs with increased pulmonary blood flow and pulmonary hypertension

2003 ◽  
Vol 285 (1) ◽  
pp. L222-L231 ◽  
Author(s):  
Eugenia Mata-Greenwood ◽  
Barbara Meyrick ◽  
Scott J. Soifer ◽  
Jeffrey R. Fineman ◽  
Stephen M. Black
Keyword(s):  
Blood Flow ◽  
Smooth Muscle ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Immunohistochemical Analysis ◽  
Muscle Layer ◽  
Pulmonary Epithelium ◽  
Pulmonary Vessel ◽  
Smooth Muscle Layer ◽  
Vegf Signaling

Utilizing in utero aortopulmonary vascular graft placement, we developed a lamb model of congenital heart disease and increased pulmonary blood flow. We showed previously that these lambs have increased pulmonary vessel number at 4 wk of age. To determine whether this was associated with alterations in VEGF signaling, we investigated vascular changes in expression of VEGF and its receptors, Flt-1 and KDR/Flk-1, in the lungs of shunted and age-matched control lambs during the first 8 wk of life. Western blot analysis demonstrated that VEGF, Flt-1, and KDR/Flk-1 expression was higher in shunted lambs. VEGF and Flt-1 expression was increased at 4 and 8 wk of age ( P <0.05). However, KDR/Flk-1 expression was higher in shunted lambs only at 1 and 4 wk of age ( P <0.05). Immunohistochemical analysis demonstrated that, in control and shunted lambs, VEGF localized to the smooth muscle layer of vessels and airways and to the pulmonary epithelium while increased VEGF expression was localized to the smooth muscle layer of thickened media in remodeled vessels in shunted lambs. VEGF receptors were localized exclusively in the endothelium of pulmonary vessels. Flt-1 was increased in the endothelium of small pulmonary arteries in shunted animals at 4 and 8 wk of age, whereas KDR/Flk-1 was increased in small pulmonary arteries at 1 and 4 wk of age. Our data suggest that increased pulmonary blood flow upregulates expression of VEGF and its receptors, and this may be important in development of the vascular remodeling in shunted lambs.

In vivo support for the new concept of pulmonary blood flow-mediated CO2 gas excretion in the lungs

2015 ◽  
Vol 308 (12) ◽  
pp. L1224-L1236 ◽  
Author(s):  
Yoshiko Kawai ◽  
Kumiko Ajima ◽  
Maki Kaidoh ◽  
Masao Sakaguchi ◽  
Satoshi Tanaka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Artery ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Systemic Arterial Pressure ◽  
Maximal Velocity ◽  
Clinical Models ◽  
A Cell ◽  
Induced Changes

To further examine the validity of the proposed concept of pulmonary blood flow-dependent CO2 gas excretion in the lungs, we investigated the effects of intramediastinal balloon catheterization-, pulmonary artery catheterization-, or isoprenaline (ISP)-induced changes in pulmonary blood flow on the end-expiratory CO2 gas pressure (PeCO2), the maximal velocity of the pulmonary artery (Max Vp), systemic arterial pressure, and heart rate of anesthetized rabbits. We also evaluated the changes in the PeCO2 in clinical models of anemia or pulmonary embolism. An almost linear relationship was detected between the PeCO2 and Max Vp. In an experiment in which small pulmonary arteries were subjected to stenosis, the PeCO2 fell rapidly, and the speed of the reduction was dependent on the degree of stenosis. ISP produced significant increases in the PeCO2 of the anesthetized rabbits. Conversely, treatment with piceatannol or acetazolamide induced significant reductions in the PeCO2. Treatment with a cell surface F1/FO ATP synthase antibody caused significant reductions in the PeCO2 itself and the ISP-induced increase in the PeCO2. Neither the PeCO2 nor SAP was significantly influenced by marked anemia [%hematocrit (Ht), 70∼47%]. On the other hand, in the presence of less severe anemia (%Ht: 100∼70%) both the PeCO2 and SAP fell significantly when the rabbits' blood viscosity was decreased. The rabbits in which pulmonary embolisms were induced demonstrated significantly reduced PeCO2 values, which was compatible with the lowering of their Max Vp. In conclusion, we reaffirm the validity of the proposed concept of CO2 gas exchange in the lungs.

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