On-line measurement of the dynamic velocity of erythrocytes in the cerebral microvessels in the rat

Ma, Ying‐ping; Koo, Anthony; Kwan, Hon C.; Cheng, Kwok-Kew

doi:10.1016/0026-2862(74)90059-4

Cited by 76 publications

(30 citation statements)

References 16 publications

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“…Dual-slit techniques have been widely used to measure blood flow in the microvasculature of various organs/tissues by using transillumination (8) - (12) or fluorescence labeled red cells and intensified video-camera system (13) - (15) . This technique was extended to the measurement of red cell velocities over the cross-section of single microvessels (16), (17) .…”

Section: Discussionmentioning

confidence: 99%

Velocity Profiles of Pulsatile Blood Flow in Arterioles with Bifurcation and Confluence in Rat Mesnetery Measured by Particle Image Velocimetry

Nakano¹,

Sugii

Minamiyama

et al. 2005

JSME Int. J., Ser. C

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Blood flow velocity profile in microvessels is essential for in vivo studies of substance exchange between blood and tissue. This paper was aimed to investigate the temporal and spatial variations in the velocity profile of red blood cell (RBC) flow in arterioles with both bifurcation and confluence in the rat mesentery, using a particle image velocimetry (PIV). The microcirculation in rat mesentery was observed under a microscopic system with a high-speed digital camera. The images of RBCs flow in microvessels were recorded simultaneously with the arterial blood pressure. Based on the high-speed video images, instantaneous velocity vectors of RBCs in arterioles with bifurcation and confluence were evaluated using a high spatial-resolution PIV algorithm. Then, the time-averaged and ensemble-averaged velocity profiles over the cross-section were calculated from the proximal through the bifurcation to the distal to the confluence. The velocity profile of RBCs showed two peaks at bifurcation and confluence, respectively. The double peaks were most marked at the apex of bifurcation, but not so much marked at the confluence. The variation of centerline velocity showed that the length of vessel under the influence of bifurcation or confluence, was approximately 1.5 times the diameter at the proximal to the apex of bifurcation, but its length was reduced significantly at the distal of confluence.

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Section: Discussionmentioning

confidence: 99%

Velocity Profiles of Pulsatile Blood Flow in Arterioles with Bifurcation and Confluence in Rat Mesnetery Measured by Particle Image Velocimetry

Nakano¹,

Sugii

Minamiyama

et al. 2005

JSME Int. J., Ser. C

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“…Ma et al (1974) used correlated dual slit photometry to measure mean velocities of RBCs in rat cerebral arterioles; after division by a correction factor 1.6 (Baker and Wayland, 1974), their values for mean center velocity for arterioles of different sizes are as follows: 6.8 fLm, 5.8 mm/s; 13.7 fLm, 8.6 mm/s; 23.5 fLm, 13.8 mm/s; and 49 fLm, 26.3 mm/s. Kobari et al (1984) used delay of a sa line bolus at two points to estimate velocities in cat cerebral arterioles; values from their regression line for mean velocities are 20 fLm, 7.1 mmls (V max of 21 mm/s); 50 fLm, 17.3 mm/s; and 100 fLm, 34.3 mm/s.…”

Section: Discussionmentioning

confidence: 99%

Blood Flow in Single Surface Arterioles and Venules on the Mouse Somatosensory Cortex Measured with Videomicroscopy, Fluorescent Dextrans, Nonoccluding Fluorescent Beads, and Computer-Assisted Image Analysis

Rovainen

Woolsey

Blocher

et al. 1993

J Cereb Blood Flow Metab

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Summary: Cortical surface vessels were monitored through closed cranial windows with an epifluorescence microscope and SIT or ICCD cameras. Fluorescent dex trans or 1.3 fLm latex beads were injected into the con tralateral jugular vein for plasma labeling and for vascular transits. For close arterial transits, these tracers or phys iological saline were injected into the ipsilateral external carotid artery. A VTTs were calculated from intensity dif ferences of tracers between a branch of the MCA and a vein draining the same cortical region over time. AVTTs for saline dilutions of RBCs were significantly shorter (0.73 times) than for dextrans. Both dextrans and beads distributed with plasma. With FITC-dextran, inner diam eters of arterioles and venules averaged 6 fLm larger than hemoglobin under green light. This difference was likely due to the segregation of red blood cells and plasma dur ing flow. Velocities of individual fluorescent beads wereThe purpose of the present work was to develop general videomicroscopic procedures for measuring flow in single blood vessels. Local cerebral cortical blood flow increases in response to neural activity, 359 measured in pial vessels by strobe epi-illumination. Plots of bead velocities against radial position in arterioles were blunted parabolas. Peak shear rates in the marginal layer next to the vessel walls were determined directly from bead tracks in arterioles (D = 21-71 fLm) and were 1.32 times the Poiseuille estimate. The calculated peak wall shear stress was 39 ± 14 dyn/cm2 (mean ± SD) for these arterioles but was probably severalfold greater in the smallest terminal pial arterioles. V max near the axes of arterioles increased with D+O.5• The calculated peak wall shear rate was highest in small arterioles and decreased with D-O.5• The calculated flow Q increased with D+2.5• These methods permit direct, simultaneous, dynamic measurements on multiple identified cerebral microves sels.

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“…Equation (A.4) enables us to model the relationship between CBF and PO 2 under a range of conditions: (a) PiO 2 from 0.3 to 6 ATA, equivalent to normobaric and hyperbaric hyperoxia; (b) capillary BV from 250 to 1,000 mm/sec, simulating hyperoxic vasoconstriction or hyperemia during HBO 2 , as previously reported (Ma et al, 1974;Grunewald and Sowa, 1977;Wei et al, 1993;Kleinfeld et al, 1998); (c) blood PO 2 at the arterial terminus of the capillary was assumed to be 53% of PaO 2 in the aorta, based on studies in rat brain showing that external surface PO 2 on the arterial end of the capillaries averaged 58 710 mm Hg in normoxia (Vovenko, 1999;Ivanov et al, 1999) and 154711 mm Hg while breathing 100% oxygen (Ivanov et al, 1999). In these studies, systemic PaO 2 were 86710 and 345775, respectively.…”

Section: Appendix Amentioning

confidence: 99%

“…Here P 0 is the blood PO 2 at the arterial end of capillary, L is the capillary length of 1,000 mm (Ma et al, 1974;Seylaz et al, 1999), V is the blood velocity. By combining equations (A.1) and (A.2) it is possible to compute a PO 2 value for any point of the tissue cylinder:…”

Section: Appendix Amentioning

confidence: 99%

Cerebral Blood Flow and Brain Oxygenation in Rats Breathing Oxygen under Pressure

Demchenko

Luchakov

Moskvin

et al. 2005

J Cereb Blood Flow Metab

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Hyperbaric oxygen (HBO 2 ) increases oxygen tension (PO 2 ) in blood but reduces blood flow by means of O 2 -induced vasoconstriction. Here we report the first quantitative evaluation of these opposing effects on tissue PO 2 in brain, using anesthetized rats exposed to HBO 2 at 2 to 6 atmospheres absolute (ATA). We assessed the contribution of regional cerebral blood flow (rCBF) to brain PO 2 as inspired PO 2 (PiO 2 ) exceeds 1 ATA. We measured rCBF and local PO 2 simultaneously in striatum using collocated platinum electrodes. Cerebral blood flow was computed from H 2 clearance curves in vivo and PO 2 from electrodes calibrated in vitro, before and after insertion. Arterial PCO 2 was controlled, and body temperature, blood pressure, and EEG were monitored. Scatter plots of rCBF versus PO 2 were nonlinear (R 2 ¼ 0.75) for rats breathing room air but nearly linear (R 2 ¼ 0.88-0.91) for O 2 at 2 to 6 ATA. The contribution of rCBF to brain PO 2 was estimated at constant inspired PO 2 , by increasing rCBF with acetazolamide (AZA) or decreasing it with N-nitro-L-arginine methyl ester (L-NAME). At basal rCBF (78 mL/100 g min), local PO 2 increased 7-to 33-fold at 2 to 6 ATA, compared with room air. A doubling of rCBF increased striatal PO 2 not quite two-fold in rats breathing room air but 13-to 64-fold in those breathing HBO 2 at 2 to 6 ATA. These findings support our hypothesis that HBO 2 increases PO 2 in brain in direct proportion to rCBF. IntroductionThe O 2 content of blood is the mathematical product of hemoglobin concentration and arterial hemoglobin O 2 saturation, the latter being a nonlinear function of arterial oxygen partial pressure (PaO 2 ). The small amount of O 2 dissolved in plasma is usually negligible. However, breathing hyperbaric oxygen (HBO 2 ), that is oxygen at pressures greater than 1 atmosphere absolute (ATA), raises PaO 2 beyond the point at which hemoglobin is fully saturated, so that the dissolved fraction becomes the main source of O 2 available to cells. But this does not assure enhanced O 2 delivery to brain, because tissue PO 2 also depends on regional blood flow.Tissue oxygen tension (PO 2 ) is a dynamic balance between O 2 delivery and consumption. Many authors have reported increased brain PO 2 in HBO 2 (Jamieson and Van Den Brenk, 1962;Bennett, 1965;Bean et al, 1971;Torbati et al, 1978;Hunt et al, 1978), and reviews are available (Jamieson, 1989;Camporesi et al, 1996;Dean et al, 2003). It is also known that total or regional cerebral blood flow (rCBF) decreases in HBO 2 as a function of pressure and time. But the contribution of CBF to brain PO 2 had never been quantified. Cerebral vasoconstriction and decreased total or rCBF have been shown in healthy volunteers and patients breathing O 2 at 3.5 ATA for brief periods (Lambertsen et al, 1953;Visser et al, 1996;Omae et al, 1998). In animals, in which HBO 2 is maintained for longer times and at higher pressures, the rCBF response is biphasic: the initial decrease in rCBF is followed by a secondary rise to www.jcbfm.com control leve...

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On-line measurement of the dynamic velocity of erythrocytes in the cerebral microvessels in the rat

Cited by 76 publications

References 16 publications

Velocity Profiles of Pulsatile Blood Flow in Arterioles with Bifurcation and Confluence in Rat Mesnetery Measured by Particle Image Velocimetry

Velocity Profiles of Pulsatile Blood Flow in Arterioles with Bifurcation and Confluence in Rat Mesnetery Measured by Particle Image Velocimetry

Blood Flow in Single Surface Arterioles and Venules on the Mouse Somatosensory Cortex Measured with Videomicroscopy, Fluorescent Dextrans, Nonoccluding Fluorescent Beads, and Computer-Assisted Image Analysis

Cerebral Blood Flow and Brain Oxygenation in Rats Breathing Oxygen under Pressure

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