scholarly journals Blood Flow Velocity in the Pial Arteries of Cats, with Particular Reference to the Vessel Diameter

1984 ◽  
Vol 4 (1) ◽  
pp. 110-114 ◽  
Author(s):  
Masahiro Kobari ◽  
Fumio Gotoh ◽  
Yasuo Fukuuchi ◽  
Kortaro Tanaka ◽  
Norihiro Suzuki ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Flow Rate ◽  
Blood Flow Velocity ◽  
Blood Flow Rate ◽  
Video Camera ◽  
Vessel Diameter ◽  
Pial Arteries ◽  
Cross Sectional ◽  
Pial Artery

The blood flow velocity and diameter of feline pial arteries, ranging in diameter from 20 to 200 μm, were measured simultaneously using a newly developed video camera method under steady-state conditions for all other parameters. There was a linear relationship between blood flow velocity and pial artery diameter ( y = 0.340 x + 0.309), the correlation coefficient being 0.785 (p < 0.001). The average values for blood flow velocity in pial arteries <50 μm, ≧50 but <100 μm, ≧100 but <150 μm, and ≧150 μm in diameter were 12.9 ± 1.3, 24.6 ± 3.4, 42.1 ± 4.7, and 59.9 ± 5.3 mm/s, respectively. Blood flow rate was calculated as a product of the cross-sectional area and the flow velocity. The blood flow rate increased exponentially as the pial artery diameter increased ( y = 2.71 × 10−4 x2.98). The average values for blood flow rate in pial arteries <50 μm, ≧50 but <100 μm, ≧100 but <150 μm, and ≧150 μm in diameter were 12.8 ± 1.5, 122.1 ± 24.8, 510.2 ± 74.8, and 1524.2 ± 174.4 10−3 mm3/s, respectively. Hemorheological parameters such as the wall shear rate and Reynolds' number were also calculated. The data obtained provide a useful basis for further investigations in the field of cerebral circulation.

scholarly journals The Natural-Mineral-Based Novel Nanomaterial IFMC Increases Intravascular Nitric Oxide without Its Intake: Implications for COVID-19 and beyond

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1699
Author(s):  
Tomohiro Akiyama ◽  
Takamichi Hirata ◽  
Takahiro Fujimoto ◽  
Shinnosuke Hatakeyama ◽  
Ryuhei Yamazaki ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Flow Rate ◽  
Vascular System ◽  
Vascular Complications ◽  
Blood Flow Rate ◽  
Vessel Diameter ◽  
Human Hand ◽  
Natural Mineral ◽  
Living Body

There are currently no promising therapy strategies for either the treatment or prevention of novel coronavirus disease 2019 (COVID-19), despite the urgent need. In addition to respiratory diseases, vascular complications are rapidly emerging as a key threat of COVID-19. Existing nitric oxide (NO) therapies have been shown to improve the vascular system; however, they have different limitations in terms of safety, usability and availability. In light of this, we hypothesise that a natural-mineral-based novel nanomaterial, which was developed based on NO therapy, might be a viable strategy for the treatment and prevention of COVID-19. The present study examined if it could induce an increase of intravascular NO, vasodilation and the consequent increase of blood flow rate and temperature in a living body. The intravascular NO concentration in the hepatic portal of rats was increased by 0.17 nM over 35.2 s on average after its application. An ultrasonic Doppler flow meter showed significant increases in the blood flow rate and vessel diameter, but no difference in the blood flow velocity. These were corroborated by measurements of human hand surface temperature. To our knowledge, this result is the first evidence where an increase of intravascular NO and vasodilation were induced by bringing a natural-mineral-based nanomaterial into contact with or close to a living body. The precise mechanisms remain a matter for further investigation; however, we may assume that endothelial NO synthase, haemoglobin and endothelium-derived hyperpolarising factor are deeply involved in the increase of intravascular NO.

Evidence of active regulation of cerebral venous tone in individuals undergoing embolization of brain arteriovenous malformations

2013 ◽  
Vol 115 (11) ◽  
pp. 1666-1671 ◽  
Author(s):  
Alexey Y. Ivanov ◽  
Andrey E. Petrov ◽  
Elena A. Vershinina ◽  
Michael M. Galagudza ◽  
Timur D. Vlasov
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Arteriovenous Malformations ◽  
Resistance Index ◽  
Cerebral Veins ◽  
Jugular Veins ◽  
Cross Sectional ◽  
Brain Arteriovenous Malformations ◽  
Active Regulation

Cerebral venous drainage is generally believed to be regulated primarily by hydrodynamic forces. To gain further insight into the regulation of this process, we investigated the response of blood flow velocity and cross-sectional area (CSA) of the internal jugular veins (IJVs) to local hemodynamic shifts. All procedures and assessments were performed on patients ( n = 30) undergoing embolization of brain arteriovenous malformations (AVMs). The procedure efficiency was verified by the postembolization reduction in time-averaged maximum blood flow velocities, as well as the elevation of pulsatility index and resistance index in the arterial feeders. In cerebral veins, the dominant IJV pressure remained unchanged during the procedure. At the same time, AVM embolization caused a significant reduction in maximal CSA (84 ± 7.6 to 68 ± 7.7 mm2, P < 0.05) and minimal CSA (68 ± 7.0 to 51 ± 7.0 mm2, P < 0.01) of the IJV located ipsilateral to the AVM, while the maximal linear blood flow velocity in the IJV remained unchanged (71 ± 4.9 and 85 ± 8.4 cm/s, P = 0.098). Consistent with previously published studies, the data obtained provide further evidence of active regulation of the venous outflow, probably mediated by certain neurogenic and/or endothelium-dependent mechanisms.

Effect of body position and graduated compression stocking length on femoral venous blood flow velocity

2003 ◽  
Vol 18 (4) ◽  
pp. 198-202
Author(s):  
A Limpus ◽  
W P Chaboyer ◽  
C Purcell ◽  
P J Schluter ◽  
H Gibbs ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Body Position ◽  
Venous Blood ◽  
Vessel Diameter ◽  
Compression Stocking ◽  
Venous Blood Flow ◽  
Significant Difference ◽  
Three Body

Objectives: To measure the effect of graduated compression stocking (GCS) length and body position on peak femoral venous blood flow velocity (PVV) and vessel diameter (VD). Methods: Twenty healthy adult volunteers had PVV and VD measured, using colour Doppler ultrasound, at baseline in three body positions. Knee- or thigh-length GCS were assigned randomly.Arandom sequence of the three positions was used to measure PVV and VD. The procedure was repeated, after a two-hour washout period, using the other length GCS. Results: There was no significant difference in the mean change of PVV ( P =0.74) or VD ( P =0.54) measurements from the baseline between thigh- and knee-length GCS. However, significant mean changes in PVV ( P =0.02) and VD ( P <0.001) measurements were observed for the three body positions, after adjusting for baseline values. Conclusions: In healthy volunteers, thigh- and knee-length GCS do not have an effect on PVV or VD, and body position affects PVV significantly, with or without GCS.

Abstract 295: Importance of the Rate of Platelet Activation by Thrombin for Regulating the Size of Thrombi Formed Under Low Blood Flow Velocity Conditions

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Shinichi Goto ◽  
Kengo Ayabe ◽  
Youth Kawamura ◽  
Noriko Tamura ◽  
Shinya Goto
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Platelet Activation ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Low Flow ◽  
Coagulation Cascade ◽  
Computer Simulation Model ◽  
Rate Condition ◽  
Low Flow Rate

Background: Platelets, coagulation cascade including thrombin and fibrin, and fibrinolysis by plasmin along with blood flow are known to play regulatory roles in thrombogenesis. However, quantitative and interactive contribution of these factors are not fully understood. Method: We developed a computer simulation model of thrombi at sites of vessel injury by implementing quantitative parameters of blood flow, platelet, coagulation cascade and fibrinolysis. In this model, we defined thrombi as the area where the amount of activated platelet become 80% or more of the global platelet count of 3.0х10 5 /mm 3 upon vessel damage We have measured the 3-dimensional size of thrombi as defined in various conditions with various parameters of flow velocity, rate of platelet activation by thrombin, rate of thrombin production on the surface of activated platelets, rate of fibrinolysis and rate of plasmin production. Results: Rate of platelet activation by thrombin had the largest influence on the size of thrombi under low flow rate condition of 0.5 (cm/sec) (Fig1 A). When blood flow rate increased to 2.0 (cm/sec), the absolute importance of this parameter decreased (Fig1 B). Conclusion: Our results show that the rate of platelet activation by thrombin, which are signaled with PAR-1 receptor in human, has a marked effect on the size of thrombi in low flow rate condition suggesting the benefit of blocking this receptor in low blood flow condition such as venous thrombosis.

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