Splanchnic hemodynamics in portal-hypertensive rats: measurement with gamma-labeled microspheres

1982 ◽  
Vol 242 (2) ◽  
pp. G156-G160 ◽  
Author(s):  
R. J. Groszmann ◽  
J. Vorobioff ◽  
E. Riley
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Experimental Models ◽  
Hypertensive Rats ◽  
Venous Flow ◽  
Reliable Technique ◽  
Splanchnic Hemodynamics ◽  
Significant Difference ◽  
Normal Rat ◽  
The Difference

A method to quantitate hepatic arterial flow (HA), portal venous flow (PBF), and blood flow through portal-systemic shunts (ShBF) in portal-hypertensive rats is described. This method relies on the injection of two differently radiolabeled microspheres (15 micrometers) into the left ventricle and spleen. To evaluate the usefulness of this technique, studies were performed on normal, cirrhotic, and portal vein-ligated rats anesthetized with ketamine. With this method, PBF is calculated indirectly from the sums of the blood flow of the splanchnic organs that drain into the portal vein. In the portal-hypertensive animals with portal-systemic shunting, this technique allows for the determination of PBF perfusing the liver [hepatic fraction of portal flow (HFP)] and PBF escaping through portal-systemic shunts (ShBF). The portal vein-ligated rats have higher HA flow (0.68 +/- 0.08 ml . min-1 . g-1) and lower HFP (0.08 +/- 0.01 ml . min-1 . g-1) than either the cirrhotic (HA: 0.27 +/- 0.03 ml . min-1 . g-1, P less than 0.01; HFP: 1.20 +/- 0.20 ml . min-1 . g-1, P less than 0.01) or the normal rat (HA: 0.29 +/- 0.06 ml . min-1 . g-1, P less than 0.01; HFP: 1.39 +/- 0.16 ml . min-1 . g-1, P less than 0.01). No significant difference was found between the cirrhotic and normal rats. The ShBF was higher in the portal vein-ligated rats (21.4 +/- 2.8 ml/min) than in the cirrhotic (4.6 +/- 2.5 ml/min, P less than 0.001) or normal rats (0.03 +/- 0.005 ml/min, P less than 0.01). The difference between the cirrhotic and normal animals was also significant (P less than 0.05). This is a simple, rapid, and reliable technique that allows for the quantitation of splanchnic hemodynamics in experimental models with portal hypertension.

scholarly journals Sustained density of neuroendocrine cells with aging precedes development of prostatic hyperplasia in spontaneously hypertensive rats

BMC Urology ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Yuki Kyoda ◽  
Koji Ichihara ◽  
Kohei Hashimoto ◽  
Ko Kobayashi ◽  
Fumimasa Fukuta ◽  
...  
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Prostatic Hyperplasia ◽  
Neuroendocrine Cells ◽  
Initial Growth ◽  
Hypertensive Rats ◽  
Initial Development ◽  
Spontaneously Hypertensive ◽  
Significant Difference ◽  
The Difference ◽  
Wistar Kyoto

Abstract Background Neuroendocrine (NE) cells may have an impact on the development and initial growth of benign prostatic hyperplasia (BPH) according to previous human studies. Methods To explore the relationship of NE cells and BPH development, we compared the density of NE cells and also prostatic weight in spontaneously hypertensive rats (SHR), which develop by aging, and Wistar-Kyoto rats (WKY) as control. The total weights of the epithelium and stroma in the ventral lobes of 8-, 12, 16-, 28- and 56-week-old SHR and WKY were calculated using Image J software. NE cells in the ventral prostatic ducts (VPd) were quantified using immunohistochemical staining for serotonin. Results Although there was no significant difference in the estimated total weight of the epithelium and stroma in the ventral lobes adjusted by body weight (ES weight) between the two groups at 8, 12 and 16 weeks of age, ES weight was significantly greater in the SHR group than in the WKT group at 28 and 56 weeks. The density of NE cells in the VPd decreased with aging in the WKY group, whereas it was sustained until 16 weeks and then decreased with aging in the SHR group. The difference in the density between the two groups was most marked at 16 weeks of age. Conclusion In the natural history of BPH, NE cells may play an important role in the initial development of BPH because sustained density of NE cells in the VPd precedes the development of prostatic hyperplasia.

Acute Hepatic Encephalopathy in the Rat: The Effect of Cross-Circulation

1974 ◽  
Vol 47 (6) ◽  
pp. 609-615
Author(s):  
Jacqueline Roche-Sicot ◽  
C. Sicot ◽  
Michèle Peignoux ◽  
Denise Bourdiau ◽  
Francine Degos ◽  
...  
Keyword(s):  
Hepatic Encephalopathy ◽  
Portal Vein ◽  
Flow Rate ◽  
Exchange Flow ◽  
Systemic Blood ◽  
Normal Rat ◽  
Acute Hepatic Encephalopathy ◽  
The Difference

1. The effect of cross-circulation on hepatic encephalopathy (evaluated by electroencephalography; EEG) induced by hepatectomy in the rat was examined. 2. Systemic-systemic cross-circulation induced improvement of the altered EEG in only two out of seven liverless rats when the exchange-flow rate was 6.4 ml min−1 kg body wt.−1, and in all seven liverless rats when the exchange-flow rate was 14.0 ml min−1 kg body wt.−1; the difference is statistically significant (P = 0.011). 3. Systemic-portal cross-circulation (systemic blood from the liverless rat being infused into the portal vein of the normal rat) induced improvement of the altered EEG in all seven liverless rats although the exchange-flow rate was only 6.4 ml min−1 kg body wt.−1 4. It is concluded (a) that a certain level of exchange-flow rate is required for cross-circulation to be efficient, and (b) that, for the same exchange-flow rate, systemic-portal cross-circulation is more efficient than systemic-systemic cross-circulation.

Hepatic blood flow distribution: consideration of gravity, liver surface, and norepinephrine on regional heterogeneity

1993 ◽  
Vol 71 (2) ◽  
pp. 128-135 ◽  
Author(s):  
W. Wayne Lautt ◽  
Joshua Schafer ◽  
Dallas J. Legare
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Hepatic Artery ◽  
Arterial Occlusion ◽  
Flow Distribution ◽  
Arterial Flow ◽  
Blood Flow Distribution ◽  
Hepatic Arterial Flow ◽  
Venous Flow ◽  
Core Samples

Blood flow distribution within the livers of cats and dogs was assessed using 15-μm microspheres injected into the hepatic artery and portal vein. Representative vertical core samples (n = 11–18) were taken from the thickest part of each liver. Heterogeneity was assessed in several ways. The difference in total flow to different lobes was greater in dogs than in cats, and in dogs, those lobes with highest portal venous flow had lowest hepatic arterial flow. Overall flow variance was very high in both species, with adjacent surface samples in a single lobe showing variance of 15–22% for both vessels. The ratio of highest to lowest flow within core samples averaged 2.1–3.4 for both vessels in both species. The hepatic arterial flow was highest to the surface 2 mm of the liver. Portal flow most often (31% of all samples) showed a pattern of highest flow to the top, graduating down to lowest flow to the bottom (dorsal side) of the vertical cores. However, this pattern appeared much more frequently in the most ventral liver lobes and very seldom in the lobes lying beneath the liver mass. Norepinephrine reduced heterogeneity. Hepatic arterial occlusion for 10 min produced minor and inconsistent reduction of heterogeneity. Rotating cats from back to front and again to back disrupted patterns of distribution but not in a way that could be interpreted as due to effects of gravity. Flow patterns changed with time. The heterogeneity of perfusion appears to be under dynamic and multiple interacting forces.Key words: blood flow distribution, blood flow heterogeneity, hepatic artery, portal vein, liver.

Evolution of portal hypertension and mechanisms involved in its maintenance in a rat model

1985 ◽  
Vol 248 (6) ◽  
pp. G618-G625 ◽  
Author(s):  
E. Sikuler ◽  
D. Kravetz ◽  
R. J. Groszmann
Keyword(s):  
Blood Flow ◽  
Portal Hypertension ◽  
Portal Vein ◽  
Rat Model ◽  
Portal Pressure ◽  
Portal System ◽  
Hypertensive Rats ◽  
Hemodynamic Changes ◽  
Sequence Of Events ◽  
Radioactive Microsphere

In rats with portal hypertension induced by partial ligation of the portal vein, we have recently demonstrated an increased portal venous inflow that becomes an important factor in the maintenance of portal hypertension. The sequence of events that leads into this circulatory disarray is unknown. We evaluated chronologically the chain of hemodynamic changes that occurred after portal hypertension was induced by partial ligation of the portal vein. In this model it is possible to follow, from the initiation of the portal-hypertensive state, the interaction between blood flow and resistance in the portal system as well as the relation between the development of portal-systemic shunting and the elevated portal venous inflow. The study was performed in 45 portal-hypertensive rats and in 29 sham-operated rats. Blood flow and portal-systemic shunting were measured by radioactive microsphere techniques. The constriction of the portal vein was immediately followed by a resistance-induced portal hypertension characterized by increased portal resistance (9.78 +/- 0.89 vs. 4.18 +/- 0.71 dyn X s X cm-5 X 10(4), mean +/- SE, P less than 0.01), increased portal pressure (17.7 +/- 0.9 vs. 9.5 +/- 0.6 mmHg, P less than 0.001), and decreased portal venous inflow (3.93 +/- 0.26 vs. 6.82 +/- 0.49 ml X min-1 X 100 g body wt-1, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals MON-488 Technologies of Diffuse Optics in the Diagnosis of Thyroid Cancer

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Gloria Beatriz Aranda Velazquez ◽  
Giuseppe Lo Presti ◽  
Lorenzo Cortese ◽  
Davide Contini ◽  
Alberto Dalla Mora ◽  
...  
Keyword(s):  
Blood Flow ◽  
Thyroid Cancer ◽  
Near Infrared ◽  
Thyroid Nodules ◽  
Microvascular Blood Flow ◽  
Flow Index ◽  
Diffuse Optics ◽  
Significant Difference ◽  
Blood Flow Index ◽  
The Difference

Abstract BACKGROUND: The most common tool to test malignancy in the study of thyroid nodules (NT) is ultrasound and fine needle aspiration biopsy (FNAB). However, the sensitivity and specificity of the method and the effectiveness in thyroid cancer are limited; therefore new methods to study thyroid nodules are required. In this way our goal is to introduce hybrid diffuse optical instruments that are capable to measure and discriminate altered microvascular blood flow, blood volume and tissue scattering coefficients of TN. Near-infrared diffuse optical technologies aim to overcome the shortcomings of present techniques while screening for malignant thyroid nodules for early and fast diagnosis of cancer. This idea was based on the previous experience in breast cancers with diffuse optical techniques. METHODS: We have developed a device based on near-infrared diffuse correlation spectroscopy (DCS), which is a technology aimed at retrieving the microvascular flow of a certain region of tissue by mean of low power near-infrared laser light, and used in combination with a commercial ultrasound system (US). In order to combine these devices, we have developed a probe enabling multimodal data acquisition and subsequently we have analyzed the optical properties and the blood flow index in the thyroid lobes of eleven subjects who presented a thyroid nodule. RESULTS: Four subjects have required FNAB: P4 and P7 were reported as being malignant (Bethesda VI and IV respectively) while P6 and P8 were evaluated as being benign (Bethesda II). Surgical removal confirmed papillary thyroid carcinoma in P4, while denied the result of FNAB for P7 (Multinodular thyroid hyperplasia). We have considered the contralateral lobe as intra-subject reference to validate the feasibility of the DCS system in a very absorbing tissue as thyroid is. The difference between the blood flow index of the nodule and the contralateral lobe is maximum for subject P4, while the difference in benign subjects is lower. T-test showed no significant difference between benign nodules and contralateral lobes. Subject P7 showed a small difference as for other benign subjects despite the FNAB results indicating presence of malignancy. CONCLUSION: Apparently diffuse optics technologies would be able to differentiate malignant thyroid nodules from benign thyroid nodules, but more measurements require confirming our preliminary results as that diffuse optical technology can complement the current techniques such as US and FNAB. A new measurement campaign is being scheduled with a completed, fully integrated device that was developed within the LUCA project (http://www.luca-project.eu).

scholarly journals Oscillations and chaos in renal blood flow control.

1993 ◽  
Vol 4 (6) ◽  
pp. 1275-1287
Author(s):  
N H Holstein-Rathlou
Keyword(s):  
Blood Flow ◽  
Signal Transmission ◽  
Deterministic Chaos ◽  
Open Loop ◽  
Tubuloglomerular Feedback ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Model Studies ◽  
Mechanism Model ◽  
The Difference

In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model studies show that the key parameters determining the stability of the TGF system are the open loop gain of the system and the time delays in the signal transmission through the various components of the feedback loop. Within a broad range of parameters, the system is unstable and has self-sustained stable oscillations. The parameter range where model studies show instability overlaps with the physiologic range for the values of the same parameters. The system appears to be poised on the border between stability and oscillation, and a small parameter change may cause the system to move from one state to the other. In renovascular and spontaneously hypertensive rats, regular oscillations give way to highly irregular, chaotic fluctuations. The chaotic fluctuations appear to have the same mechanism as the regular TGF-mediated oscillations. The irregular fluctuations most likely represent a parameter-dependent transition from a limit cycle (regular oscillation) to deterministic chaos. The key parameters causing the transition have not been identified. Associated with the difference in the dynamics of TGF between normotensive and hypertensive rats is a change in the dynamic autoregulation of total RBF. This is especially prominent in the frequency range in which TGF operates, and it is suggested that a causal relationship may exist between the two phenomena. This difference may play a role in the pathogenesis of hypertension by altering the renal response to the normal fluctuations in arterial pressure.

In silico analyses of blood flow and oxygen transport in human micro-veins and valves

2022 ◽  
pp. 1-16
Author(s):  
Rajeeva Pandian Navaneeth Krishna ◽  
Abhishek Jain
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Experimental Models ◽  
Vortical Flow ◽  
Venous Flow ◽  
Venous Valves ◽  
Hypoxic Environment ◽  
Oxygen Gradients ◽  
Direct Measurements ◽  
Complex Fluid

BACKGROUND: Almost 95% of the venous valves are micron scale found in veins smaller than 300μm diameter. The fluid dynamics of blood flow and transport through these micro venous valves and their contribution to thrombosis is not yet well understood or characterized due to difficulty in making direct measurements in murine models. OBJECTIVE: The unique flow patterns that may arise in physiological and pathological non-actuating micro venous valves are predicted. METHODS: Computational fluid and transport simulations are used to model blood flow and oxygen gradients in a microfluidic vein. RESULTS: The model successfully recreates the typical non-Newtonian vortical flow within the valve cusps seen in preclinical experimental models and in clinic. The analysis further reveals variation in the vortex strengths due to temporal changes in blood flow. The cusp oxygen is typically low from the main lumen, and it is regulated by systemic venous flow. CONCLUSIONS: The analysis leads to a clinically-relevant hypothesis that micro venous valves may not create a hypoxic environment needed for endothelial inflammation, which is one of the main causes of thrombosis. However, incompetent micro venous valves are still locations for complex fluid dynamics of blood leading to low shear regions that may contribute to thrombosis through other pathways.

Finger dexterity, skin temperature, and blood flow during auxiliary heating in the cold

2003 ◽  
Vol 95 (2) ◽  
pp. 758-770 ◽  
Author(s):  
Dragan Brajkovic ◽  
Michel B. Ducharme
Keyword(s):  
Blood Flow ◽  
Skin Temperature ◽  
Heat Content ◽  
Finger Dexterity ◽  
Significant Difference ◽  
Forearm Skin ◽  
The Difference ◽  
Finger Skin ◽  
Forearm Muscle ◽  
Body Heat

The primary purpose of the present study was to compare the effectiveness of two forms of hand heating and to discuss specific trends that relate finger dexterity performance to variables such as finger skin temperature (Tfing), finger blood flow (Q̇fing), forearm skin temperature (Tfsk), forearm muscle temperature (Tfmus), mean weighted body skin temperature (T̄sk), and change in body heat content (ΔHb). These variables along with rate of body heat storage, toe skin temperature, and change in rectal temperature were measured during direct and indirect hand heating. Direct hand heating involved the use of electrically heated gloves to keep the fingers warm (heated gloves condition), whereas indirect hand heating involved warming the fingers indirectly by actively heating the torso with an electrically heated vest (heated vest condition). Seven men (age 35.6 ± 5.6 yr) were subjected to each method of hand heating while they sat in a chair for 3 h during exposure to -25°C air. Q̇fing was significantly ( P < 0.05) higher during the heated vest condition compared with the heated gloves condition (234 ± 28 and 33 ± 4 perfusion units, respectively), despite a similar Tfing (which ranged between 28 and 35°C during the 3-h exposure). Despite the difference in Q̇fing, there was no significant difference in finger dexterity performance. Therefore, finger dexterity can be maintained with direct hand heating despite a low Q̇fing. ΔHb, T̄sk, and Tfmus reached a low of -472 ± 18 kJ, 28.5 ± 0.3°C, and 29.8 ± 0.5°C, respectively, during the heated gloves condition, but the values were not low enough to affect finger dexterity.

Effects of pentobarbital sodium anesthesia on splanchnic hemodynamics of normal and portal-hypertensive rats

1985 ◽  
Vol 249 (4) ◽  
pp. G528-G532 ◽  
Author(s):  
S. S. Lee ◽  
C. Girod ◽  
D. Valla ◽  
P. Geoffroy ◽  
D. Lebrec
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Portal Hypertension ◽  
Portal Vein ◽  
Regional Blood Flow ◽  
Hypertensive Rats ◽  
Pentobarbital Sodium ◽  
Portal Vein Stenosis ◽  
Pentobarbital Sodium Anesthesia ◽  
Vein Stenosis

To determine the effect of pentobarbital sodium anesthesia on the rat with portal hypertension due to portal vein stenosis, four groups of rats were studied. Cardiac output and regional blood flow were measured by radioactive microspheres in anesthetized and conscious sham-operated and portal-hypertensive rats. Anesthesia markedly decreased cardiac output in both sham-operated (109.7 +/- 4.6 vs. 77.8 +/- 1.4 ml/min, P less than 0.001) and portal-hypertensive rats (130.1 +/- 7.6 vs. 93.8 +/- 5.3 ml/min, P less than 0.01). In spite of this diminution in cardiac output, pentobarbital did not significantly change absolute blood flow values of splanchnic organs in either group. However, the fractions of cardiac output perfusing the splanchnic organs were significantly increased by pentobarbital in both groups because of the decrease in cardiac output: sham operated, anesthetized, 22.86 +/- 1.19% vs. conscious, 14.83 +/- 1.02%, P less than 0.001; and portal hypertensive, anesthetized, 26.67 +/- 0.71% vs. conscious, 19.07 +/- 1.44%, P less than 0.001. The hyperdynamic circulation of the portal vein-stenosed rat compared with the sham-operated rat continued to manifest itself with significantly increased portal pressure, cardiac output, and splanchnic blood flow, whether the animal was anesthetized or awake. We conclude that, despite marked hemodynamic changes induced by pentobarbital, the rat with portal vein stenosis remains a useful experimental model of portal hypertension.

Fluorescent microsphere method is suitable for chronic bone blood flow measurement: a long-term study after meniscectomy in rabbits

2004 ◽  
Vol 96 (5) ◽  
pp. 1928-1936 ◽  
Author(s):  
H. Anetzberger ◽  
E. Thein ◽  
G. Löffler ◽  
K. Messmer
Keyword(s):  
Blood Flow ◽  
Tissue Sample ◽  
Left Ventricular ◽  
Bone Blood Flow ◽  
Reliable Technique ◽  
Fluorescent Microsphere ◽  
Long Term Study ◽  
Significant Difference ◽  
Long Term Experiments

The fluorescent microsphere (FM) method is considered a reliable technique to determine regional bone blood flow (RBBF) in acute experiments. In this study, we verified the accuracy and validity of this technique for measurement of RBBF in a long-term experiment and examined RBBF after meniscectomy. Twenty-four anesthetized female New Zealand white rabbits (3 groups, each n = 8) received consecutive left ventricular injections of FM in defined time intervals after meniscectomy: group 1 from preoperation to 3 wk postoperation; group 2 from 3 to 7 wk postoperation; and group 3 from 7 to 11 wk postoperation. To test the precision of the FM method, two FM species were injected simultaneously at the first and last measurement. After the experiment, humeri, femora, tibiae, and reference organs (kidney, lung, brain) were removed and dissected according to standardized protocols. Fluorescence was determined in each reference blood and tissue sample, and blood flow values were calculated. Blood flow in kidney, lung, and brain revealed no significant difference between right and left side and remained unchanged during the observation period, thus excluding errors due to shunting and dislodging of spheres in our experiments. Comparison of relative bone blood flow values obtained by simultaneously injected FM showed an excellent correlation at the first and last injection, indicating valid RBBF measurements in long-term experiments. We found a significant increase in RBBF 3 wk after meniscectomy in the right tibial condyles compared with the nonoperated left side. Similar changes were found in the femoral condyles. RBBF in other regions of tibia, femur, and humerus revealed no significant differences between right- and left-sided bone samples of the same region. Our results demonstrate that the FM method is valid for measuring RBBF in long-term experiments. In addition, we were able to demonstrate that meniscectomy leads to an increase in RBBF in the tibial condyles at a very early stage. This increase might be caused by stress-induced alterations of the subchondral bone.

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