Fluid dynamics and the thromboembolic reaction in mesenteric arterioles and venules

1991 ◽  
Vol 260 (6) ◽  
pp. H1826-H1833
Author(s):  
M. G. Oude Egbrink ◽  
G. J. Tangelder ◽  
D. W. Slaaf ◽  
R. S. Reneman
Keyword(s):  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Vessel Diameter ◽  
Area Reduction ◽  
Dynamic Factors ◽  
Cell Velocity ◽  
Red Blood Cell Velocity ◽  
Stenosed Vessel ◽  
The Difference ◽  
Velocity Changes

In the mesentery of the anesthetized rabbit, the thromboembolic reaction after wall puncture lasts six times longer in arterioles than in venules, a difference that cannot be explained by fluid dynamic conditions before puncture. In the present study, it was investigated whether this difference in response between arterioles and venules results from a different degree of stenosis by the thrombus and/or a difference in velocity changes resulting in a different pressure drop over the thrombus. Arteriolar and venular mean red blood cell velocity and vessel diameter were measured before puncture and after this injury in the stenosed vessel segment and upstream. Thrombi with similar heights were formed in arterioles and venules and induced similar degrees of stenosis. A surface area reduction less than 55% induced only a small and similar decrease in volume flow (less than 10%) in arterioles and venules. Reduced velocity, a measure of wall shear rate, increased similarly in both vessel types for similar degrees of stenosis. In conclusion, changes in fluid dynamic factors, as induced by thrombus formation, cannot be held responsible for the difference in thromboembolic reaction between arterioles and venules.

RED BLOOD CELL VELOCITY CHANGES WITH AGE AND SEX IN THE COMMON CAROTID AND SUPRA-ORBITAL ARTERIES

1985 ◽  
Vol 14 (2) ◽  
pp. 102-108 ◽  
Author(s):  
J. J. BASKETT ◽  
R. R. LEWIS ◽  
M. G. BEASLEY ◽  
R. G. GOSLING
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Cell Velocity ◽  
Red Blood Cell Velocity ◽  
The Common ◽  
Velocity Changes ◽  
Age And Sex

Analysis of Volumetric Residence Time of Blood Elements in Stenosed Arteries

2003 ◽  
Author(s):  
M. C. Kim ◽  
C. S. Lee ◽  
C. J. Kim
Keyword(s):  
Residence Time ◽  
Transient Flow ◽  
Fluid Dynamic ◽  
Viscous Drag ◽  
Shear Stresses ◽  
Drag Forces ◽  
Area Reduction ◽  
Dynamic Factors ◽  
Recirculation Zones ◽  
Computational Fluid Dynamics Cfd

Blood flow in arteries is known to be closely related to atherosclerosis. Presence of recirculation zones, and low, high, and oscillatory wall shear stresses have been suggested to be important fluid dynamic factors causing development and progress of atherosclerosis. Our study was motivated to develop fluid mechanical indices between residence time of blood particles in arteries and atherosclerosis. In rigid models of stenosed arteries with 75% area reduction, trajectories of blood particles were numerically computed and used to determine local volumetric residence time (VRT) of platelets. The motion of particles in the model artery was computed by considering viscous drag forces between blood particles and presolved transient flow field from computational fluid dynamics (CFD). Many cardiac cycles were considered in the computation to reflect temporally accumulative characteristics of VRT in the recirculation zones. Our results showed that VRT in the recirculation zone was relatively low in the first cardiac cycle. However it increased in the subsequent cycles as more particles were trapped in the same zone. The results suggested that VRT contour calculated in the present study would be an effective indicator of the presence of atherosclerosis.

scholarly journals Intravital imaging of the kidney in a rat model of salt-sensitive hypertension

2017 ◽  
Vol 313 (2) ◽  
pp. F163-F173 ◽  
Author(s):  
Bradley T. Endres ◽  
Ruben M. Sandoval ◽  
George J. Rhodes ◽  
Silvia B. Campos-Bilderback ◽  
Malgorzata M. Kamocka ◽  
...  
Keyword(s):  
Rat Model ◽  
Vessel Diameter ◽  
Normal Diet ◽  
Tubular Damage ◽  
Creatinine Concentration ◽  
Two Photon ◽  
Cell Velocity ◽  
Induced Hypertension ◽  
Red Blood Cell Velocity ◽  
Salt Sensitive Hypertension

Hypertension is one of the most prevalent diseases worldwide and a major risk factor for renal failure and cardiovascular disease. The role of albuminuria, a common feature of hypertension and robust predictor of cardiorenal disorders, remains incompletely understood. The goal of this study was to investigate the mechanisms leading to albuminuria in the kidney of a rat model of hypertension, the Dahl salt-sensitive (SS) rat. To determine the relative contributions of the glomerulus and proximal tubule (PT) to albuminuria, we applied intravital two-photon-based imaging to investigate the complex renal physiological changes that occur during salt-induced hypertension. Following a high-salt diet, SS rats exhibited elevated blood pressure, increased glomerular sieving of albumin (GSCalb = 0.0686), relative permeability to albumin (+Δ16%), and impaired volume hemodynamics (−Δ14%). Serum albumin but not serum globulins or creatinine concentration was decreased (−0.54 g/dl), which was concomitant with increased filtration of albumin (3.7 vs. 0.8 g/day normal diet). Pathologically, hypertensive animals had significant tubular damage, as indicated by increased prevalence of granular casts, expansion and necrosis of PT epithelial cells (+Δ2.20 score/image), progressive augmentation of red blood cell velocity (+Δ269 µm/s) and micro vessel diameter (+Δ4.3 µm), and increased vascular injury (+Δ0.61 leakage/image). Therefore, development of salt-induced hypertension can be triggered by fast and progressive pathogenic remodeling of PT epithelia, which can be associated with changes in albumin handling. Collectively, these results indicate that both the glomerulus and the PT contribute to albuminuria, and dual treatment of glomerular filtration and albumin reabsorption may represent an effective treatment of salt-sensitive hypertension.

The influence of loud sound on red blood cell velocity and blood vessel diameter in the cochlea

1992 ◽  
Vol 63 (1-2) ◽  
pp. 102-107 ◽  
Author(s):  
Wayne S. Quirk ◽  
G. Avinash ◽  
A.L. Nuttall ◽  
J.M. Miller
Keyword(s):  
Blood Vessel ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Vessel Diameter ◽  
Loud Sound ◽  
Cell Velocity ◽  
Red Blood Cell Velocity

Microvessel PO2 measurements by phosphorescence decay method

1993 ◽  
Vol 265 (4) ◽  
pp. H1434-H1438 ◽  
Author(s):  
I. P. Torres Filho ◽  
M. Intaglietta
Keyword(s):  
Vessel Diameter ◽  
Phosphorescence Decay ◽  
Cell Velocity ◽  
Skin Fold ◽  
Red Blood Cell Velocity ◽  
Phosphorescence Emission ◽  
Special Circumstances ◽  
Made In

A system is described for the in vivo noninvasive measurement of intravascular PO2 at the microscopic level. Under special circumstances the method can also be used to measure interstitial PO2. The PO2 determination is based on the O2-dependent quenching of phosphorescence of palladium-porphyrins bound to albumin. This compound was injected intravenously in the dosage of 30 mg/kg body wt and dissolved in saline to a concentration of 15 mg/ml. The phosphorescence emission was excited by epi-illumination with a strobe xenon arc and measured by a photomultiplier in a well-defined tissue area as small as 15 x 30 microns. A selected portion of the phosphorescence decay was fitted by a single exponential, and the Stern-Volmer equation was used to calculate PO2. Calibration was performed in vitro using saline and blood and was in agreement with previous reports. In vivo observations were made in normal tissue regions from the unanesthetized hamster transparent skin fold chamber preparation. The method allows PO2 determinations, in the range of 0-80 mmHg, in microvessels with diameters of 15-100 microns. Simultaneous transillumination of the tissue also allows measurement of vessel diameter and red blood cell velocity in the same vessels.

Effects of NO-Donors on Thrombus Formation and Microcirculation in Cerebral Vessels of the Rat

1996 ◽  
Vol 76 (01) ◽  
pp. 111-117 ◽  
Author(s):  
Yasuto Sasaki ◽  
Junji Seki ◽  
John C Giddings ◽  
Junichiro Yamamoto
Keyword(s):  
Blood Flow ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Red Cell ◽  
Cell Velocity ◽  
Red Cell Velocity ◽  
The Mean ◽  
Wall Shear ◽  
Dose Dependent

SummarySodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1), are known to liberate nitric oxide (NO). In this study the effects of SNP and SIN-1 on thrombus formation in rat cerebral arterioles and venules in vivo were assessed using a helium-neon (He-Ne) laser. SNP infused at doses from 10 Μg/kg/h significantly inhibited thrombus formation in a dose dependent manner. This inhibition of thrombus formation was suppressed by methylene blue. SIN-1 at a dose of 100 Μg/kg/h also demonstrated a significant antithrombotic effect. Moreover, treatment with SNP increased vessel diameter in a dose dependent manner and enhanced the mean red cell velocity measured with a fiber-optic laser-Doppler anemometer microscope (FLDAM). Blood flow, calculated from the mean red cell velocity and vessel diameters was increased significantly during infusion. In contrast, mean wall shear rates in the arterioles and venules were not changed by SNP infusion. The results indicated that SNP and SIN-1 possessed potent antithrombotic activities, whilst SNP increased cerebral blood flow without changing wall shear rate. The findings suggest that the NO released by SNP and SIN-1 may be beneficial for the treatment and protection of cerebral infarction

CSO Modelling Considering Moving Storms and Tipping Bucket Gauge Failures

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
M. Hochedlinger ◽  
W. Sprung ◽  
H. Kainz ◽  
K. König
Keyword(s):  
Hydrological Models ◽  
Rain Intensity ◽  
Hydrodynamic Models ◽  
Data Intensive ◽  
Storm Flow ◽  
Cell Velocity ◽  
Combined Sewer ◽  
Moving Direction ◽  
The Difference

The simulation of combined sewer overflow volumes and loads is important for the assessment of the overflow and overflow load to the receiving water to predict the hydraulic or the pollution impact. Hydrodynamic models are very data-intensive and time-consuming for long-term quality modelling. Hence, for long-term modelling, hydrological models are used to predict the storm flow in a fast way. However, in most cases, a constant rain intensity is used as load for the simulation, but in practice even for small catchments rain occurs in rain cells, which are not constant over the whole catchment area. This paper presents the results of quality modelling considering moving storms depending on the rain cell velocity and its moving direction. Additionally, tipping bucket gauge failures and different corrections are also taken into account. The results evidence the importance of these considerations for precipitation due the effects on overflow load and show the difference up to 28% of corrected and uncorrected data and of moving rain cells instead of constant raining intensities.

Sign in / Sign up

Export Citation Format

Share Document