A Model of Oxygen Exchange Between an Arteriole or Venule and the Surrounding Tissue

Weerappuli, D.P.V.; Popel, Aleksander S.

doi:10.1115/1.3168335

Cited by 29 publications

(18 citation statements)

References 20 publications

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“…Another possible explanation is the oxygen loss from arterioles to adjacent capillaries. This has been suggested as a theoretical possibility [15][16][17], and as an experimental observation [11]. These possible explanations should be investigated further.…”

Section: Discussionmentioning

confidence: 76%

Intravascular Inhomogeneous Distribution of Oxygen in Arterioles of Rat Cremaster Muscle.

Kobayashi

Takizawa²,

Tanishita³

2002

JJP

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It is increasingly apparent that arterioles are a significant source of oxygen delivery to tissue [1][2][3][4]. Oxygen continuously diffuses from the blood into the interstitium because the walls of the vessels in the microcirculation are permeable to oxygen. However, cross-sectional oxygen distribution in microvessels in most previous studies has been assumed to be homogeneous.Tsai et al.[5] measured microvascular and tissue oxygen gradients in rat mesentery by phosphorescence quenching microscopy and showed a large drop in oxygen partial pressure, PO 2 , at the vascular wall. It has also been reported that 65% of the arterioles in hamster retractor muscles have a symmetric velocity profile with a high centerline flow and that 95% of the arterioles have a symmetric profile of oxygen saturation of hemoglobin, SO 2 , with a high oxygen level in the center and a low oxygen level close to the vascular wall [6].The objective of this study was to examine the intravascular inhomogeneity of oxygen in the arterioles of striated muscle. We measured (1) SO 2 profile by microspectrophotometry, and (2) PO 2 profile with a coaxial PO 2 microelectrode [7]. We did PO 2 measurements with the microelectrode since it directly measures local PO 2 without any assumptions. MethodsAnimals. Animal care was in accordance with the guidelines of the Animal Care Committee of Kitasato University, and followed the Guiding Principles for the Care and Use of Animals approved by the Council of the Physiological Society of Japan. Male Wistar rats weighing 120-180 g were intraperitoneally anesthetized with 1 g/kg urethane, intubated, and ventilated with room air with a tidal volume of 10 ml/kg at a respiration rate of 70-90/min. An arterial catheter was introduced into a carotid artery to monitor mean arterial pressure. Data were collected only when mean arterial pressure was Ͼ90 mmHg but Ͻ130 mmHg. Rectal temperature was monitored and maintained at 37.0Ϯ1.0°C with a warm plate. The cremaster muscle was exposed and spread according to Baez [8]. We examined arterioles with 110Ϯ22 m (meanϮSD) in outer diameter, and SO 2 was measurable over the width of 70Ϯ11 m in the arterioles.Measurement of SO 2 by microspectrophotometry. For microspectrophotometry, the muscle was fixed on a transparent illumination stage of a microscope and covered with gas-impermeable film Japanese Journal of Physiology, 52, 579-583, 2002 Key words: oxygen, spectrophotometry, microelectrode.Abstract: Previously, cross-sectional oxygen distribution in microvessels was assumed to be homogeneous. The oxygen profile in the arterioles of rat cremaster muscle was measured using microspectrophotometry and a PO 2 microelectrode, showing a drop in SO 2 as well as PO 2 close to the vascular wall with a flat PO 2 profile in the perivascular tissue.

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Section: Discussionmentioning

confidence: 76%

Intravascular Inhomogeneous Distribution of Oxygen in Arterioles of Rat Cremaster Muscle.

Kobayashi

Takizawa²,

Tanishita³

2002

JJP

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“…In 1919, the transfer of oxygen from microvessels to tissue was analyzed theoretically by Krogh.1 Because of the difficulties in determining the oxygen tension in both tissues and microvessels, in vivo experimentation has been used to support theoretical analyses. [2][3][4][5] We have recently constructed a system by which the concentration of hemoglobin and the degree of oxygenation can be calculated; this system is composed of a scanning spectrophotometer and an inverted microscope and is used to record the absorption spectrum of erythrocytes flowing in single microvessels in living tissues. 6,7 Furthermore, the flow velocity of erythrocytes in the microvessel has been determined with a novel device by adopting the method of dual-spot cross correlation, and the diameter of the microvessels has been measured by using the digitized video image with an image processor.6.7 The rate of oxygen release from the 1 wavelength range (within 200-900 nm), and the detector could count 1x 103 to 3 x 106 photons/sec.…”

Section: A Methods For Measuring the Rate Of Oxygenmentioning

confidence: 99%

A method for measuring the rate of oxygen release from single microvessels.

Tateishi

Maeda

Shiga

1992

Circulation Research

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A system determining the rate of oxygen release from erythrocytes flowing in single microvessels was constructed with an inverted microscope by connecting 1) a scanning/grating spectrophotometer equipped with a photon-counting detector through a thin light guide, to obtain the visible absorption spectrum of a spot (5 ,m in diameter) focused on a microvessel, 2) two photomultipliers (connected to a microcomputer via an analog-to-digital converter) through two light guides, to determine the flow velocity of erythrocytes by calculating the cross correlation between the light-intensity changes of two spots (3 ,m in diameter, 5 ,um apart from each other) focused on the microvessel, and 3) an image processor through a video camera, to estimate the diameter of microvessel from the digitized video images. The rate of oxygen release from single microvessels 7-25 im in diameter in rat mesentery was measured under the superfusion of deoxygenated solution: 1) The maximal rate was obtained in capillaries, and the rate in arterial microvessels was larger than that in venous microvessels, when similar diameters were compared.2) The rate was maximum at pH 7.0-7.2, and it decreased in more acidic and alkaline pH values.3) The rate decreased with a decrease in temperature. The reliability of the measurement using the present apparatus was tested in detail. (Circulation Research 1992;70:812-819 *oxygen release * spectrophotometry * photon microvessel can be estimated on the basis of 1) the change of the absorption spectra obtained at two points on a microvessel, 2) the flow velocity of erythrocytes, and 3) the diameter of the microvessel.This article deals with 1) the constitution and the characteristics of an apparatus for measuring the rate of oxygen release from erythrocytes flowing in single microvessels to tissues, 2) the comparison of the rate of oxygen release from single microvessels (arterioles, capillaries, and venules) of various diameters in rat mesentery, and 3) the effects of pH and temperature on the rate of oxygen release. Materials and Methods Microscopic Observation of Microvessels in Rat MesenteryWister rats (male, 6-9 weeks old, 180-250 g) were cared for in the Laboratory Animal Center, Ehime University, School of Medicine. This study was carried out in compliance with the guide for animal experimentation and with permission from the Committee of Animal Experimentation, Ehime University, School of Medicine.Rats were anesthetized with phenobarbital (50 mg/kg i.p.). After laparotomy, each rat was placed on an acrylate plate (with temperature controlled by circulating water) equipped on the stage of an inverted microscope; then, a portion of mesentery was lightly fixed on a cylindrical platform (10 mm in diameter and 5 mm in height, made of transparent acrylate) attached to the acrylate plate and was covered with another transparent acrylate plate (see Figure 1). A peristaltic pump (SJ-1215, Atto Co., Tokyo) was used to superfuse the wavelength range (within 200-900 nm), and the detector could count 1x 103 to 3 ...

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“…The hematocrit (H wall ) at the blood wall interface was assumed to be the product of the capillary hematocrit 19 and fractional capillary volume. 44 Using the same notation as equation (2) - (5), the hematocrit in the arteriolar and venular lumen were assumed to be: Hðx; y; zÞ ¼ H core;n ; 0<r n <R 1;n H core;n À ðH core;n À H wall Þ r n ÀR 1;n R 2;n ÀR 1;n…”

Section: Governing Equationsmentioning

confidence: 99%

A Model of NO/O2 Transport in Capillary-perfused Tissue Containing an Arteriole and Venule Pair

et al. 2007

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The goal of this study was to investigate the complex co-transport of nitric oxide (NO) and oxygen (O2) in a paired arteriole-venule, surrounded by capillary-perfused tissue using a computer model. Blood flow was assumed to be steady in the arteriolar and venular lumens and to obey Darcy's law in the tissue. NO consumption rate was assumed to be constant in the core of the arteriolar and venular lumen and to decrease linearly to the endothelium. Average NO consumption rate by capillary blood in a unit tissue volume was assumed proportional to the blood flux across the volume. Our results predict that: (1) the capillary bed, which connects the arteriole and venule, facilitates the release of O2 from the vessel pair to the surrounding tissue; (2) decreasing the distance between arteriole and venule can result in a higher NO concentration in the venular wall than in the arteriolar wall; (3) in the absence of capillaries in the surrounding tissue, diffusion of NO from venule to arteriole contributes little to NO concentration in the arteriolar wall; and (4) when capillaries are added to the simulation, a significant increase of NO in the arteriolar wall is observed.

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A Model of Oxygen Exchange Between an Arteriole or Venule and the Surrounding Tissue

Cited by 29 publications

References 20 publications

Intravascular Inhomogeneous Distribution of Oxygen in Arterioles of Rat Cremaster Muscle.

Intravascular Inhomogeneous Distribution of Oxygen in Arterioles of Rat Cremaster Muscle.

A method for measuring the rate of oxygen release from single microvessels.

A Model of NO/O2 Transport in Capillary-perfused Tissue Containing an Arteriole and Venule Pair

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